Popeye17

Hello everyone, I'm new here. I'm building a small 18 inch cabin cruiser, and am looking for suggestions on what size prop to use and where to get it. Also what angle to drive it from. It's my first boat, and hope to use the electrics and motor from an old RC plane I got at a yard sale years ago. There aren't any hobby shops close, so, internet is my only source of info. Any thoughts on the matter are greatly appreciated.

Jim A

All Day Dan

My Feedback: (5)

Try Dumas Products. Dan

MACK Products Model Marine

http://www.rcuniverse.com/forum/rc-s...l#post11009591

Got RPM

OP, a lot depends on exactly what motor and ESC you salvaged from your plane. Some may work fine, some may not, but we cannot give helpful suggestions without this information. A boat this size will not require a lot of power, if the motor etc. are from a larger plane they likely won’t work.

You will need a battery and a charger to match the motor and controller. What frequency does your radio have? Some airplane radios cannot be legally used in the US for ground or water models.

Is this boat a kit? If so the the plans may show the motor position and shaft angle. Without that information I would mount the motor as far forward as practical and run the shaft through the bottom so that the top of the prop is about 3 mm below the hull bottom. Of course you won’t know this until you answer the questions above.

Few hobby stores have many usable parts for boats, so you are not at a disadvantage. The site below is a very good one for both parts and information found on the site’s forum.

https://www.offshoreelectrics.com/


.

mfr02

For a cabin cruiser of that size, rather than a race boat that offshoreelectrics seem to specialize in, a 3 blade prop about 3/4" to 1" driven by a 385 brushed motor running on between 1/2 and 3/4 its rated voltage. Again, for cruising type boat, within quite broad limits, prop angle is not critical. What fits will work perfectly well, but a long shaft with the motor as far forward as it will easily go is the best way. You get a shallow angle and plenty of room in the rest of the boat for the other stuff like radio, ESC, servo and battery. The boat is quite small, so shouldn't need a lot of power.

Popeye17

Thank you all for your suggestions. You have been most helpful. The boat is being scratch built from plans for an 18 footer that I scaled down. It was originally set up as an outboard, with a false transom so it looked like an inboard. The motor was from a small plane, set up as a pusher. It's quite old but still runs well. This is being a real fun project. I can't wait to run it.