am i wrong? NOT an AC vs. Carboat question.

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irod
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am i wrong? NOT an AC vs. Carboat question.

Post by irod »

so i'm wanting to do a couple of things with a new/different boat:
1.) fish. i love to fish. hardcore fish.
2.) jump the dikes to access more areas to fish and explore.
3.) carry 4 adults and live bait, most of the time. I like to shiner fish.
4.) i'll proudly say i'm a novice and don't really have a desire to race or do wild stuff. just fish and explore.

I'm not really a hunter or frogger. i don't think we'll do a lot of group riding or camping or booze cruises. some, but not much.
I'm not much of a mechanic. I can change a starter or water pump but I'd never attempt any sort of overhaul. I do have an excellent aircraft mechanic connection that i trust with flying machines. i have a degree in mechanical engineering so i understand how things work and how to trouble shoot, but i don't have the experience to do major engine work.

what i 'think' i want from this boat:
i am looking/dreaming for a used boat.
1.) aluminum hull--being a florida east coaster, i'd love to have a Hamant, Panther or Diamondback.
2.) 13' hull minimum, 14' being my pot of gold at the end of the rainbow. and as wide as humanly possible. i want to have a lot of front deck space for that fishing thing i mentioned.
3.) side by side rear seating, with a bench forward. on those rare occasions the queen wants to just go ride with just she and i, i'd like to sit side by side. i'll never be going alone. and if it's a full boat that's 2 adults, and 2 full sized sons. we're not big people. 120 to 185 lbs.
4.) deep hull. I don't think i'm at all interested in a deck over or sled for my purposes. but i would like walks. i think i want deep to help with any mistakes i might make. I've got 35 years of boat ownership with thousands of days on the water in boats from offshore billfish wagons to bass boats to high speed redfish tournament boats, but i'm smart enough to own up that i'm a novice in airboats and will sacrifice some things for additional safety factors.
5.) removable live bait tank. 20 gallons is 160lbs. like another person in the boat, right. i can rig this, but i mention it because of the weight. so this is like carrying 5 people. but only 'most' of the time. not all the time. the bait tank would be installed/removable forward, to put more weight forward of beam.
6.) won't be carrying a 180qt Yeti, but a modest cooler.
7.) i think i want to hang with AC, and I'm guessing i'll need as much HP as possible. i'm leaning toward 540 lycoming. carbed or injected--whatever's available. i don't think i want to go smaller, do i?
8.) i realize the boat i've described most likely does not exist as a used boat on the market right now (side by side seating is rare for AC motors, i have come to realize), but i'd like to find at least a hull and engine that will do what i'm wanting and then adapt rigging to suit my wishes.


with a very open mind, i'd love to hear if i'm barking up the wrong tree. i know a couple of things i've mentioned might go against the curve or are controversial. help me understand if i'm way off base.
i know there are aircraft guys who will reply with remarks, and i appreciate car motor discussion as well. but keep in mind i really think i prefer the lycoming so unless i'm just not pointed in the right direction, i'd rather not inititiate a 'versus' debate.

thanks for everyone/anyone taking time to help a fella out.

irod.
Last edited by irod on Sun Aug 27, 2017 5:53 pm, edited 1 time in total.

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mojoe
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by mojoe »

I'm an A/C guy, so this is hard to say (sorry Kwan), but you are describing a car motor barge.

4 people plus a livewell is a BIG load and that is where a high hp car motor really shines.

Basically, an airboat performs well when set up at around 1/4hp per lb. A good 6cyl AC motor will reliably push a 1000-1400lb TOTAL load reliably damn near anywhere you want to point it. 4 people and a full live well is already at that weight and you haven't added in the boat, motor, rigging, gas etc.

A/C motors can be modified to create significantly more hp, but reliability goes out the window.

A V8 CM will create enough hp to push the load you want. If you want it reliable and well set up, you better get your wallet out!

Also, consider a 14' hull bare minimum for that kind of load. I mean, have you ever been in a 14' boat? Ever been in one with 4 people, a livewell, batteries, 30 gallons of gas, a V8 and a couple hundred pounds of steel? 14' is a bare minimum!
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by BANANA BOAT »

On concur with Mojoe

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by boatair »

My 540 would not be happy if asked it to do all you want. I hate to admit this sounds like a job for a geared carmotor to me. Maybe a gso0480 or a gso0540 could do what you require but I am not sure.

