How to fill cracks radiating out from Keel Bolts?

[Ranger26Honolulu]

My 1973 Gary Mull Ranger 26 (hull 285) has 10 keel bolts. Two bolts on the starboard side (in the middle of the boat) have badly rusted heads and the fiberglass beneath the washers is split--radiating out about an inch from the washer, with a pea-sized hole in the center of the crack. All 8 other bolts are fine. This makes me wonder if before my ownership the boat took a minor impact on the center of the starboard side keel, which then put the most stress on these two bolts--which were then depressed downward with impact. Or, maybe just normal wear of hard sailing.

My question is: 1) How do I dry out the cracks (and associated holes);
and, 2) what material do I fill it with?

I want to use a hardening substance to squeeze into these cracks. They are roughly the diameter of a pencil, and I can stick a pencil into the holes deep enough to go about half the pencil's length. The shallow bilge is dry, but these holes are damp due to the minor amount of rain water that infrequently finds its way into the boat, and the WD-40 I sprayed onto the bolts when wire-brushing off the rust. Lots of rusted metal bits and muck in the cracks--I don't know what material lies underneath the bilge fiberglass.
I dont' know much about epoxy and fiberglassing. This will be my first project tackling this kind of thing (my first sailboat). I'm looking for specific product names to go buy, and a how-to procedure.

A haul-out would be nice. But that won't happen for another year, so until then all projects will have to be done on the water.
Thanks, JW

 

[Bob McL]

My first suggestion is that you not just "fill" the cracks - grind out around both sides and add new glass fiber and resin. I would use "epoxy" and not an "ester" (poly or vinyl) resin. Check: http://adventure.howstuffworks.com/how-to-maintain-a-boat1.htm

 

[Brian M H23]

My boat has similar cracks: I ground them a little wider, cleaned the dust out, mixed some chop strand into epoxy and filled them. I then made a backing plate in place of the washer that goes between both bolts.

I feel fine about it!

 

[Ross]

Reading that "How stuff works" link makes me wonder if the writer has ever actually made such a repair.

 

[TomH]

Keelbolt cracks

These are not the type of cracks that you want to cover or putty up. It might be a good idea to let someone at the "yard" look at the stress cracks, the only fix is to remove and re-bed the keel. That being said if you don't sail in open water or push the boat if you lost the keel you might not put yourself or freinds and family in a bad situation. If you sail in an open bay....

 

[sailingdog]

The problem is probably the keel bolts. Steel or iron expands about 10% when it rusts.... If the bolts are rusting... that may be the cause of the cracks. You really need to drop the keel and inspect the keel bolts. Chances are very likely you'll need to replace them at this point in time. The boat is 36 years old... and the chances that your keel bolts are fine is probably close to 0%.

 

[Bob McL]

Ross . . While the article doesn't cover all situations, it pretty well covers what you expect with glass. I had a Lotus Europa get whacked when I was parked in San Francisco and had about six or seven pieces I had to "glue" back together (The Lotus is a fiberglass car). Used a thick duct tape on one side - ground out the opposite a little more than half way. Then glassed the area with five layers of light weight cloth, starting with a smaller patch in the center migrating to the largest piece. Just let the stuff get tacky before adding the next layer. Then did the other side the same way. That was 26 years ago and the car has never developed any cracks or stress points in that area. My son has the car now.

 

[Ross]

Ross . . While the article doesn't cover all situations, it pretty well covers what you expect with glass. I had a Lotus Europa get whacked when I was parked in San Francisco and had about six or seven pieces I had to "glue" back together (The Lotus is a fiberglass car). Used a thick duct tape on one side - ground out the opposite a little more than half way. Then glassed the area with five layers of light weight cloth, starting with a smaller patch in the center migrating to the largest piece. Just let the stuff get tacky before adding the next layer. Then did the other side the same way. That was 26 years ago and the car has never developed any cracks or stress points in that area. My son has the car now.

