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.Select to expand quoteJacko51 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. Select to expand quoteJacko51 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
"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 )
Select to expand quoteJacko51 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?
nice one Chris ...the pipe is under some stress ...some old windsurfing mast .might be a better option later ..
as that pipe will break under weight ..i think a tramp still would be a better option ..then you can go from one side to the other
yes foil it ..lol... nah ..stay down ..
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.
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.
Select to expand quoteHeavy1 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..
made 2 new test on the boat this week, with the new modification.. lot less flex on the frame, and i am sitting on the correct side this time,LOL.
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.
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
Select to expand quotekato 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.
Thinking outside the box. Due to the back being under water and at an angle. Those are at an angle of attack that should create some lift. They also point inwards so not to slice anyone leg that would come to close.. horizontal windsurf board fins.
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
Select to expand quoteused2surf said..
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 Bob. Thank a lot for the ideas. The problem with the seat being far back. Is that if I put it any more forward. It would be in the way of the dagger keel. I needed access to the center keel to be able to move them down and up.. I original wanted to have the seat more forward. That said . Once you start moving the back lift up and the problem is not so prevalent . I do have another design in mind and would glad help you build one.. the hardest is to find 2 old boards with 220 litres min. The best would be racing paddle boards.. like those
www.ebay.com.au/itm/Fanatic-14-Falcon-SUP-Stand-Up-Paddle-Board-/254785434154?chn=ps&norover=1&mkevt=1&mkrid=705-139619-5960-0&mkcid=2&itemid=254785434154&targetid=921081725029&device=m&mktype=pla&googleloc=9070583&campaignid=10101785240&mkgroupid=102311925820&rlsatarget=pla-921081725029&abcId=9300368&merchantid=7364522&gclid=Cj0KCQiA_qD_BRDiARIsANjZ2LCqt6nlwtxQjZ357qOuUL96Zo6MDygWz2d3NCxI8reCGpiS6xCbQdoaAoeTEALw_wcB&pageci=90d0cb0b-599a-4d2d-88e6-0dcfa9b682dd
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
Thanks Bob.
Btw the horizontal fins seem to work fine.. the back lifts when I start moving.. my only wonder is does it reduce more drag than it causes.
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!
Select to expand quoteDW773 said..
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!
Hi. I'm not sure what you mean. By stay. I have remove the horizontal fin as I think they may be causing too much drag.. I have modified the seat to be more forward . Hopefully my head will clear the sail.. I sit lower but just in front of the center keel. That will allow the rear to lift . Reducing drag and improving turns. Also I added 2 normal fins at the back for better tracking in head wind
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.
Thanks for all the support on this thread. Made almost 4000 viewers.. the engineering and design worked well to a certain speed. A small mistake of putting 2 back fins brought the downfall of it all. The centerboard and the rear fins on both board at the same time acted like 4 locked wheels. Unable to steer. I kept getting faster and faster down wind. And because my sail cannot do a 360. It locked at about 120 degrees approx and kept powering. The rudder handle broke as it could handle the speed. Then the sail broke the frame. Without the fins it would have steer upwind and loose speed without problem.
Thanks again.
Select to expand quotedecrepit said..
Bugger Christopher, it was all going so well
Yes.. learn the hard way when you have 2 surf board parallel to each other. You can't have 4 keels . Very hard to steer. Like having 4 locked wheels
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.
Select to expand quoteswoosh said..
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.
True that..?? I had 2 of them on the design. 90mm in diameter so that any bottle or can would fit.
