Speed

[JB9]

J9 touched 12.9 kts yesterday afternoon at BBSC. Gusty, shifty, challenging sailing but great fun in a 50+ year old boat. Only capsized 3 times in what was probably F6 gusts. Does anyone else have a GPS on board?

[Michael Brigg]

The prefered method I thought was to dribble gobbets of spit over the side and measure the time to travel, "Pooh-stick" fashion towards the stern.

(Well that was Shakewell's method anyway!)

It sound like you were a bit dry mouthed for that method!

[Ed]

Actually.......'sniff'......

I think you will find 'Radar' is the standard agreed way of speed-checking Jollyboats....

RN Radar of course!

All in the history dear boy!

eib

ps don't carry a GPS....always really wanted to. Do you use a Velocitek? or something more standard?

Some of the ICs do and have always found it interesting that boats seem to top out at whatever is their top-speed and that is it. You can spend more time at 'top-speed' but it is hard to go faster.

We have always talked about trying to put on a 'speed trials' at a CVRDA event......and must admit that looking at the weather forecast for this w/end.....we may never get a better time than Roadford this w/end!

I wonder if I can persuade Neil to measure and set a 1/4mile strip.

eib

[JB9]

We use a Garmin 401 which is just like a large watch.

[Michael Brigg]

At the risk of seeming picky, (ie "I'm going to be picky.")

...Does the CVRDA have any rules about these devices?

Many classes ban them from racing with a rule about use of equipment that uses external devices for deriving information (or some similar wording.)

Esentially the rule needs to be able to allow simple Non magnetic Compass devices such as a Tack tick, but needs to outlaw satellite navigation systems capable of computation such as SMG.

I believe the Finn simply bans all non-magnetic compass/navigation equipment.

Any thoughts?

They are of course fun for cruising and a useful safety aid but in racing... I feel they detract from skills such as laying a mark accurately in a tidal current.

[Brookesy]

The Finn class has for some time allowed the Tactic Micro as do an increasing number of classes, however the next step up which provides boat speed and vmg etc is currently not allowed.
Do we really wish to open this can of worms? I am however a great believer in allowing these devices to be used, as often crews with them are distracted by watching their 'instruments' and it allows the sailor with his 'head out of the boat' to take advantage of the shifts or whatever else is going on and gain a real advantage.

[Rupert]

Where boats within the cvrda have class associations, they will need to follow their class rules on such matters, so a "Finn" is still a "Finn" and not a boat that looks like a Finn, weighs like Finn but actually isn't. Only using the Finn because of its mention above - it applies to all classes. Those boats which no longer have such things as class rules can, I suppose, do as they like, but I hope, and doubt, we will have an electronic revolution on our hands at the front of the fleet, outsailing everyone else by electronic wizardry. Especially at Shearwater...

Al in all, they sound like great fun for going out for a blast, and even for looking back at after a training session (!) to see what tweaks worked, but I can't see us going all America's Cup during the racing - not enough hands or eyes in a boat with no tactician!

I'd love to see how they work one day though, please!

[Ed]

...Does the CVRDA have any rules about these devices?

don't make me laugh

we have enough problems trying to make sure boats are even trying to be within their own rules!

I would love to see how many of our boats are sailing within a 'strict' reading of the rules.

Thinking about it:

My Firefly doesn't....no mast gate, dubious mixture of MkI and MkII gunwhales (checked with NFA who weren't worried about it) and suspect there are some other issues with it, but I am sure if I put a mast gate back on it would be fine for the nats.

My New IC doesn't.... as has no string/elastic between daggerboard and boat (but sailed at Worlds like that - as did many others)

My Finn doesn't....as no floor-boards currently, but again, no-one seems too worried and it will get done sometime.

The Old Canoe 'Conquest' wouldn't measure I suspect to new rules, but may well be OK within original set.

Jollyboat???? We don't even know which version of the rules we have is the accepted version - 65, 71(may not of been voted on at last ever AGM) and 98 (certainly never voted on) and few of the boats would fit into a strict measure of most of them!

