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New guy to the forum

L

lugnutz

Member
Hello to all you Southern Guys! I just logged on and found your site. I've been on lots of forums but mainly cars and trucks and have found most to be a great bunch of people doing the same thing I am just in different places. I retired from the Coast Guard a short time ago and moved to Northern Michigan and find myself with a crap load of time in the winter. I usually pass the cold days restoring cars or trucks but kind of got a wild hair to build an airboat. I don't build things like everyone else does, I like to do things a bit different, so I hope you guys won't mind me bouncing a few things off you so I don't hurt myself or someone else. Thank you in advance.
We don't have many airboats up here. The Great Lakes are too big for them and the smaller inland lakes aren't grassy so if you want to get someplace on the water you drive there in a conventional boat. I want to build an airboat for primarily winter/ice use.
Question #1 (of many I am sure): I plan to use a converted marine 327 SBC to power my creation. I have researched the propeller speed/noise issue and agree that a reduction gear is neccesary. Has anyone ever tried to use a marine standard reduction gear? I have a Paragon redgear on the back of one of my 327's and have thought alot about trying to bolt the prop to the output flange. I would also have the ability to put the propeller in neutral. Am I whacked or what??

Thanks for your input!
Tim
 
You got a couple guys up that way that build ice boats.

Hardwater Airboats/Cranberry Creek Marina - Robert Hanko - 440-967-3932 - he wrote nice article for us in Jan/Feb issue on Ice Fishing Lake Erie.

Ron Miller at 616-813-8405 - wrote article for us in Jan/Feb about ice rescue - he is northern rep for Alumitech

1000 Island Airboats builds some unique looking airboats - you can see it in our Island Hopping in New Hampshire article also in our January/February issue. Gary Anderson - 866-247-2628

These guys know alot about building boats that will handle well and survive in those cold frozen playgrounds.
 
That would be interesting but I don't think the paragon gear would be a good choice. The biggest problem I can see is putting the transmission in gear will give a HUGE shock on the flex plate. The engine would probably die every time you put it in gear. The normal props on a boat that would have a 327 with a paragon gear is probably under 20". The inerta required to start a 70ish" prop would be to much for the unit to handle. If you put an actual clutch on the engine and could slip it a little on engagement it would work but to modify a paragon gear to use a clutch would take a lot of work.
Just my late night thoughts.
Tim
 
I hadn't thought about the differance in inertial force, although the boat propeller is pushing water which is so much more dense than air.
 
yeah but a boat prop is only 12 to 24 in max lenght on typical every day boats. airboat props for a gear reduction depenting on ratio starts at about 76 in. and go all the way to 84 in. plus they weight alot more. i would think that sudden jar would eventually snap the gear box.
 
I think it will be close to how it works in a boat because the motor probably will turn the same max RPM in the water and on the airboat so I bet it will act just as the smaller prop does when it's in water and you put it into gear. To me there is one way to find out!
 
welcome to the world of anything is possible and this site has a lot of people that will help provide advise or tell you what worked for them.
Let the fun begin
 
Hi and welcome! My first thoughts about using a marine gear box would be that the Paragon is a crashbox when compared to the Velvet Drive which can be adjusted to a certain degree. The second thought is that if the prop is only slightly out of balance, neither gearcase is designed to take much of a radial load at the tailshaft. They are both heavy and require cooling. Just food for thought
 
I thought about the cooling and would run an external cooler. I was mainly thinking of starting the engine in gear and leaving it in gear probably 90% of the time. Only shifting out to rev the engine(clear it out) while warming it up. Aren't props balanced to aleviate the radial forces??
Thanks for the responses!!!
 
Gyroscopic forces will be your problem when turning sharply or spinning boat.
As you said, starting in gear will eliminate problems.
 
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