View Full Version : Prop Torque

05-12-2011, 10:33 AM
Hi, My boat leans over to the right when at speed. I suspect it may be due to Prop Torque. Does any one have any solutions to counter?

Also if a prop is say 442X what do these numbers mean?

Finally, is a bigger prop always better?

05-12-2011, 11:08 AM
1) What boat? You can move the packs towards the left to counter the torque roll.

2) There a a lot of threads on prop identification, use the search to rind them. Here are a few recent ones:

3) No, larger is not always better, or faster for that matter. Too big and you will go slower and burn up your motor, ESC and cells.


05-12-2011, 11:29 AM
Here is what the numbers mean:


X is the style of the prop
4 = 1.4 multiplier to get pitch
42 = 42mm diameter of the prop.

So, 1.4 x 42 = 58.8mm pitch which means the prop will move water 58.8mm (2.31") on each revolution. That of course doesn't account for any slippage, etc. Using the same formula, an X642 prop would have a pitch of 2.645". That added pitch will put more strain on your motor and battery. If your motor and esc and batteries are running cool, you can upgrade to the X642 but be careful!

Good advice above. DO NOT just increase the size of the prop if you don't want to burn stuff up and put more weight on the port (left) side of the boat to counteract the torque.

05-12-2011, 11:30 AM
Thank you.

05-12-2011, 11:33 AM
You're welcome. Choosing the right prop is always a mystery for me too. Ask your boating buddies what they use first on the same boat/motor/batts/esc and then start with the smallest prop and work up.

05-12-2011, 11:35 AM
The Boat is a 1.1m single v hull (Hobbyking Vanquish). Leopard 40 1500KV motor and 180 ESC. Current running 2 x 5000mah 4S in parrellel but will be swapping to 5000mah 3S in series as soon as they arrive.

Does that sound like a good set up.

05-12-2011, 11:48 AM
Thats a big hull for a 40 series motor, Be carefull you dont go to big on prop size on 6s. Martin.