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by Deano »

The Laws of Physics consistently remain somewhat disinterested with what a person wants to do.

I'll be surprised if the previous viewpoints don't end up being unanimous. :|
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by OneBFC »

Reality is you need to maintain between 4 and 5 lbs of total boat weight per hp on an airboat to avoid anxiety issues on when and where you can go.

Then, you need to make sure you use the right prop and overall setup to properly utilize that power to get proper thrust numbers that also are at the right push point height from the bottom of the boat.

All boat builders know this already so if you talk to them, they will get you set up well.

From my rough calculations with some fudge factor applied, you should be looking at 550 to 650 hp and a 4 blade 82 to 84 inch prop.

I would also think you shouldn't disregard a deck over. They are inherently harder to sink and safer to run overall in my opinion.

OH, I agree that this is a bit too much to ask from an AC engine for a multitude of reasons. Technically possible to do it with a healthy gso480 or gso540, though I wouldn't think it's a good path for a first time owner.

Good luck with your potential boat build!
-Russ
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The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by hdsadey »

If you got the means this the perfect boat for what your describing 45K

https://orlando.craigslist.org/boa/d/di ... 37709.html
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mojoe
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by mojoe »

OneBFC wrote:Reality is you need to maintain between 4 and 5 lbs of total boat weight per hp on an airboat to avoid anxiety issues on when and where you can go.
Tomatoe tomato
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OneBFC
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by OneBFC »

Indeed mojoe, didn't meant to imply what you wrote wasn't valid.
-Russ
-----------------------------------
The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
Life begins at 2 BAR, Just a good ole boy

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by irod »

"hang on, let me overthink this" because its what i always do.
both OneBFC and mojoe add a very valuable data the equation. HP/weight
apparently i need to find one of those beautiful tour for sale if i want to do what i think i want(ed) to do. ;^/
I'm sure this has been done a dozen times on here, but...

hull weight (from Diamondback) 35lbs per foot@14 feet is 490lbs
engine weight (from posts here and other places) SBC is 600lbs, AC V6 is 450lbs
rigging weight (average from posts) 300lbs (steel)
poly weight 1.34lb/sq foot including fasteners is about 84lbs
4 people at 175 each is 600lbs
full 20gal bait tank is 160lbs
misc gear estimate at 200lbs
batteries at 41lbs each is 82lbs
fuel at 20gal at 6.3lbs/gallon is 126lbs


that's a loaded boat of right at 2800lbs. (my skiff is lighter. yikes)
by a 4lbs per HP ratio i'd need 693hp
by a 5lb per HP ratio i'd need 554hp.

holy cow.

but if i had a 2 seater 13 foot boat, i'm still looking at between 400 and 500hp. not being an aircraft power engineer, nor being versed in breakaway forces and gravitational sheer, i simply expect the HP to weight ratio is a radical curve. meaning that the HP line remains at a slight curve, and at some point on the weight axis, the HP line increases like a mountain peak.
and the HP ratio estimates are just that--estimates, of course.
this is very educational and entertaining to experience and learn. thanks to everyone who's replied so far.
*hdsadey i saw that boat and i really do like that hull and design. i sure hope i won't have to dig that deep into mommas purse, though. if i have ask her for that much, SHE'll want to drive.

irod

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by CarMotorBarge »

Your weight estimates are low. You need at least a 40 gallon fuel tank, add a gearbox that is 70 lbs, poly with fasteners will be around 200 lbs, and you didn't include the weight for the walk boards you want. Also the radiator and prop add weight. It all adds up.
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by mojoe »

We are not saying this hp/weight ratio is a must. There are many other variables and thrust pushes an airboat, not hp. This is just a ballpark to keep you from getting stuck all over.

I mean, the reason to get an airboat over a typical kicker boat is so you can go places you otherwise couldn't. Almost any airboat will run well if there is even a little water. And there are quite a few "underpowered" airboats on the water.

It's just that getting stuck sucks and loaded like you describe in a typical AC boat, you WILL get stuck.

