Does anybody know where i can get hold of one of these speedometers which attach to the leading edge of the dagger board (for training purposes only).

I remember seeing them adverties many years ago but does anybody know if they are still available or if there is a similar product on the market?

I had one of  those sitting in the garage, just sold it on ebay last week;

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7159797234&rd=1&sspagename=STRK%3AMESO%3AIT&rd=1 - http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=715 9797234&rd=1&sspagename=STRK%3AMESO%3AIT&rd=1

Slight price difference tho with GPS,  the protrim can also be used for judging tides.  GPS is a little luxurious for improving boat speed.

Rick, did you find it useful at all?

If you enjoy looking at the numbers to know how fast you are going, that's fine. If you want to learn about boat tune, forget it. The numbers change on every wave and in every gust. You need the budget of an AC campaign to be able to tune a boat from instruments.

For example: 1000m beat. A big gain from a tuning change would be a couple of boatlengths, which is something around 10m. That is 1%. Boats go to windward at, very roughly 5 knots, with the speed oscillating +/ 0.2 knots (at least) as you take waves. That's four times your 1% tuning gain, so it is completely lost in the noise.

Take it from someone who has spent thousands of hours helming yachts racing offshore, staring at the 20/20s. You can't tune a boat off instruments: the only thing sensitive enough is another boat to compare to.

So measuring how quickly you regain speed after tacking is not going to work with a speedo???

My idea of the protrim is not to constantly see how fast ur going but to improve speed through manouvres.  I am well aware that two boat training is the best way to improve boat speed, except its not too handy if ur the only boat of ur class at a club.

Planing boats shouldn't have as much speed variation through the water as heavy yachts do anyway.  I'm not convinced by GPS over short distances, its very accurate over 8-9 meters but improving the speed through a tack in a dinghy should be done in less than this distance.  Also GPS only gives you speed over land, being a member of a club with relatively strong tidal currents means that this is not as good an indication as speed over water measurement

That would work.

I've sailed both and the opposite is true. Yachts are heavy and therefore it takes a fair amount to speed them up and slow them down. Dinghies accelerate and declerate quickly by comparison. In most dinghies, you can tack and tack back on a 30 second windshift and gain. If you did the same in a yacht, you'd grind to a halt.  

I would say that the opposite is true especialy as you go up wind and drop on and off the plane as you get in and out of the groove.

A GPS could be useful over the course of a leg if you waypoint the windward mark then you can look at your VMG as you change from fast and low to pinching to try and work out the change points, never tried though

Well I have tried and it doesn't work for the same reasons tuning on a boatspeed indicator doesn't work. If you turn the damping to something around seconds, the VMG dances all over the place. If you turn the damping to minutes, the breeze is never 100% steady for that long. Not all hand-helds let you change the damping anyway but the units yachts have usually do. The point is changes you get from tuning are very small compared to the changes constantly caused by other factors.

The only way you could make it work is record all the data (breeze speed & direction, speed, VMG, sheet settings, rig settings) and shoreside, feed it into a computer, average it out over weeks of testing and try to make sense of it. That is what the AC teams do but it is completely outside the resources the rest of us have available.

Two-boat tuning is the way to go. That works because, if you do it right, both boats experience the same changes to the breeze etc. and therefore you can make conclusions about the results of tuning changes. Have you noticed that the successfully AC and Volvo campaigns now almost invariably have at least two boats? Allowing two-boat tuning is one major reason for spending all that extra $$$$.

Small world on-line

You'll be able to answer the question about if it's any good then as I never got round to using it ...

Looks like a good gadget; the function that showed how long it took to recover speed after a tack looked pretty handy ...

regards,

Rick

If anybody has one of these to sell please  PM me!

Chees

Oi!

Wait your turn

Only kidding, but i did ask first!

Contact SSailor for payment too . He will not mind!

What do you sail?

Have a look on ebay for GPS fitness watches, the type that tell fat people how far they havent run.

Less drag, and 

THESE WILL BE AGAINST ALMOST EVERY CLASSES RULES!!! 

But if its a watch they will never know

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=75230&item=7162872575&rd=1 - http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category =75230&item=7162872575&rd=1

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=75230&item=7160823474&rd=1 - http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category =75230&item=7160823474&rd=1

Apparently they tell the time aswell.

This will not help you pull though :|

Stefan,
Sorry to disagree - but actually this is possible on a yacht (or boat with batteries) without spending too much money - certainly not AC levels of money

All you need is
1) PC (or perhaps a handheld computer that can install PC software) - has to work on the boat

2) An NMEA output from a yachts' log and GPS etc

3) Some polar generation software like http://aquilon-performance.com/ - http://aquilon-performance.com/ - £200 (300 Euros)

This software will firstly get all your polars organised (assisting with performance analysis between sails and settings) - and also, when racing, allow you to work out how you are doing against the polars.

The software outputs 2 figures - one a "live" percentage (however very impacted by waves and micro changes in apparent wind direction / speed) - and a rolling percentage calculated over the last 60 seconds (used for tuning)

If you are not allowed computers on board while racing, you can just take the paper printout of the polars formed while training... and this is still helpful.

(This software is used on a number of UK solo offshore boats - including Sam Davies on her Figaro)

You can also use the polars to assist with navigation routing - as they can help deduce downwind gybing angles - and for decisions about which side to pass islands etc.... I admit this may not be too helpful for dinghies though! (although you can always analyse a race - and work through all the options - and base your on the water decisions from the previous analysis)

Alex

I sail a 505 and an RS300,

If the garmin GPS are so good, why are you interested in the protrim?

Also, the idea is not to race with the speedo, just train and improve tacking/gybing techniqus.

Didnt say they where so good did I?

Just pointing out an alternative.