Suitable material as a filler under fibreglass

[GILow]

Originally Posted by Uncle Bob

Hey thats only 1000 litres of water in plastic drums on deck near the bow.

Or 100 slabs of beer... that might be more useful...

[GILow]

Originally Posted by Wotname

So back to the false floor out of plywood, coated all sides with epoxy, glassed into place and air below.

I have a real concern about an air gap. When we first bought the boat there were a pair of tanks in the keel constructed in much this way that had gone "off" and the smell was seriously awful. Sea-sick inducing kind of bad and the project of removing them remains the biggest and nastiest boat project I have ever completed to date. Long may it remain so too.

I am trying to avoid creating some kind of mini-tank that might suffer the same fate. I did initially consider a glassed in plywood top with one of those dinghy style inspection hatches, and I have not yet completely ruled it out, but it would become, I suspect, another point of maintenance and a fiddly one at that because it would be a good three feet below the cabin sole. Not easy to reach.

Two givens about the boat:

1. We have enough storage space for both water and fuel such that sacrificing volume from the keel, though not ideal, would not be shooting ourselves in the foot. (or keel)

2. We have more than enough ballast already, so adding ballast would probably be counter productive, but not the end of the world.

All this strongly points in favour of foam, PROVIDED I can prevent it rotting or causing other problems, and that is where I become concerned.

So the next logical option would be some kind of volume increasing, weight reducing treatment of fibreglass resin, of which there are a few suggestions already, which I am chasing up today.

Subject to cost, that last option is looking most promising so far, but all options suggested to date have their merits.

Matt

[dilligaf]

I guess I don't understand........as far as I calculate it would be 50 gal of water?

[GILow]

Originally Posted by dilligaf

I guess I don't understand........as far as I calculate it would be 50 gal of water?

Err...? What would be 50 gal of water? The void I am filling or something else?

[Wotname]

Originally Posted by GILow

I have a real concern about an air gap....

All this strongly points in favour of foam, PROVIDED I can prevent it rotting or causing other problems, and that is where I become concerned.

So the next logical option would be some kind of volume increasing, weight reducing treatment of fibreglass resin, of which there are a few suggestions already, which I am chasing up today.

Subject to cost, that last option is looking most promising so far, but all options suggested to date have their merits.

Matt

I hear you about the air gap
Do remember that close celled foam is really hundreds of thousands of enclosed air gaps
So back to finding a cost effective and low density resin enclosed filler but gee, 100 litres is a lot bog

How about converting the space into beer storage, still problematic but more useful outcome

[GILow]

Originally Posted by Wotname

How about converting the space into beer storage, still problematic but more useful outcome

Hmmmm.... might have a chat to Cascade... or Boags... one of them may be able to help.

[Snowpetrel]

Sounds like a very worthwhile project. A mate did this with his boat. I'll try to find out what he used. I think it was some sort of self leveling epoxy flooring stuff.

Maybe filling the chain locker with water might put her down in the bow?

I've thought of filling the bilge with fresh water to find out the exact quantity needed, suck it out with a wet and dry and measure it. I guess you don't need to cover every bump as long as the water can drain cleanly it would work well.

Sent from my HTC_0PCV2 using Cruisers Sailing Forum mobile app

[GILow]

Please do let me know if you can find out what your mate used and if they were happy with the result.

Originally Posted by Snowpetrel

I've thought of filling the bilge with fresh water to find out the exact quantity needed, suck it out with a wet and dry and measure it.

Yes, this will work. But be warned, as I discovered when I drained the slime from our rear tanks, 450 litres is a lot of decanting of a wet and dry vac that only holds 15 litres at a go.

You might be better off measuring it as you fill, then turning the bilge pump on. I certainly would have preferred to use the bilge pump on our boat but I am too fond of dolphins to let what was in the rear tanks go anywhere but down the sewer system. So I lugged all 450 litres of slime the length of the pens (200 meters each way) to the nearest sewer point, in 30 litre increments.

