Suitable material as a filler under fibreglass

[GILow]

Hello all,

I am looking for some advice on filler materials, suited to the following scenario:

Our boat has an encapsulated keel, filled originally with lead in some form. This was then, I assume, glassed in. Later the P.O. added another layer of lead ingots over the top, and poured fibreglass resin over these. Hence we are at the heavy end of the range of displacements for our make and model of boat.

Unfortunately the top layer of ingots is a bit lumpy, and has a tendency to pool water in the pits and troughs between the ingots. Enough so a truly dry bilge is only possible with a towel of some sort.

I would like to smooth the whole surface out, creating a V shaped fibreglass "tray" with a fall toward the stern of the boat, where I will install a hose that can carry any collected water past the engine bay sump (which is isolated from the rest of the boat to contain any spills of oil, diesel, coolant etc) and dump it in the rear of the keel which has a much lower surface. There I can put both bilge pumps instead of having them split fore and aft of the engine bay as I currently do. This way I get true redundancy. As it is we'd have to take on around 1.5 tons of water before the water would bridge the engine bay and give both pumps a shot at the job.

To do this I am going to need some significant bulk. I could just pour in more fibreglass resin, but the volumes I am looking at could make that an expensive exercise. I feel like I need to fill around 50 to 100 litres of volume to make this work properly, maybe more if the right material could be found.

Can somebody suggest a suitable filler material for the task? Ideally it would be something that I could pour in as a liquid and then glass over the top? I wondered about some of the two part liquid foams? They'd have to be closed cell I assume? Any traps from using them in this situation?

Matt

[Wotname]

There are probably better ways but...
I would shape up the final top surface in thinish plywood, fill the void below with pour in closed cell foam and then glass over the plywood taking it well onto the existing hull surface.

[GILow]

Originally Posted by Wotname

There are probably better ways but...
I would shape up the final top surface in thinish plywood, fill the void below with pour in closed cell foam and then glass over the plywood taking it well onto the existing hull surface.

Well, that is what I am HOPING will work (though I hadn't considered the plywood, so that's an interesting idea). I am just wondering about the poured foam down there in the keel? Might it cause problems? Trap moisture? I dunno... getting paranoid I guess...

Matt

[zeehag]

concrete was a popular filler in many encapsulated keels. it is possible to pour and fair it so it is smooth. then lay fg to keep water from going into the keel.
mine is concrete with stuff in it to add weight(taiwanese). there is a fg layer or two over the concrete in the areas under the engine and fuel tank, where water tends to sit ...
do NOT use the foam. i peeled out so much of that rotted stuff.. seems salvor placed foam in the bilge to keep the fail fuel tank somewhat stable. donot do the foam. is a crappy mess, and cannot be faired withou t cutting the skin.
we used to make race car seats of the two prt goam. that is a good use for it, but not in your bilges. concrete is a better filler for bilges. fairs easily and when ye use the right kind is not a problem.
use the yellow pail of treated concrete with epoxy in it. works great.

[Frankly]

Q Cell powder is available to add to both epoxy and polyester resins to produce a lightweight filler. Should be able to trowel it pretty smooth and then add a final layer of glass to give it a little tougher finish surface. Small bags are used for surfboard repair but buy in bulk ($50 US) for a large job.

Frank

[model 10]

Long before they started using micto balloons in Bondo they used Diatomaceous earth and polyester resin to make bog. There are epoxies out there in gallon cans that cost way less than West and other fancy brands.
So go to the garden store for your filler and make your own epoxy filler

[RNW]

Earth and epoxy might be a bit heavy and hard to work. Give some thought to sawdust instead with a layer of epoxy glass fibre on top. It's used a lot in similar situation s

[model 10]

Originally Posted by RNW

Earth and epoxy might be a bit heavy and hard to work. Give some thought to sawdust instead with a layer of epoxy glass fibre on top. It's used a lot in similar situation s

Diatomaceous earth is light, you can eat it.

[RNW]

True. But it's very fine and has a big resin ratio. I guess a bit of testing would show the easiest way.

