JOG Nab Tower 2018 Track

In addition to the discussion in the last post.

This is the track from the Race loaded into Google Earth.

You can load the attached .kml file into Google Earth to see the data that we are collecting in more detail.

The .kml file is here:
KML File For JOG Nab Tower Race Tracking

Clicking the link will open the track on the Google Maps site. To view the data associated with each point you need to download the actual kml file and load it into the desktop version of Google Earth.

You can see very clearly the point off Portsmouth on the return leg where the wind completely dies …


The JOG Nab Tower Race 2018

For those of you that don’t know the Solent the Nab Tower is a large navigation mark in the Eastern approaches to Portsmouth.

It has an interesting history. It was originally designed as one of a series of forts to be built across the English Channel during World War 1. The structure that makes up the tower was built at Shoreham by a team of 3000 workman. It originally had a concrete floating base with a steel superstructure.

The aim was to tow the seven tower structures out into the English channel, sink them in place in a line, then link the structures with steel boom nets. The idea being to close the English Channel to enemy shipping – particularly submarines. The tower cost £1m to build in 1918. Only one of the towers was actually completed. It was never deployed in anger.

In 1920 (on a very calm day by all accounts) it was towed into position above the Nab Rock off the Eastern End of the Solent. It replaced an existing light ship.

The 20 plus metre tower consisted of a series of water tight compartments that made it float and a steel and concrete upper structure. Flooding the lower compartments caused it to settle in place on the Nab Rock; all be it at an angle of 3 degrees. Something I hadn’t realised until I went looking at the history of what I assumed was just a big lump of concrete. Since 1920 the tower has had a number of upgrades and refurbishments. Originally it was a manned lighthouse, today its automated. The steel structure has been replaced and a helicopter pad installed on the roof.

You can find more about Nab Tower at:
Trinity House – The Nab Tower

Thats enough history for now.

JOG’s Nab Tower event this year was our first serious race of the season. Its a pretty simple idea. Leave Cowes at about 9.30am sail East down the Solent with the tide, pass between the forts off Portsmouth then head South East to the Tower. Round the Tower to Port, Sail back west to the Winner Navigation mark on the approaches to Portsmouth then back to Cowes. Remembering to leave Snowdon to starboard on the way out and port on the way back. If the breeze is good then the tide should turn soon after you round the Tower. Its roughly 35 miles there and back. A good early season warm up that if the weather is nice gets a good turnout.

Most of the crew met up Friday afternoon to sail Jengu over to Cowes for the race start on the Saturday morning. After rigging the boat up we headed out into the Solent passing Hugo Boss on the way in. After a brief man overboard drill to recover my hat we got down to the serious work of hoisting and dropping Spinnakers.

The gentle breeze was ideal for spinnaker practice giving us plenty of time to get the choreography right.

I’ll be honest the A1.5 we used has been in the shed for the last 2 years. It came with the boat and I wasn’t quite sure what it was. According to the North website its ideal for 0-10knots of wind and good when the sea is lumpy up to 12knots true. Friday with 0-6 knots true looked like the ideal day to take it for a spin. It turns out we’ve had this beautiful white asymmetric spinnaker sitting in the shed all this time. It flies beautifully in the light wind and rolls over to windward letting us sail quite deep angles. After much gybing dodging ferries and tankers we headed to Cowes for the evening feeling confident about our spinnaker handling.

Saying that; having sailed in the Solent for the last 10 years now I suspect we have had our 0-10knots true wind day for this year…

Saturday dawned with none of Fridays sunshine, but a little more breeze from the East. So as predicted we were looking at a long beat to the Tower followed by a deep reach or run back to Cowes.

Our start was OK, safe and close to the Gurnard cardinal in the deep water. We try to be conservative at the JOG start line; with a 2knot tide over the line coming back after an over the line start is really bad news. We were probably row two on the grid, we sailed relatively low and fast on starboard for the first mile East from Cowes. Rolling a couple of faster starting but slower boats in the process losing a bit of ground to windward on the boats that had started closer to shore but getting into a position where we were in clear air. We had a couple of benchmark boats around us to compare our progress against; Jybe Talking the J109 of Chris Burleigh and Hot Rats a First 35 from Hamble. Sailing low looks like the data in this image:

Once clear of the first group of boats we started to sail in a higher “mode” and this is where it got interesting. Sailing high looks like the data in this image:

We experimented with Jib In-Haulers briefly with the No. 3 last year but didn’t have much success. This year with a new Elvstrom C1 non overlapping Jib we can in-haul the Jib a lot further. Jibe Talking with a similar sail plan, IRC 1.006 versus Jengu’s 1.01, were using the windward jib sheet to in haul the Jib. The theory is if you in-haul the jib you get to sail a higher angle because the sail is sheeted closer to the centre line. Last year we had a big issue with the Jib back winding the luff of the main sail when in-hauled. This year we’ve resolved that problem by sailing with a much tighter outhaul and correspondingly flatter mainsail. The boats balance is very good with that sail plan; we can sail the boat to windward with no hands on the wheel.

With the breeze touching 10-12knots at times we were able to maintain the gap to Jibe Talking sailing between 27 and 30 degrees to the Apparent wind. Sailing low is 30-35 degrees to apparent with the boat speed in the 6-7.5 knots range. High we are aiming for 27-30 degrees to apparent with boat speed in the 5.5-6.5 knots range. We can sail higher as close as 25degrees but at that point the boat speed starts to really drop off.

For the first 30 minutes with the breeze staying stronger we were able to maintain and slightly build the gap to Jibe Talking. They started further to leeward, slightly astern and settled a hundred metres or so back.

Then the breeze started to drop off a couple of knots to the 7-8knot range at which point Jibe Talking were able to sail slightly higher and break out of our dirty air. Whilst we could keep them behind by sailing slightly lower, in a straight who can point higher in the light stuff competition we got resoundingly between. By the time we got to Gilkicker Point off Portsmouth, Jibe Talking were ahead. The wind dropping and Jengu slowing is in the data image below:

At that point we tacked across the deep water to the Island shore. In reality we had sailed most of the Cowes – Portsmouth leg in 16metres of water at the edge of the deepwater channel. With hindsight we probably should have tacked further out into the Solent to the north of Ryde Middle to get the best of the East going tide. Its a trade off; the cost of two tacks to get to the deep water versus the extra .5knots we would get from being in the faster tide. Pointing high probably wasn’t the solution. We gave time away to the boats in the deeper water and didn’t gain enough ground to do anything other than stay at the edge of the deep water out of the shallows. Tacking across the East going tide we gained the advantage of the lee bow tide pushing us upwind.

