A Photo & Discussion Forum for Wharram Design Enthusiasts
I built one last year. Works great. Made the vane a bit smaller than wharram specs. For trim tabs I used stainless steel universal joints on the rods to allow for the change of angle along the trailing edge. Used it for two seasons now and the universal joints seem to be holding up just fine on the waterline.
Here are some pics.
I can email you some videos of Wilson in action (my windvanes name!) if you send me an email address.
Pics posted above. I bought 304 stainless universal joints from springfixlinkages.com here in the uk. Not 316s/s but they dont appear to be corroding as yet. I used the 10mm ID for 10mm rods, drilled them on a drill press to be able to bolt with 3mm bolts. Springfix part # R3694.010
Hope that helps
I don't know if I'll be able to explain myself. I'd go with Rory's idea but wouldn't use a universal joint. Just end the rod shy of the trim tab. Then attach to the rod a U shaped piece of metal, horizontal (parallel to the water line) and with the open part of the U looking backwards. And from the aft part of the trim tab a smaller rod that will go into the U. So when the upper rod rotates it moves the U which transmits the movement to the smaller rod attached to the aft of the trim tab.
Some experimenting needed to make sure the trim tab rod won't go out of the U, that's all. Cheap, easy to fix.
Sorry for my English, don't know if it was clear enough.
Your photo is fine, when my boat is dry, i'll probably make the the same mok-upp and see what way to go.
And Rory i have send you a friend request so we can exchange video. Writing mail addresses in public fora can result in a lot of spam.
By the way, thanks for your advice on sailmakers, i have a new main from Rolly Tasker and i am pleased with it.