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GPU - mixed messages


Well-known member
Today, I spoke with an airboat builder. He told me what a great engine the GPU was for an airboat and that it was one tough engine. According to him it was nearly bulletproof.

I phoned a different airboat builder in my same state to see if he repaired GPUs. He advised against purchasing an airboat with a GPU. His reasoning was that GPU engines are not built any more and parts are becoming scarce. He also mentioned that a Lycoming engine would be a better purchase due to the availability of engines and parts.

Why would one airboat builder suggest a GPU and another condemn a GPU? What is the real story?

Thanks for you input,
Because the guy is trying to up sell you. GPU are good motors and plentiful and cheap.
Both are correct. There are lots of GPU's and plenty of parts available for them. The down side is they don't make parts for them anymore. However, lots of parts are out there and at reasonable prices. Complete units can be had for less than $1000 dollars. They put out a lot of power for the money.

The nice thing about a Lycoming is that parts are still made but they are expensive. Just be careful what Lycoming you buy. The O-290 is no longer produced and the parts are getting hard to find and very expensive. The O-320 and the O-360 are the way to go but you will pay to get a good engine. A good core will cost four to ten times what a 220 GPU costs.

I have one of each and the GPU is the best buy for the money I've ever spent. If I had the money I would go with the O-540 or the O-520 but the O-470's do a nice job too for the money. Just remember, money is the answer to most problems. If you have a lot of it, no problem. Most of us have to make due with the best we can afford for the least can come up with.
tf, I'd be proud to have a boat with a GPU on it. They're a little heavy because they were never intended to be used in an A/C type environment, but you can lighten them, and they've logged millions of hours turning propellers. JMO
The airboat builder in LA said that he had a GPU but was getting rid of it due to the advice of a Jr. Jernigan? who supposedly knows about GPU parts.

According to the first airboat builder I spoke to, the GPU was a dependable, reliable machine.

I live in Louisiana and am looking for an airboat for the first time in the 13 - 14 ft category.

Service is certainly a consideration. Where would one have a GPU repaired in Louisiana if the need arises?

What are your thoughts?

Hey Tom, If possible I would reccommend a Chevrolet but if your bent on getting one with an AC engine I wouldn't worry about either Lycoming or continental they both have their place. Most boats in Tx and La now are Automotive power.

You can put a 350 in a 14ft Boat that will run awesome. You can carry a heavier payload with the automotive engine. Parts are cheaper. You won't have to worry about aviation Fuel and anyone nowadays can work on a Chevy. In texas we only build a couple a year anymore with A/C engines. If you want to come by the shop we can take you for a ride in several models of boats so you can see what you want before you buy. I'm sure some of the guys in La would do the same thing for you.
Go run one with both kinds of engines before you buy. We are located on the TX/LA border on I-10, stop by any time.

Where is the 12x8 airboat that you have for sale in the classifieds? Is it in Orange, TX or FLA?

How does it run? How many hours does it have on it? When was the last time it was overhauled? What kind of gurantee do you have with your pre-owned airboats? How many times has it been sunk?

My wife and I went by your shop in Orange, TX but you never offered to take us for a ride.

Surely I'm not that ugly! If so, I can't help it, I was born that way.

Tom, the 12x8 is in N.Florida in the Panhandle. It is in like New condition. the boat has never been sunk. and the engine has very low hours & recently been overhauled.
I placed the ad for the guy who wants to sell it. I will get with him to get more answers for you. I know this boat runs great though. I built this boat for myself and only sold it right before I got married.
We do not warranty used airboats. We sell them on consignment, but we do not sell just any used boats. We only try to sell the higher end quality used boats.

If you buy a New boat we put a
Lifetime warranty on the Hull,
5 year warranty on Metal work
2 Year Warranty on the Polymer
1 Year Warranty on the Engine

I don't recall meeting you at our factory but we do take demo rides but usually by apointment only. If we took every tire kicker that walked in the door for an airboat ride we would never get any work done. I apologize for not getting you in a boat to help you determine what you were looking for. If you want to take a ride, all you need to do is schedule an apointment to come in and I will have a boat in the water with gas in it.

Let me know If I can Help,

Are you calling me a “tire-kicker�? (Just kidding)

Is the airboat you have advertised for sale on the classifieds a 2005 model and only two years old?

I need to ease into airboating to be sure that I like it. It may not be for me, thus the reason for going with a pre-owned airboat.

I feel that it is important to start with an airboat that is dependable and reliable so you don’t get frustrated dumping an inordinate amount of time and money in it. One’s frustration level gets high quick concentrating all your efforts keeping it running and having it worked on. I prefer a good used airboat to start out with.

My wife and I didn’t’ meet you. We spoke with your father, Stan, the couple of times we went to your factory in Orange, TX. He was cordial but never once mentioned taking an airboat ride. Both times we went there it was close to closing time so perhaps that is why a demo ride was not mentioned, no problem. Thanks for letting me know about demo rides.

The pricing of airboats is perplexing. In Airboat Trader, there is 1977 Airgator for sale for $19,500 with a wooden prop. Why would someone pay this for a thirty year old airboat when airboats only a few years are advertised for a similar price or cheaper with less wear and tear equipped with a composite prop? I just don’t understand how the worth of an airboat is determined. It is confusing to me.

Thanks for the input on GPUs, any other input would be appreciated.
Well, many people put their selling price into what they have invested into a boat.
optional equipment makes the price vary as well. However, an older aluminum hull that is in perfect shape does not scare me at all if all the metal work has been rebuilt with a good running engine. Some older model hulls are better than new models of some builders. I think other people on here would agree with me about that.
Designs of some older hulls are sliders where most new hulls have better turning capabilities.

