1st Air boat - Build ideas - Thoughts?

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The-Pun
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1st Air boat - Build ideas - Thoughts?

Post by The-Pun »

Hey everyone, so I'm looking to build a 13-14 Ft Aluminum hull boat on a budget.

Trying to pick up a nice boat with trailer for around 1500 and then putting on a aluminum 5.3 EFI chevy motor and doing a cam, intake and headers. Figure it'll make around 400 HP at the crank and it'll be a great budget built motor.

Has anyone had any experience with this motor on an airboat and the measurements used to weld up a motor mounts and all that? ANY input on gearbox, prop, and all that would be greatly appreciated!!

Trying to keep budget to 7000!!

Dirtman
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Re: 1st Air boat - Build ideas - Thoughts?

Post by Dirtman »

Don't mean to rain on your parade but just don't think the budget you have allotted is going to be able to get the desired result. Nice aluminum hull alone will probably run you around 1800 to 2000 or more depending on how good it is and wether it has poly or not. Motor mods might not be too bad if you already have it. If going with a carbon adjustable prop anything less than a 1000 is probably going to have some issues to be addressed, like new leading edges or just refinishing. Then you have seats and cushions, gauges, wiring and plumbing will eat up more than you think. Trailer and various other parts like rudders, gas tank, materials to build rigging are all going to nickel and dime you. And then you still have a gearbox to purchase and I haven't been watching prices on used gearboxes but I would think you are still in the 1500 to 2000 range for a box in good condition. Might be better off to search for a complete boat already put together. Its always cheaper to buy a nice used one than build a nice one Just be careful what you are looking at
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Deano
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Re: 1st Air boat - Build ideas - Thoughts?

Post by Deano »

Realistically, your budget amount would have a much better chance of being attained if our plan was for a 'glass hull running direct drive. Without meaning to sound pessimistic, IMO your desired goal vs. budget amount do not belong on the same spreadsheet.

If a man could by a 'nice aluminum hull and trailer' for $1500, there would be far fewer glass hulls in service. :|

If you hypothetically figured a good gearbox at 2k and a good prop at around $1500, you are already half way through your budget and still need a boat, a trailer, an engine and everything else to connect them.

Or, if figure $3500 for a hull and a trailer, you are half way through your budget and still need an engine, a gearbox, a prop, and everything else to connect them.

In either case, those numbers are fair and practical. Be aware also, that "everything else to connect them" will end up being a measurable percentage of your total. It will not end up being a passive jar of change here and there.

I agree with Dirtman (and many others who have answered this same question in the past), that you will very likely be better off trying to find a boat that's in or near your budget. If your are hesitant to believe that, spend some time researching what you are proposing, and you will find that you can't buy (let alone build) the boat you are describing for that amount.
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The-Pun
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Re: 1st Air boat - Build ideas - Thoughts?

Post by The-Pun »

Thanks for the responses

I could always do a fiberglass hull. Here is one with full cage and rudders for 500 obo - probably could get him to do 400

https://orlando.craigslist.org/bpo/5554205389.html

A 5.3 motor can be picked up complete for around $500 - used headers, cam, and valve springs will probably set me back a 800 ish.

What are the advantages and the disadvantages to a direct drive vs a gearbox?

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trailerdon
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Re: 1st Air boat - Build ideas - Thoughts?

Post by trailerdon »

A direct drive application will limit your RPM's too 3k'ish. there for your 400 hp motor @ 5400 RPM will only produce a portion of its hp. Maybe you should consider an a/c boat ?

Olf Art
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Re: 1st Air boat - Build ideas - Thoughts?

Post by Olf Art »

First things first, OK? Have you ever actually driven an airboat? A lot of the questions you're asking would be second nature to someone who's actually spent some time running them ...... if you don't have that kind of experience then building your first airboat would be really stupid in my opinion.
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kwanjangnihm
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Re: 1st Air boat - Build ideas - Thoughts?

Post by kwanjangnihm »

Test Motor #1-Stock LM7 5.3-Liter

Block: Stock
Crank: Stock
Rods: Stock
Pistons: Stock
Cam: Stock
Heads: Stock
Intake: Stock
TB: Accufab 78 mm
Headers: QTP 1¾-inch long-tube
Peak Power: 363 hp at 5,300 rpm
Peak Torque: 385 lb-ft at 4,400 rpm
Torque Curve: Exceeded 360 lb-ft of torque from 3,700-5,200 rpm

Image

Direct drive caddy motor stock specs below for a comparison.
This engine has 200+ more lb-ft torque at 3000 rpm.

Engine: V8-500 400 Horsepower
Carb: 4 Barrel
Bore-Stroke: 4.30 x 4.304
Compression Ratio: 10.0
Horsepower: 400 @ 4400
Torque: 550 @ 3000
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.

CarMotorBarge
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Re: 1st Air boat - Build ideas - Thoughts?

Post by CarMotorBarge »

The-Pun wrote:Hey everyone, so I'm looking to build a 13-14 Ft Aluminum hull boat on a budget.

Trying to pick up a nice boat with trailer for around 1500 and then putting on a aluminum 5.3 EFI chevy motor and doing a cam, intake and headers. Figure it'll make around 400 HP at the crank and it'll be a great budget built motor.

Has anyone had any experience with this motor on an airboat and the measurements used to weld up a motor mounts and all that? ANY input on gearbox, prop, and all that would be greatly appreciated!!

Trying to keep budget to 7000!!
You won't find an all aluminum 5.3 LS for $500 at the junkyard. The 5.3 engines you find for $500 Will have cast iron blocks and probably have over 200k miles on them. I live in Orlando if you need help.
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer

stonny9
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Re: 1st Air boat - Build ideas - Thoughts?

Post by stonny9 »

I know someone who just built a boat. They already had the fuel tank, motor and rudders but bought everything else. Granted they bought a nice new aluminum hull w/poly. I wanna say I was told $18k in parts. Nice boat though and could definitely win some awards for homebuilt.

All the labor was done by owner. Most if not all of the bolts were even free from me. All of the small stuff adds up. Lights, flag, gas pedal, steering cable, gauges, wiring, paint, etc.

But If you shop around for used parts for say a year then you might be able to do it. I believe in paying for it once so I wouldnt cheap out on something. I would look for a used boat that has most of the major things that you want. You can change the small stuff for lower cost. Seating arrangement would be easy to change if say u bought a front steer and wanted rear.
Last edited by stonny9 on Tue Apr 26, 2016 3:56 pm, edited 1 time in total.

OkeeFrmPhokee
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Re: 1st Air boat - Build ideas - Thoughts?

Post by OkeeFrmPhokee »

I have a 12 ft 3/4 Deckover (fiberglass) with trailer all it needs is tires for $500..Includes gas tank, rudders, and grass rake. Also has new steel flex on bottom- no rigging but has good stringers..
Text 561-261-3634 if interested

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