Hovercraft Design

Hello everyone, I am looking at designing and building a hovercraft to use on the local lake we have here. My question is on the body and what people think of my idea for the construction materials.



so my idea is to create the majority of the body using pourable close-celled polyurethane foam, so the bottom section looks like the pic above (http://www.aeromarineproducts.com/boat-foam.htm) and reinforcing it with fiberglass or a resin to give it a harder shell. Pros? Cons? Other ideas? Thanks!

 

Cored shapes

I think its rational, however in my own hovercraft building experience it may be overkill. What advantage does it have over pre-formed and generally lighter, pressure surfaced laminated panels? We have built craft out of Deco-lite but Core-cell core panels are readily available, lighter and easier to form and shape.

 

Hey, very interesting exterior shape over there! Any anticipation about what it will look like when it's finished?

 

I would say the benefit would be that the foam would be cheaper then the core-cell panels and would provide more buoyancy, wouldn't it?

 

I think that when planing on building a "one off" you should be looking at other home built craft for simplicity and not sophisticated factory built craft like a Neoteric.

Building a shell to be filled with expanding foam without rupturing can have a certain learning curve to it, a step easily skipped using traditional home built methods of fiberglass laminated foam (closed cell rigid insulation).

The fiberglass cloth covered poly-honeycomb materials do offer buoyancy, several home built Nidacore/Plascore craft exist. I don't 100% trust it for the abrasion the bottom of the hull can be exposed to, but would trust it if laminated or extra protected were added (but this also adds weight).

The product Monopan already has these extra layers built into it, and I recently heard that a hovercraft is currently being built with it.

Keep it simple stupid - KISS is the best way when dealing with hovercraft as it tends to keep the weight down which will always be your primary concern and challenge.

I bookmarked this two-part closed cell foam you found mswheel2. My old Scat II hovercraft uses a two-part open cell foam (Boston Whaler-ish), and over the years have found it to absorb moisture.

One has been built, there is video out there of it operating. Another is near completion or is recently completed, news should be posted on rambat's website.

EDIT: I also heard that some people have been using Tycor.

http://tycor.milliken.com/Pages/home.aspx

Every designer has their favorite materials, Sevtec for instance recommends something different than Universal.

 

Form foamed

I suspect the original thread idea cost is greater if a mold is required to either lay-up a skin or to pour foam into for body shapes. My GTH hovercraft was done after a lot of thought about how to create a sleek shape without a mold. The thickness of the panel material allowed back-cutting for curves, core for buoyancy and no framing required. However, a much more exotic shape like the cage-like concept shown would require something like you propose. Its not efficient to mold anything with simple prismatic shapes that can be formed out of panels. Also attached is my finished GTH Hovercraft.

 

Did you use any balsa core below the waterline?

Have you been able to do a moisture content test on the original craft?