Another tack saw us out through the forts heading South East for the tower. Our other benchmark boat Hot Rats was still behind us so whilst we had lost touch with Jibe Talking we were holding our position against the rest of the fleet. A couple more tacks staying in the deep water away from the island shore saw us reach the Tower. In reality we probably over stood slightly; we able to came into the tower fast and carried the speed into the mark rounding.

Anyone who has sailed near to the Solent forts will confirm they have a surprisingly large wind shadow. Maybe its due to their round shape but they project a large zone of disturbed air. Add to that 50 or so sailing boats; there is a huge potential to get stuck mid rounding and drop a couple of places.

A lot of other boats were giving the tower a very wide berth, with our boat speed we able to turn relatively tightly around the tower and get a good line on the exit. Tacking around the Tower looks like this in the data:

A good spinnaker hoist of the A2 not A1.5 set us off on the return leg. The wind had picked up to 12-15 knots, ideal for blasting downwind under the heavier A2. The speed topped out at 10 knots which felt quite fast.

We kept Hot Rats behind us all the way to the Gybe mark at the Winner navigation mark and got the inside line on one of the double handed Fast 3200’s gaining a couple of places going towards the forts. The Gybe looks like this:

We reached the line between the two forts in good shape solidly mid-field; then the wind went very light.

This is a recurring theme; we are quite good in the 7-15knot range, not particularly brave in 20knots plus and lost at sea in anything under 5 knots. We clearly have an issue getting the boat going in the really light stuff. The wind dropped, the spinnaker collapsed, the mainsail flapped in the wash from the passing boats and the 2knot + East going tide pushed us back towards the Tower.

You can see from the image of the data that the boat speed dropped right off.

Its the classic dilemma; do you follow the bulk of the fleet that has just made it around the fort on the Island side but parked up; hoping to sail on the Island shore along Ryde Sands in a load of dirty air. Or do you go the other side and pick up the earlier change in the tide on the Lee-On-Solent side. We went north mostly because thats the way the boat wanted to go and to a certain extent once North of the mainland side fort thats the way the tide takes you into the shallows off Portsmouth. We got to maybe 250 metres South East of new Navigation marks for HMS Queen Elizabeth when the breeze completely shutdown. We were back to drifting around where we had the previous evening.

The data here shows us drifting almost.

Time to break out the A1.5; the great advantage to no wind is it makes spinnaker changes a lot easier. Dump one down the hatch pull the other one out of the bag. After much gentle coxing and quietly cursing the power boats leaving a wash coming out of Portsmouth we go the boat sailing in the right direction. After being parked up for maybe 15minutes we got the boat going in the right direction and as the night before the big white sail proved more than happy to take us in the right direction.

With the big sail up we get moving again and the tide starts to turn with us. You can see the Waterspeed starting to match then be overtaken by the Speed Over Ground.

With the big separation between the half of the fleet that went north with us and the bulk that went south it wasn’t clear where we would rejoin. We pointed the boat at Gurnard and did our best to keep the boat speed up. Gently the breeze increased; now we were getting into the theoretical upper range for the A1.5 it being a bit of an unknown quantity we were waiting for it to explode in a million pieces but it held together beautifully.

Somewhere around Norris we rejoined the main fleet; and I think part of the Warash Spring Championship fleet as well. We had a close port and starboard pass with Night Owl 2; us on Port flying our spinnaker, Night Owl on starboard also flying their spinnaker. We crossed ahead by maybe 50 yards but at one point I thought we might have had to gybe out of the way which wouldn’t have helped our cause.

Coming down to the finish line we struggled to pass North of the Snowdon buoy and had to do a short Gybe onto Starboard to gain some ground to seaward. Gybing back we raced the last mile or so into the finish with one of the Fast 3200’s All or nothing. By the time we got to Snowdon the tide was running fast to the west carrying us quickly towards the final mark.

You can see in the next set of data that there is a clear 1.5->2knot difference between the water speed and the speed over ground.

We had to negotiate a large very slow moving cruising Beneteau that for some reason had decided to raise its cruising chute in the approach to Cowes; their spinnaker handling needed practice, we were away and over the finish line by the time they got the sail flying.

You can see that from the Polars for the session below where we are fast. The number in brackets is the fasted that the boat has sailed on that True Wind direction/True wind speed combination. If we are getting it right as a crew we should be matching the figures in brackets.

Overall with the more data we collect the better idea we have of how we can expect the boat to perform. But we still have a long way to go there are a lot of blanks on the Boat Polar data tables. I would expect the data values to get a smoother more separated curve as we get better as a crew and collect more data.

So what have learned ?

We have good boat speed in the 8-15knot range.

Our spinnaker handling is much better and the results are more predictable.

Our tacking is much, much better. We can be up and running on the new tack with the Elvstrom C1 a lot quicker than we ever managed with the huge overlapped No 1 from North.

The A1.5/A2 spinnakers are a good combination of sails to have in the wardrobe.

The depth gauge needs checking. We were getting an extra two metres of water on deck compared to Niall’s reading on the chart plotter below. We replaced the Nexus server box that runs the on deck instruments and think that we missed a setting somewhere on the server. The plotter is measuring from the bottom of the keel; the deck displays from the actual transducer. Its a 2 metre difference and something we need to fix before we go to the Western Solent for the next set of races.

We need to spend more time sailing the boat in the really light airs and working out how to get the boat moving again once its stalled. Something that became apparent during the Spring series race we did on the Sunday.

Next race is the JOG Cowes – Yarmouth – Cowes weekend the third weekend in May. It will be interesting to see if we can work our way up the fleet then – hopefully we will have a more consistent breeze…

Bill/May 2018

Winter 2016 Updates and Upgrades – Bob-stays, In-haulers And Rudder Bearings

Jengu, as with any boat, is a work in progress. The more we fix and fettle the more we find we need to fix. As a consequence January 2016 saw us working on more of the issues with Jengu that had been highlighted after a full seasons sailing.

