Crack on hull at forward edge of centerboard slot

[tuntini31]

My boat has a crack at the forward edge of the centerboard slot underneath on the hull. I have attached pictures (click on URL) since it will be easier than explaining it.
It goes all the way thru to the bildge. (I filled with water with a hose and it leaks out). Can I just fill with the putty epoxy stuff where you mix the two colors together and it hardens and then sand it smooth? Thanks! OR how would you fix it? Thanks!

P.S. Should this be in the repair forum?

[GreenLake]

P.S. Should this be in the repair forum?

Probably would have been best if you had simply added to your existing thread there. Perhaps the admin can do something about that?

My boat has a crack at the forward edge of the centerboard slot underneath on the hull. I have attached pictures (click on URL) since it will be easier than explaining it.

Thanks for the pictures. That looks like a substantial crack. It looks like the laminate is torn right through for several inches.

It goes all the way thru to the bilge. (I filled with water with a hose and it leaks out). Can I just fill with the putty epoxy stuff where you mix the two colors together and it hardens and then sand it smooth? Thanks! OR how would you fix it?

I would NOT use the putty.

Yes, you could get it to be watertight - but. The area is under high stress, because the CB trunk has to hold all the flexing from the CB, and those loads are substantial. That corner is the place where the hull is connected to the CB, and much of the load has to be absorbed here.

Any "repair" aimed at merely sealing the crack will not hold up to those stresses. After all, the original laminate didn't.

So, you're better off "doing it right." The good news is that this should not be all that hard. See next post.

[GreenLake]

Otherwise, repairing fiberglass with expoxy is not hard. Searching the sites for West System or System Three will give you links for manuals, such as the Epoxy Book. (Searching this forum will dig up some disucssion of working with epoxy as well). Reading up on that will give you some necessary background if you have never done epoxy/fiberglass work before.

What you don't do is just pour epoxy into a crack. A proper repair starts by widening the crack, so the expoxy can actually get in there. After that, you could use epoxy mixed with glass fibers to fill the crack (short shavings of mat or cloth would do in a pinch). That would get the crack watertight.

After that, you'd want to put an extra layer or two of glass over the crack as a patch, to support the area. If that would make a bump on the hull, you would first need to grind away a bit of the existing material, so the repair becomes flush. In that case, adding some reinforcement on the inside (backside of crack) would also be useful.

Perhaps this will give you a start towards a repair.

Given the rather massive crack you are showing us, I'll change these recommendations a bit (not the one about following the link to the Epoxy book and reading the chapters on repairing cracks - please do that).

[GreenLake]

In my view, a crack like this is best restored by inserting a patch.

Normally you'd grind a shallow depression (see the Epoxy book) until its depth reaches the thickness of the hull where the crack was, with the sides all clean laminate, and each side 12x as wide as the laminate is thick.

In your case, there are two complications. One, the hull is not flat, but angled. Actually, just grinding a flat spot would give you the correct geometry to fix the crack along the keel line.

The second complication is that the crack most likely goes up the front face of the CB trunk. In that geometry, it's not possible to grind a shallow depression from the inside of the CB trunk.

But, unlike the hull, your repair can protrude a fraction of an inch above the surface, so you could apply a flat patch.

The CB trunk part of the crack, I would saw/file square, and then fill the actual crack with thickened epoxy (you could just cut short, 1" length of fibers off a piece of cloth and stir them into laminating epoxy).

For strength reasons, you'd want both parts of the crack to get further reinforcements. One way to do that is to drill a hole for an inspection port, also called a deck plate, so you can sand the area of the damage from the inside and place several pieces of glass cloth, whetted out with laminating epoxy.

Adding a port, would allow you to make that part of the repair with the boat right side up. And a port is always useful.

So, here are the steps:

• Grind and cut from the outside (boat turned over, wear dust protection).
• (Turn boat)
• Cut out hole for the port, and place patches 2-3 layers of glass on the inside of hull crack and CB trunk.
• Insert deck plate and seal.
• (Turn boat)
• Fill the CB part of the crack as described.
• Place an Extra layer of glass cloth (or two) on the inside of the CB well, one piece wider than the other (4" and 2"). (There should be enough room for the CB to pass)
• Place several layers of glass cloth over the hull crack area, widest first, until you've built up the hull to close to the original V
• (Alternate orientation by 45 degrees)
• Sand of bumps and use a fairing compound to get a smooth hull.
• Paint bottom (Turn boat over and start sailing)

Looks like a good number of steps, but a weekend should see you through it (well, except for painting the entire bottom, but enough for a temporary coating of the patch).

