I like the idea of an electric solenoid connected to a cleat that is activated by some kind of level switch.  It could be all self contained with it's own battery.  It could also be located below and go to the cleat via an engine shift cable if you are really worried about water mixing with the electrics.  To some it might sound complicated but I think it would be more reliable than arms or levers sticking in the water which are vulnerable to breakage.

Cheers, Paul

On 27/11/2011 12:02 a.m., heinrich_meurer wrote:

 

Rob your idea looks very good but could be prone of catching weed or harpooning innocent photographers in the water trying to get a spectacular shot of your proa. To avoid unnecessary drag it would be submerged/wave piercing? What about a system which is sometimes used to engage the emergency break of small home build windmills. The trigger gets released by vibration and consists of a vertical tube with a heavy steel ball balancing on top of the tube sitting in/on the tube. The steel ball is tied with a piece of cord to a levarage arm engaging the break. The leverage arm sits near the top of the break. If overrotation happens the vibration kicks the steel ball off- it accelerates in free fall to warp 5 and engages the break. The same principal could perhaps be used to release a sheet. I am assuming here that a gravity triggered break/cleat release is ok. It would have two advantages: it releases also when a wave is trying to capzise the proa in combination with a gust. It would release also in case the proa stuffs its bows and is "going down the mine". Also it would have a variability in release moment/sensitivity if one works with different diameter adapters for the tube end the steel ball is sitting on. Full bore during day time and less diameter if at sleep. Try to get a tungsten or DU ball for less windage and corrosion resistance and more punch on the release mechanism :-)

Heinrich

--- In harryproa@yahoogroups.com.au, Rob Denney <harryproa@...> wrote:
>
> I have posted a sketch to the Files section showing a simple anti
> capsize device. Any comments, improvements or other ways of doing
> it, please let me know.
>
> Inspiration was the moth foiler's wands which set the angle of
> incidence of the hydrofoil.
>
> Attach a longish skinny float (maybe a piece of 50mm/2" dia pvc pipe
> 4m long) to a wand so the float is close to the windward hull.
> Attach a cam cleat to the wand axle and the bouyancy on the float will
> keep the cleat horizontal. If the hull flies, the weight of the
> float and the wand, plus the pull from the sheet cause the wand angle
> to change, the axle and the cleat rotate and the sheet pulls itself
> out of the cleat.
>
> The float has to be long(ish) so it is in the same wave train as the hull.
>
> When it is not required, it can be pulled up under the bridge deck, or
> easily removed.
>
> It would be better if the cleat was on top rather than underneath, but
> I could not make this work simply.
>
> It would be even simpler if the device was in the boat rather than in
> the water, but there is too much motion for this to be reliable.
>
> Compare it to the units the big tris use http://tinyurl.com/6rwtgku
>
> rob
>