Another prop question?

[nigel]

Hi,
I have a 30" mono with a Feigao 7L, Hacker Navey 77 and plan to use 11.1V 3 cell lipo, can someone suggest a prop please. I am new to electric from Gas and would appreciate the assistance.

Cheers Nigel.

[Jeff]

Nigel, generally in a 30 inch mono a 9,8,7xl is used with a 40-45mm prop on 12cells or 4s lipo. You need a prop in the 40-45mm range to make the hull handle corectly BUT I do not think your 7l will pull a prop of that dia. Hopefully someone like Jay(fluid) will respond to this about your anp draw and how small aprop you can get away with. Both the motor and voltage in that large of hull is something I do not have exact experiance with.

Jeff

[saleens7]

if you build it light enough, an L size motor could work in a 30" mono....although your turning about 38,000 unloaded rpms, which means youll have to run a smaller prop to keep the motor from overheating...and with a large hull, if you run too small of a prop, it could cavitate alot and take forever to get on plane (if it even does)....now you could use 7XL on 3s lipo and turn about 26,000 unloaded rpm...i would suggest the 6XL, although there is a chance it might pull more amps than the esc can handle....in fact, the 7XL's max stall current is more amps than your esc can handle, but if you "baby" it, it shouldnt pull that many amps....because of the longer can, you will have more torque and should be able to turn a 40mm prop without heating up too bad (you have a watercooling jacket for the motor, right?) however, i would still worry about the amp draw

of course this is just a rough guess....and as jeff said, people like fluid can help you out much better than i can...

[Steven Vaccaro]

I'm with them. I would not suggest a "L" size motor in a 30" boat unless its on a gear drive. If I had to try a prop I would try a x435 first. It may not even get the boat on plane. But its better than frying the esc on the first run.

[SJFE]

I am in agreement with the motor size. I would not even attempt to run that setup with a 77 amp esc. I suggest a Feigao 11,10 or 9XL. An alternative would be the KB-8XL. The big motor will draw les amps and be easer on the esc.

[saleens7]

however, you will have to run a 4s lipo (or 12 nimh cells) to get reasonable rpms with any of those motors..

[nigel]

Thanks for all the great info, this is a very helpful site. I had a brain fart in my initial post, the hull is actually 25 inches long. The motor does have the cooling sleeve from offshore electrics. I did think this was going o be an odd battery, motor hull combo from the very little I have been trying to read up on. I wanted the boat to show a little of what electrics are like at my local club, no real need for super long run times. I wanted to stay away from 12 cell because of weight. I guess if the 7L is not going to cut it then I my just have to get something that will.
Once again all help is appreciated.

Nigel.

[SJFE]

Well 25 inches is a diffrent story. A 7XL would be good on 8 cells in that boat.

[nigel]

Thanks again,
Any more help now that it is a 25" boat.

Nigel.