way o/t: boat propeller pitch (planing vs. displacement)
Turbo Mini Forums

just bought a mint condition 2nd hand 30hp evinrude for my 18ft bathtub

(my boat only needs about a 15/20hp motor tbh, but cant pass this up)

its off a little speedboat, and as my boat is a bit of a chugger (does about 10kts max), im thinking of swapping the prop for a more sensible one to make the most of the engines rpm

now i was thinking of going for a prop with less pitch (essentially like a lower f/d), and therefore shifting the engines powerband into my boats speed range, also would have thought a deeper pitch would just cavitate after a certain rpm/terminal velocity?

but the chap at the local marine place reckons my thinking is wrong, and i should go for more bite?

he thinks that this way, i can get the same speed for less required rpm, as the engine is a bit on the big side, it should be able to pull her along at a fraction of the rpm? therefore i could cruise around in relative peace and quiet, never having to max the engine out, also saving fuel

i can see both sides here, what do you lot think?

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

0-60? dont think it matters, id go for the higher fd/ pitch

disclaimer, other than model boats i have no experience what so ever :)

Yes i moved to the darkside

Instagram @jdm_brett

test it with the prop you got with it, maybe it will be a little on off when manouvering, otherwise i think youll be fine is it a 2 stroke?

I have a slightly to big prop on my fishingboat, it´s doing almost 4 knots on idle (900rpm) also 30hp but inboard diesel…

internationally known as "big" swede

yeah its a 30hp 2 stroke, ill give the current one a try, see how it goes, just got a feeling its gonna be far to quick for the boat :(

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"