Pant

Hi.

I have been thinking about a new prop for my Motley Crew (800cm).

I have a stock kv1800 motor (max 80max).

I have been using an 45/1.4 (2 blades) steel prop with 4S LiPo's and it was running great.

I have also been using 5S packs but the motor will rev to much(36K) so I will stick with 4S.

So the question, is it possible to run 48/1.4 (2 blades) or will it be to much for the engine
and just generate heat? Should I stick with the 45/1.4 prop?

I'm using the boat for sport running and I don't want to replace motors and ESC's every months :-)

For ESC I will be using a 120 or 180amp.

785boats

With the 180A ESC I would try the M642 (42/1.6)to start & M545 (45/1.5) if the heat is ok on the first one. Both on 4s. They might be too much for the 120A ESC.
A 48mm prop is going to really load the thing up. Especially if the boat is running too wet.

Pant

Hi.

Thanks for the answer.

I have been reading that the stock 1800kv motor can use max 80amp for 5 seconds.

Is the the maximum amp usage for the motor for any condition and a to large prop will only slow the motor down
IF the ESC can handle the amp required by the motor?

785boats

When a 'Max amp' rating is given, it usually means the maximum "efficient" amp rating. Loading it up with bigger props will decrease the revs while increasing the amp draw, & therefore the heat, because of reduced efficiency.
In boats we usually end up drawing more than the "Max" amp rating of the motors.That's why we need a good overhead margin with the ESC. For example I've had an 86 Max amp motor pulling around 130A in a hydro for 2 full race seasons. Needed a 200A ESC to cover that.
An increase in pitch can create more speed but with less extra amp draw than an increase in diameter.
The M series of props that I suggested also create less of an extra amp draw over the X series because of the removal of the tongue.
Also, too big of a prop on a cat can cause handling problems because of prop walk & prop torque.

BACKEMF

I have run a 447 2 blade in my Miss Geico. It is Detounged a fair bit and after 6 laps plus mill on a 1/6th mile course the motor comes back quite hot. Good for competition but, not for sport.