*CRUNCH* Something broke! Mast crutch support? *pics*

[GreenEggHead]

We took our little sailer out on Mosquito Lake for the second sail and she fared very well. We tacked across the lake, and on our way back across, she was bumping on the waves pretty good. We heard a loud crack and the sound of crunching fiberglass. We immediately pulled down the sails to investigate. Here is was we found. We limped back to the dock with the jib and loaded her up and brought her home.

The line is tied to the keel lever.



From another angle:



And I busted off some of the cracked fiberglass to investigate what was underneath what I think might be called the mast crutch?





What now?

[kokko]

Wow!

It appears from the photos tha the mast support is screwed into a block of wood embedded int he fiberglas. The only reason for that glas to breask is if the screws were not holding it in the wood. Remove the fiberglass, and replace the wood if necessary. That would shouodl be holding the screws secure, and the wood should be securely in the slot. You don't want any wobble when the mast support is screwed down.
Reglas the area, reseat the mast support and redrill.

You will sail another day.

[GreenEggHead]

Yes wobble it did. When it cracked, the mast was quite wobbly. It seemed to loosen up the tension in the stays enough to allow the mast to sway.

The wood isn't really embedded in the glass, it just slides around. Looks like I will have to unscrew the mast support from the top and bottom, dremel away all the messed up fiberglass, clean it up, reinsert the wood if it's in good shape and mix up some epoxy to rebuild that section of hull. Then hopefully I will be able to reinstall the mast support and it will be strong enough to support the mast again.

I've never done fiberglass before, but I think by reading some of the other posts about repairs I can get enough courage to try it. Luckily it's down in the cuddy and it doesn't need to look perfect. Just want it to be strong.

I'm worried about the bond between the new fiberglass repair and the old stuff underneath.

[kokko]

I would somehow embed that wood too. It wobbles, and the whole structure wobbles

[GreenLake]

The wood is apparenly only intended a backing plate. Its task is to hold the screws (think of it as a giant nut and washer). Being loose is not a problem for that purpose. (Once the fiberglass is restored, and the screws are tightened, there should be no wobble).

What seems to be an issue is that the laminate might not have been strong enough, so the repair may need to add some more thickness.

Also, I would make sure to cut back the old laminate rather far, so that the connection between old and new is not in the highest stress area.

Here's a suggestion how to proceed:

1 Cut away several inches around the repair.
2 Bevel all the edges. (The ideal slope for that is 1 in 12.)
3 Take cardboard and cut and fold to make a mold that fits into the inside of the channel (you might need two pieces so you can fit them in). The cardboard should extend a bit underneath the old material, just to keep it in place.
4 Shave the wood so it fits inside the cardboard
5 Place the wood
6 Precut your fiberglass and mix the epoxy
7 Coat the cardboard with epoxy on all sides and fit into the opening.
8 Coat the cardboard and edges of old material with epoxy
9 Add a layer of glass
10 Squeeze out excess epoxy until glass is wet out

Add the other layers the same way until done.

For the cardboard I would not use corrugated, because that's hard to coat fully with epoxy. If you mix only a small batch of epoxy and let it cure after step 7, even thin cardboard should work (cereal box or from back of a paper pad).

For the new laminate, you should precut the first layer so it fits the entire repair, even the edges. The next layer gets a little narrower, so it fits part of the edges. When done, there's going to be a bit of a rough area around the edges of the repair where all the layers terminate. If you did things correctly, you should be able to grind that area flat, once the epoxy has cured.

To add strength, you should add two final layers, that build up a thicker laminate in a "stair step" fashion, with the two steps at equal distances, the first starting say an inch or so beyond the mast support. The idea is to gradually increase the wall strength, to distribute the stresses gracefully. (If the new layers overlap the joint from new to old, they would help reinforce that as well).

Since you are new to epoxy: I recommend you build a dummy first, do a few layers over a cardboard mold. That should give you a feel for how this works. Better to be able to throw out a not-quite perfect first attempt than to be stuck with it inside your boat.

Good luckl!

[dtrop01]

A couple of years ago at NACs in Eugene, I had the same thing happen to me. Here's my fix.

Along the lines of the previous post, I expanded the hole to get to clean, solid fiberglass.

You then have two options....find a block of spruce, mahogony...or ideally a delrin or other plastic that you can shape to fit the size of the opening and comes just below the bottom of the top surface of the keelson. My thinking was to distribute the load down to the bottom fiberglass.

If using wood, coat with epoxy thoroughly. Having a square bottom allows a channel for water to pass from the box tank to the drain hole alongside the keelson.

I then built up multiple layers of fiberglass to bring the surface up to the rest of the keelson.

To further distribute the load, I found a piece of aluminum plate (can't remember the thickness, somewhere between 1/8 and 3/16" and cut it to fit extending pass the repair and fastened this into the keelson. Since the shear loading on the plate is not as great as the compression loading (hence it failed in the first place), i drove three screws through the plate and into the block.

I then added my mast step and was good to go.

Haven't had any issues since.

If you like, I can probably take a pic of the repair and email you.

Don Trop
#2835 Killer Tomato

[K.C. Walker]

Greenegghead,

I don't know what the other end of that mast support looks like. It's not like what's in my boat. Maybe you could cut it down and reinforce the keelson.

The layup in the keelson on my boat looks to be quite a bit heavier than the picture you have shown. I'd be tempted to build up and strengthen the keelson. You could put a plywood cap on it pretty easy and then glass over the top of that down the sides of the keelson to reinforce the sides. If you made the plywood the same width as the keelson and went forward and aft a good amount you could distribute the force and beef up the whole thing considerably. I think that would be less work than trying to reinforce it by cutting away the old and reinforcing it from the inside. Of course, you may need to shorten your mast or that mast post.

If you thoroughly sand the gelcoat on the keelson, which looks original to me, the epoxy will bond to it fine.

It's always good to read the fiberglass repair book by West System http://www.westsystem.com/ss/assets/How ... enance.pdf .

KC