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Types of hull / polymer

mascara

mascara

Well-known member
Hi Airboaters,

Could you help to list the different type of hulls available.?

Is there such a thing as a V shaped hull?

For areas which have waves, would the V shape be better than the conventional flat hulls?

For aluminium thickness use in airboats, is there a standard thickness or does it vary according to the terrain.?

Polymer for use in airboats vary in thickness, are there polymers that can withstand very sharp corals in our seas?

Would polymers like 3/8 in thickness able to withstand the corals or is there an alternative?

Airboats or any watercraft are not allowed anywhere on land in singapore except when going up a trailer, so would
a reinforced bottom of the airboat, for example another layer of aluminium for the airboat be better than a polymer?

Please advise.... :?
 
Hey Mascara,
Just like an ocean boat, an airboats hull is designed according to the terrain it will run. The hulls are generally flat-bottomed with some differences in the round or sharp shape of the chine area. Generally, a Glades-type boat is flat bottomed and the deep water boats have a rounded shape.
The hull material can be fiberglass or aluminum. The aluminum material is generally 6061-t6 or 7075-t6 with thickness ranging from .090 to .125 in.
High density polyethylene is used to protect the bottoms from rocks and debris, but if abused, they will show their damage.
Stainless steel is also used to "skin" bottoms that will run rocky areas on a regular basis, but stainless is not slippery and should be reserved for "rock boats".
V bottom boats don't slide very well and are designed to part waves. Not a good airboat hull design because airboats steer by sliding the stern opposite from the direction of desired travel and power out of the slide.

Look, observe and really study the pics and boats on this site.
If you're looking to build an airprop V-hull ocean boat....it will be just that.
Youtube some converted v-hull jon boats...you'll get the idea.

Whatcha tryin na build?
 
Hi, Glades Cat

Thanks for the advice,

I am trying to build a boat by one of the established airboat companies in Florida. In Singapore we are surrounded by a saltwater envoirment. We do not have lakes or marshes like those in Florida, all our larger ponds are fresh water ones used only for drinking and no motorised boat is allowed on these ponds.We are a very small island and btw your lake michigan is larger than singapore !!

In the seas surrounding us are corals which are RAZOR sharp and i have seen how badly a boat can be cut up! My pupose of the airboat is to be have the ability to glide across them when the tide is low as sometimes the tide just hides the corals beneath the surface of the water by just a few inches, so sometimes we can actually WALK on these corals by wearing marine shoes and admire the marine life.

I am not sure how an aluminium airboat can take on these corals without getting cut up too badly. A boat with an outboard motor will definitely not be able to approach these corals without getting damage to the props and hull which is usually made of fiberglass.

So my idea would be to build an airboat with a durable hull which can get me real close to the corals at low tide and have the stability of a boat during the ride to the corals as the waves can make the ride very bumpy
and uncomfortable if the hull is too flat.

Any idea how to make this "dream" airboat"?
 
Airboats are not made for handling large chop or waves. Could make a boat with a V-hull and a small flat bottom, but I don't think there are any companies that off a hull like that, it would have to be custom build. Plus with a small flat running surface it would get beat up pretty easily and I also think there could be more of a tipping hazard.

Truthfully, I think you might be better off with a hovercraft that rides on a cushion of air vs an airboat that ride in the water. If you were cruising in an airboat in deep water and ran across or hit coral that was only in 1 or 2 inches of water it could very bad. Just my opinion, but I don't think an airboat it best for water you want to do. Once you take in to consideration the shallow coral and waves you might encounter I think you chances for sinking your boat or hurting yourself would be very high. Then again I don't know how the hovercraft curtain would hold up to the coral either.
 
Mascara,

There are all kinds of hulls out there, and as far as I can see there's no one hull that is just plain good at everything. For your situation you could utilize a progressive v-bow design which will greatly improve wave handling capabilities. As for the bottom, a variable deadrise or very shallow v will certainly be more comfortable than a flat bottom in waves but wouldn't fair to well when trying to run dry.