The Tideway.....who knows, but I somehow doubt it would survive a real proper measurement - too many bits replaced.

But they are all trying to stay within the 'ethos'. I think the bigger question for 'us' is what do we think of major re-builds of old boats to bring them right up to date and take advantage of rule changes.

Old boats, with bigger sails, higher masts, lighter hulls etc than the hull was originally designed and built for??

I, personally, am less worried about this than some, but still I can see that this is potentially a much bigger challenge to our 'rules'

eib

[Obscured by clouds]

hah! had to laugh at ed's last post.

For what it's worth, I think for the purposes of CVRDA as long as the boat stays within the ethos of the assoc. rather than the class association [if there is one, that is] then that is what counts.

I think carrying a gps is fine, to show how fast these old girls will go, if only for bragging rights.

Whilst renovating/tarting up Unit 2/7 I agonised somewhat over the work I had to do on the transom, until I realised that this might the last Unit around so what I did was immaterial from a 'class rule' standpoint. as long as I did'nt radically alter things then the ethos and spirit of the original design remains.

The Unit seems to have been a testbed for ideas anyway so I suppose I can write whatever rules I want

[neil]

I'm happy to lend out my Velocitek for the Roadford weekend if required. The GPS will have to be fixed to the boat, not to the boom as a decent gybe will spike the output.

I use it for practice and boat tuning, it's useful to watch the impact of shifting weight a few inches, but don't use it for racing.

GPS is not the best ways of measuring distance travelled over time, especially conventional GPS but it will allow comparative testing and will be fine for a bit of fun (just don't start the Albacore can do 20+knots on here)

I don't have time to go into the various errors in the GPS signal, and the receiver issues and you wouldn't thank me for it, but there's better ways of doing it. It's been many years since I wrote the code and Kalman Filters etc, and it costs serious money for differential or RTK GPS as the differential kit will give you decent accuracy, but you won't fit it in a dinghy,

If you look at the kit that's used at Weymouth you'll see that it's just measuring the time it takes on a known distance.

One solution would be to agree a relative wind angle, set up 2 buoys a known distance apart and time the trip between the 2 buoys, but we'll never agree the process so just a fix GPS in the boat, watch the number go up and brag about it.

There's no difference in receiver's hardware - they all use the same components with slightly different software looking after the filtering. It's then down to the user interface and branding as to what's a "good" GPS.

[Ed]

Well....my thought was certainly to lay two buoys (or two boats would be better) and use GPS to station them 1/4 of a mile apart, across the wind and then time boats over both directions to attain an average.

It wouldn't be a peak-speed but an average over 2 x 1/4miles drag-reaches.

You are saying this would be very hard to do??

To what level of accuracy? Would it really need total accuracy...or would a CVRDA 'rough' approach give some fun results that would at least be consistent for all those taking part?

Would google maps be just as good at laying the marks?

Is there a way to use a compass and trigonometry?

Gosh, this almost feels like trolling

eib

[Graham T]

At Kielder we have the "Greased Cougar Trophy" which runs all year. Our main sailing area has a circle of twelve buoys 900m apart with a central mooring for the committee boat when we are club racing. This not only gives us a simple way of having a pretty true windward mark every race, it also means we have fixed marks a known distance apart. The Greased Cougar is a self timed event where you simply time your run from one mark to it's opposite number as close to the central mark as you can and put the results on a board in the clubhouse where they are pored over every windy weekend. We have formula to work out average speed and for the sake of the trophy incorporate PY so the results are relative.

[Ed]

What fun....

love the idea of that!


eib

[Garry R]

For on the water speed measurement in a cvrda event (and of course sticking to the ethos of CVRDA) I am sure that if you use a GPS system designed before 1965 and built before 1985 no one will object. I believe that you can still buy them at car boot sales and antique shops - they are those propeller devices you chuck over the side.........

[JimC]

GPS/Racing/Rules etc... a piece of PVC tape over the readout so that you can't use it in any way whilst sailing would be the sporting thing to do I think.