Repairing damage to keel support structure

[mat jam]

I would be interested in hearing from the forum their thoughts about a couple of keel repairs - one completed, and one about to begin. Not sure if anyone has seen these channels - Sailing Uma (completed) and Bums on a Boat (in the process).

My thoughts on,

Sailing Uma - I believe a Pearson - did temporary repairs to their wobbling keel by replacing internal wood structural supports with cheap Styrofoam and using their fingers to squeeze out epoxy from the fiberglass overlay. And on the exterior they only replaced the immediate area around the de-lamination forward of the keel and added layers at the upper forward keel area. I may have missed some things.

BOAB - I beleive a Carter 33 - they had surveyors and a Naval Architect make suggestions and will be fastening metal plates on the top sides of the keel support cross stringers. I do not know what else they will do.

With the popularity of the boating lifestyle on a limited budget and doing DIY repairs are we in for some fatalities ahead.

I am all for DIY but it appears amateurs are learning from amateurs and in some cases not doing the proper repairs for critical areas. I say this because there have been numerous suggestions to watch and follow the first example. These kids were planning on heading to the med and have been reckless in disregarding safety lines and protocols and when numerous posters tried to warn them about the reasons for the safety equipment they blew it off. Now they are planning to head to the arctic Greenland area.

[Suijin]

I watched the BOAB videos just recently and in my opinion the suggested repair is inadequate.

Metal plates, even 1/4” stainless, laid flat on top of the stringers, don’t have the rigidity required to fix this. The stringer is a box structure and the sides are what provide the support against vertical stress (the weight of the keel or the weight of the boat on the keel). The top of the box stabilizes the sides to prevent torquing. So a plate laid along the top will do little. Add to that the recommendation that they be screwed down...the screws will just pull.

In my opinion a better solution is reinforcing the sides of the box. I would template out 3/8” G10 plates, as long as I could make them, and glass them in on either side. Or I’d laminate four 1/4” pieces to make two 1/2” plates. Probably overkill but better to make it too strong than have the problem resurface and its only incrementally more work. Whatever was easier in terms of available materials.

I would do it once the boat was back in the water and the oil canning had settled out.

Many sailing vlogs on YT are just extended slow motion train wrecks. I’m all for people just heading out and learning by doing but the penchant for ignoring advice, not to mention presenting oneself as some pedantic expert is annoying.

And if I had a buck for every YouTuber who lost their dinghy because they towed it in 25 knot winds and wondered where it went...

[psk125]

Fixing a keel is something that needs to be done right. (Cheeki Rafiki, anyone?)

[LongWinded]

This thread obviously hasn't aged well.

[Ballsnall]

Oh no, did they die?

[LongWinded]

Not in the lest, in fact UMA who did the repair with XPS foam (often thought not to be suitable in marine aplication) has crossed many of oceans in worst weather than most. Even that of a hurricane thrown its way. My response is to the arm chair sailors who never have had to think outside the box.

[RaymondR]

Originally Posted by Suijin

Metal plates, even 1/4” stainless, laid flat on top of the stringers, don’t have the rigidity required to fix this. The stringer is a box structure and the sides are what provide the support against vertical stress (the weight of the keel or the weight of the boat on the keel). The top of the box stabilizes the sides to prevent torquing. So a plate laid along the top will do little.

Not sure about this bit?

Usually the area of the hull adjacent to the keel is sufficiently strong to carry and distribute the tensile loads caused by the gravity and acceleration loads on the keel and the frames are included and beefed up in that area to transfer the bending loads generated by the vessels heeling from sail loading on the mast or the vessels rolling. Consequently these frames are acting as beams.

In a beam the side plates, in a box beam, or web, in an I beam, is there to hold the top and bottom flanges in place. The flanges take the tensile and compressive loads generated and the webs only experience shear loads.

However I would not just use bolts to fasten a plate to a formed beam, although I would use bolts to hold it in place, I would also bond and glass it in place to endure the forces were properly transmitted.

Reinforcing the frames with more glass fibre on all three sides as you suggest would probably be a better solution as the modulus of elasticity of the material is the same and consequently loads would be more evenly transmitted into the adjoining hull material.

[Midday Gun]

Originally Posted by RaymondR

Not sure about this bit?

However I would not just use bolts to fasten a plate to a formed beam, although I would use bolts to hold it in place, I would also bond and glass it in place to endure the forces were properly transmitted.

Reinforcing the frames with more glass fibre on all three sides as you suggest would probably be a better solution as the modulus of elasticity of the material is the same and consequently loads would be more evenly transmitted into the adjoining hull material.

Bonding a metal plate into the laminate to stiffen it up doesn't seem the best idea, likely the laminate will flex around it and possibly split.

The normal solution is plenty of layers of unidirectional glass running along the tops of the floors.

[Rumrace]

Fixing a keel no big deal. Fixing the hull “ For Sale” sign would be my method. Can’t fix a horse with a bad back either.
I’m not familiar with a Carver 33 sailboat. Very familiar with Carver power boats. The 33 was short lived new measurement on the 32 hull. 32 Aft was a doll. If a stringer is broken I’d look at another boat. You can fix cosmetics on a glass boat but structurally repairs are makeshift. Typical two part paper thin epoxy coat doesn’t replace the structural cell loss from the water damaged hull after a pox repair.
Go google some delaminating boats which were repaired. The patches are fine and it’s their rigidity which broke areas with flex.

[Spot]

The original post is old and seemed to be fishing for negativity against specific YouTubers. The first 'necro' reply has some love for Dan and Kika from Uma. I saw the video of that repair a while ago and thought they did a good job fortifying the beams above the keel attachment. The foam in their repair is there only to hold the glass and resin in place until it cures.

One can watch it for themselves:

https://youtu.be/OyKy-cDy6e8

Aware of but not familiar with the 'Bums', I imagine that repair can be 'googled' too...

[pcmm]

Originally Posted by LongWinded

Not in the lest, in fact UMA who did the repair with XPS foam (often thought not to be suitable in marine aplication) has crossed many of oceans in worst weather than most. Even that of a hurricane thrown its way. My response is to the arm chair sailors who never have had to think outside the box.

The truth is in this case, the type of foam really doesn't matter much. The strength of the repair, (they essentially made new floors) comes from the shape of the laminate not the core material. So the XPs really is nothing more than a form.

[RaymondR]

Originally Posted by pcmm

The truth is in this case, the type of foam really doesn't matter much. The strength of the repair, (they essentially made new floors) comes from the shape of the laminate not the core material. So the XPs really is nothing more than a form.

Right on bro. The original material will still have structural properties which will be considerably increased by the addition of new materials and enhancements to the section properties.