Our number one priority was to check the rudder assembly. We had noticed a wobble to the steering when sailing in a cross sea, investigating further while the boat was still in the water showed that there was about a millimetre of play at the base of the rudder post where it came through the hull. This translated to a noticeable side to side movement in the wheel when a wave caught the rudder blade side on. In early January 2016 we took advantage of the reasonably good weather to lift Jengu at Gosport Boat yard so that we could drop the rudder out of the boat to inspect the bearings. Surprisingly the boatyard in January wasn’t that busy ..just us and the swans… but then it was -6 degrees centigrade at 8am that morning.

Disassembly of the rudder showed that the nylon rudder bearing had worn a groove in the stainless steel shaft. Jengu has solid Nylon bearings unlike some other J109’s that have a hollow nylon ball with roller bearings around the rudder shaft.

The Nylon bearings are very hard and will wear the stainless steel shaft over time. We had a couple of options to remove the play in the rudder.
We could completely replace the rudder assembly, something which we didn’t have the budget to do and would have taken too long too get the parts anyway.
We could put a sleeve around the shaft but the sleeve would have been very thin given the limited amount of wear.
Finally we could make a new nylon bearing to fit the worn shaft.

We went with option three – its a short term fix but should be good for a couple of years – waiting for a new rudder assembly while the boat was sitting in the yard wasn’t really practical and Jengu couldn’t go back in the water until the rudder was fixed.

The socket into which the nylon bearing fitted was also worn but not badly enough for us to replace it at that point. We will look to do that as part of next winters refit.

The Nylon bearing fits into the metal socket a bit like an eyeball. With the rudder post going up through the centre of the bearing. The image here is from the Jefa website and represents the steering assembly for a similar type of boat. The are some differences in the way that the wheel is connected to the quadrant but the detail for the bearings and post is very close to the J109
The nylon bearing turned out to be quite sensitive to the air temperature; on the colder days we visited the yard to check progress the bearings were a very tight fit on the rudder post. As the day warmed up they would be a lot easier to rotate and slide on or off the post.

Whilst the rudder was out we looked at the pedestal that the wheel is attached to. Last season we had a big leak around the base of the pedestal that meant we took on a lot of water in certain sea conditions or heavy rain. Greg from the yard removed the wheel, compass and unbolted the pedestal.

There were two bolts securing the unit to the deck through a very thin flange of glass fibre. Effectively the pedestal was held in place by a couple of small bolts, some very old sealant and the downward force of the chains for the steering gear. To get the steering assembly secure and stop the leaks we would have to fibre glass a new flange onto the pedestal. This would need to be capable of taking some heavier duty bolts to fix the pedestal to the deck before we resealed the whole unit back down to keep the water out. We were waiting for the rudder bearing to come back from the fabricator so Greg from the yard got to work on rebuilding the pedestal.

Removing the wheel and pedestal from a J109 makes a lot of space in the cockpit ….

We also had a couple of upgrades we wanted to do.
First we wanted to fit a bob-stay. A line between the hull close to the water line and the end of the bowsprit. This is designed to resist the upward pull on the end of the bowsprit generated by the asymmetric spinnaker and make it possible to put more tension in the luff of the spinnaker with the halyard.
Secondly; we wanted to fit in-haulers to make it possible to sheet the non overlapping headsails closer to the centre line of the boat.

Fitting the bob-stay was relatively simple. We did some research on the internet and went for the simplest method we could find; bearing in mind that we might need to detach the bob-stay in future.
To attach the stay to the bow at the waterline we drilled a second drain hole to the anchor locker and enlarged the first drain slightly. For those of you who have read the post you will know about how we filled the anchor locker with water during one race last season when the existing drain hole got blocked.
Adding the second drain and enlarging the existing one would have the side affect of increasing the drain rate for the water in the locker. We also removed the small stainless cover over the drain hole. I’ve never really understood what benefit other than cosmetic these fittings have. The gel coat around the new and enlarged holes was refinished to make sure the whole assembly was smooth and water tight. The actual structure of the J109 at the bow below the anchor locker is very solid.

Jerry the Rigger then added a longer u-bolt to the end of the bowsprit with an eye nut rather than a plain nut on one side. The U Bolt holds a low friction ring on top of the bowsprit for the tack line to run through. We then used a stripped piece of Dyneema to create the stay. The Dyneema has a length of shock cord inside so that it shrinks in length when the tension is released and some outer coat to protect it where it goes through the hull.

The in-haulers were slightly more complex. We did some more internet based research to see what other people had done. We found Bill Knellers artica on the J109 Class Association forum that a lot of other people including Kerry Klinger from Quantum Sails had contributed to very useful. J109 In-hauler Thread

Our final setup gives us slightly less mechanical advantage than that proposed by Kerry and Bill but should be sufficient for our purposes. We didn’t cross of the lines, Bill and Kerry’s designs assume that the crew will work these lines from the rail. Experience with our last boat showed that adjusting the in-haulers is usually done at the same time as the sheet is trimmed and genoa car position adjusted so all the control lines were lead to roughly the same place on each side.

As can be seen from the images we fixed the Cam Cleat and Cheek Blocks close to the main clutches on top of the cabin roof. On each side one of the bolts attaching the deck organiser on the cabin roof was replaced with an eye bolt. There is a voice at the back of my heading saying that the eye bolt will be a trip hazard and it will be my bare foot that catches it but taking that approach minimised the number of holes we had to drill in the cabin roof.

The remaining blocks were left floating free so that they could be removed if not required. We attached the forward end of the line through the low friction rings to the ring at the base of the mast.

The complete list for those interested:
2 x Harken 150 Cam Cleat – with a custom wooden block placed to lift the rope over the deck moulding and a wide loop fairlead.
2 x Harken 40mm Swivel Block
2 x Harken 40mm Cheek Block
2 x Harken 40mm Swivel Becket Block
2 x Barton 22mm Low Friction Ring.
2 x stainless steel bolt with an eye at one end.

