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Old 25-01-2019, 12:36   #1
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Replacing ribs and keel board 21' trailer sailor

Ahoy,
I am working on a new-to-me 41 year old Luger Southwind 21' sailboat.
The 2-piece hulls were factory-made and then builder-assembled.
Due to a faulty cockpit drain pipe and general neglect, it sat on its trailer with water in the bilge- no drain hole, bilge pump, or even linter holes in the ribs.
Since the ribs are now cracked and weeping I am thinking it it time to fix these before I replace the bunks and other items. I basically have gutted the interior to rid the boat of mice droppings, mice-destroyed EPS flotation, sub-par 12vdc wiring, and various types of shag carpeting.

Plan is to to cut out old, wash/dry/acetone/sand to 80 grit, replace wood with new versions with liner holes, and glass over with 3 layers 7.5oz woven cloth and epoxy. Originals were builder-glassed with chopped mat and polyester.

Does this sound plausible/feasible? I could use more exotic materials such as PVC foam and carbon fiber but I would then have to engineer something to distribute the load from the swing keel bolts currently born by the keel board.

I have built surfboards and paddle boards and a glassed plywood boat so the glassing itself is not the issue, just making the right decisions upfront as far as materials and methods.

Thanks!
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Old 26-01-2019, 07:24   #2
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Re: Replacing ribs and keel board 21' trailer sailor

Sound like a great approach. You will have a basically new boat. Go for it
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Old 27-01-2019, 16:35   #3
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Re: Replacing ribs and keel board 21' trailer sailor

Aloha and Mahalo Alamoana!
It will be nice to have a fresh interior to the boat.
Too bad I do not have heated workspace to get it done pre-season.
They are talking -20F and below here this week...
I bought some better multi-tool blades when I cut out the bunks and they worked really well on fiberglass. The cheaper ones dulled in a matter of minutes.
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Old 27-01-2019, 16:56   #4
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Re: Replacing ribs and keel board 21' trailer sailor

If you remove all the old ribs at once the (rather thin) hull may dramatically change shape. You might consider doing them one at a time, or perhaps every other one... somehow retain enough to maintain the shape.

It will not bn too hard to end up with a stronger structure that original... the Lugers were not very robust builds at best! Should be a fun project.

Jim

PS the holes through the ribs are called limber holes.
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Old 27-01-2019, 18:55   #5
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Re: Replacing ribs and keel board 21' trailer sailor

Thanks Jim.
I had not considered that the hull could/would move as the ribs are being replaced.
I could brace the hull across and then down, unbolt the swing keel, cut the ribs at the keel board, replace the keel board, re-bolt the swing keel, then go after removing and replacing the ribs every other as you suggest.


PS l-i-m-b-e-r holes, got it
Any advantages to using a vinylester versus epoxy resin?
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Old 27-01-2019, 20:01   #6
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Re: Replacing ribs and keel board 21' trailer sailor

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Any advantages to using a vinylester versus epoxy resin?
Better get advice from someone else on this. My impression (no experience) is that vinylester is a bit less expensive and quite adequate for this sort of work, but it's just an impression garnered from reading posts here on CF.

Jim
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Old 27-01-2019, 20:51   #7
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Re: Replacing ribs and keel board 21' trailer sailor

I would call these parts keelson and floors;-)

Your plan is sound. Jim is right, the hull could/will move, so support it well before you remove the old parts, which in itself may be the worst part of the project. I would go fo epoxy, as wood is normally more happy with it. But, as the strength is in the laminate, vinylester would also work and is cheaper.

I am not sure your drawing is correct, I would assume the keelson is in one piece and the floors are shaped to fit, but I am not sure. In this case, you have to remove the whole assembly before replacing it. You do not have to shape the pieces to fit perfectly to the hull, you can use epoxy and high density filler.
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Old 27-01-2019, 21:46   #8
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Re: Replacing ribs and keel board 21' trailer sailor

Thanks MartinR. I agree that floors over keelson makes sense. If the floors are removed above the keelson, the remainders could stay attached to the hull while the rest of the keelson is removed, right?

Another picture, shows that the floors are maybe 2 1/2 to 3' (75-90cm) at most in length (ice cream pail is 8" (20cm)diameter and red bucket is 11" (28cm)) and there are two other longitudinal pieces that run through this section as well.


