looking for scrap rotor blade sections.....experimenting with water foils......

mcbirdman

Gold Member
So I am working on the conversion of a two smaller catamaran hulls to a sporty cat motorboat. I would like some foils that I could place slightly aft of center of gravity to help raise the stern a bit out of the water as it seems to drag a little. Does anyone have some rotor blade sections from bent up blades they could send me? I would be happy to pay for shipping.

Ideally maybe a 5 foot section to span between the hulls and/ or smaller ones we can play with to see what we can do to improve the performance.

****edit - I could piece together pieces that are smaller..... even in 2 foot or so range. Depending on what we can find I might put two small canard type foils on front and try to make a longer one slightly aft of center to add some list.....I am flexible.......********************************


It looks like for the first time in years our family is going to get the boats out for a week of camping together. My sailboat won't keep up with my dad but with a little boost should keep up and I think we are close to water sking speeds for the kids. We did some testing in November (brrrr) and I think we were around 14 or 16mph but I think we can do a a bit better since it has a 35 on it......

Thanks,

James
 

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Kevin_Richey

Yamaha gyro...Oregon, USA
James: Why not make a airfoil shaped one out of those newer plastic/sawdust deck boards? You could have one board running through, and stack two, and then, three boards on the one side to make the large CofM portion. Glue them together, sand or router your airfoil shape.Add a few coats of marine spar finish.

Or, buy some of those plastic airfoil-shaped covers the aircraft suppliers sell that one can slide over wing spars. Plug the ends, and no sanding or router work needed. Both suggestions should cost you less than paying shipping for donated old rotorblades, in this age of higher shipping fuel surcharges.
 

mcbirdman

Gold Member
I could make them out of something like those deckboards or whatever. I just figured that a few feet of good arifoil cut off a bent up rotorblade wouldn't cost alot. even if it was 2 or so 4 foot sections. But you might be right.... might cost alot. I also figured that with busted rotorblade section the shape would be better than anything I could just whip out.....

I was unaware of the hard slip covers you were talking about.... Hadn't seen them before...... That is interesting.....

Still, finding a way to add aircraft parts on a boat is pretty cool.........

Thanks for ideas Kevin, appreciate it.....good hearing from you.
 

mcbirdman

Gold Member
No Title

Hi Jake, . . I am looking at creating lift AFT of Center because the hulls have a curve up at the chine near the back like a banana...

Thanks, I agree about the trim tabs.....I did install the automatic trim paddles on back.... We got a little testing done before winter set in.... It did help get us past the stern wave and much faster. The Trim tabs are automatic and have helped get me on plane but I figure that I could make something that will lift the boat even when hitting a trough in the waves.

I did just install one of those fins on the motor anticavitation plate to see if it will also help lift. I have not tried it yet......we were getting water inside the hulls and I am not sure the extent it messed up the tests but I am mounting two automatic bilges and using 3m 5200 caulk after scraping off PO's silicone caulk job that is peeling.....

Kite boarders use an amazingly small foil to lift them And the board out of the water. The problem with full foil lift is constant trim adjustments so I thought just lifting on the back a little I can retract the device as needed.

TriToons seem to use the center pontoon a little lower to increase efficiency of the bow wave and then allows the drive unit to follow behind the split water so it isn't dragging as much. The extra pontoon also allows a bit more weight to be carried too.

I figured I will either put an adjustable height torpedo like float with wings on it to increase capacity , or play around with using some channel material about 8 inch wide on last few feet of hull to allow more surface area for planing if I don't put a foil underwater spanning the two hulls.....

I think we are up to about 16mph and watching the videos it seems to be sitting back as expected on the hulls but with the taper it means it is rocked back. Too much adjustment of paddles seemed to just plow the nose so I figured we could use more than just trim in the back..... a foil to lift the hull and more efficient than flat plate trim paddles I was thinking.
 

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