Air-boat design . . .

Hello,

I am new to this forum and thanks for allowing me to participate.

I am trying to locate hull design software that a novice in could dig into. I am somewhat familiar with and own AutoCAD 2010, so hopefully a good hull design add-on is available for use with AutoCAD or a standalone package. Preferably I would like to use a trial version to see if it works for me, etc. Shareware would be great, but if needed I would be glad to purchase a package.

I am planning on building a proto-type of a small 2 person aluminum air-boat with a 15-20 hp 4-cycle engine. If it works out in terms of cost and performance, I am considering manufacturing a few to test the market need in SE Georgia.

Also, does anyone know where to start the process of getting coast guard approval, what is required, average length of time to get approval, etc.

Thanks,

 

Software packages don't design boats, they just make lines in the locations you tell it to. It will not tell you if the lines are optimized for you needs. This is where the education part comes in. Considering the cost and time to become a yacht designer, let alone a certified naval architect, you should strongly consider the idea of buying plans or at the very least consulting with a designer. Boats built as "passengers for hire" or other commercial service have to hit a crap load of requirements that can be a simple overwhelming task for the budding designer to absorb, let alone execute effectively.

Can you learn enough and research enough about the various disciplines required to pull this off? Sure you can, but for most of us it means a few years of study and research in some sort of higher education setting. If you project has this kind of time, I'd recommend WestLawn (> http://www.westlawn.edu/ <) as a first and economical step to that end.

 

I remember seeing a small air boat powered by a B&S industrial engine (one of the V twins that are around 20hp I think) a few years ago. It was being produced by a kit aircraft company in the US, Great Plains. Their website doesn't list it now, but I found a link to what looks to be an old web page that's still up (the links from it don't work): http://www.greatplainsas.com/airintro.html

I remember talking to the guys from Great Plains at an air show in the US maybe 8 to 10 years ago and they seemed a helpful bunch. You could do worse than give them a call and see what happened to the project - might save you a bunch of work.

 

Yea, but will it pass USCG certification?

 

No idea, I really don't know how far they got with the project. I also don't know what's required for USCG certification, presumably it's a bit like the RCD over here, is it? If so, then I wouldn't have thought it too hard to ensure compliance, as the RCD at least isn't too onerous for things of this size.

I'm pretty sure the guys at Great Plains would be able to advise on this aspect, though, as I mentioned above they were a friendly bunch with a helpful attitude when I spoke to them.

 

You might be better served taking a look at existing designs. Airboat design is pretty mature, and while it's a low volume speciality there are plenty of designs and small manufacturers, especially here in Florida.

I think what you're talking about re the Coasties is the capacity / load certification. Inspected vessels are only for boats taking 6 or more pax for hire and there are a bunch of them that run in the Everglades. For production boats you need "level floatation" and you have to follow fuel and ventilation rules as well as nav light and elect standards.

If you want to test a market do market research, take a look at existing manufacturers of similar vessels in similar markets. Sounds to me like you're putting the cart before the horse.

$.02 Steve

 

Thanks for all the replies. Let address a few of the concerns and comments.

I agree with PAR, in that most engineering-design-type software is literally a computer-based tool that aids in design usually via the medium of drawing & drafting, (i.e., CAD), and without some formal engineering background, at a minimum, is challenging task. Personally, besides being a student of engineering, since graduate school I have always professionally worked in the manufacturing sector, but never studied any type of boat design or architecture. I am retired now and somewhat bored, so . . .

Having said that, this project is aimed at personal & family recreation, including fishing & hunting, carrying up to 2 adults and a few pieces of gear. It will not be designed for paying passengers or tours, but designed so the air-boat could be manufactured & sold. I plan to build 1-2 prototypes to shake the design out. I need to keep the water draft to ~2" or less. I have located some plans for a similar air-boat for $12.50 and is made from plywood. I plan on using suitable aluminum plating with a dense wood trim.

Since I own and operate AutoCAD 2010, I was hoping to locate hull-design software to aid in determining draft, approximate surface speed based on hull and HP, etc.

I hope this explains my thoughts a little better. Please comment as I am eager to learn.

Thanks,

 

When I was a younger man I used to hunt ducks in the Everglades with a friend of mine. He had a 14ft alum boat with a 35 evinrude on the back and we would run down the canals along RT 27 until we found a canal heading north from that, then we would work our way to some open water, put out decoys, and wait.

On one trip very early in the morning we were towing the boat North towards Andytown when suddenly we saw a deer cross the road ahead. A few seconds later an airboat came up the enbankment across the road and down the other enbankment in chase. I learned after that some airboats had stainless steel bottoms to deal with that type abuse. That tidbit also explained the sparks I saw as the airboat crossed the road.

Now I do believe there may have been adult beverages involved, deer season was closed, but the story here is airboat draft. I once called on an airboat manufacturer that would test ride his repairs by turning on the sprinklers and then running the boat on wet grass. He told me he could run it on dry grass but it killed the grass

Steve

 

Hello,

The plans I found are for the air-boat shown in this web-site: http://www.airboatfun.com/

It's a straight-forward flat-bottom approach. They claim ~ 20mph with the one-seater pushed by 10HP. Check it out.

BTW: What is a good 15 to 20 HP 4-cycle engine with (what I like to call) a favorable performance-price ratio?

Thanks,

 

That's a great story! I can see it happening. I live on the Ogeechee River in SE Georgia, so I understand that some hunters will not let a deer go. They'll (or their dogs) run it for hours if needed.

Thanks,

 

Based on personal experience I'd say it's tough to beat the V twin industrial engines. Briggs and Stratton have the Vanguard series, Kohler have pretty much the same specs, as do Kawasaki. All seem to be dimensionally similar and pretty much interchangeable.

I have a 620cc B&S Vanguard that is rated at 20hp, but has been tuned to deliver 38hp. Take a look at this site for the best prices on these engines over on your side of the pond: http://www.smallenginewarehouse.com

I reckon you could get a reliable industrial 4 stroke of around 18hp for maybe $1200 or so.