Your idea of a central pin under tension sounds good.

If the profile of the leeboard starts under the horizontal lower guard the straight side would keep the board parallel to the centreline at all times. An upper guard should make it possible to have a central pin under tension.

Maybe not that much tension, just keep it parallel to cl.

Up and downhauls to keep it where you want it.

I wouldn't bother with vertical adjustment, it's is enough complication as is.

 

regards,

Rudolf  

 

----- Original Message -----

From: cateran1949

To: harryproa@yahoogroups.com.au

Sent: Thursday, October 15, 2009 2:06 AM

Subject: [harryproa] Re: sailing BD with leeboard

 

great news.
I looks like there can be a braces and belts solution. Faired and polished rudders reducing drag and improving lift and a leeboard set up.
I have been thinking on how to have a reliable kick up system.

I was thinking of a moulding on the lw hull that the board sits in going from just above the waterline to the top of the hull with a central pin under tension. If the board hits something it can pop out of its bed. Reattach by pulling some strings to rotate it back and it should snap back in. It would work especially well with an ogive It may be possible to get some variation in depth with a slot for the central pin but only so much as it would be pretty draggy if it was in the water. Vertical adjustment would require either roler bearings to allow it to move vertically uder tension or a quick release of tension such as a cam lock system such as used on bicycle quick releases but with a good long vertical lever
--- In harryproa@yahoogroups.com.au, "Rudolf vd Brug" <rpvdb@...> wrote:
>
> Hi,
>
> Today we have tried sailing with the leeboard I made using a Tom Speer proa 3 series foil.
> The foil was 1.5m deep. I didn't want to make it taller as loads might get too high for the materials used.
> It is wood, ply over a post of Douglas pine I had lying about 190x45 mm. I used ply frames to get right shape and a pine strip with rebates at both ends to take the ply skins.
> It sure looked ok and it worked up to the moment I luffed to fast and killed it. It broke just at where the ply stopped.
> With the board we just pulled the sheet and sailed off after hoisting the sails.
> We had to work the board sometimes to get it alongside the lw hull. When it got working I could decrease the rudder angle. We stopped several times to do things and simply pulled the sheet and got going.
> After the board broke and we got it out of the water I pulled the sheet and we luffed into the wind. We had to get it downwind and then it went.
> With both main and jib up.
> Wind was about 8-10knots. We had flat water, contrary to the first time
> It occured to me the finish of the rudders which is less then perfect might have something to do with this also.
> It seems that by polishing your rudder you can get 20 % more lift from it. So no paint and halfway filling and sanding may not be improving things.
>
> regards,
> Rudolf
>