As you can see from the images the position of the low friction ring is roughly level with the shroud base. We have a North 104% No3 headsail that we will use the in-haulers with. The clew is quite low and the in-hauler will bring it about 30cm further inboard.

We finished off the maintenance with some work on the keel.

The keel has clearly come into contact with the seabed more than once over the years. I still don’t understand how you can have scuff marks on the top side of the keel. There were also flints embedded in the leading edge. Our berth in the marina at Gosport seems to have acquired an extra foot or so of mud over the last year or so; presumably due to the dredging thats being done in Portsmouth for the navy’s new aircraft carriers. Jengu had been back in the water since August and in that time the soft mud has polished the eroding anti foul off the bottom 30cm of the keel – its as if she is sitting in a mud berth.

Once the gashes had been filled and rubbed down to a smooth finish we re-anti-fouled the keel.

We took our upgraded boat for a spin the second weekend in March and everything worked so we are set for another years sailing … or at least until the next spot of boat maintenance is required.

Lets hope the sunshine carries on for the next 9 months.

Bill April 2017

Final Testing Session For 2016

The beginning of November saw us return to the Solent again for an informal weekends sailing with London Corinthian Sailing Clubs offshore group.

The Not Race and Hot Toddy evening have become a traditional end of season outing. Its a simple format, we get together at Hamble Point on a Friday night in November to eat and drink. Saturday morning we have the Not Race before sailing somewhere for dinner and to compare Hot Toddy recipes. Sunday is recovery time before we sail home.

The event brings together an interesting mixture of boats. This year we had everything from a 1900’s gentleman’s racing yacht to a selection of production charter boats. The Not Race is so called because its not a race in the traditional sense. Boats start at staggered intervals and aim to complete a set course around the Solent in the shortest possible time. The staggered starts mean that if the conditions are kind and the race officers maths correct, big if, the yachts should reach the destination at the same time.

Jengu being the fastest boat in the fleet, by some distance, had to give the other boats a considerable head start. Aeolus, the oldest boat, started first and over the next 45 minutes the rest of the fleet set off in pursuit. The course consisted of a series of broad and close reachs with one beat across the Solent; nothing too taxing.

With a brisk and building Northerly force 3-5 breeze it took about an hour and a half for Jengu to catch Aeolus. We overhauled the other boats along the way before we got to Aeolus somewhere between Norris and Browndown on a screaming close reach.

As a days sailing it provided an excellent opportunity to run all of the collection software and systems that we have been developing this year. We had setup the route in the data collector software when the sailing instructions were released; in the warm on dry land. In the run up to our start slot we turned off the engine and started the collection software. Picking the correct, boat, route and configuration option then creating a new recording session. On Jengu the laptop connects to an Actisense USB-NMEA gateway to collect the data from the instruments. This was all connected up and tested before we left the dock. We could see that data was flowing correctly into the software.

We left the collector running and sailed the course. Once we finished we stopped the collector, crucially, before we started the engine to motor up the Medina past Cowes.

Reviewed the data we collected a couple of things immediately became apparent.

Firstly; we had only recorded about an hours worth of data which seemed strange as the collector was still running collecting data when we can came to stop it. Some more detailed examination of the power settings on the laptop we were using showed that when running on battery it was setup to go to sleep after 60 minutes. Windows will put itself to sleep if there are no keyboard or mouse inputs; even if the computer is doing things like collecting data in the background. When we touched the mouse to stop the collector the laptop woke up and the collector started running again. From a testing stand point this was a little frustrating. We had an hours test data most of it the start sequence !

Secondly we had a number of corrupt values. Our original test boat two years ago would generate messages where the sentences were mangled, there is no other way to describe them, with very high values. We thought it was just a glitch with the wiring on that boat but it looks like Jengu has the same problem. So we had a boat speed profile that looks like the one in the image below.


We can clean the data up using the data collectors NMEA Data tab; we are able to filter the displayed data down to show only the VHW Water Speed and Heading sentences. We are also able to identify the invalid records that had been collected. On the next image the invalid data is in column C8. You can filter for just the invalid elements on the NMEA Data tab using one of the drop lists at the top.


Its worth noting at this point that the Data Collector will use a checksum to make sure the messages it receives are valid. The source system generates a check sum value based on the sentences content and a standard shared algorithm. The receiving system can then regenerate that checksum to make sure that no corruption has occurred in transit.

We have an option built into the Data Collector to either accept or discard sentences that fail the checksum. Generally we tend to accept the invalid messages and weed them out later. Early testing showed that some systems were not correctly generating the checksum value so we were getting a lot of false fails leading to us reject more records than we needed to. Its also possible to manually rebuild a sentence where, for instance, an individual element has been merged with its neighbour.

Having removed the invalid records we needed to recalculate the summary data. Summary information and Polar values are calculated as the information is collected. Invalid data like that identified above will distort the summary and polar values. We use the Recreate Session Summary Data function on the recording session to perform the necessary recalculation.


This deletes the summary data for the session and runs all the collected messages into the collectors sentence processor again. As it works its way through the collected source NMEA 0183 sentences the summary information is rebuilt. With a long collection session this can take some time. Our hour long session had collected 30000 NMEA 0183 sentences; multiply that up for a days collection and you are looking at a lot of data to churn back through. It takes longer to process the sentences that feed into multiple calculations; Our 30000 NMEA sentences could generate 100000 calculations. The recalculation time is also very dependent on the performance of the computer performing the calculations; generally though it should be significantly less than the original collection time. We left the laptop churning and went to lunch…

A short while later we had the data cleaned up and the graphs displaying nicely.


The tabular data is complete too.


We can view and export the full summary data for analysis in Excel.


The track can be exported and uploaded to Google Earth; though the track we generated was mostly us circling prior to the start you can see us sailing to the first mark.


Sadly we seem to have missed the part of the sail we spent hammering up and down at 10 plus knots.

So that is our final on the water test for 2016. Now that we have a working test boat and have the software that talks to it we will be focusing on releasing an updated version of the data collector in early 2017. There will be more details of that in the next post.

Bill December 2016

To Poole and back – more adventures in boat maintenance

The 2nd weekend in September saw us back on the water after the August break.

