Using structual foam

[drb]

does any one have any experience using foam as a core to fiberglass over.

i am converting a runabout to a centre console and I was originally going to make new gunnels out of ply and fiberglass over (and under) I made a template of the original curves and then basically made the gunnel off the boat. Now that i have put it in place I am not happy with the result.

my latest idea is to use some type of structural foam like is used in foam sandwich construction. Should i construct the gunnel in place, shape and level it as required and then glass it.

Has anyone here done this sort of thing before...

Any advise on suppliers or on materials...

all input is very much appreciated.

thanks

Dazz

[lenm]

I have a bit of experience in using fibreglass hardfoam/sandwich construction.
My thoughts would be to maybe use a hardfoam such as Klegecell or Divinicel (Spelling??).
It's pretty expensive stuff though and you would probably need to apply more layers of fiberglass to it (top & bottom)than you would to the ply for the same impact resistance/rigidity.
How strong does it need to be??
The hardfoam is superlight, very easy to work with and can be cut with handsaws and sands very easily.
Where are you located??
Try calling large fibreglass places such as 'Fiberglass International'
You might change your mind when you find out the price.
Maybe they can recommend something else.

[gavsgonefishing]

Among many other things I am making new sidegunnels up for mine, and then making a new rear gunnel to follow the line of the boat aronnd ( hope that makes sense).

I decided to cut the old gunnels from about the middle of the boat to the back, reshape the orginal section to something a little more practical, get them smooth enough to apply a fibreglass mould and lay up the new gunnels. Is this the sort of thing you are doing? I am working with 600mm original sections, and will need to make up about 1800mm for each side, and approximately 1800 for the back (after the back has been layed up I will be cutting it in half widening it to fit live bait tank, dead bait tank, storage and stubbie holders, all made in the garage out of glass.

I decided to keep away from the ply as the glass is strong enough and does ( should) look as good as bought one. Peice of mind re the weight and the rotting..

I have some initial pics, and a heap more info if req

[blaze]

I have used cardboard and body filler for making moulds for unuassul shaped pieces, after all its only a mould
cheers
blaze

[NQCairns]

I for one would be interested in any pics or further info/tips, soon I will be building the entire rear gunnel section for a now full height transom. I think it will be the hardest part of the entire boat to get 'right'. The more I think about it the closer to last it falls on the jobs list :-/

[gavsgonefishing]

nqcairns, I'm a little bit behind you, I just about to cut the rest of the transom out(the engine well, motors, existing gunnels, floor, side panels etc etc are now gone I have built all glass stringers and middle runner out of moulds, they have been cut and glassed in with the tanks. I then strengthened the hull with 4 x 450 chop, 1 roving,1 x chopstrand, glassed the stringers etc then put another 2 x 450 chop over the lot.
I ve got to lengthen the hull then add the new full height transom

I figure that the back gunnel is going to be a little fiddley, so I am making up the moulds now after I complete fixing the original side piece. Once I am happy with the shape I will spray the original modified 600mm gunnel section with 2 pac primer/ filler, rub back for a good finish, wax the top up, and lay (at this stage)2 x 450 chopstrand on the top of the gunnel. This will serve as my mould. I figure 600mm sections are easier to work with shape etc.

I will lay up another 2 more moulds, fit back on the boat, and glass the sections together to get the correct shape, clean the joins up, apply your wax on the underside and start laying up. I was thinking 8 x 450 chop, no roving as it is a little hard to use on curves. ( this may change pending on the result). use the same mould for the sides, just cut at the 600mm joins, fit to the boat,reglass the mould, clean it up and start again etc.

The rear gunnel is upside down on the garage so it is easy to work on. It will be cut length ways, widened to 400mm (using a sheet of glass I have layed up on melemide (spelling)). Then glass the tanks etc in

The live bait tank etc has been made, they need to be raidiused on the inside then sprayed with flowcoat before I fit them to the new gunnel.

That will do for starters

[NQCairns]

Gav big project! how long is the boat? If I had not already rebuilt the transom I would have extended the hull into a pod arrangemet not just a bolt on, but too late now.

Have you considered 450gm multiaxial (45deg by 45deg) lovely to work with and near the strongest stuff out there weight for weight, another thing I wish I had thought of nearer to the start. I used mostly triaxial which I liked and then biaxial (to cut costs and weight) which is total crap to work with compared to the multi. I have got the multi up and over 25mm stringers without problems. look forward to hearing more on you project. nq

This site needs a project forum real bad!! too much good stuff disapears into the ether, but I will never ask again no way..... MMmmmm mayby once more but that will be it! ;)

Ausfish is lucky it's the best site in Oz.

[gavsgonefishing]

Weve hijacked Dazb's post.

If you remember late last year I asked for some help on pods vs no pods on a 4.3 markham whaler that I put 2 4s 50's on. It turned out they were a little heavy for the back end. I also had problems with the hull cracking and one of the tanks decided to shift.

After a bit of research I decided to strip it back and start again strengthening the hull etc etc. There was a lot of pros and cons about the pods, and I will find out soon enough whether what I am doing will work. the basic story is I need lift at the back end, and the way to do that is to give the boat more bouyancy via the pods,the extra length and weight redistribution.

Now its just got out of hand, everything I see I have to change in some way.

Its still in early days but I have some pics, might start another post if your interested. I hpoe to have the thing floating by winter, pending work. wife and apathy.

[drb]

Weve hijacked Dazb's post.
:) :) :) :)

After advise from here and industry sources I have decided to build it as such.

Outboard edge of gunnel 4mm external A bond ply.

Top of gunwale 25 mm closed cell foam

inboard edge of gunwhale is a honeycomb composite material that I have forgotten the name of but bends very smoothly but is strong as when covered in glass


all of this will be covered in at least 3 layers of 600gsm glass (been using CSM to date but will probably go for traxial or similar)

(note the 3 different spellings #::))

I agree that we need a project forum. I'll post piccies of mine soon

Dazz

[NQCairns]

Daz below is a list of some of the composte materials I have found used on the net, might help? are you building a mold or are you doing it freehand?

Nydacore
Divinacell - Vinyl foam
Klegecell
Styrofoam
Polyurethane foam (closed cell?)
plywood

[drb]

I am laying it up freehand over the foam and then finish off with Qcells + 2 pak.

[gavsgonefishing]

Dazb

How are you going to get the consistancy on the shape without using a mould and using several different materials for
several different angles?

What sort of shape are you trying to achieve?

Nqcairns I havent had a chance to get to the f/g shop to check out the multiaxial, maybe late next week

[drb]

Gav,

basically materials are to make up some form work so to speak. Glass will be laid over the top.

Consistency comes from sanding the QCells , hard work but if I were to make a mould I would have to sand the plug anyway.

[gavsgonefishing]

Dazb keep us updated on how you go. For a once off sounds like I'd be better off making the shapeon the boat out of ply, clean it up then lay the glass up.

As you get down the track a few picks would be goog