I wasn't letting this stuff get in the waterway.

[Snowpetrel]

Ohh, I think he pushed a tub into the wet mix to make a shallow sump.

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[GILow]

Originally Posted by Snowpetrel

Ohh, I think he pushed a tub into the wet mix to make a shallow sump.

Greggegner made the same suggestion. Very neat idea, I have been sketching a variation using a plastic bowel and a skin fitting embedded in whatever I use. Could work well. Would really love this bit of the boat to be completely dry if possible.

Matt

[Nicholson58]

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

I use US Composite 635 THIN epoxy resin with 3M microballoons as filler. Ratio is 3 gallons of epoxy to 10 gallons of balloons. Mix using a drywall paddle in a large plastic bucket. Consistency is Kraft marsh mellow cream. Density is very low. Cure time is about 2 to 4 days. Very hard and can be sanded & painted.


You can use heavy polyethylene film to form & shape it. The film wont stick to the cured epoxy.

Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc.

[GILow]

Originally Posted by Nicholson58

I use US Composite 635 THIN epoxy resin with 3M microballoons as filler. Ratio is 3 gallons of epoxy to 10 gallons of balloons.

Thank you Nicholson58, that is a great lead. I like those ratios too.

Matt

[UNCIVILIZED]

This idea's theoretical, as it hasn't been tested yet, but...
How about filling up the space in question with ping pong balls encapsulated in an epoxy & microballoons mixture?
The mix is, I think, one of epoxy & microballoons. And it was mentioned in a rudder rebuild thread within the last couple of months. ~Odds are it was the mix, above, recommended by Nicholson58.

What you use in terms of epoxy & filler is important, as you need something which isn't going to go exothermic on you. - Which is a key point that I don't think has been mentioned yet.
However in the rudder rebuild thread, the mixture used was several inches think, but by design, took several days to cure. And didn't have any heat problems at all, despite it's thickness, & the volume of epoxy used. For which, I complimented he who suggested it.

As to ping pong balls, I know that in some classes of racing power boats, they are/were used for floatation for quite a while. As they provided the most sealed bouyancy per volume, for the lightest weight. And I gather that they did okay in terms of holding up in such applications.
IIRC, they were mostly fixed in place by sections of fishing net, & or via net bags affixed to structural members in the hulls.
So they'd be worth looking into. As would doing a test of them embedded in such an epoxy mixture. It'd let you use a lot less resin, & still fill up the space in question. Plus you wouldn't be adding that much weight.

Before you begin to apply any bonding agents:
- Pressure wash the area well a few times
- Then abrade thoroughly

Option B, might be to look into the specifics of what kind of foam surfboard makers use. And so long as it's closed cell, odds are it's cheaper than structural boat building foam. As it's a lot lower density IIRC. Plus it works well with Polyester Resins, also. Again cheaper than going to the epoxy option. Although as you're doing 2ndary bonding to resins which have long since cured, it'd be wise to use epoxy for any of that work. Especially on any glass used to hold things in place in the cavity in question.

[GILow]

Originally Posted by UNCIVILIZED

How about filling up the space in question with ping pong balls encapsulated in an epoxy & microballoons mixture?

Cool! MEGA micro baloons. I could imagine it would be fiddly to keep the little buggers in position, but interesting, very interesting.

I'll check out the surfboard foam idea too, I particularly like the compatibility with Polyester resin because I am comfortable working with that stuff. I don't THINK the area will have any significant structural demands, at least not as long as I can keep the filler weight nice and low using one of the many options suggested so far.

Matt

[UNCIVILIZED]

Originally Posted by GILow

Cool! MEGA micro baloons. I could imagine it would be fiddly to keep the little buggers in position, but interesting, very interesting.

Matt

Just build little dams to hold them, & the epoxy/microballoon mixture in place until the resin sets up. Not a complex task.
Plus, you'd lay down a layer of the bog first, which would help to hold the first layer of balls in place (along with the dams).