August for some people might be Cowes week and the peak of the sailing season but for us its always been school holidays and time out with the family. This year we took advantage of the downtime to take Jengu out of the water and resolve some of the remaining items on the issues list. As with most task lists its very much two steps forwards one backwards, but at least we now have new items at the top of the list.

We have had Jengu since the beginning of 2016; she is very much a project boat. Whilst she has an excellent racing pedigree having won the 2012 J109 nationals with her previous owners she came to us in need of some serious TLC. In her previous existence she must have been a very dedicated race boat used for a lot of inshore racing, given the excellent state of the head and cooker we don’t thing anyone actually slept on her.

When she came to us she was optimised to race one design, with a No.1, 2, 3 head sail setup, large overlapping Genoas rather than the all purpose blade Jib plus No. 3 found on most of the IRC focused J109’s. Consequently, our IRC rating is quite high 1.027 compared to most of the IRC boats who are in the 1.09-1.020 range. Our long term plan is to race Jengu mostly under IRC, so we will be adding a bob stay, in-haulers and probably an A0 over the winter. But for now we are racing in one design configuration to learn the ropes.


Late July saw us at Yarmouth for the Taittinger Royal Solent Regatta. After struggling against wind and tide to get to Yarmouth on Friday, Saturday and Sunday saw mostly light, shifty winds, building towards the end of each race. The racing takes place in the Western Solent in a strong tide which in places runs at as much as 2 knots.

We’d gone to Yarmouth with high hopes, the skipper and I think a few other people, mostly on other London Corinthian sailed J109’s, thought we would be able to take advantage of our more generous sail plan to at least beat the IRC J109’s on the water. The reality was somewhat different. I think its safe to say our boat speed didn’t set the world on fire and we finished the weekend with a series of DNF’s and DNS’s. We did however go swimming in the Solent off the back of the boat and the parties were awesome.

Saturday had started with the instruments crashing and showing Error No.3 as we motored out of Yarmouth towards the start. In the land of Nexus Error No.3 is no data. Jengu had sailed 500 miles since the last time we tinkered with the instruments without a glitch. That mileage had included this years Round The Island Race and a 150 mile thrash to Dartmouth with JOG.

We survived all that rough weather to loose all the data in pretty much a flat calm. No amount of rebooting or fiddling would bring the instruments back to life. So we sailed most of Saturday dinghy style with just the chart plotter, not great when you are trying to stay out of the tide in a boat that draws more than two metres. Fortunately the B&G plotter connected to the NMEA 2000 bus still worked and we were able to anchor for our afternoon swim based on instructions from our very patient navigator sat at the chart table.

Sunday after a limited amount of further connection checking the instruments came back to life and we were able to race but our boat speed was comical.

The whole experience convinced us that whilst in June we had made progress with Jengu further work needed to be done. The list of priority items we needed to fix was actually quite short; just the depth and speed transducers and to check the state of the hull. Both of those meant that Jengu needed to come out of the water.

We booked ourselves a lift out at Endeavor Quay for the bank holiday week. Not surprisingly there wasn’t a lot going on in the boat yard on the Tuesday we did the lift out, just us, Alex Thompson working on Hugo Boss and the Royal Navy, we felt a little out of our league.

The lift out showed us the state of the bottom of the boat. The hull aside from the waterline, didn’t look too bad but the keel had the beginnings of a set for Finding Nemo.

Most of the wildlife power washed off leaving a thin layer of anti foul.

Jengu is painted with black eroding anti fouling. The pro’s and cons of anti-fouling are described on numerous other websites; Have a look at this article from Practival Boat Owner; PBO Anit-Foul Article

Eroding anti-foul is rubbed off by the action of the boat sailing through the water taking with it the sea life that has taken up residence. As with hard anti fouling it contains chemicals to inhibit the growth of weed, barnacles etc.. From a boat maintenance perspective the fact that it washes off is a big advantage. Hard anti-fouling, that just works by killing the wild life with chemicals, rather than killing and setting it adrift, builds up over the years and needs sanding back. Applying another coat of eroding anti-foul just involves cleaning and preparing the surface.

I’ll be honest painting and decorating is not my idea of fun. We got the team from Gosport Boatyard to do the hard work; the result is a much better finish than I could ever achieve. We used International Micron Extra 2 in black to give a smooth coating. We also added a band of hard white anti foul just above the waterline. Previously the black eroding anti fouling ended at the waterline. This led to a buildup of weed on the gel coat giving Jengu the appearance of growing a beard at the bow. The beard growth could be removed with a pan scrub but the process was time consuming and we needed to do it on a monthly basis.

Once we had the anti-fouling tasks under control we moved onto replacing the depth/log transducers. We’ve been working with MEI from Port Solent for a couple of months to upgrade Jengu’s electrics. This task had been on their list for a long time but had been stalled by the need to get Jengu on dry land to do the work. With the parts delivered they completed the work in under a day. We replaced the existing Nexus Log transducer with a DST 800 combined speed/depth unit from Garmin.dst400 This had the advantage that it only required one hole in the hull and that the hole required was bigger than the existing hole. The engineers from MEI bored out the existing hole and inserted the new transducer. This assembly was then sealed in with Sikaflex to create a water tight through hull fitting.

The Garmin DST 800 is an NMEA 2000 unit so it can be connected directly to the boats NMEA 2000 backbone. This required a cable run under the cabin floor and a T Piece with terminator in the forward cabin, again under the floor. The old depth transducer was left in place with the cables disconnected. At some point over the winter we will remove the redundant device and fill the hole.

Finally we needed to resolve the loose connections with the instruments. We decided to take the bull be the horns and replace all the existing cable connections. We had used standard electrical connectors ae235 to connect the Nexus network cabling together. There doesn’t seem to be a standard connector from Nexus available to join the four core cables together. The chocolate block connectors worked fine in a relatively dry environment but looked to be shorting out when the going got rough, damp or when there was a lot of vibration.

After a discussion with the support people at RS components we settled on Phonenix field install connectors as a better method of making the connections. F6486618-01 The connectors are waterproof to IP67 standard and have screw connection terminals that make them ideal for connecting to cables where you don’t want to use a soldering iron. These are male and female plugs so a unit can be disconnected from the network without interfering with the wiring itself.

