Prop Question

[34Hatt]

With 330B in your 32' I think you will land up needing something like a 21"x21" 4 blade this is also what I landed up with. The old rule also was to try and keep it square. I don't think there is a need to go any bigger dia. Dia gives you lift and pitch gives you the speed. The 21" dia gives my 34' plenty of lift which is heavy in the back end.
1.5" shafts are fine just do a good job Installing the props and make sure they are scanned. Tom Slane run 330b's with 1.75 to 1 reduction on a 1.5" shaft swinging a 22"x26" wheel.

[Jackman]

Is there a need for me to go 1.75 to 1? I spoke with a lot of people and looked at Tom's Got Bait repower and they used the 1.5 to 1, I believe. I'm just checking...Once they're in I don't want to have to take them out for a long time.

[sammidog]

Get Gerr's book. It will tell you what reduction to use. I think 1.5 would be fine. Although heavy for a 32 footer it really doesn't weigh that much.

[34Hatt]

Well 1.75 should be better higher ratio usually is. I stayed with 1.5 since 21" was the biggest wheel I could fit. Also I knew the 1.5 work well in a 34C and I knew 21"x21" worked had a 34C in Cape may to compare with. So it came down to being a known package verse unknown and It is more stress on 1.5" shaft you safety factor goes down more!

[Jackman]

The other thing was the HP factor. I could have gone with 370's but I think there comes a point at which you have to decide is too much too much? I think I'll be happy with the 330's, even though the 370's aer only 1k more each.

[REBrueckner]

Do not extend the shaft beyond the aft end of the strut such that the front of the propeller hub is more than 1/2 the shaft diameter or you'll run the risk of vibration....

[REBrueckner]

As the prop tip clearance from the hull bottom gets smaller, water turbulence increases causing noise, possible cavitation corrosion at the prop tips, and some loss of efficiency. Instead of increasing prop diameter to such an extent, you can try larger pitch or cupped props.

[Banshee36]

My series One 36c, 1.5:1 TD trans, 330b Cummins, 1.5 Shafts, 22x22.5 3 Bladed Austral props. 1370 Hours no problems. with a 1:5:1 gear in your boat you will be fine, but remember. When you put her in gear she goes.
JW

[the kuz]

My 1977 36C is set up just like Banshee's, except 22x23 3 blade Michigan Nibrals and 1.5 ZF trans. Next time out for spring cleaning, I will most likely take out .5 to 1.0 " of pitch since I now turn up right at 2800 WOT (600 hrs on engines) vice about 2850 I got during the sea trial when first installed. Before I do that though, I'm going to clean up everything below the waterline really well, and put her on a diet. She is loaded up much heavier than when we first got her back. Be sure you leave some room for 1000 lbs of stuff when you figure things. If I get a good weight this spring, I will post it. I'm guessing somewhere around 22K. If you PM me, I will mail you a copy of my sea trial data sheet. Regards, Bob K

[Maynard Rupp]

Let us not forget that the 32' Hat has tunnels so none of the discussion about extending shafts or the normal hull clearence applies. I am told that it is better to fill most of that tunnel with propeller. Our 36C has roughly 21/2" clearence around the prop tip to the tunnel. An earlier thread here said it is OK to decrease that number to 1". While the early 36C has trouble swinging 23" props, our later 36C,(same design as the 32'), uses 26" props. I would go larger dia. long before I would increase pitch. That statement only applies to boats with tunnels. They are a different animal.