Pumping thickened epoxy into hard to reach areas

Submitted byThor onSat, 05/30/2020 - 18:39

This is a bit off topic but I have learned more from this forum about using epoxy than any were else I figured I might get an answer here.

My problem is I have a fiberglass MC Scow sailboat and the hull is delaminating from the internal Keel. I want to inject thickened epoxy into the inside of the keel through approximately 1 to 1.5” holes and need to reach about 40” in. The plan is to tip it on its side and let gravity help it onto the gaps. I have west system fillable caulk tubes and will attach a long straw (orange drive way marker left from snow plow service) if I don’t get a better suggestion. 

just got a WiFi borescope and figure that I might be able to tape it to the straw and see if the epoxy is covering. Probably will totally muck up the scope.

i don’t need a perfect or even pretty joint, it will be inside and  Not visible, but need to cover a good portion it.

In the attached pictures the grey part is the keel with floorboards, and there are flanges around it which I have glued with West Systems Six10. 

Kell with bailers removed


It has not been wet since last fall. 

I am trying to rebound. When they made the boat a mass of thickened resin was put under the keel and pressed into the hull. I have sailed this boat for 25 years and the bond has now failed.


Sun, 05/31/2020 - 02:06

I'm having trouble visualizing the relationship between the hull and keel.

This is a fixed ballast keel boat?

A sketch of the cross section would make the problem clearer.

Working blind from 40" away seems like a big challenge. What does Melges say about this problem?

Brian Nystrom

Sun, 05/31/2020 - 07:48

If it's the latter, unless is was heavily flushed with fresh water afterward, you're not going to get the epoxy to bond. Even then, it's iffy due to mineral buildup, mold/mildew/algae, etc.

John, what I called the keel is internal, I will call it a spine instead. The MC Scow has leeboards, which are retractable and not in the area I am working now.

I don’t know why my pictures are upside down.  The picture with the clamps is around the bailers, which is one access point. Looking in there I have this image. 

View under floor board from bailers

Brian, the boat has only been sailed in fresh water and always pulled out after sailing. It was in storage in a heated warehouse all winter. I know it would be better to rip everything apart but that is a bigger project than I want to take on.


Sun, 05/31/2020 - 11:06

It doesn't look like a very big gap, so I'd probably use unthickened epoxy if using WEST or SystemThree.

There are side stays for the mast? It seems to me that that sort of force will tend to increase that gap, so without really re-bonding the problem will just continue. I wonder how big the gap is when under sailing stress.


How did you find the problem? Can you feel the hull flexing?

Attacking the problem from the hull side would be an option. It's pretty easy to plug holes later - the 'miracle of epoxy'. You could use 'sheet metal' screws (pan head, all threaded screws) to pull that gap closed after getting epoxy in there. (Use the screws as clamps). Afterward plug the screw holes with epoxy thickened with milled glass fibers and cab-o-sil.

Found the problem at the bailers where you can see both the floorboards, strongback (looked up the proper term)  and hull, and there was a crack visible. Pushing on the hull showed movement.

Everything for one side is masked and I will see if I can fill a caulk cartridge and make a seal with surgical tubing to the driveway marker tubes and hope I can get enough of it were it needs to be. I will let you know if it works.

I have started pumping the epoxy in and it mostly worked. The biggest problem was the orange tube which was a drive way marker from the snow plow service are poor quality. When pumping hard is split open and made a mess. luckily I had masked everything. Turned out that as long as I the pressure was not high it worked. I was able to get a good amount of epoxy into the space between the floorboards/strongback and hull. When I do the other side I will use silicon tubing left over from making the Moroski deck fittings. I used a short piece of the tubing to join the caulk tube  to the tube. 

Caulk tubes with tubes addedCaulk TubesMC Scow on side

Exercise balls to press on hull