F6486618-03 The result is a much tidier area behind the switch panel. We also put connectors between the Mast Display units and their cables at the point where they go went into the mast. One of the conclusions we reached was that a single short would crash the whole Nexus system not just the units attached directly to the shorting connection.

The Nexus instruments automatically initialise with a device ID. If the cable connection isn’t complete, 3 out of 4 cable connections are good but one is faulty, the instrument doesn’t initialise properly. You then can’t configure the instrument and devices with matching numbers will conflict. As discussed in the post about replacing the wind instrument its very important to introduce the devices back into the network one at a time. That is a lot easier to do if you can simply unplug all the devices then plug them back in one by one.

After a couple of days work we had the system back up and running. With the transducer installed and the hull anti-fouled we were ready to go back into the water.IMG_0424

After a day at Gosport Boatyard where a couple of other issues, including a leaking port light, were resolved we headed for a Friday night at Cowes before the start of the Junior Offshore Groups Cowes Poole race on the Saturday morning.

The weather forecast for the weekend was varied, Saturday looked like gusting to 20-25knots with rain, then more rain, before the weather cleared through, the wind dropped and the sun came out. The forecast was for a steady South Westerly breeze for most of the weekend with Sunday being by far the better day. Our start was at 9.15am so we were going to be going West down the Solent with the last of the ebb tide, high water having been at about 6am. Thats an Ebb Tide out through the Needles with a South Westerly Force 5-6 blowing gusting to 28 knots at times. The wind over tide at the Needles looked like it would be a good test of all the work that had been done over the previous couple of weeks.

We got going early, breakfasting as we left the dock and motored away from Shepherds Wharf down the Medina to the start. Our race start was conservative but placed us in a good position, not too early, in clear air away from the other boats we hit the line at more or less full speed. We were lying 3rd or 4th having followed Just So and Alaris over the line, we initially went low to get good boat speed and clear air then started to climb back to windward to tuck into position behind J-Taime another J109 being sailed double handed. The course took us out of the Solent using the North Channel then up to the North Head buoy, along the edge of the Shingles to the Christchurch Ledge buoy, back to the Needles Fairway buoy then on to Poole.

As we expected the sea conditions, a South Westerly Force 5-6 wind against an ebbing tide, made for a very rough ride out to the Needles Fairway turning mark. We then turned West towards the finish line at Poole. The last ten miles were a fetch in 20 knots and more wind, we carried the No. 3 and the full main all the way to Poole.

Its worth saying that there are no photos of that 10 mile leg to Poole, its safe to say it was very wet and very fast. With 6 of us including the skipper sitting on the rail we were maxing out at about 11 knots speed through the water. Nick sitting forward on the rail got very wet from the waves, the rest of us just got wet from the driving rain.

But everything worked. Having set the course up on the B&G Vulcan as a route prior to the start the bearing and distance to the next way point appeared on all of the Nexus instruments. The B&G could work out when we passed a mark and updated itself to direct us to the next one. This gave the helm the bearing and distance to each successive mark without the crew having to leave the rail. cowes_poole_result With the rain lashing down we counted down the miles to the finish, desperately looking for that extra half knot that would take us away from the other boats. In the end we followed J-Taime for about 20 miles about a 100m astern. The class 4 fleet crossed the line minutes apart after 4 hours racing.

Relieved we headed to Poole to dry out. As is always the way, by the time we reached the quay the rain had stopped and the sun was starting to come out. We spent most of the rest of the day bailing out the boat. We’d taken a water over the deck and a lot of it was either in the bilge or the anchor locker. Once we had cleared the drain hole for the anchor locker we turned the boat into a laundry to dry everyone’s gear out. Then headed out for a well earned meal.

Sunday was a completely different day. As forecast it dawned with a zephyr, blue sky and sea, so we took our time over breakfast in the expectation that the race start would be delayed. Breakfasted and with the crew who had stayed ashore back on board we headed out to the start line to join the other boats milling around. After about half an hour of holding position enjoying the sunshine, standing on the bow to drain more water out and passing sail repair tape to another J109, Red Arrow, the committee boat announced that racing would get underway.

This time we got a blinding start, with the No. 1, that we had high hopes for at Taittinger, finally paying off. In the light Force 2-3 Southerly breeze we were able to make better boat speed to windward than most of the rest of the fleet. We again hit the line at speed in clear air and were able to pass the majority of the fleet on the line. Sadly, we once again fell back into yesterdays position behind J-Taime, albeit in 2nd place.

This was looking promising, the boat speed was looking good and we were holding our position against the rest of the fleet who appeared to be luffing each other higher and higher away to the south. We made good progress back towards the turning mark at the North Head Buoy. About a 3rd of the way to North Head, Just So, another J109, raised its Asymmetric and started to come down to us. As they had moved further to windward they now had an angle on the next mark that allowed them to fly the Asymmetric kite on a very close reach. They crossed ahead of us and J-Taime to take the lead.

We looked at the possibility of hoisting our A2, but we were still sailing to close to the wind. Instead we decided to head up to put ourselves between the mark and the fourth placed boat Moontiger IV which had also hoisted its Asymmetric. We luffed them for a short time, but were unable to keep them behind us. So we hoisted our A2 and sailed a slightly lower course. Alaris the fifth placed boat was a way back but catching and we didn’t want to concede another place.

As we neared North Head and the Shingles bank the wind headed us slightly and we dropped the Asymmetric to give us a better run to the mark. Alaris was still flying their Symmetric kite and started to gain on us. The fleet converged as we reached the North Head buoy. We headed up a little closing the gap to windward to one of the slower boats from the earlier class starts that we were now starting to overtake. Alaris continued to carry their spinnaker right up to the mark but the slower boats meant that to get past us they would need to sail higher than their spinnaker would allow. We rounded the mark well, in wide, out close and Alaris overshot ending up closer inshore.

We turned and headed east up the North Channel to the castle at the Hurst narrows the next turning point from which we could sail up the Solent with the tide. Alaris and the rest of our class had dropped back. We made it into the main channel, the water swirling at a couple of knots past the castle. Once out of the rough water we hoisted the Asymmetric again and started to head up towards the island shore.