A new boat with a 350 Starts in the Lower $20,000 range . So some poeple preffer to buy a new boat because it has all the warranty's and you know where it has been. If you find a good quality second hand model you can expect to pay 12-20 thousand for the type of boat you are looking for.

You also see alot of inexspensive boats on the airboat trader that are Florida design boats that will not work for many Tx/ La applications. These boats work great in shallow water and the terrains of Florida. Depending on where you are in La, there are areas of very deep water, stumps, logs, swampy areas that are completely different than in Florida that require deeper sided hulls, deeper transoms, x-tra braces ect.

A 29" Deep side is much deeper than what is needed in Florida, a Florida 20" Deep side would be way to shallow for La Marsh. (Unless it's decked over)

Why would I need an airboat with 29� sides when my 20/42 tunnel hull aluminum boat with 20� sides has worked well for years?

I am new to airboats and don’t understand, please explain.
Great answer, Faron.

So Tom, are you convinced yet that these folks know what they're doin ? Or are you still miffed because they didn't stop everything they were doing and take you for a ride ?
Tom, anything you here on this site from these guy's comes from lots of experience and hard learned lessons. Everyone here is here to help, That's the best thing about S.A. The best thing to do is get in one enjoy the experience,soak it up. I guarantee you will be sold. This is the best source for quick info that took these guy's years to figure out. Have fun and keep us posted.

The fine folks in the SA forum know what they are talking about. That’s why I’m asking questions and I appreciate the input. It’s apparent by reading the various posts and the replies given in this thread of the airboat knowledge. Heck no, I’m not miffed about the ride, I never expected it in the first place. Faron gracefully extended an invitation to ride by saying, “Make an appointment� which says a lot about his character. I hope you picked up on the humor and didn’t take my comment serious about the ride. As I said, it was right at quitting time when we went by. I am really not that ugly. J

The only way to find out information is to ask. Hopefully no one is offended by asking questions.

Initially I was interested in a mini airboat for bowfishing (2 guys) and a pleasure boat. It appears that might be lacking in power. I am now leaning toward a 13’ – 14’ Florida boat powered by a GPU with 20 inch sides. Now Faron has me considering a small boat with a 350 and 27 inch sides.

It is confusing to decide what you need. Please keep your comments coming.

I learned something about Cont. Gpu engines the other day. They are not all the same. I have a friend that just bought an airboat with a Canadian mfg'd GPU on it.
From far away it looked similar but up close it was very different. He was surprised that I noticed the difference and he explained then that it was still a GPU but manufactured in a plant in Canada. The crankcase has a maple leaf cast into it by the accessory housing, the valve covers each have two plug ports on the bottom, and the oil sump is external not part of the crankcase as other GPU's. The oil sump was factory not some custom fabricated piece. He has had a couple of airboats and one with the other style GPU on it and he says this one is by far stronger than the other one. Anyway maybe they are all made in Canada but this one is definitely different from the ones I've seen before.

The one thing about most GPU's is that they are probably worn out and need a rebuild before you put them on an airboat. They have long gone past their intended service life when the military retires them. I'm sure there are exceptions, but I would assume the worst. And there is something with running the oil line for the cooler, if you run if from the wrong spot you can damage the engine too.

There are plenty of discussions on here about GPU's just search the forum.
There are pros and cons for every engine.
TF, if you run in deep waters, get the high sides. I have an 11-6 Gilileo with 18 inch high sides. It has a Lycoming O-320 and is very light compared to my newest boat. The new boat is a 13 foot Laser/Bandit Hull with 22 in sides. I have a Continental 220 GPU on it and the boat is very heavy compared to the Gilileo. The GPU hull is 7 foot wide and has 12 inches of freeboard. The Gilileo only has 4 inches of freeboard because the hull is only 6 foot wide.

The Gilileo is lighter and more nimble and perfect is the shallows. On plane in deep water I get water over the top on the starboard side when I make right turns, mostly due to torque roll to that side. It's nothing the sump pump can't handle but still a pain. If the side was a few inches higher I would be happier. I even sank the darn thing at a steep boat ramp once because water came over the transom. I sure wouldn't take it out in deep rough waters.

The GPU Laser/Bandit Hull is faster, has more power and gives me great comfort with the higher sides. Even though it is heavier, there is less boat in the water. It even gets on plane faster. I have a 72 inch wood prop and I cruise at 35 mph on the GPS at 2000 RPM. The only down side is it's not as nimble as my previous Gilileos but a lot safer. I have no idea of the conditions you will be running in but 27 inch sides sound good to me. Just be sure to check out the actual freeboard on the boat you buy. The wider hulls displace more water.
Des Moines,

On occasions it will be necessary to traverse deep water at but most of the airboating will be on the bank and flats. Other places, it will be necessary to run 7 ft canals in order to access shallow marsh.

I usually venture out on days the wind is not too bad, thus avoiding the rough water.

With your explanation, it makes more sense to go with an airboat with 27 inch sides for the safety factor.

How do you like your GPU? How many hours does one usually have to have before any work on them?

Thanks for your input,
I ran a gpu on a 15x7 alum. hull with 24" sides for 10 years and never had any real problems, other than a couple of broke valve springs. When I got it we put new rings in it and converted to a holley carb. The only problem I had was having a heavy load in deep water when it was rough, other than that I never worried. They are great engines for the money and pretty simple to work on plus they run on 93 octane and great gas mileage.

That’s pretty awesome ! I didn’t realize GPUs were that reliable, running them for 10 years

What size GPU did you run? Where do you have your GPU serviced if any problems? Do you still have your GPU airboatt? What kind of hull were you running? I wasn’t aware that the GPUs got such great gas mileage, thanks.

I see that you live in Beaumont, TX. I live just down I-10 from you in Sulphur, LA.

It’s a small world.