Scratch cat 36"

[Boaterguy]

if you put a vaporizer/boiler in there, run the steam over the prop to reduce cavitation, it works with engine exhaust, I don't know about steam, you could even try it with water just to add a little pressure behind the blades

[Jesse J]

Jesse, are you running 4s2p?

4S1P - I think the batteries are bunk; Nanotech 4000mah 45-90c (ya right!). Test yesterday failed... extra ride pads peeled off and lost a wire drive/prop! speeds didn't even break 30mph...

Now going with 45mm CF props and epoxied ride pad (so now all ride pads are same depth). I tipped up the props a tad too. If the snow storm is short lived, might get back out this afternoon for another test.

video on the way.

not sure what to make of the vaporizer idea... haven't ever heard of it. please explain more.

[Meniscus]

Jesse, you need to consider running 4s2p. With twin, you're experiencing voltage sag. If you switch to 2p, you should be jamming on plane much better. I wouldn't run 5s or 6s until you get up on plane better.

[Boaterguy]

on full size race boats, the exhaust from the engine is run over the prop in order to reduce cavitation, theres an article on it somewhere, but I forget the site. I was thinking if you boiled water, it would be similar enough to the exhaust, and could also be run over the props. Less cavitation = more speed.

[Jesse J]

Jesse, you need to consider running 4s2p. With twin, you're experiencing voltage sag. If you switch to 2p, you should be jamming on plane much better. I wouldn't run 5s or 6s until you get up on plane better.

if you mean how many packs are in the boat: 2 4S packs, even though each motor only sees one 4s pack, so if that is technically 4S2P then yes.

ran again today.... 28mph on 4S still, but the 45mm CF props... 10mph below what you had calculated. I am wondering if the hull is too heavy - Dad might have rightly named her the "spruce goose"...

Here is video from yesterday. Today she did get a little looser, but still slower than expected. Any reason to not try the 51mm CF props if I stay on 4S?

[Meniscus]

If the hull is too heavy with foam, then you risk pulling some heavy amps. You mentioned it was nearly 10 lbs. ready to run. Is that a guess?

If it is indeed that heavy, it may be too much. In any case, I don't have experience pushing heavier hulls. Perhaps someone else has more experience with more weight could chime in.

[Jesse J]

so you are saying you are a lightweight? I will need to weigh her accurately, might not be that much. Ran today and on 6S2P....... 44mph. somethin aint right...

[Meniscus]

Yes, I'm a lightweight. And you said you have the timing at 15 percent?

[Jesse J]

ya, 7lbs w/o batts, reprogrammed swordies to hi timing. will try on 45 props and if timing is back to where it should be, then will go back to 442 props. Then to throw the data loggers in and see that both are working the same amount.

[Simon.O.]

If it is any help at all, I ran 42 props on mine for a while and had the struts here there and everywhere and could not get the Cat to fly even with some not to clever rpms.
I fitted the 45's and got the results !

[Boaterguy]

Try to lower the stinger a little bit, it seems to be running pretty dry

[sambini]

What would be a good size sinlge motor for the single drive version?

Thanks