My personal suggestion would be a progressive v bow that transitions from a variable deadrise towards the bow and tapers back to a very shallow v (more rounded than v-shaped) or flat bottom. And when I say progressive v don't confuse that with a traditional v-bow boat, more of a "bull nose" that's squared off. We've successfully used this bow design to run 3-4+ foot waves on Lake Michigan and Boston Harbor in our USCG prototype.

You've got lots of options out there, there are some great airboat builders on here and I'm sure you'll find what you're looking for.
 
Hi, Bigjake & MIlsar,

Thank you both for your advice.

Hovercraft was used in singapore quite a while back but they died a natural death as these were not very useful, given the corals we have and the waves. The airbag at the bottom of the hovercraft were torn to shreds when they went over the corals. The wind and the occassional high waves made the hovercraft very light footed and tipped over very easily.
There is currently one large hovercraft used for SAR but i think is now retired due to high maintenance cost.It is i think a 50 seater craft and is now lying on a harbour somewhere.

Milsars advice is very interesting and i think it may be what i am looking at.
I think with a thicker gauge aluminium we may be able to avoid the corals and sharp rocks from tearing the hull apart and also a thicker polymer may help too.

Would you have a picture of the hull that the USCG uses? It would be great to use that as a reference when i talk to the manufacturers.

Really appreciate any comments.

Cheers! :cheers:
 
Hey Mascara,
Have you considered a multihull boat. An aluminum catamaran with a flat-bottom and modified bow sponsons might fit the hull design you seek. You can skin it with Stainless and have a very hard, gouge-resistant bottom. You can power it with airprops, single or dual engine.
I currently own a catamaran ocean boat and can attest to the stability and wave-handling ability of multihulls.
They aren't cheap. You will use, on average, 30% more material than a single hull design.

What size boat/how many passengers, are you looking to build?

You have our curiosity piqued.
 
Hey Mascara
I think I might have the only V type hull ever made. and it was made in 1973 call an Bullfrog out of Melbourne, Florida. It's a true flat bottem boat but it has a round bow design made to cut waves. all glass and it slides great in skinning water and digs in deep water. I havn't seen any other hull like it since I bought it 5 years ago. their trick was to put your name on the top deck of the boat and tilte it under your name ( or so I was told ) my was a SMITH hull. YOU can see pics of it in my galley. It is a one of a kind.
 
mascara said:
Hi, Bigjake & MIlsar,

Thank you both for your advice.

Hovercraft was used in singapore quite a while back but they died a natural death as these were not very useful, given the corals we have and the waves. The airbag at the bottom of the hovercraft were torn to shreds when they went over the corals. The wind and the occassional high waves made the hovercraft very light footed and tipped over very easily.
There is currently one large hovercraft used for SAR but i think is now retired due to high maintenance cost.It is i think a 50 seater craft and is now lying on a harbour somewhere.

Milsars advice is very interesting and i think it may be what i am looking at.
I think with a thicker gauge aluminium we may be able to avoid the corals and sharp rocks from tearing the hull apart and also a thicker polymer may help too.

Would you have a picture of the hull that the USCG uses? It would be great to use that as a reference when i talk to the manufacturers.

Really appreciate any comments.

Cheers! :cheers:
Click to expand...

Mascara,

We are the manufacture of the USCG boat I referenced. It's a unique design made for chop, waves and ice on the great lakes here in the US. When considering a traditional airboat swamping and sinking are definitely a concern, not so with our design. There's enough positive floatation designed into the hull that you can fill the crew space completely with water and it will not sink, well let me clarify...it will sink to a point where only a few inches of the hull are above the waterline. The bilge outlet is above that waterline so then the high volume bilge pumps evac the water and the boat slowly returns to it's original static draft. Airboats in general are not required by ABYC to meet level floatation. We had to in order to meet USCG requirements for their particular series of rescue boats. It had to be able to be fully operational in 3-foot seas, meet level floatation and a host of other specs. So what you are asking for can and has been done. But like bigjakesrq said, what you're looking for is not an off the shelf boat. A cat type boat might get the job done as well, it'd certainly be stable!

