Repairing a loose keel on an older Cal 27

[Scorpius]

An older Cal 27 has arrived in the yard with a loose keel. The owners touched a reef going ahead, then struck again while backing off. Upon investigation in the bilge there was water ingress and the aft-most keel bolt was broken. As there are something like eight keel bolts down there it is apparent this has happened before.

After lifting and blocking the boat, and building a cradle to keep the keel upright when detached from the boat, the nuts on the keel bolts were fairly easily removed and the boat was lifted off the keel. They separated without difficulty.

Upon examination it is apparent the keel has been loose for some time as some of the keel bolt holes are seriously enlarged and elongated. We're thinking that occurred before the previous repair as the holes for the obviously newer keel bolts were not worn nearly as much.

The plan is to replace a couple of the old bolts and add a few resulting in probably eleven in total. The owner has received a repair kit of five new bolts from the builder.

There is quite a bit of fibreglas damage which will be repaired - including doing something about the enlarged holes (there's a fibreglas wizkid here in the yard. He's apparently REALLY good - highly recommended).

There's also fibreglas damage where the washers under the nuts have cut and crushed into the glass - which of course will also be repaired.

We're contemplating having a 1/4" stainless backing plate made, cut to fit down into the bilge recess, and bedded in epoxy, to better spread the load of the keel bolts on the bilge fibreglas.

Is this a good idea? Does anyone see a downside? I've been accused of overkill in the past (dual backstays and forestays, etc.) and perhaps this is a classic example. Maybe making it too strong will cause the bottom of the boat to rip out on the next grounding. That would be a bummer.

Comments? Thanks to you all in advance.

[michaeld]

We had a 1979 2-27, hull #627, with an encapsulated keel. What a sweet sailing machine! By all means, repair it so when the day comes, the next steward of your Cal will be confident in your attention to detail. Good luck.

[Scorpius]

Originally Posted by Scorpius

An older Cal 27 has arrived in the yard with a loose keel. The owners touched a reef going ahead, then struck again while backing off. Upon investigation in the bilge there was water ingress and the aft-most keel bolt was broken. As there are something like eight keel bolts down there it is apparent this has happened before.

After lifting and blocking the boat, and building a cradle to keep the keel upright when detached from the boat, the nuts on the keel bolts were fairly easily removed and the boat was lifted off the keel. They separated without difficulty.

Upon examination it is apparent the keel has been loose for some time as some of the keel bolt holes are seriously enlarged and elongated. We're thinking that occurred before the previous repair as the holes for the obviously newer keel bolts were not worn nearly as much.

The plan is to replace a couple of the old bolts and add a few resulting in probably eleven in total. The owner has received a repair kit of five new bolts from the builder.

There is quite a bit of fibreglas damage which will be repaired - including doing something about the enlarged holes (there's a fibreglas wizkid here in the yard. He's apparently REALLY good - highly recommended).

There's also fibreglas damage where the washers under the nuts have cut and crushed into the glass - which of course will also be repaired.

We're contemplating having a 1/4" stainless backing plate made, cut to fit down into the bilge recess, and bedded in epoxy, to better spread the load of the keel bolts on the bilge fibreglas.

Is this a good idea? Does anyone see a downside? I've been accused of overkill in the past (dual backstays and forestays, etc.) and perhaps this is a classic example. Maybe making it too strong will cause the bottom of the boat to rip out on the next grounding. That would be a bummer.

Comments? Thanks to you all in advance.

I blew it. Older Catalina 27, not Cal 27. My brainfart. All those little pieces of plastic look the same

[coopec43]

After seeing how many people have lost their lives because yachts have dropped their keels I'd get expert advice.


Why do keel failures happen and what can we do to prevent it?
https://www.yachtingworld.com/news/k...ng-facts-60006



https://www.yachtingmonthly.com/gear...-a-yacht-30650

[tkeithlu]

Let's think it through.

Is the damage that you see to the hull reasonable for the damage you see at the impact site(s) on the keel? That's a judgement call, but it helps you judge whether your repair will be adequate.

Reconstruct the impact. It hit a rock here, shifting the keel in this direction, bending the bottom of the hull here, etc. That energy went somewhere, and that's where the damage is.

