Which prop for a 15hp on my 3.8?

[sergeant]

I have a Honwave 3.8 AE with a Mercury 15HP 2str, some have commented in the past that I perhaps should change the prop to suit the boat, in which case which prop should I purchase to improve performance?

Also, I notice that the engine has an angle adjustment near the transom mounting (setting 1/2/3), which would be optimum?

[lightning]

You need an RPM meter to see what the engine is doing at full throttle, then you need a prop which allows it to achieve somewhere between the minimum and maximum.

For instance my Tohatsu 9.8 has a max recommened RPM of 5-6,000 and with the standard 8.5 pitch prop it achieves 5500.

I tried a 9.5 and it only managed 5 000 rpm at full throttle.

[sergeant]

Thanks dude, perhaps I'll just stick with what I have then. It flies with 2 people onboard, with 4 people it feels rather sluggish at low revs but great at higher revs.

[Fenlander]

>>>It flies with 2 people onboard, with 4 people it feels rather sluggish at low revs but great at higher revs.

I think that's very much what to expect with an inflatable and 15hp. With two (or three if light) a 15hp will pop a sub 4m inflatable on the plane quickly and it feels easy. If you are talking four adult weights the outboard feels a bit bogged down until it pushes the boat to a speed where it's skimming along nicely.

I've always found the standard props on 10/15hp outboards about right for SIB use.

[sergeant]

Originally Posted by Fenlander

f you are talking four adult weights the outboard feels a bit bogged down until it pushes the boat to a speed where it's skimming along nicely.

I've always found the standard props on 10/15hp outboards about right for SIB use.

Yeah it does feel bogged until you get to a certain threshold, where it then carries the boat really well.

Guess as you suggest, I'll stick with the existing prop for now

[Locozodiac]

If it's mandatory to go out boating with 4 mates, you need to install an induction tach and check max wot rpm achieved with 4, then you can dial best prop pitch to optimize best top rpm for that combo.

Happy Boating