Repairing keel: scrap metal & oil?

[troppo]

I have a problem with the keel on my fibreglass boat. Last year I found an ancient and small crack underneath the keel. It was into the sealed ballast section. I drilled a small exploratory hole and it leaked litres of water stuff then chemical smelling fluid. After two weeks it had just stopped dripping but the epoxy and glass cloth patch I put on did not seem secure. No matter how I tried to clean it and dry it, the weeping fluid kept contaminating the patch. Had to go back in the water with a dodgy patch.

Today I pulled out my boat and pulled off the old patch. Only a little water came out so the patch worked better than I expected. I drilled an access hole up higher in a void (tapping on it it sounded hollow) as I intended to push water through to remove the chemical which was stopping the previous patch from sticking properly and to blow warm air through to dry the interior a bit.



Access hole.

After I cut the access hole into a void, I found there was a lead ingot in the background (good, I expected that) and scrap metal (that shocked me).



The scrap metal looks like ferrous and coated with oil or something. I guess that is to stop it rusting. It is also the stuff which prevented me from fibreglassing up the hole last year.



I put some water in the access hole and it came out the hole in the bottom of the keel.

So, do I just pump some detergent and water through so the bottom crack gets cleaned and when dry I can fix it with epoxy and glass cloth?

Do I put oil in via the access hole after the bottom crack has been repaired so the scrap metal does not rust?

Is it safe for fibreglass having oil in the keel?

Any suggestions?

troppo

[wesgardner]

I would hesitate on putting any oil in there as then it will be harder to get any kind of patch to adhere. I'd dig all the loose fasteners (wasn't aware that's what they used for ballast???) out and maybe flush with water then denatured alcohol. Clean it up wipe it with acetone, patch, fair, paint, sail.

[gjordan]

Using scrap metal/ boiler punchings is an old method of ballasting a boat. It is almost always done with a filling if oil to keep it from rusting and expanding, which could cause damage to the surrounding structure. I have only seen it on steel boats but it would work with fiberglass until, like you having to do a repair. My only comment is to replace the oil after you figure out how to clean the area enough for the glass repair. You will probably want to check your bilges to make sure you dont have any leaks that could allow water to penetrate the keel from the top. In this day and age, you should probably use a bio-friendly oil , such as fish oil or some other non pretroleum product. By any chance was your boat home built from a bare hull? That would explain the budget ballast. Best of luck. ____Grant.

[troppo]

Thank you for your replies, fellas.

Wesgardner: I would only put oil in once the repairs to the bottom of the keel have been completed. Unfortunately, the scrap bolts and screws are only an extra bit of fill around the main lead ingots from what I can see. Using tweezers, I can probably remove a cupful of the scrap bolts, the hole I cut is too small to remove any more.

Gjordan: Ah, I had not thought of using environmentally friendly oil. I will see what I can source. Even vegetable oil would be better than old sump oil.

My boat is a Top Hat 25 and I have read that the Australian company making them originally sold some as parts (hull, deck, liner whatever) and owners put them together. However, some of them were so badly constructed, so I believe, that the company stopped offering the DIY option and would only sell them complete. I have suspected for some time that mine was DIY and a middling sort of job was done by the original owners. Either that or my boat was built on a Monday when the crew had hangovers from the weekend.

Update: I have been flushing water and detergent through the access hole I cut. After the water drains through, a seepage of oil starts up again. However, it is reducing!

I tested my next step today (for when the oil stops dripping). I have a heat gun I can set at 70 degrees C and it fits exactly in the hole I cut and can push warm air through. Next week I will likely set it up on a stand so as I do other jobs it can be moving warm air through the inside of the ballast area in the keel.

troppo

[troppo]

Update:

Repairs are completed. I used a variety of cleaners, flushing them into the ballast section via the access hole I cut. Collected the cleaners as they dripped out the hole under the keel. The hole under the keel is one I drilled in the hairline crack that seeped gunk.



Used a heat gun set at 70 degree C to blow through the keel. In the access hole, out the hole under the keel.



After a week of flushing, there was almost no oil seeping out. I would flush and then put the heat gun blowing through. The warmth helped the oil to flow out.

Finally, I did a last small flush using a syringe into the hole under the keel with some mineral turps which seemed to be the best for removing the oil. Then a small flush with methylated spirits just to make sure all was clean.

Drilled out the hole under the keel with a bigger bit to give fresh surfaces. Plugged the hole with a thin strip of linen cloth soaked in epoxy and pushed up with a stick. The cloth was like a sponge holding the epoxy in place. When completely set, I checked it to see if any contamination had caused any problems with setting. All good.

Using an angle grinder and sanding disk, I cut a bowl shape ready for doing the standard fibreglass repair. The plug got sanded back but it was only there to stop any contamination seeping into the patch I was about to apply.

All seemed good. Applied the many layers of fibreglass cloth and epoxy. Covered with peel ply held on by masking tape to keep it all in place and stop epoxy dripping down.

Also ground out the access hole I had cut in the side of the keel and did the same sort of repair there.

Since I was running short of time on the slip I used the heat gun to set the epoxy faster.



Both patches looked great the next day. Sanded back nicely. Coated with two pack primer/undercoat.



Day after I painted with antifoul.



The keel crack was a problem as oil in the ballast had stopped the original repairs from sticking properly. Needed the access hole drilled so I could flush and dry the interior. Once the contaminant was stopped from getting into the repair I was able to fix the keel crack. And also fix the access hole. Overall I am very happy with the repair.