Wondering more and more how to manage the 500# (227kg) swing keel...


I appreciate all the input and the proper terms.
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Old 27-01-2019, 21:49   #9
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Re: Replacing ribs and keel board 21' trailer sailor

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I would call these parts keelson and floors;-)
Dang, Martin, but you are right! I didn't look far enough outboard in the picture, and when the OP called them ribs, I thought they went on up the hull. Silly me... should have known that Luger wouldn't have done that fairly complex sort of construction.

This makes for a simpler repair, and one less likely to distort the hull. With the keel removed, there is little loading on the keelson or floors, and thus little force to distort things.

So, OP, I think you can remove the lot with little risk if the boat is well supported.

Go fer it, mate!

Jim
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Old 27-01-2019, 22:37   #10
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Re: Replacing ribs and keel board 21' trailer sailor

This looks to be a very strong construction and from the picture looks to be in fair shape. it looks like there are stringers both sides of the floors also. The cracks in the floors are only in the center piece, where the floors are thin and along the floors? Is there any delimitation that you can see between the hull and this keel support construction?

Personally, I would start drilling a few holes into the wood to check the moisture content and if it is rotten. Maybe you can get away with only glassing over the whole area.
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Old 28-01-2019, 06:08   #11
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Re: Replacing ribs and keel board 21' trailer sailor

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This looks to be a very strong construction and from the picture looks to be in fair shape. it looks like there are stringers both sides of the floors also. The cracks in the floors are only in the center piece, where the floors are thin and along the floors? Is there any delimitation that you can see between the hull and this keel support construction?

Personally, I would start drilling a few holes into the wood to check the moisture content and if it is rotten. Maybe you can get away with only glassing over the whole area.
Have to agree with Martin. Much of the strength in fiberglass construction comes from the shape of the "ribs": the "top hat" or "U" shape creating a rigid beam. Some builders simply use cardboard to laminate around, and leave the inside of it hollow. You do need strength down there to handle the forces involved with the keel/centerboard. (Perhaps that is what caused the cracks in the first place? A sideways grounding would put a lot of torque on that bilge area.) Taking out all the floors and rebuilding them seems like it could be overkilll. You also don't want to 'glass over the keelbolts. If there are cracks in the fiberglass perhaps just grinding them out and re-glassing that area would be enough. It would be a LOT less work, and opening up the cracks would enable you to check the condition of the wood to see if it really needed replacing. If the boat has gotten as far along as it has without limber holes, they may not be overly necessary.
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Old 28-01-2019, 06:56   #12
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Re: Replacing ribs and keel board 21' trailer sailor

I checked out the specs on this boat. This seems to be a very nice pocket cruiser with good performance. Lightweight, good sail area, high aspect ratio lift keel. Will be fun to sail and will be able to give many modern boats a run for their money.

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Old 28-01-2019, 06:57   #13
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Re: Replacing ribs and keel board 21' trailer sailor

Thanks Everyone!
The second photo is from earlier in the season and it is more difficult to see the defects. The first photo with the text shows some of the issues and standing water.


-some of floors are not laminated fully to the hull, water runs under them. I was told by another who had built 2 Lugers that these pieces were 'user' installed versus 'factory' installled. I am guessing the kit builder did not remove the wax from the hull first or did not bed them properly so the resin ran out.

-some of the floors are cracked over the keelson and the cores are wet/oozing (now frozen).

I was not thinking of glassing in the keel bolts. Unbolt, drop, clean, recaulk, reinstall.
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Old 28-01-2019, 07:09   #14
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Re: Replacing ribs and keel board 21' trailer sailor

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I am guessing the kit builder did not remove the wax from the hull first or did not bed them properly so the resin ran out.
Very probable
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Old 28-01-2019, 11:55   #15
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Re: Replacing ribs and keel board 21' trailer sailor

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I checked out the specs on this boat. This seems to be a very nice pocket cruiser with good performance. Lightweight, good sail area, high aspect ratio lift keel. Will be fun to sail and will be able to give many modern boats a run for their money.

That's what I am hoping for MartinR!

Thanks again to everyone, for all of the input!
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