Bob, I agree that it covers the basics but I wonder how much of what was written was text book knowledge unsupported by experience. I can give you a fairly complete explaination of how to hang wall paper but until you have done it a few times you may well wonder if it is possible to do it without making a huge mess.
I have some experience with fiberglass repair and construction and that is why I am given to wonder about the writers experience.

 

[Bob McL]

I agree that some people are better at writing (or information gathering) than at doing. But you still need to attend to your boat. What approach are you going to take? . . . and be sure to let us know how it turns out!

 

[sailaway78]

Pull it

I am in agreement that the boat should be pulled, and inspected. If this is not possible, I would do some research and find out how it's made, is it solid glass or is there a wooden keel stub in there under the glass. Find someone who is familiar with this particular model of boat. Telling you how to fix it is pretty much a shot in the dark, without knowing whats under there. If there is plywood under there, you can be pretty sure it is gone, not just under the cracks, but the entire keel stub. The plywood was a pretty common practice on lots of boats. When you find out how it's made, then a much better judgment can be made on how to fix it.

 

[Ross]

Re: Pull it

The op's observation that a pencil could be inserted into holes along side the keel bolts indicates to me that there are major voids in there that weren't part of the original construction. Those cracks are for me an indication of a load being applied to an unsupported, under strength section of fiberglass.

Edited for spelling.

 

[Maine Sail]

Keel stub

Two bolts on the starboard side (in the middle of the boat) have badly rusted heads and the fiberglass beneath the washers is split--radiating out about an inch from the washer

If the fiberglass is sunk in around the washers it is a good sign that the keel stub was laminated with plywood and it is wet and rotting. Many productions boats built in the 70's & 80's had plywood laminated into the keel stubs. The rusted heads could probably be related to a constantly wet core beneath them.

with a pea-sized hole in the center of the crack.

This could be any number of things namely a core sample done by a PO or a survey to ascertain the condition of the keel stub. It could have also been a bolt or screw hole that held a bilge pump or float switch..

All 8 other bolts are fine.

Maybe they appear fine above the stub but what is happening where you can't see them? Are they stainless?

This makes me wonder if before my ownership the boat took a minor impact on the center of the starboard side keel, which then put the most stress on these two bolts--which were then depressed downward with impact. Or, maybe just normal wear of hard sailing.

In all my years of boating I have only ever seen the forward most or aft most bolts damaged due to a grounding. If it had a side load grounding all the bolts on one side would have been stressed quite evenly and more so evenly than a grounding while traveling forward.

My question is: 1) How do I dry out the cracks (and associated holes);
and, 2) what material do I fill it with?

First you need to know if your keel stub is cored with plywood or if it is solid glass. This can be done by drilling a core sample into the stub. If you get saw dust or brown coffee like goo from a rotting wood you have a wood laminated keel stub. Before doing anything the wet wood must be removed.

If it's solid glass simply Dremel out the spider cracks in a v-shape to about 1/16" deep and fill with thickened epoxy as this is likely only cosmetic in a solid glass stub.

I want to use a hardening substance to squeeze into these cracks. They are roughly the diameter of a pencil, and I can stick a pencil into the holes deep enough to go about half the pencil's length. The shallow bilge is dry, but these holes are damp due to the minor amount of rain water that infrequently finds its way into the boat, and the WD-40 I sprayed onto the bolts when wire-brushing off the rust. Lots of rusted metal bits and muck in the cracks--I don't know what material lies underneath the bilge fiberglass.

I think we'll need a photo to better asses the situation..

I dont' know much about epoxy and fiberglassing. This will be my first project tackling this kind of thing (my first sailboat). I'm looking for specific product names to go buy, and a how-to procedure.

You're not quite there yet. Please get us a photo and we can better walk you through this..

A haul-out would be nice. But that won't happen for another year, so until then all projects will have to be done on the water.
Thanks, JW

If you have plywood in the keel stub this is not a job that can be done in the water so it will obviously need to wait.

This is a photo of a keel bolt sinking into a rotting core:
Photo Courtesy Digital Marine Survey