If you change the transmission
ratio you change the power transmitted for the same engine rpm
and old propeller
. To correct you need to recalculate the size and pitch
of the propeller
to restore the thrust. There are thick books
that can assist in doing the calculation but you need to consider the available "propeller free space" at the end of your propeller shaft in relation to the hull
or aperture if you have a full keel
with cut-out for the propeller.
- - The considerations will determine the maximum diameter propeller you can install. With each diameter propeller there are only a few "pitches" available. If you need "more" propeller than you need to get a propeller with more blades.
- - Once the calculations are done then you need to "test" the resulting recommended propeller and see if you get what you are needing. If not then you "borrow" the next size propeller and try it in real life. Normally you can find a propeller shop with a large assortment of propellers you can try if you let them know you will buy the final best one from them.