Honda 90

[Alan Mckewan]

I have just changed my 115 two stroke for a recent 90HP Honda four stroke on my 5.5 Humber ocean pro. It came with a 15 inch prop having been previously used on a heavy services dory. Does anyone know what size prop I might need? Is the 15 too small?

[Alan Priddy]

Alan You need at least a 19 inch to make the boat work well.

[Alan]

What revs are you pulling at WOT? As I'm sure you know the ideal set up is to pull the manufacturers stated max revs at WOT with your "normal" load. IIRC 4 strokes dont rev as much a 2 strokes so say 5000rpm? If you are over reving then you need to increase the pitch. If you are not achieving RPM then you need to reduce.

I would imagine with a 15incher you'll be off the rev counter! Not sure whether you'd spin a 19incher but I'dve thought a 17 inch for sure. I seem to recall that we ran with a 15 inch on the 50hp Yamaha (the second engine!) on Spirit during RB4.

HTH,
Alan

[wavelength]

we run a 5.5 humber ocean pro with a 90 four stroke mercury all new last year. The prop is a 17 inch standard ali prop and WOT revs are between 5100 and 5400 depending on load. Sometimes thin we could do with a spare slightly less pitch for ski-ing

[Allen]

I used to run a 5.5 Delta with the Honda 90 and 19" stainless prop. It worked OK

Allen

[Alan Priddy]

Hell! He is agreeing withg me.

A good night was had by all, but I still have to ask the question WHY ?

[Allen]

You've no idea how hard that is ...... but the answer to your question is - can't remember, you were the one on best behaviour

[Alan Mckewan]

Just gave the Honda 90 its first run - it pulls 5900 rpm at wot on the 15 inch prop (book rev range 5000-6000), but the speed could be better. Do ordinary mercury or suzuki props fit OK? If so I should be able to borrow a 17 and a 19 to try out...

[wavelength]

sounds just like mine (see above)- may have to acquire a 15" for ski-ing etc and generally dragging the little darlings behind!