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.

Bill/June 2016

Originally published June 29 2016