I have modified the Rudder today with a large and deeper plate. Should have more authority. . Hope the pvc last long enough to have some fun. The beauty with the pvc is that it is easy to replace.

Jacko51 said..
Your Rudder may not be too small. Need a rudder on each hull and you are not using it correctly. Should be pointing down not parallel like in the vid.
And maybe some foils like these - Goodall Foiling VIPER (goodalldesign.net) instead of the centreboards

Dude . I looked into Goodall Foiling VIPER .. you miss the point of my project. It's a dot cheap fun to do experiment. Far from a professional model. Your good all design foiling viper is a 23;950 euro boat.. you can't compare.

Jacko51 said..
Your Rudder may not be too small. Need a rudder on each hull and you are not using it correctly. Should be pointing down not parallel like in the vid.
And maybe some foils like these - Goodall Foiling VIPER (goodalldesign.net) instead of the centreboards

Jacko51 said..
"And maybe some foils like these - Goodall Foiling VIPER (goodalldesign.net) instead of the centreboards "
Chill out dude.That was my attempt at being funny.
Re Rudder. I think you missed the point. Google Catamaran Rudders to see how they should sit in the water. ( Not a criticism just a suggestion )

No problems mate,,:-) i did think of doing those rudder, but its very hard on a surfboard without getting into a complex cable system, i tried to keep it simple, i will keep thinking about it, see if i cant come up with something. on a serious note, what do you think of the hydrofoil,, the cheap one.. might help?

a trap would be cool, but i would have to drill the board to do it, i did not want to do that, also its hard to create a solid mast mount. i did consider it,, the pvc cost me a lot, i will try to improve it. i added 2 more tention ropes to help reduce the stress. watching the video made me realise that the outer board was shaking a lot because i was sitting on the wrong side. sail pushing on the board i was sitting and making the other one too light. i will try again soon and take another video to see the diffence in stress.
i am trying to stick with the pvc design as it is easy to repair if it breaks. better flexing that something snapping because it is too rigid.

im hoping to try on friday morning the new improvement.

Heavy1 said..
Hi Chris,
Very nice neat implementation.
Ive done something similar, but the aim was not to make a Catamaran sail boat , but a catamaran windsurfer.

Using two D2 sail boards or two racing sups you can make a craft with incredible stability and amazing glide and upwind ability.
Cross spars are best done with old windsurfer masts. and a third small windsurfer sits in the air in the middle. That has a nice deck plate and a nice area to stand. The ultimate learner craft, although to transport it you need to make sure its easy to assemble.

can you send me a picture of the one you done.. i already have another design in my head if i do sell this one one day. i was looking at 2 racing sup as well because they cut into the water better, unfortunaly they are very expensive. by project was meant to be a cheap one so the wife dont kill me. i do consider mine to be a catamaran windsurfer because i am using a windsurfer sail and 2 windsurf board.

this design allows both board to move up and down independently from each other. the grey pipe is fixed to the boards, the blue can rotate around the grey..

What can I do to lift the back of the board without causing too much drag.. wonder if a long back fin would help.. got to be cost effective too. Thinking of making a wooden foil.. but it's hard work to get it right.. suggestion welcome.

kato said..
There's a lot of flex in that 90 deg elbow which is no good. Try stiffening up that and allowing the flex into the cross member's . Nice project

Watch the second video. 2 attempt. It's much better. The joints are mounted on a 1cm thick rubber washer to the board to take the extra flex from the joints.

My two cents worth, youve done a great job, I'd been thinking of something similar for a long time but don't have your expertise, always thought of using starboard starts and two sails. I never thought of the mast mounts that youve come up with brilliant as always there was the problem with stays etc getting in the way, also I figured the frame to board mounts would have to be flexible to allow the boards to track the water individually but the pvc seems to have alleviated that issue as well. A per lifting the back I think one seat on a slider would be simpler and I don't see the need to sit so far back with the cut of the sail? Another thought is that as you are using center boards and I think you have the boom tethered to the back of your craft so you are not using yourself to create the center of effort you could move the mast track well forward? As I said just my two cents worth. I always wanted to create something that would skim along in really shallow water. Cheers and best of luck Bob

Hi Chris thanks for the reply but I've long since given up on the idea as cost prohibitive but you never stop thinking about this stuff. My idea was to plane like a sail board but getting enough drive to lift out the hulls was always going to be a problem, I probably needed something like a couple starboard hypersonics that plane in light winds but as you said finding two old free boards ????? maybe there might be a few of those old serenitys out there, they were designed as light wind cruisers? Now the foils thats an interesting rabbit hole to start thinking about, maybe I should have just bought a Hobby Tri Foiler. Best of luck and as long as youre having fun more power to you Cheers Bob

Hi Chris. Good on you for having a go ! It beats the **** out of going to the pub and drinking beer all day. Could I suggest running another stay to the front of the centre board case. It would allow you to put more power into the sail. Look forward to seeing your next video!

The end of the windsurf cat. Got stuck into the high wind pass the sand bank off Melville today because of a lack of steering caused by the 2 rear fins. Boat kept going downwind faster and faster until it all exploded in piece.. that's how it felt the sail came off breaking the frame into 2 piece. One of them slicing my fingers . I had to disconnect the sail as it was keeping the boar upside down. Lost the sail. It should be somewhere in the swan river now still tension and attached to the boom. Lost the2 bcf chairs. Only recover the board and paddle back to shore. Ended in need point Walter.. I do have now 2 perfect mistral that will be going for sale soon. What a shame. Took 2 hours to get back. Hope someone find the sail.

Bugger Christopher, it was all going so well

I'm not sure if anyone else has mentioned the cup holders yet. But I'd just like to comment that they appear critical to success of the design, in case they somehow get overlooked in future revisions.