Is the egging from a single impact, or is it the result of getting the boat home with a loose keel flopping around?

Are there any cracks, delaminations, or shifts elsewhere in the hull that might be due to transmission of the energy of the impact(s)? Everything in line?

Will the repair strengthen the hull, or just cover up fiberglass failures? Patch from the inside using layers of glass, not from the outside with caulk or jell.

My guess from reading your post is that you are doing OK. I am concerned about strengthening the egged bolt holes, and about hidden damage on the lower hull.

[Spot]

I am wondering if some sort of fiberglass tubes around the keel bolts would help to start the repair of the egged-out holes. Use the tube to mark center so to speak, glass them in, and fill in/patch the rest. I am also wondering about stainless backing plates being subject to crevice corrosion effects from not getting air to the one side.

[jimbunyard]

Would be extremely leery of adding keelbolts, or altering any such engineering decisions without extremely qualified guidance.

A steel plate of the correct alloy, properly prepared (no sharp edges, well bedded, would add 'strength' perhaps unnecessarily.

G10 integrally glassed into the structure with properly sized washers would probably be stronger and be more trouble free for a longer period.

Have a look at this thread. This guy is a real wiz-adult.

https://www.cruisersforum.com/forums...ir-164093.html

[Scorpius]

Originally Posted by michaeld

We had a 1979 2-27, hull #627, with an encapsulated keel. What a sweet sailing machine! By all means, repair it so when the day comes, the next steward of your Cal will be confident in your attention to detail. Good luck.

Thank you for this. This is what we are thinking.

[Scorpius]

Originally Posted by coopec43

After seeing how many people have lost their lives because yachts have dropped their keels I'd get expert advice.


Why do keel failures happen and what can we do to prevent it?
https://www.yachtingworld.com/news/k...ng-facts-60006



https://www.yachtingmonthly.com/gear...-a-yacht-30650

That's exactly what I'm trying to do here. Having read an awful lot of posts on this forum I'm confident there are "experts" on here far superior to anyone we can find locally. We are in a VERY remote area (Lund, BC) with a very small population. Not too many Catalina engineers.

[Scorpius]

Originally Posted by tkeithlu

Let's think it through.

Is the damage that you see to the hull reasonable for the damage you see at the impact site(s) on the keel? That's a judgement call, but it helps you judge whether your repair will be adequate.

Reconstruct the impact. It hit a rock here, shifting the keel in this direction, bending the bottom of the hull here, etc. That energy went somewhere, and that's where the damage is.

Is the egging from a single impact, or is it the result of getting the boat home with a loose keel flopping around?

Are there any cracks, delaminations, or shifts elsewhere in the hull that might be due to transmission of the energy of the impact(s)? Everything in line?

Will the repair strengthen the hull, or just cover up fiberglass failures? Patch from the inside using layers of glass, not from the outside with caulk or jell.

My guess from reading your post is that you are doing OK. I am concerned about strengthening the egged bolt holes, and about hidden damage on the lower hull.

1. There does not seem to be any damage to the hull other than the egging of the bolt holes, some fibreglas damage at the keel-hull interface, and some damage inside where the nuts and washers on the bolts have "dug into" the glass in the bilge. The hull is also being scraped down to gel coat for repainting and so is being examined pretty closely. No apparent damage elsewhere.

2. We have mentally reconstructed the two accidents. It is appears the previous owner bumped the bottom, broke a couple of bolts, and opened up a "smile" at the front of the keel-hull joint - but probably not causing a significant leak into to boat. It appears he continued to use the boat for some time causing the the keel to flop around and "egg" the original bolt holes. At this point we suspect she began to leak significantly and was pulled from the water. However it doesn't look like the keel was separated from the hull. New bolts were added from the inside (a kit is available from Catalina) and tightened up. Then it looks like Sikaflex was applied around the outside of keel-hull joint to stop any residual leaks and provide a fair surface, then it was all painted over. This time basically the same thing happened except there was additional damage (including breaking the aft-most bolt) when the boat was backed away from the original impact point and hit another rock going backwards. There's quite a mushroom at the bottom of the aft end of the lead keel from that impact so I'm thinking it was a pretty hard hit. The hull-keel joint opened up again and she started to leak fairly badly - so the current owner promptly brought her here and is determined to do a good job. The damaged glass (it doesn't go more than 3/8" deep anywhere) is being cut out and will be replaced. The keel-hull mating surfaces will be re-surfaced to provide a close fit - and the proposal is to put more bolts in (again a kit from Catalina) to replace the broken ones and add a couple. There seems to be lots of room between the existing ones so I'm not thinking we will weaken the lead keel structurally.