[Lojanica]

If I understand your issue I would build a raised graded bilge area out of rot proof foam board and drill 2" holes with a holesaw every 6" or so as vents. Put a large diameter riser tube at the top and bottom to allow expansion of the foam (Like concrete footing pour tubes. Use 2 part heavy, dense pour foam. Then cut the pour foam flush with the foam board after it hardens and glass over the top.

To hold the foam board up just cut foam board and turn it parallel to the pour so you don't make dams that block the pour foam.

Smooth surface. Doesn't weigh a lot. Cheap and easy. This can easily be done in one day.

When you glass the top just use stitch mat and use epoxy. Progressive epoxy polymers (paul oman) has good quality affordable bulk resins.

You could also build in a small sump at the other end of your main bilge sump and therefore add a small pump on that end on another circuit. Since it's a back up I would probably use a manual foot pump. Redundancy. Also make sure you have a good grade so water truly flows well into your desired bilge area.

I have done this before and it worked well. The key is to make sure your foam board is well vented during the pour otherwise you'll blow out your foam board.

Also pour from the bottom not the top as the foam will expand up

[Richfind]

I have used vermiculite with polyester resin for jobs like this. It is available at Home Depot, Lowe's and gardening centers. It is light weight, high volume and cheap. You could use it with epoxy but that is more expensive. Use just use enough resin to make a peanut butter consistency. Trowel it in forming the shape you want. You should not plan on sanding it afterwards. After the vermiculite/resin mixture cures come back in with a micro balloon mixture of epoxy resin at the consistency of ketchup. Mix in some white pigment for that enviable white bilge. You could put a layer of fiberglass in before the epoxy if you thought you needed it.

[Cadence]

Originally Posted by GILow

Hello all,

I am looking for some advice on filler materials, suited to the following scenario:

Our boat has an encapsulated keel, filled originally with lead in some form. This was then, I assume, glassed in. Later the P.O. added another layer of lead ingots over the top, and poured fibreglass resin over these. Hence we are at the heavy end of the range of displacements for our make and model of boat.

Unfortunately the top layer of ingots is a bit lumpy, and has a tendency to pool water in the pits and troughs between the ingots. Enough so a truly dry bilge is only possible with a towel of some sort.

I would like to smooth the whole surface out, creating a V shaped fibreglass "tray" with a fall toward the stern of the boat, where I will install a hose that can carry any collected water past the engine bay sump (which is isolated from the rest of the boat to contain any spills of oil, diesel, coolant etc) and dump it in the rear of the keel which has a much lower surface. There I can put both bilge pumps instead of having them split fore and aft of the engine bay as I currently do. This way I get true redundancy. As it is we'd have to take on around 1.5 tons of water before the water would bridge the engine bay and give both pumps a shot at the job.

To do this I am going to need some significant bulk. I could just pour in more fibreglass resin, but the volumes I am looking at could make that an expensive exercise. I feel like I need to fill around 50 to 100 litres of volume to make this work properly, maybe more if the right material could be found.

Can somebody suggest a suitable filler material for the task? Ideally it would be something that I could pour in as a liquid and then glass over the top? I wondered about some of the two part liquid foams? They'd have to be closed cell I assume? Any traps from using them in this situation?

Matt

Matt,

Since it sounds as just wanting to fare the surface with no structural requirement I'd us polyester resin mixed with commercial talc or glass micro spheres/balloons. Bondo without the cost.

[roverhi]

If you want to go cheap, there are concreted products with very fine aggregate made for doing repairs and also plaster that you could use to smooth the surface. Lay a layer or two of cloth and resin over the top and you are done. If you want to stick with glass, micro balloons in polyester resin will also work. If you truly want the goo to stick, use epoxy instead of the polyester resin but that will cost more.

[Johnniegee]

I,m with Zee Cement. Have a bag of fast cure incase you get holed.

[Cheechako]

Concrete has been used a lot in commercial fishing boats also. Simple, and cheap, easily molded to the shape you want. ...if you don't mix it too watery. Many a sailboat hull has been made of concrete. Some boats in WWll were also.
You likely want a concrete sand mix, but might google it.