The good news, you will have plenty of man power to get out and push!
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by Williamalvin »

I would say the boat you describe in your initial post is not far fetched. Most of the boats we fish with on the west coast on the gulf are like you describe i.e. Two side by side with bench down below and love that set up.Take bench seat out for deck when fishing 2. My last boat had a GPU run dry ground with 4 people with 13' cottonmouth hull. I now have 16' alumitech with igso 540 that will break ground at 1400 rpms. As mentioned a lot can be said for setup and experienced driving. Hard Dry ground is easy to run. It's swamp muck and blazing trails that seems to me what everyone else is describing. From what you explained it sounds like an AV 540 on 14' with 2 up top and bench below(removeable is nice) will work for 98% of what you will use it for. As long as you don't stop in swamp muck or want to blaze trails in high grass, I think a boat is very feasible for much less than 45k. Experience in driving will allow you to handle situations where others may get stuck(after it happens once or twice). Just have to start in motion and stay in motion..you are a mechanical engineer and can figure that out. You can ask people with the set up you want for a ride and see if it is what you are expecting or not.

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by One Eyed Gator »

I fish the gulf coast Waccassasa Bay alot. We fish places most guys would never thing about taking there boats. Luck yto get 3 years out of the poly. Our area has a lot of oyster bars and some nasty sharp rocks.
I usually fish with 3 people, 4 is an issue especially if someone is not a good caster, and carry everything you listed plus a few tools and parts, no live well yet but i am working on that part.

I run a 14' x7-6 alumitec 20" sides and a short rake. Motor is a bone stock (285-300hp) carbed 5.3, 2.68 stinger and 79" 3 bld R, all Stainless rigging.

For me after airboating for 15 years. I would like a 14x8 with a little taller sides and somewhere between 400-550hp. BTW GM LS Motor.

Do remember this if you have one of the baddest airboats in the area you're gonna go places others can not. Point being if something does happen it could be very difficult to get out.

I started with a direct drive caddy it would run dry but you had to know how to drive it. Gained a good deal of knowledge from getting stuck a time or two and now have a much better idea of what to expect when I see certain type of terrain and I have a good idea of what the boat will and won't do. Not that I listen to myself when I says maybe you shouldn't try yo get to that fishing hole. In a boat with big power you can get a false since of security because it will go the most place you want to go and some place you shoundn't and you will not realize until it is to late.

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by mojoe »

Looks like we all agree, and I want to point out. 2-3 passengers with no live well (as one eyed gator mentioned) is a TOTALLY different power requirement than 4 people plus a live well.

2-3 passengers with no bait is what I run regularly in my SV 540 on a small light hull. Go anywhere I point it with 1-2 people but the hull is too small to be safe in deep water fishing. Gotta know how to drive it to make it look easy with 3 people and a full tank of gas. Add a bigger hull, another person and the weight of another person in the live well and it changes things... A LOT!!

That is important to understand. One more person and a full bait tank on a 19' skiff with a 90 hp on the back is barely noticeable. Add one more person and a full bait tank to a 260hp airboat and it is VERY noticeable.
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by irod »

incredibly invaluable information from each of you gentlemen.

mojoe, what boat are you running your SV 540 on?

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by Deano »

The last couple of posts in particular are both very good ones and offer IROD very valuable insights that he currently lacks, but will attain up the trail. These are very valuable bits of info worth much more than he'll realize on the front side.

Still, I will point out for IROD's benefit that it wasn't the Laws of Physics changing that allowed you to get a different answer.
What changed was the way your boat was spec'd, what you can and will carry, and how you will use it.

No question that an igso540 will tote the mail, but then you need a couple more feet to maintain that deck space. :dontknow:
Personally, if you're going to change how you spec the boat, and you "carry 4 adults and live bait, most of the time" I would start with a 15 or 16 footer anyway. Believe what MoJoe says in that regard. You can build an engine to push a 13 footer w/4 people but any subsequent fishing experience will be more kayak like than what you'll want, especially given the expense.

Needless to say everything to do with this sport is a compromise, attempting to fulfill every want and still having to humor reality.
If your biggest desire is to have, and use the boat you initially described, which is what we perceived by the wording of your original post, then I believe you got a near unanimous response.

If your bigger desire is run an AC engine, nothing wrong with that. There is plenty of experience here to help you attain that end.
Realistically, you will have to trim your desired specs though, if you still intend to "jump the dikes to access more areas".
On that note, that is where the bulk of your excessive power requirement is coming from. Takes a lot less to stay in the water.
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by SWAMPHUNTER45 »

If you plan to go running dry with a 16ft boat and 4 passengers, you are getting into the "big inch, wide blade, gear driven car motor territory".

I have seen several good running aircraft powered boats struggle to carry a lesser load.

A heavier and solid build boat with higher sides will ride like a dream in that deeper water with a little wind and chop.