3. We believe the egging of the keel bolt holes occurred as the PO continued to use the boat after the initial accident while the keel flopped around.


4. We're not seeing any damage elsewhere on the hull. It's a pretty light boat and both hits seem to have been very low on the keel - probably causing the bow to dive. The extra energy would have been absorbed thusly without damaging the hull other than right at the hull-keel joint.


5. We certainly intend to strengthen the hull with this repair. Layers of glass will be applied to the inside and, as I say, we have a fibreglas whizkid here that we (and others) have a lot of faith in. He's VERY experienced as we are just outside of Desolation Sound and there's an awful lot of rocks around here. There are always several plastic boats in the yard being repaired after various unfortunate encounters.


6. We're still puzzling over the best way to fix the egged-out holes. I guess they could be filled with epoxy, then re-drilled - or the holes could be drilled out larger and sleeves inserted. Does anyone have any thoughts?

Thanks for your considered and thoughtful reply.

[MartinR]

Depends how bad the "egging" in the fiberglass is. I can see no reason why a small amount should be a problem. The keel is held sideways by friction against the fibreglass, through the tension of the keel bolts.

Of course, if the holes are very big now, they need to be filled and re-drilled. Should not be an insurmountable problem.

I do not think you should reinforce anything beyond the original dimensions. This can end up with something else than designed giving way, normally not a good thing. If the keelbolts had washers on the inside, then this is the way you should go. Unless you find somebody who can do the calculations.

[captlloyd]

Yep, all your ideas are good and if your glass guy is as good as you say he is he should know exactly what to do. Extra plate in the keel, Hell yeah, little extra weight down there is good. This is not rocket science. It will probably be stronger than new.

[Scorpius]

Originally Posted by captlloyd

Yep, all your ideas are good and if your glass guy is as good as you say he is he should know exactly what to do. Extra plate in the keel, Hell yeah, little extra weight down there is good. This is not rocket science. It will probably be stronger than new.

Thanks for this. "A little extra weight down there" is the reason why the bottom plate on the long keel on my steel boat is 3/4" steel plate. I've grounded a number of times in my 35 years sailing her (after all there are a LOT of rocks around here and I explore areas others fear to go) and generally can take the scratches out with a file in a few minutes - if I bother at all

I remember my daughter calling me after passing her Space Craft Propulsion and Guidance Systems exam and saying "Guess what Daddy? I'm a Rocket Scientist now". I've been thinking of calling her for some engineering guidance (she now has a PhD in Aerospace Engineering from MIT and is working at Rolls-Royce on the jet engine design team. Talk about a proud papa!

[Scorpius]

Originally Posted by jimbunyard

Would be extremely leery of adding keelbolts, or altering any such engineering decisions without extremely qualified guidance.

A steel plate of the correct alloy, properly prepared (no sharp edges, well bedded, would add 'strength' perhaps unnecessarily.

G10 integrally glassed into the structure with properly sized washers would probably be stronger and be more trouble free for a longer period.

Have a look at this thread. This guy is a real wiz-adult.

https://www.cruisersforum.com/forums...ir-164093.html

Wow! What a repair! It must have cost a fortune! Fortunately, after careful inspection, we are confident we have nowhere near as much damage - but I will bring this reference to the attention of the owner.

Being a steel boat guy, I've never heard of G10 before but, having looked into it, it seems it might be a better solution than SS - and probably much easier to work with (drill etc.). Thanks for the suggestion. Does anyone have any idea how to get the stuff? Preferably in the Vancouver, BC area. We need a piece 8" wide and about five feet long.

[vectorfins]

https://www.professionalplastics.com/contact