The tactics were simple, sail as high and fast as we could, keep flying the spinnaker and keep Jengu between Alaris and the finish line so that they would have to sail around us to overtake.
With the wind blowing off the island from the East/South East, it would head us occasionally, increasing then decreasing as we passed each valley on the shore. We did our best to stay in the deeper fast flowing water past Yarmouth and up to Newtown creek. We overhauled a number of other boats going up the Eastern Solent mostly from the earlier starts.

NJOS from the later class start caught and over took us at or around Newtown creek and proceeded to do a very slick spinnaker peel, switching one sail for another. We carried on with the fast and high strategy. We gained the ground back on NJOS who fell away to leeward with their new spinnaker. Alaris maintained the gap but couldn’t get closer than a couple of hundred metres, The dirty, disturbed air that both Jengu and NJOS created meant Alaris closed up to about a 100m, found they couldn’t sail over us then dropped back in the turbulence. That cycle repeated itself a couple of times.


Finally we got to a point far enough up the Solent that we could see Cowes to the East and the finish line. As we cleared the headland the wind shifted and headed us, the shift was probably about 90 degrees. In a mad scramble we dumped the spinnaker down the hatch and headed up back onto the wind. NJOS followed us further to leeward. Alaris did more or less the same thing a couple of minutes later but clearly with warning as they had seen us headed as we cleared the headland.

Now we were heading for the outward end of the JOG start/finish line at the Gurnard Cardinal mark. The wind blowing from the south meant we were now beating up to what was effectively a windward mark with a strong favourable tide still behind us.

It quickly became obvious that we weren’t going to make it in one tack. 5 boat lengths to leeward of the mark and a little way short we tacked over onto port. We sailed that tack for a couple of minutes to be sure that we would clear the cardinal mark then tacked back over onto starboard. We crossed the finish line beating NJOS by metres. We had maintained the distance to Alaris and the rest of our fleet and held onto 4th place on the water.

We beat Alaris on the water by 59 seconds after 3 and a half hours racing, though it felt like much longer than that and lost out on handicap by less than 10 minutes.


As a crew we have clearly improved but still have much work to do. But we’ve proved its possible for us to produce competitive results and be consistently not last. Most of all Jengu now works and we are getting a good understanding of what not to do. Its a good way to end the season and something to build on for next year.

Bill October 2016

Jengu Does Dartmouth

Last weekend was our first serious race outing for Jengu. We’ve had a couple of other trips including circuits of the Solent, racing to the Nab Tower and St Vaast, but this was our first serious test of the systems that we have installed and configured over the last 6 months.

As described in the last post we have been struggling to get the wind related data correct and out of Jengu’s systems. Now that is working we needed to test that everything worked together and that the instruments presented a consistent and realistic picture of what was going on.

After a brief stop to scrub the weed off the bottom of the boat, we set off for the race start at Cowes. We left ourselves some time to sort the boats systems out and check that all the sails, lines, sheets etc worked.

The race start was at 4.30pm, Cowes to Dartmouth is 120 plus miles, the course going with the tide out of the Solent past the Needles West to Dartmouth in South Devon. The weather forecast was a brisk but relatively benign SW F3-4 going around to the NW and dropping off by lunchtime Saturday; so we were expecting a night of beating to windward towards Portland Bill.

A quick exploratory trip over the start line showed that we were better using the smaller No. 3 rather than the larger No. 2. If we had more crew weight on board and were prepared to spend all night sitting on the rail we could probably have carried the No. 2. 24 hours is a long time to sit on the rail and doing a sail change in the dark on a new boat is no fun at all.


Our testing showed up an issue with the boats speed indicator. The log transducer is basically a paddle wheel that sticks out the bottom of the boat. The rate at which the water turns the wheel is translated into a boat speed by the electronics. The faster the boat goes, the faster the wheel turns, the faster boat speed is recorded/displayed.

Marine life likes to grow on the paddle wheel. Unlike the rest of the boats hull the wheel isn’t anti fouled so there is nothing to stop creatures taking up residence. Normally you can withdraw the transducer through the hull to clean it. With other boats in the past I’ve found small shrimps and crabs living in the wheel assembly. Jengu’s transducer had worked on our previous outings so it seemed reasonable to assume that something had taken up residence — we needed to evict it.

Initial attempts to extract the transducer from the hull showed that it was well and trully stuck in its casing and didn’t want to come out. The transducer sits in a round plastic fitting moulded into the bottom of the boat. The transducer we have has been on the boat since day one and this one was clearly welded in place with an accumulation of many years anti foul (we have the same problem with the depth gauge but thats another story). We didn’t want to apply too much force to the transducer incase we broke the fitting and left a 40mm hole in the bottom of the boat. So we tried the alternative approach racing up and down the Solent at maximum speed (any excuse to surf around) to dislodge the marine life.

Success; so now we have all the data points we need. Boat Speed, True and Apparent Wind Speed, Heading, True and Apparent Wind Direction, GPS Latitude and Longitude. All this information is available to the laptop onboard via the Actisense NGW-USB gateway.

After that our race went pretty well given it was only the third time we had competitively sailed Jengu. Twenty hours later, after surviving the breaking waves at the end of the Needles channel, and nineteen hours of beating into the forecast F3-4 we were off Berry Head still being headed by the South Westerly.

We watched the rain clouds approaching would they the bring the forecast change of wind direction ? Would our trip out into the Channel to avoid Portland pay off ?

As we got closer to the headland we could see two of our competitors in the distance on a more inshore course. The clouds gathered the wind started to shift first into the south/south east. Feeling smug we followed it around getting closer to the heading we wanted. Then the wind shutdown altogether and the rain started.

We could see the other J109 Jazzy Jellyfish a short way off, we scrambled for the No. 2, we weren’t going anywhere, neither was Jazzy Jellyfish a couple of minutes with no head sail wouldn’t matter…. Jazzy Jellyfish, double handed, had hoisted an Asymetric.

Then the wind started to fill in from the North West, 4knots, 5 knots, 8knots. We started to move in the direction we wanted to go, Jazzy Jellyfish dropped their Asymetric and raised their No. 3, the race was back on. We had better boat speed and overhauled them half way between Berry Head and Dartmouth with maybe 2 miles to go. Unfortunately for us the wind continued to build and by the time we reached Dartmouth we had 20knots True accross the deck. Jazzy Jellyfish was sailing slower but higher. That seems to be the way with the J109, you can have the big sail plan and sail fast and low or the small more managable one and sail high and marginally slower.

