Tuesday, March 31, 2009
Friday, March 27, 2009
Monday, March 23, 2009
I’ve got quite a list of things to look at while testing the PI Garda box, but a diagram I saw in Seahorse has been in the back of my mind and I wanted to do a Moth version. In the Jan 2008 edition there was a great article by Steve Killing on the 2007 International C-Class Catamaran Championship, and there was a diagram that accompanied the text showing the anatomy of a C-Class gybe. I thought this was quite interesting, and following my own observations during the event I thought a foilborne gybe would be nice to try and show in this format. I’ll try and get some screen grabs from the video to go with it soon.
These gybes were selected for the consistency of the trace before and after the gybe. I got a bit carried away with having the box on, that I did quite a few gybes in quick succession and so the track wasn’t very smooth between them, with the exit from one gybe blending into the entry to the next. The gybes shown here are gybes 2, and 5 of the day, and probably not my best, but representative of good foiling gybes (I hope!). Both plots show the point of lowest speed, and when I was heading directly downwind. I got a bit more organised for the second plot, and all the points except the lowest speed one are separated by 2 seconds. So the average gybe takes about 10 seconds if you think of it terms of time taken from average reaching speed on one tack to getting back up to that speed on the other tack. This seems like a long time, but then you watch the video and it doesn’t seem that long. Now consider that your average VMG downwind through the whole manoeuvre is only just less than your standard VMG numbers…. Good gybes in these conditions have minimal loss, and open up a host of tactical options.
This was from my first day out sailing with the PI Garda box. There was an average windspeed of just over 9 knots for the period I was on the water. (Measured from my onboard weather station – which is a bit low at 1m above the sheerline on the bow, but more accurate than me guessing the windspeed or checking the harbour wall data afterwards.)
Top speed measured on the day was 19.1 knots in 10.0 knots of breeze.
Plenty more data coming as I learn more about the software and what it can do.
Monday, March 16, 2009
I was approached recently by the guys at Cosworth about testing their new PI Garda GPS sailing system, and providing them with some data they can use. I’ve come across the PI kit before in my work with Skandia Team GBR, and Victory Challenge, but I’ve not seen it used on anything quite as small as a Moth. I’ve now had it on the boat a few times and should be able to publish the data here soon.
The Pi Garda system from Cosworth Electronics, is a sophisticated GPS linked to wind gear that records and analyses a lot of interesting factors such as wind speed and direction to produce key performance measures such as VMG and polars along with standard tracking data. On top of this the analysis software used can do a variety of analysis tasks such as; automatic tacking and gybing analysis and layline & startline tools, all synchronised with relevant video. I’m still learning about all the different features that can be done, analysed or added on in the way of sensors or custom fittings. Strain gauges, rudder sensors and inertial measurement tools have all been mentioned, but to start with I’m sailing with a system that has the ‘black box’ GPS, with an IMU giving me heel and pitch angles, all linked to some Raymarine wind gear mounted on the bow.
Testing has begun – so technical minds out there – what data would you be interested in? Data I’ve got so far to be posted soon.
About Cosworth Electronics: Cosworth Electronics’ pioneering technologies heralded a turning point in racecar innovation, helping to create champions in Formula 1, IndyCar, and many more. Now their marine division are looking into the world of performance sailing, including Americas Cup Syndicates, speed record challengers and Olympic sailors.
Sunday, March 15, 2009
- Stern sinking - how far can you go without doing the full spin over backwards. - (The going over the front option was attempted but aborted early on!)
- The transom sink spin whilst capsized - but climbing over the board to stay dry during the operation.
- Bow sink spin whilst capsized - again going over the board and staying dry.
Saturday, March 14, 2009
Mike Lennon won the day with a 1,1,1,ocs scoreline, to my 2,2,2,rtd. It was good close racing though, with the lead changing about 4 times in the first race, and Mike just getting through underneath me on the final beat in the first race to win by about a boatlength. Race two he lead initially but I crossed ahead up one of the beats only for him to hook into a nice shift on the right to get me back. A silly capsize mid tack on the first beat in the third race left me with a bit to do, but I had a good run to be third at the leeward mark, and slowly ground down Rod Harris to pass him on the final run for another 2nd. A few big nosedives before the next race resulted in my little wand nipple attachment parting company with my wand bracket just before the start of the fourth race, and unable to fix it on the water, I headed home downwind in lowrider mode - which was rather wet!
A few suffered gear failure in the breeze, with unfortunately Simon Payne in his new UK Mach 2 on its second outing being amongst them. Simon was out early, and looking very fast in the early big breeze. He was high upwind, and looked very solid downwind, but his forestay attachment didn't want to stay out for the races and the mast took on a little bit more rake than intended. An issue with the first prototype boats only, so no big deal, but a shame we didn't get to properly line up against him. First impressions though - that boat is quick.
Light winds forecast for tomorrow...
Friday, March 13, 2009
I'd met Nigel years ago on the J145 Jazz, where I did a number of the RORC races with them, and the Middle Sea Race. I bumped into him again recently at an RYA coaching meeting, and offered any help while he was Weymouth based. Hopefully I'll be able to help out a bit more when he's back in town.
Its been a while since I sailed anything much bigger than the Moth, so it was good fun to sail a new boat, and learn about the demands of solo sailing.
- Figaro sailing in Weymouth
- A new foiler in town.
- Full GPS instrumentation inc wind gear on a Moth - eagle eyed readers will have noticed a new supporter of mine, or seen some footage at the dinghy show.... More in full soon.