snapmorgan

iTrader: (2)

Looking at the dyno sheets on my Pfaff 700's, I see that they make max HP at 5700rpm. I can only turn the 32B1's that came with the boat 5200rpm. Any chance the boat would pick up any speed with some 30's? That should put me very close to the max HP. I have a LH 30 and can probably borrow a RH to try. Running low 90's now, always looking for more.

They make 677@5200, 700@5700

BenPerfected

In my experience, the best way to prop comparison test is in calm water with a stop watch. This gives you both top speed and acceleration. Do you have access to a river?

Mbam

Hard to say, most likely won't go any faster. But it would sure accelerate harder.

Are your current props labbed? If not that would make a big difference.

ezstriper

depends on how much HP you are giving up at 500 rpm below max HP

dereknkathy

Only talking 25 hp diff. As Marcbam said, same top speed, higher rpm. It would all depend on how well the boat does everything, docking, planing, cruise, fuel burn as to which prop would be preferrable.

snapmorgan

iTrader: (2)

I have no issues with planing or cruise speed. Current props are not labbed. I probably just need to do some back to back testing and decide from there.

snapmorgan

iTrader: (2)

I am also turning the props out as well. Might try turning them in and see what happens.

Trash

If you aren't making peak HP then you are likely suffering on top speed. In addition acceleration will be improved by propping down from your current set.

The best analogy I can give is look at cars and their top speeds. Many, if not most, pull the highest MPH in something other than top gear (i.e top OD gear). Usually 4th gear for a 5 speed tranny or 5th gear for a 6 spd tranny.

endeavour32

iTrader: (4)

I went from labbed 30's to labbed 26's. In the end top speed was the same even though there was close to a 700 rpm difference. Planning was good with both props, the big change was in acceleration. As you can expect the 26's were way better.

You could either lab your current props and gain 200-250 rpms or have them de-pitched and labbed and get exactly where you want to be. If it were me, I would have your 32's made to work with your current set up. Won't be the cheapest, but in the end you will be happier.

t500hps

You simply need to test. Once we built bigger motors in a 382 I ended up with 4 sets of props. In the end:

28P 15 5/8 maximus cruised the best, 60GPS @ 3,500 with a WOT of 83 @ 5,250
32P Labbed Bravos cruised 58 @ 3,500GPS and WOT of 82 @ 5,350
30P Labbed Bravos cruised 53 @ 3,500GPS and WOT of 87 @5,600

So, what do you want? I wanted cruise speed and stayed with the Maximus.