Seeking Advice: Props for B28 w/ 350s

[moguls2go]

What prop size is appropriate for the aforementioned setup? A friend is in the midst of a repower and asked for some advice.

[MarkD]

I have a 1988 with 350 Merc's and original equipment was 17"X17" 3 blade. I had them cupped when I repowered from 260Hp to 300HP.

[Tooeez]

I have 17 x 16 3 blade with 1:5 to 1 reduction.

[cmccool]

The original mercruisers were redlined around 4200rpm while the new ones are up at 5000rpm so will probably be overpropped running original props.

I repowered mine and with 17x15s, my WOT is 4650rpm.

16x16s will spin up to over 5000rpm. I now run 16x16s with a medium cup.

Cliff

[Jeff]

My 1979 28 was repowered to the 5.7 260 hp motors from the original 228 and props were changed from 17x16x1 to 17x17x1 1/4 .
I cruise at 2800 rpms and depending on load average between 19-21 knots. Full throttle is 3900 rpm and 30 knots so I am considering going back to 17x16 since my motors should be getting over 4100-4300 rpm at full throttle.