Thanks Dave, yes it's about 34". Complete novice at this, so any help is much appreciated. I didn't find the specs you found when I was looking. Guess I'm going to be finding something else to do with the motor.

Looking at the specs
ROXXY BL Outrunner 4240/10, 980rpm / Volt, 130g
For electric sailers up to 4500g
Scale and sport models up to approx. 2900g.
If you have the 34" Fire Boat then this is too big.
Mark suggested above a 3542/1000 and I agree.
The smaller model is very light with a small transom and I found it has tendency to lean under the tork effect of the prop. Turning had to be slow and gentle to avoid capsize. This is not such a problem on the 48" version.
Props should be no greater in diameter than the motor and should be chosen to keep well within the motor and ESC ratings. A wattmeter will help you check this and a good rule of thumb is to run at about half max current for best results.

I' doing somehthing very similar, rebuilding one from the 60s, when I get time to finish it. I picked up a Brushless outrunner, Robbe/Roxxy Outrunner 4240/10
- is this about right?
- Will it be OK with a 4S/5000mAh lipo?
- What prop would you suggest to start with?

Mark. Many thanks for your advice. Regards, Kevin

Thanks for your advice Shaun. Regards,
Kevin

Hi Kevin,

I have had a lot of success with Tornado Thumper out runner motors paired with Fusion Hawk ESC. For a really exciting performance you could use a Tornado Thumper V3 4260/06 500KV - Brushless Outrunner paired with a Fusion Hawk BL 60A HV N618/Li 26 ESC, however it would probably be a little less exciting and more appropriate given the flatness of the hull when the Crash tender is on the plane to use a Tornado Thumper V3 3542/05 1250KV - Brushless Outrunner paired with the same speed controller.
Motors are available at https://www.overlander.co.uk/motors/brushless-motors/outrunner-motors/tornado-thumper-v3-3542-05-1250kv-brushless-outrunner-rc-motor.html
https://www.overlander.co.uk/motors/brushless-motors/outrunner-motors/tornado-thumper-v3-4260-06-500kv-brushless-outrunner-rc-motor.html
and the speed controllers at:
https://wheelspinmodels.co.uk/i/85116/
I appreciate they are not the cheapest of options but I have found their reliability to be second to none.

Shaun

Hi Kevin, I would recommend a brushless motor, and have great success with Airtec motors, real model shop with real people on the end of the phone. The one i would use is AXP 3542/1000.
They recommend a 60 ah ESC but i would up this to 90 or 100, just in case of a fouled prop etc.
Just type in Airtec Hobbies its all on there website

Mark