first run with scratch cat... a rocket! need some help tho

[Fluid]

Sponsons with dihedral instead of flat surfaces will run deeper in the water. I've had several cats with similar bottoms, and IME the bottom of the strut needs to be even with or above the center lifting rail. You are still riding on the prop. Raise the strut 1/4" or more to get the hull down in the water.

Where is the CG in % from the transom bottoms? It may run best around 32-34%. And you may be right - you may need more weight depending on the design of the tunnel floor. It's tough to diagnose a custom build from afar because there are so many small design features which can influence catamaran performance.


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[dana]

i cut away two small frame pieces to make room to move the batteries forward. i got a full 2 inches so we'll see what that does. plus i added some negative angle to the strut. what about a 3 blade prop?

[Jesse J]

I like seeing COG moving forward. I have my ESC in front of my motor and motor pretty far forward. This way my batts end up a little farther back, but still has pretty nice ride. I can give you specifics, but I usually have best luck right where Jay said 32-34%. I don't see why you would want 3 blade prop?

[dana]

well i moved the batteries forward and raised the strut all the way upand now she stays in the water, so i'm getting somewhere. it's still porpoising however. got a little better on that but im not sure if its because i moved the batteries forward or raised the strut. im gonna guess maybe a little of both. altho im wondering if moving the batteries way back would help this problem. currantly they're in the middle of the hull almost exactly. i think i'll leave the strut where it is for now and try moving the batt's way back, see what that does. doesnt really make any sense to me how that would help but we'll see

[Jesse J]

At this point Dana, I would recommend doing one change at a time, that way you can isolate the problem. I would leave batts there and play with strut angle, then fine tune depth. Have you made little marks on your hull so you know exactly what your COG is?

[dana]

no i havent. i really dont know how to do that

[dana]

i think i got it all tuned up finally. i put a rather large pack of silica from another package i had been saving way up in the front of the hull. it musta weighed and once or two, and VOILA! its running REAL nice right now. awesome!