Input on workboat build needed

[JBMac]

I’ll try to keep this short but not sure if I’ll be able to : I’ve been lurking around for a while, trying to make the most informed decision I can on a boat purchase. I worked for a company for over 20 years that had two air boats and did small jobs for customers (company mainly did terrestrial weed control) I resigned/retired at the end of last year and started my own company. I landed a sizable contract that is going to require an airboat a couple of months out of the year on a large private property. Mainly spraying invasive plants at a mining facility. I don’t need to go fast, but I do need a lot of push to get through some of the heavy vegetation. For power one of my main goals is reliability in a When I left, my previous employer had a couple of Alumi techs With 383 power plants, belt reduction. Our first boat was a Combee fiberglass hull custom built for us with a ground power unit. I spent a lot of time on that boat and it always seem to carry the weight of the water tank well. I found a used hull, stand and cage that looks nearly identical to the one I operated so many years ago. I guess my main question is are these:

I’ve got a 383 short block that suffered a detonation episode with only a few hours on it. Two pistons now have breather holes in them. Crank will need to be turned but everything else llooks good. It’s headed to the machine shop today. If everything checks out, aluminum heads or iron? Carburetor or Holley sniper fuel injection?

For the drive, I’m most familiar with the belt driven reduction units, or with the gear style be more reliable? Assuming I can get 400 hp from this motor, any recommendations on prop for a working airboat application?

Thanks in advance!

 

[John Fenner]

Ok, the belt drives are HEAVY to start with, I would suggest a gear drive, there are a few great builders of those units, Ox, Ballistic, Rotator, do a review search, or even post a poll to see everyone's input.
Now as far as props go for that application I'd suggest contacting Whirlwind directly, my guess would be a stump puller 3 blade or whisper tip, all depends on ratios and RPMS at the peak of the torque curve.
Carburetor is simplest "in my book" an air/fuel gauge with a wide band O2 sensor installed works great, once basic tune and jetting complete just keep an eye on it.
Now the detonation part,, was likely due to poor timing and curve settings, that will be the major factor as well.

 

[JBMac]

Ok, the belt drives are HEAVY to start with, I would suggest a gear drive, there are a few great builders of those units, Ox, Ballistic, Rotator, do a review search, or even post a poll to see everyone's input.
Now as far as props go for that application I'd suggest contacting Whirlwind directly, my guess would be a stump puller 3 blade or whisper tip, all depends on ratios and RPMS at the peak of the torque curve.
Carburetor is simplest "in my book" an air/fuel gauge with a wide band O2 sensor installed works great, once basic tune and jetting complete just keep an eye on it.
Now the detonation part,, was likely due to poor timing and curve settings, that will be the major factor as well.

Thanks for your input John, I appreciate it. I’m looking forward to getting this project rolling- spending the day on a boat and getting paid for it is not a bad deal at all!

 

[kwanjangnihm]

JBMac this is a good read on building an efficient airboat.

"Build a Fuel Efficient Four Passenger Quieter Airboat"

I have been following the recent posts by David Wine (Water Walker) and by private email, I asked him to send me the article he once mentioned back to me that he wrote. He did and I found it interesting enough to feel it is worth posting here for all to see. It would be interesting to see...

southernairboat.com

 

[Aeon]

aluminum heads for sure! lighter and less heat. You could get into a a whole thing about iron holds heat and heat makes HP and blah blah but ill take the modern combustion chambers with weight savings every time. you can boost compression enough to offset any loss in HP due to heat.

is your stand setup for a car motor? is it setup for a reduction and if so what reduction? a aircraft stand will not let you stick a car motor on it. That said stands are cheap and you can replace it with what ever you need to fit.

belt drives are great, we have some that have been running since the 90s with piss poor care. They keep spinning along. That said when i built my new boat i put a ox box gear drive on it.

word of warning on used hulls and rigging. check to see what condition the rigging is in. They have a bad habit of being rusted out and you might need to do a lot of rebuilding to get it back to full strength