3/16" bottom with 3/8" UHMW will do you just fine on the coral. If really concerned you could step up to 1/4" bottom which we did on our USCG boat. If you do a search on here for "new USCG design" you'll find plenty of pics of our USCG design and more info on our purpose built boats on our website listed in my signature block.

If serious I'll draw up exactly what your asking for and shoot them to you for review.
 
Hi, Milsar, Bigjake,Twistedscott,

Thanks for the info,

I will go into the different website to see what you have suggested.

Catamarans are a common feature here but if it is outboard powered then the issue of a damage engine remains and with fiberglass hull the damage can be frightening too.But with a airboat engine it may just do the trick
but i have never seen one yet .

Milsar idea of a USCG approved craft may seem feasible, given the tough
conditions it has to meet.

One reason why i was looking at an airboat approach is that:

1. it is highly manuveureable .

2. It takes up very little waterline height and therefore will not damage the corals easily.

3. Sometimes when a tropical storm strikes, we may have to make a run for the shore or beach to take cover and an airboat can beach easily and
take cover.

So the gist of all would be a easy manuverable craft with the strength to rough it out and also take the cut from the sharp corals, seems like a airboat built for superman ! but i think it can be done. Cost and ease of maintenance may be another factor due to the extreme in humidity and the heat as we are very near the equator! Over here if you leave a boat in the open seas and come back 2 weeks later, you wont even recognise your own boat !!.I will look into the suggested ideas and come back to you,

Cheers!
 
Hi, GladesCat,

An aluminium hull for the catamaran may do it but is it easy to put it on a trailer compared to a airboat?

I am looking at a six seater so something like an 18 x 8 footer may do the job.

One reason for the airboat engine is that it will not stir the water unlike a outboard engine which can break and kill the corals and break the engine too!

I will take a hard look at the suggestions and see how a compromise can be achieved.

Cheers.!
 
American airboats builds this one.
index.htm


http://www.americanairboats.com/extremeterrain/index.htm

Alumitech Airboats is another good big boat builder.

Diamondback builds 'em tough also.
alaskan.htm


You can make them as tough as you want...but it has to be designed and built right or it will run like crap. Extra expensive trying to uncrapify it.

sorry, I can't get the hang of posting pics.
 
Hi, Glades Cat,

Yup, i am at looking at Diamond back too. Was recommended by quite a few airboaters.

The issue now is to try to configure a good and reliable airboat which can take the waves, sharp corals ,
ease of maintenance and cost of airboat.

One question, i notice that the engine sits on a frame which is then bolted onto to floor of the airboat, from , experience
would the engine tear off or vibrate violently the base of the airboat during extended bumpy ride on 3 foot waves?
Although they use heavy duty bolt and nut, it does look a bit scary, with the base of the airboat being so thin.

Anyway i would be making my way to florida to understand the airboat and hopefully come up with a configuration.

Cheers :)
 
The coral is going to tear up the poly regardless of thickness. Thickness will only extend the life, by how long I am not sure. The old timers in the everglades that ran lots of ROCKS used to put a stainless steel sheet over the bottom. I think that is what you will need also. Polymer is just a type of plastic, sharp coral will cut it. In most situations I think poly is the best bottom protection, but I think you will need something tougher.
 
Hi Yobee,

Thanks for the tip.

I think so too, for example with stainless steel, but what are the disadvantages
of using stainless steel besides the weight?

Would i need a stronger engine to power the airboat?

I am looking at a water thunder with an aluminium block, what do you think?

Appreciate your feedback.

Cheers
 
You're looking in the right direction with a DB & WT combo. They will get you airboating with power and confidence to the promised land of shallow coral reefs in Singapore.
Good luck man.
 
Keep in mind a standard shipping container won accommodate an 8-foot wide boat, maybe 7'8" if lucky....this narrower beam will effect stability, especially in waves. Waterthunder power will certainly do the job and do it well for you, hull's a little more complicated then an off the shelf airboat, JMO.
 
I used to ship 9.5' pieces of Satellite Dishes in standard containers. Yup at an angle and a bunch of 2x4 lumber got it done.
 
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