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by mojoe »

irod wrote:mojoe, what boat are you running your SV 540 on?
I run an "old school" 12' Panther front driver.

I will ride and it will hunt, but the only way I fish out of it is if I'm parked on shore.
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Re: am i wrong? NOT an AC vs. Carboat question.

Post by Hog Guts »

Williamalvin wrote:I would say the boat you describe in your initial post is not far fetched. Most of the boats we fish with on the west coast on the gulf are like you describe i.e. Two side by side with bench down below and love that set up.Take bench seat out for deck when fishing 2. My last boat had a GPU run dry ground with 4 people with 13' cottonmouth hull. I now have 16' alumitech with igso 540 that will break ground at 1400 rpms. As mentioned a lot can be said for setup and experienced driving. Hard Dry ground is easy to run. It's swamp muck and blazing trails that seems to me what everyone else is describing. From what you explained it sounds like an AV 540 on 14' with 2 up top and bench below(removeable is nice) will work for 98% of what you will use it for. As long as you don't stop in swamp muck or want to blaze trails in high grass, I think a boat is very feasible for much less than 45k. Experience in driving will allow you to handle situations where others may get stuck(after it happens once or twice). Just have to start in motion and stay in motion..you are a mechanical engineer and can figure that out. You can ask people with the set up you want for a ride and see if it is what you are expecting or not.
You can have all the experience you want. 4 people, gear, fuel, live well, etc in a 14 foot boat is not going to be pushed well or safely IMO. Don't go there. If I had the option of taking three people fishing or going to work for the day I'd go to work..... in not saying it can't be done, I've driven through the woods with three adults on my 11'6 with a 540 but it ain't easy and it's real hard on the boat. And you have to be super careful or you'll sink it. A larger high sided boat with a large car motor like (most) everyone mentioned is also my opinion. You don't want a 14 with a 540 for that job. Easy solution.... pick your favorite fishing buddy leave the other two at home now your in business.


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Re: am i wrong? NOT an AC vs. Carboat question.

Post by One Eyed Gator »

I have built several other boats for friends the last one was a 16' diamond back high sides 26" we put a stock EFI 6.0 ( maybe 350hp ) with a 2.55 gearbox and a 80" maximus. It also does not have a live well, but he usually runs to big coolers and 4 people. Boat does ok but take 3,800 to run in deep water and will do most of what he needs for dry running. That boat would not run well with the extra weight of a live well. I have fished a good bit with him and 2 others. Every time I do it I tell myself I wont do it again, just a pain in the butt fishing with 4 people on an airboat.

Back to the AC car motor deal A/C they are sporty and nimble, add a supercharger and you need more hull and yes they can carry a load for hulls up to 13' (just my opinion). Car motor boat more like an old school muscle car bigger, still can be sporty but not quit as nimble.Hulls 13' and up.

For what I do which is mostly fishing with some swamp/ river riding I personally will never own over a 14x8. Once your over that most boat feel like driving my super duty . Now I would certainly like more HP but setup right between 400-500 hp would doing anything I wanted plus somethings I shouldn't. Up to a point I would go with a modified LS over a big block just because of the BBC weight sitting right on the back it will make even a 8' wide boat with high sides look like it is sitting low in the water.

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by SWAMPHUNTER45 »

Actually Mike I have been told riding in my big Marty Bray is like riding in an Escalade.

Just a Cadillac thing I guess...lol

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by Uhairball »

For a diehard fisherman, don't forget about the added weight of a trolling motor(s) and batteries. You wouldn't be happy without them.

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by One Eyed Gator »

If it rode like an Escalade it would have an LS motor it lol. Big boats do ride nice but they don't handle same as a smaller hull. Now it could have a ride like a juiced up Eldorado plenty of HP and torque but overall still has a heavy feel to the rear . Guy I worked for had a 600 plus hp BBC with aluminum heads on a 15x8 alumitec plenty of power and fast but still drove like a bus.
Swamp don't get me wrong you know I like a well built caddy and I am a fan of Marty's Rivermaster style hull, but you need to take a ride in 13 or 14 foot hull with a light motor putting out a little hp.

I have thought about a trolling motor but just cant bring myself to put one on my boat.

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Re: am i wrong? NOT an AC vs. Carboat question.

Post by SWAMPHUNTER45 »

I don't have one but the GPS enabled trolling motors that hold you in a spot would be darn tempting to demo

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