Need help with prop measurements and transom spacing

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
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Southern Airboat Member
Posts: 510
Joined: Mon Apr 06, 2009 6:41 pm
Location: Sanford, FL

Need help with prop measurements and transom spacing

Post by SthrnStyle3 »

I have the engine stand built for my new build. It's a 350 with a 2 to 1 precision gearbox. I'm trying to decide how far forward I need to move the engine stand to fit a prop (I don't have a prop at this moment). At 78", the prop will be about 6" below transom. I need to know hub thickness and how far past the hub centerline the trailing edge of the blade will protrude, to give me an all together measurement of how far the prop mounting surface on the gearbox needs to be from the transom. Thanks.
12' aluminum hull, 350 sbc w/ flattop Pistons and camel hump heads, side by side seating w/ double in front, 2:1 gearbox and a 78" whirlwind whispertip 2.0

One Eyed Gator
Southern Airboat Member
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Joined: Wed May 30, 2007 11:33 am
Location: Ocala,Fl

Re: Need help with prop measurements and transom spacing

Post by One Eyed Gator »

I have 2 different hubs a 2 blade water walker and a 3 blade Sensenich each is different dimension from the mounting face to the center line of them blades. The sensenich have a larger dim. also had a powershift short and it was different dimension the the other 2 hubs.

I have a similar setup with a 5.3 and 2:1 precision box. With an 80.5" 2 blade R mine is 6" below and 6" away.

FYI the precision drive has a bolt where the prop bolts on the flange on the 3 blades needed about an 1/8" removed to fit, had the mill a good bite of the water walker and we could not mill the short hub due to how close the blades mount in the hub.

Now that should not be a problem with the Whirlwind prop. Really wanted to run one of there props but I sent the a question to them on there website "contact us" and never got a response. Which surprised me based on the good comments that I have seen on SA. Sent the same question to sensenich and water walker which both responded quickly.

Will be more than happy to measure both when I get home. PM me your number and I can fill you on a few other things I encountered.


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