4 blade prop vs 3 blade

[Alexwalms]

Hello
Any propeller gurus in here?
I have a Revenger 27 with a Suzuki 300, previously had a 24p 4 blade prop and was hitting 48 knots at 6300rpm.
I’ve just fitted a 26p scorpion 3 blade prop and hitting 48 knots at 6050rpm but the boat is feeling unstable at wot.
My guess is this new prop is giving too much stern lift causing a bit of chimewalking?
I went for the 3 blade prop to get a bit more top end speed and hopefully improve fuel economy but now thinking of going back to the 4 blader

[Pikey Dave]

Originally Posted by Alexwalms

Hello
Any propeller gurus in here?
I have a Revenger 27 with a Suzuki 300, previously had a 24p 4 blade prop and was hitting 48 knots at 6300rpm.
I’ve just fitted a 26p scorpion 3 blade prop and hitting 48 knots at 6050rpm but the boat is feeling unstable at wot.
My guess is this new prop is giving too much stern lift causing a bit of chimewalking?
I went for the 3 blade prop to get a bit more top end speed and hopefully improve fuel economy but now thinking of going back to the 4 blader

I’m a big fan of 4 blade props, every RIB I’ve owned always felt more “planted” with a 4 blader. Dunno if that’s my imagination or reality. That said, 4 bladers generally give more stern lift, which puts more of the keel in the water & (imho) adds to the grip, whilst taking a bit off the top end. Which is what you’ve discovered. I’ve tried a few 4 blade props over the years & the “best” I’ve found is the Mercury REV4 which was recommended to me by the legendary Mike Vincent of South Coast Marine.
All my opinion naturally.

[Alexwalms]

Yea the 4 blade seemed a lot more stable…. I could bang it up to wot and it was very planted….. I’m thinking about sending it to steel developments to have it put up 1 pitch to drop the revs a bit and put it back on.
I’ll do some more testing first with this 3 blade to see if I can make it more stable with the trim tabs/ less trim first.
The boat also seems to lean to port more under acceleration than the 4 blade did too… guessing a bit of prop torque causing this

[Pikey Dave]

Originally Posted by Alexwalms

Yea the 4 blade seemed a lot more stable…. I could bang it up to wot and it was very planted….. I’m thinking about sending it to steel developments to have it put up 1 pitch to drop the revs a bit and put it back on.

I’ll do some more testing first with this 3 blade to see if I can make it more stable with the trim tabs/ less trim first.

The boat also seems to lean to port more under acceleration than the 4 blade did too… guessing a bit of prop torque causing this

4 bladers can run higher than 3 bladers. This can mitigate the lean to port. The lower the engine the more pronounced the lean to port…generally.

[gtflash]

Originally Posted by Pikey Dave

4 bladers can run higher than 3 bladers. This can mitigate the lean to port. The lower the engine the more pronounced the lean to port…generally.

Sound advice.

[GARYSHORT]

Hole shot vs top end speed. Also all about the pitch, which ca determine hole shot vs top end.