Composite foam board sandwich technique

I am thinking of building a very basic Prioque type
flat bottom hull with foam board and covered with cloth
and resin.

Basically I think any design programs for plywood
or steel or aluminum sheet should be able to work
with foam board as long as the thickness can be dealt
with.

Maybe the Stitch and glue method would be appropriate.

I have not been able to find any specific internet sites
dealing with people builiding boats with this
composite foam board technique
but there must be many and I want to explore all the
materials choices between the foams and resins
and cloth etc to choose from.

If anyoen knows of any pertinent links I sure would
appreciate them sharing the info.
Thanks
Scott

 

If you're thinking of making a sandwich composite hull using low density (2#/cubic foot) extruded polystyrene or urethane, basically insulation board, think again. SHeer strength, friability, and compression strength are too low to bother with for a boat hull, deck , or cabin structure. Stick with stitch and glue plywood if you want a simple, epoxy boat and you're new to this.

Foam cores such as Corecell as core materials are a different story - well worth looking at for lightweight sandwich composite hulls. But again, why bother for a pirogue?

Chris Krumm

 

foam composite sandwich components

Thanks for the suggestions. I need other recommended
components in addition to Corecell and links to others
using composite to build their boat hulls.

Are there any websites featuring composite boat construction
where I can discuss resins and foam alternatives etc. ?

By Piroque I meant hull of simple design. actually I need
a higher bouyancy hull for my amphib airplane.
see photo

Is Corecell the undisputed leader in boat hull building?
or are there other competitors ?

Thanks
Scott

 

Hi Scott,

As they would say in the UK: "Fancy meeting you here!"

CoreCell is not the undisputed leader in boat hull building. Divinycell, made by DIAB, is up there too!

Their websites are:

CoreCell: http://www.atc-chem.com
Divinycell: http://www.diabgroup.com

On both sites you can download technical litterature that might be of interest.

In another thread, you've asked about software. Here's another possibility: Hullform 9S. It's freeware and can be downloaded from the website of Blue Peter Marine Systems - I'm sorry, but I don't have the URL.

Best regards,
Søren Flening (another Profili-user!)

 

Our warehouse man built this canoe from plain insulation foam available at Home Depot. Now, I would never recommend building it yourself, it was done more as an experiment.

http://www.boatplans-online.com/proddetail.php?prod=Hiawatha

P.S. We also sell Divinycell if you want to build with foam.

 

In your place, I would check out sources for making surfboards. That is the biggest use of foam core construction by amateurs, as best I know.

 

Are your prices $30++ a sheet more than a place like fiberglassupply.com or am I just reading your pricing wrong?

 

I dont know what they have, but make sure you are comparing the same density, thickness, and plain sheet or grid scored. The grid scored sheets are much smaller. We are one of the only places I have found on the web that sells Divinycell per sheet. If you need a case or more, I can give better deals. We also will pre-cut the foam core so it can be shipped UPS.

Hope that helps

Joel

 

my God it's an hydravion... my answer will be simple:
1/ Pirogue shape is not suitable for a boat plane. The plane will never take off, and add some stability problems while taxiing. After 80 years of trials, a few thousands dead pilots and dozens of fired engineers, the answer is; stepped hull very carefully designed.

Make a search in the Nasa internet site, they have good doc. Buy a scientific calculator and take some courses for Excel programming. You'll need it.

2/ Stresses are very high on hydravion. Heavy PVC foam needed, at least 100 kg/m3 at the bottom. Imagine the stresses; you let fall down a hull in the water at 35 miles an hour... That's true engineering work for the scantlings.

Think well over all that. You'll have probably problems of certification, surely resale value loss and an insurance mess: a problem with an insurance company and its lawyers is worst than death in the States.

Better to contact the company which makes this ultralight kit, and discuss with them. Or hire a aeronautical engineer...

And finally, you'll be the first actor and stunt in the movie "The man who died in the landing crash of his hydravion". A very bad movie...

 

Have a look at atlcomposites.com. They make all sorts of panels with different cores and face materials for boats. For aircraft structures like floor boards, galleys and overhead bins they use "Fibrelam" which used to be made by ciba gigy? It's basically a honeycomb core with fibreglass or carbon skins. They are certified for aircraft structures.
Checking with the designer before changing the material is always a good idea.

Cheers,
Karsten

 

When we were teenagers and poor, we made surfboards of white styrofoam, polyester resin and mat. The trick to use polyester over styrofoam, is a layer of paper (newspaper) glued with white or yellow carpenter's glue. They took a lot of abuse and we could patch them fast enough not to loose to many waves.

 

I'm glad someone got around to the real message needed here, you're not going to design a successful hull on this thing without the engineering necessary to be successful (thanks Ilan)

Step hulls are not easy to design, without a considerable data base and a good bit of experience. This hull form is the only one that will allow you to break the suction the hull will have with the water at flying speed. The step, it's placement, rise and details are the reason it works on floats and fuselages of water born aircraft. You'll notice that these hull forms, both boats and aircraft have very similar shaped forms. The step location and arrangement are all very similar and the reason is, it works. Other styles of form have been tried, but we keep coming back to the traditional shapes seen, because it is the most reliable, effective and buildable fashion conceived. There may be better ideas in the offing, but until someone can prove repeated takeoffs without a hitch and can qualify that with data and the appropriate math, we'll stick with what is known to work.