Keel Bulge

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Ballad99
Posts: 2
Joined: Fri May 28, 2021 3:15 am

Keel Bulge

Post by Ballad99 »

Hello-
This Spring , while getting the boat ready to launch, I noticed a 4 inch diameter "wart" in the keel skin, Starboard side, protruuding approx 1/2 inch proud of the rest of the keel. I'm reasonably sure the wart was not there Spring 2020 commissioning time, since I painted the keel then. The wart sticks out enough that the roller would have "skipped" when it encountered the wart.
Overall Stbd side keel-small-IMG_1182.JPG
Overall Stbd side keel-small-IMG_1182.JPG (145.88 KiB) Viewed 534 times
Holes drilled near the bottom of the exposed area resulted in a stream of clear water draining.The glass around the wart was then cut away to expose the lead. The bulge is in the lead, so it seems the lead plate has shifted sideways until it pushed the keel skin outwards.
Has anyone experienced this happening? (I didn't find anything in a search for "keel bulge")
Is there any documentation of how the keel ballast is installed during construction? (eg. how thick are the lead plates, how many plates, etc)
I have hull number 99, 1973 according to my registration documents.
I seems to me that the ballast consists of lead plates stacked up in the keel cavity, after 1st filling the cavity with a polyester/sand slurry. The displaced slurry encapsulates everything and locks the lead in place. Is that correct?

If this has happened to anyone, suggestions on a solid repair would be appreciated.

Thanks in advance,
Dieter
Ballad99
Posts: 2
Joined: Fri May 28, 2021 3:15 am

Re: Keel Bulge

Post by Ballad99 »

Happy to report that Hull 99 is afloat again! Godenwind was launched 2 weeks ago and we've sailed her twice, including a race today.
Here's a follow up of what I've learned. I hope this never happens to anyone else, but it may be helpful for other keel/ballast problems as well.

Cause???
The water that came out of the drain holes I drilled into the keel was clear and smelled like the bilge. When I filled the bilge with water, more started to weep from the holes. After the keel skin was cut away to expose the bulge in the lead, I drilled a hole into the bulge. A small amount of clear water came out of the lead! It also smelled like bilge. Probing the inside of the hole showed a circumferential gap in the lead about 2.5 cm below the surface. It looks like a 2.5cm thick lead sheet. Open question- why was this gap not filled by the sand/resin slurry that encapsulates the ballast?

Multiple freeze/thaw cycles repeatedly pushing the bulge further outward could have caused the damage observed over the course of a single winter.

The actual cause of the leak that allowed water to migrate from the bilge into the ballast is unknown. A path of keel skin delamination extends from the front top of bilge (approx. from where the tube from the chain locker/front bilge drains into the main bilge, next to the mast step) to the bulged area.
Leak Path???
Leak Path???
IMG_1235 edit medium.jpg (157.01 KiB) Viewed 55 times
The fact that no one else has had this problem makes me think this was "self inflicted". After "Lead Mining" efforts (perhaps another post !) 25 years ago, I reglassed the top of the ballast to seal it from water accumulating in the bilge. I duplicated the way Albin built up the bilge. I may have left a small gap that opened up over time- and took 25 years for water to penetrate deep into the keel.


Repair:
1) drill multiple small holes in keel skin, both sides, to allow the keel to dry out completely
2) wait about 3 weeks (we had quite hot temperatures) until no condensation appears inside plastic sheet wrapping the keel
3) use large hammer to pound (not much effort required) exposed bulge back to original shape
4) inject epoxy (WEST System G-Flex) into drilled holes in keel skin starting at bottom
5) inject epoxy until is seeps out of adjacent holes to confirm voids are being filled.
6) wire brush exposed surface of lead. Coat with G-Flex and wire brush again while epoxy is still wet.
7) glass "window" in keel shut
8) use a sounding mallet to find remaining hollow spots. Drill more holes into the hollow spots.
9) continue injecting G-Flex into both sides of keel until there are no more voids.
10) Fair keel surface with WEST epoxy and Microlight filler
11) paint keel with multiple coats of Interprotect 2000e
12) Sand inside of bilge and reglass up to the turn of the bilge under the floor
This created 3 "bathtubs" to make sure water cannot get into the ballast again. I never liked the 2 limber hole "slots" in the keel shear webs allowing the bilge sections to drain into one. These were glassed shut as well and replaced with a single, larger limber hole through each of the 2 shear webs.
Step12 was by far the most difficult and nastiest part of the repair.
Finished keel after Interprotect Epoxy
Finished keel after Interprotect Epoxy
IMG_1257 small.JPG (101.63 KiB) Viewed 55 times
Keel/Ballast construction:
Question about Geometry of Lead in keel cavity. It would be immensely helpful to know the detailed specification of the ballast installation, and if it changed over the years Ballads were built.

1) Single lead slug?
My thoughts: unlikely due to difficulty in guiding it into place

2) Lead "plates" stacked one on top of another into keel cavity?
My Thoughts: seems easiest to construct. Individual plates could be 4-6 inches thick, all identical, making them easier to cast, relatively lightweight and easy to install. Submerging them in sand/resin slurry would encapsulate them and lock them into position.
Evidence: During "Lead Mining" operation (perhaps another post !) 25 years ago, I encountered a thick layer of hardened slurry underneath the bottom of the bilge fiberglass. After removing the glass and breaking up the slurry, the top of the lead ballast was visible. Drilling closely spaced holes into the lead and removing the remaining bits revealed it was a thin plate. Beneath it was a very thin layer of slurry and then another lead plate. These plates had recesses in them that appeared to be for lifting them into place. From this I concluded the entire ballast was installed in this fashion, consisting of multiple stacked lead plates, encapsulated in slurry.

My conclusion has a problem- If the keel was made with stacked thin lead plates, I would have seen the boundary between at least 2 of the plates in the "window" I cut in the keel skin. Instead, I found a 2.5 cm thick sheet of lead. It is possible that the lead plates on top act as a "cap" placed on top of whatever geometry of lead is in the bottom of the keel cavity.

3) The boat had a collision with a rock 35 years ago.
Damage to leading edge, bottom corner of keel (fiberglass keel skin section was ripped away exposing lead) did not reveal any details of ballast geometry.

Known for sure:
1) Water somehow, migrated from the bilge into the lead ballast
2) Freeze/thaw cycles caused the lead to bulge outward over the course of 1 Winter
3) The lead that bulged was 2.5 cm thick
4) Lead in keel did not shift, it was bulged out by water freezing
5) Ballast in the top of my keel (Hull 99) was thin plates(at least 2),
matching the cross section of the cavity, stacked on top of each other.
6) Lead ballast extends well aft, almost to the trailing edge of the keel
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