The wind shifted further putting the finishing line in the mouth of the Dart to windward of us again.

I might have mentioned earlier we aren’t the heaviest crew, tacking the No. 2 in 20 knots efficiently to cross the line turned out to be beyond us. We fluffed the first tack, then the second one, Jazzy Jellyfish tacked and crossed the line. We followed her over 4 minutes later. Exocet followed us in a couple of minutes later.

So after twenty something hours racing the 3rd, 4th and 5th place boats finished less than twenty minutes apart. We’ve definitely improved on our last outing to St Vaast and are ready for the next challenge. Knowing the instruments work we can hookup the data collector software and do some real analysis of our performance.


So to finish the trip off we headed to the Royal Dart Yacht Club for the JOG prizegiving, followed by fish and chips on the quay in the sunshine… we would have stayed longer but we all had to go to work on Monday. Five hours after reaching Dartmouth we were headed back out to sea with a flat sea and a following wind. You can’t really complain about that.

Bill/June 2016

The Wind Direction Saga

When I first saw Jengu it was November it was a foul day at Hamble Point and the wind was strong enough to be moving the boat around even though it was on dry land. I didn’t pay much attention to the fact that the instruments said it was blowing 100knots. It seemed plausible.


Fast forward to a slightly calmer day in January and its still saying that its blowing a gale and worse than that the wind is circling….

At that point I didn’t realise how long it would take to work out what the actual issue was.

As discussed in an earlier post Jengu has a Nexus system. The anemometer connects to the NX2 server with a very long cable from the top of the mast. The NX2 server then converts the data to NMEA 0183 for consumption by the other systems on the boat.

We did a visual inspection of the anemometer from the ground over the winter and it looked OK. You can’t go up the mast to check things when the boats in a cradle on dry land.


We checked the GPS and flux gate compass data. If the compass heading was rotating or the boat speed was off then that might explain the odd readings. They all checked out fine, displaying on the B&G Vulcan chart-plotter the expected values. That was a good sign for the rest of the electronics in that the GPS and Flux-gate were connected to the Nexus NX2 server; data was reaching the B&G Vulcan on the NMEA 2000 bus via the NMEA 0183 output port on the NX2 server and an Actisense NMEA 0183-2000 gateway.

Following a brief chat with the support team at Garmin we tried to check the calibration of the server and the anemometer.

This allows the correction of consistent over reading and the adjustment for an offset anemometer. For the Nexus based system and its Garmin branded decedents you can adjust the readings using the Nexus Race software. Sadly for us this didn’t resolve the issue. Unfortunately the NX2 server wouldn’t talk to the laptop…

At this point we were working against the clock to get Jengu ready for the JOG Nab Tower race at the beginning of April. We gave the support guys at Garmin another call. They agreed to check the NX2 Server box itself for a fault..

.. which confirmed the fault with the serial interface for the laptop and that the wind data interface seemed to be OK.

The boat went to the Nab Tower without any wind data… but there was no wind for most of the race so that didn’t matter – we are all dinghy sailors at heart and are used to more basic instrumentation.

With the NX2 Server back in the boat the next thing to check was the cabling. We did that as far as we could without actually pulling the cable out of the mast. We remade a couple of connections in the boat where the cables met at the base of the mast but still not joy.

Somewhat frustrated at this point we decided to bite the bullet and replace the whole wind data/anemometer assembly. Installing a new unit at the top of the mast and connecting it up to NMEA 2000 bus we fitted over the winter with new cabling. We ordered a new B&G Triton anemometer to match the other B&G equipment we had installed.

The engineers set out to replace the anemometer and complete the installation one morning in May; everyone works on their boats April and May on the South Coast so getting the parts and engineers onsite took a couple of weeks, especially as you need two engineers; one to winch the other up the mast.

The engineers first step was to remove the old, presumably compromised cable from the mast.

A bit of history : Jengu got a new mast in 2015 whilst with the previous owner. It would appear that the cables (VHF, Nav light, Anemometer) in the mast are taped together. It probably made sense when the mast went in, its clearly easier to pull three cables taped together up a 60 foot mast, but it does make life difficult if you want to replace one and leave the rest undisturbed.

…there was no way they were going to just get the Nexus cable out of the mast. People started muttering about taking the mast out.

So we went back to Barry and Alex from Garmin Support, they have been immensely helpful all the way through the previous episode with the NX2 server. Could we just replace the unit at the top of the mast and plumb it into the NMEA 2000 network somehow ? The answer was yes and they gave us a list of parts to order including a replacement mast head unit, Nexus/Garmin converter cable and and box of tricks to process the data.


It was a bit of a gamble we didn’t know whether the cable in the mast was any good but given the VHF and Nav lights worked fine it seemed sensible to assume it was OK.

So with a list of parts ordered from Hudson Marine we waited for the day when Andy from MEI at Port Solent (plus colleague to winch him up the mast) could go back up the mast to install the new bits.


To cut a long story short it all worked. Andy replaced the anemometer and discovered that at the point where the wand was clamped to the top of the mast the Nexus data cable had been pinched. The wand had basically severed the outer casing of the cable causing it to short out.

It was a bit of a surprise that the Nexus server was still interpreting the data coming down the mast as valid….only the human eye could tell it was nonsense. So now we have working wind data after a couple of months sailing without it and can proceed to getting the NMEA Data Collection software working on Jengu.

So what did we learn…

  • We now know where all the cables go in the boat and roughly what they do.
  • We’ve also traced and removed all the redundant cables that have been left in the boat over the years. I now have enough spare Nexus cable to rewire another boat… if nothing else its saved us some weight.
  • Go to the top of the mast first. OK so we couldn’t have done that in January but we could have done it in April. It would have told us whether the anemometer was broken and which might have saved a lot of other work.
  • Label your cabling. We spent a lot of time trying to figure out which cable was important.
  • If you are going to install a field fit Nexus cable connector you are going to need your glasses. Its got the smallest Allen key I’ve ever seen.

So now all we have to do is persuade the data from the transducers to display on the instruments. But that’s for another post.

Bill/May 2016