Bolt On Keel Bedding

[Dave,397]

This one goes Way off topic, but I cannot think of anyone better to ask than Tim.

First, I should explain that once upon a blue moon I owned a Ranger 23. As I still had a few trinkets, I sought out the R23 group on MSN which was more or less owned and operated by aero. legend and R23 godfather Arvel Gentry. A few months ago, the site and all of Arvel's stuff just sort of disappeared. As Mr. Gentry was getting on in years, one can only fear the worst.

Which brings us here...one of the other group members has sort of resurrected the group, and I (put down your coffee, fellows, you will spill laughing) have ended up the de facto technical advisor by virtue of having more unwanted intimate knowlege of the Ranger 23 than any of the other members of the present group.

So, the question at hand. One of the fellows has need to drop and re-seat the keel after some repair to the keelbed floors, which is not uncommon on these boats. That much, I can talk him through. Back when I re-did mine, I just spread a bunch of Dolfinite in there and together she went...of course, now that stuff is sort of antique. 5200 seems like a better choice. My inclination is to use as little as possible while making a circle around each bolt and a double-ring around the keel periphery--my thought being that while we want it well-sealed, we also want a pretty good amount of direct contact between the keel and the keelbed itself.

Last week I watched a locally renouned "pro" do a similar job on some big Catalina or similar, and he used at least one full cartridge of 5200 if not more, merrily scraping off the excess as is spooged out while the keel was forklifted up and subsequently bolted down. I politely inquired and was informed that you cannot possibly put too much in there, etc., etc.

So, Tim, my question (at last!)---which way is it best done? I have searched around for an answer to give the fellow, and have yet to find one near definitive from a source I knew to be credible. That leaves You!

Thanks,
Dave

[Tim]

Well...I'm honored. I think?

I'm afraid I have to agree with the fellow who used a whole tube ot 5200 on the hull/keel joint. This is what I would do, and have done (to the tune of multiple tubes for each keel) in some new construction at a reputable builder. (I hate name-dropping and don't intend to do so anymore...). Since dropping and rebedding/rebolting a keel is a job that one should only do once on any particular boat (and only if necessary), I believe the joint and seal should be considered to be more or less permanent. Whatever it takes to ensure it stays that way is a prudent action.

The idea is that 5200 is not only a fine flexible sealant, it is also (as we all know) an extraordinary adhesive product. A lead keel bonded with 5200 is typically strong enough (depending on the size of the bearing surface) to hold without bolts--not that this is recommended. I have seen this in action. When the lead keel on a 42-footer remains in place, held only by 5200 installed some years earlier, with no bolts installed and the boat lifted in a Travellift, I become impressed--all the more so when it takes the better part of a day to free the thing. I know that's the kind of bond I want on my own keel!

When the keelbolts are torqued down to spec, no amount of sealant is going to prevent the surfaces from mating closely, if their tolerances allow it. Since the tolerances between a lead casting and fiberglass keel stump are typically less than perfect, a large quantity of sealant--often 5200--is the best bet to ensure that any minor undulations and imperfections are filled with product. Using less than the "too much" approach only ensures that there will be empty spaces and voids in the area--again, using a typical imperfect joint as a mental example.

In addition, the flexible adhesive acts as a minor "cushion" between two hard, imperfect surfaces. And the additional adhesive qualities of the 5200, in one way or another, relieve at least part of the stress on the keelbolts. Even with a perfectly-fit ballast/hull joint (a rarity), I would tend to use far more sealant to ensure even coverage throughout the area. Seeing stuff ooze out all over the place would only make me happy in knowing that I surely had the best bond, and the best coverage, possible.

Is this practice wasteful (i.e. all the spooge-out that occurs)? Well, on some level it is. However, there's no way to perfectly meter the amount of sealant/adhesive that goes in there, and the only way to ensure an all-over bond and seal is to use way too much and allow the excess to squeeze out of the joint. My feeling is that, with any fastening where sealant is used, if you don't have substantial all-around squeeze out, you didn't use enough product to form the proper seal.

A well-executed keel joint (one that was engineered appropriately from the get-go) should last the life of the boat. This is frequently not the case in the real world. But the point is that any time this joint is created, or re-created, all attempts should be made to make it as strong and as permanent as it can be.

[JetStream]

I would like to echo Tim's reply. It is interesting that I posed this question to Tim recently outside of the forum. I had been considering the use of polysulfide (Boat Life) as opposed to polyurethane (5200) for the potential of removing the keel again later. Tim and others convinced me that I don't want to do it again. If something should happen making that a necessity, you face that when it happens - and there are ways.

Another thing I might point out is that I plan to use a LOT of sealant and will place more of it in the center to have to ooze out. One thing I don't want is an air pocket to form somewhere on the keel interface. My keel is 16" across at the joint and an air pocket would be very possible if I'm not careful. You spoke of a whole tube. My joint is 16" x 64" plus the end faces. I was figuring on a case of 12, with a couple extra tubes in case I need them.

[New Wave]

I had my Ericson keel rebedded about five years ago. Pacific Seacraft, which used to make the boat, recommended epoxy instead of 5200. I'm not sure why, but I suspect that you want a rigid joint. The other piece of advice was that the epoxy had to be applied within 10 minutes of cleaning the lead surface.

[William]

Interesting stuff. I have a C&C 24 which was humbled a bit by hurricane Isabel this year. Mostly cosmetic damage from an adjacent loose boat, but when the boat was pulled I found that the paint had cracked nearly all around the keel-hull joint. I just bought the boat (in the water) a few months before the hurricane, so I don't have experiece with the thing. One guy at the marina suggested I just scrape out the crack as much as possible and fill it with 5200. Is this likely to be sufficient? Or what?
Thanks

[Tim]

Cracks at the keel-hull joint on a boat with an externally ballasted fin keel like your C&C 24 are extremely common, and are normally the result of typical sailing stresses. However, the character of the cracking is what is important to note here. If you see large, deep cracks, it could point to loose or failing keel bolts, indicating a need for replacement or retorquing.

If, however, the crack is fairly mild in nature, consistent around the joint--particularly at the leading edge--and not overly deep, wide, or ragged, it is probably just caused by normal stresses and movement in the joint. When you think of the stresses placed on this narrow, abrubt joint, it makes sense.

Obviously, without seeing the crack firsthand there's no way to know for sure. Most likely, you are only experiencing the normal, and virtually unavoidable, cracks caused my movement and sailing stress. If this is the case, then reaming out the loose material as much as possible and filling with a strong, flexible material such as 5200 should be as effective a repair as possible/needed. Rigid materials like epoxy and other body-type fillers will likely fail after a season, since there's no way to completely remove all movement from the joint. The benefit to something like 5200 is that not only will it seal the joint, but the impressive adhesive qualities will help hold the sections tighter together, and with the flexible nature of 5200, it will not tend to crack or tear either--barring significant (and atypical) amounts of movement or working.

If you happen to have a photo, please pass it along for us to see and better judge what is going on. If you need assistance with photo posting on this board, feel free to email it to me, and I'll post (tlackey@triton381.com) Otherwise, good luck, and happy sailing!

[New Wave]

FWIW, my epoxy repair has not failed after 6 seasons.