[tuntini31]

I found this and it seems perfect for the job

http://solutions.3m.com/wps/portal/3M/e ... JFL5HG9Dgl

Then there's this too, but it seems like the first link is the better stuff to use

http://solutions.3m.com/wps/portal/3M/e ... JFL5HG9Dgl

Hopefully these links are allowed sorry if there not. I just like to get feedback from the experts here on the stiff before I buy. Thanks everyone for all the help so far!

[GreenLake]

I found this and it seems perfect for the job

3M™ Short Strand Fiberglass Reinforced Filler

Then there's this too, but it seems like the first is the better stuff to use

3M™ Marine High Strength Repair Filler

I just like to get feedback from the experts here on the stiff before I buy.

I've worked with the Marine High Strength Repair Filler. I had a hole in the hull below the water line where someone had "fixed" it with some putty. When I was sanding that area, I felt it move and could push it in with my finger

The hole was about finger sized and after cleaning it out, I had no problems filling it with the repair filler. It's plenty strong for a job like that. But --- and here comes the big but --- in my case this was a circular hole, not a crack, and it's not in a highly stressed area. Unlike your crack, there's no reason to expect that the repair will be stressed and come apart again - after all, I sailed with a bit of putty under the paint for many years, not being the wiser.

Your crack will need the reinforcement of a glass patch as I've tried to describe it to you, otherwise the repair won't be permanent.

That said, I believe the filler is a a reasonable method to fill the part of the crack that will be between two patches of laminate (inside and out).
(the 6th bullet item in my list above, and assuming that you have assiduously removed any damaged laminate from the edge of the crack).

You might be tempted to see this a temporary repair, it might even last you to the end of the season - but I won't recommend that, because if it lasts the first few trips out, I suspect you'll get complacent and think it will last forever. (Like the previous owner who "fixed" the small hole on my DS with putty). If & when the crack opens up again due to high loads on the CB, you may find yourself with lots of water coming into the boat when you are far from land - a situation best avoided.

So do it right - and make sure you back up whatever repair you do with a glass layer (or several) inside and out.

[K.C. Walker]

Greenlake is covering it pretty well here. I think he is giving you good advice. In the location that you have a crack, putty adds almost no strength and the crack is because the centerboard trunk was not strong enough to hold up against the stress put on it at some point. Now, it is much weaker than it was, so it would take far less force to open the crack. Fixing it right does take time, but so does fixing it poorly. As Edward Deming said, "if you don't have time to do it right the 1st time, how are you going to have time to go back and fix it later"?

[talbot]

After the crack is patched, you could consider installing thwarts in the cockpit, as in the DS I. I began installing them just to make a rowing seat, but once I got into the project, I decided to make it structural. They brace the CB trunk against the port and starboard tanks, and should minimize the kid of flex that may have caused the crack in the first place. It is probably my imagination, but I like to think the boat is a little stiffer and points higher than it used to.

[tuntini31]

Thanks guys!! Btw, I yard launched and careened the boat, but it seems as though the crack has closed up and is now extremely barrow, almost hairline.

[GreenLake]

Narrow it may be, but it will be as deep into the laminate and as weakeing to the structure as before. Good point, though, you don't want to permanently widen the crack by a repair because you inserted more material than can fit.

However, this means, you do need to widen the crack now, so that whatever you use (see earlier posts) can be thick enough to be effective.

The suggestion about the thwarts is well worth it, in my view. I have a DS1 and I know why I don't leave them off the boat.

[Alan]

Careened, as in laid on her side? Seems to me that would close the crack just from the weight of the upper side pressing down on it.

I'll defer to the more experienced people on this, but it seems to me that if you could get the boat completely upside down you'd have a better idea of how wide the crack really is.

[tuntini31]

Well ya I figured it was due to the weight...the concern was not
That it was, since it was on it's side and it was closes up a little, how much material or whatever to bridge/fill the hole. Idk I'm going to just repair and see what happens..at least get one sail out of it and do a more permanent repair after the season is over if I don't the more permanent repair now

[GreenLake]

Let us know how it turns out.

[tuntini31]

Ok I will! I don't think I will be able to install another inspection port. So I will have to use the two small ones and reach in side to repair. Im going to patch the inside with fiberglass and use epoxy on the outside

[dbk0630]

Talbot (or others),

I'm always interested in pointing higher... so I'm curious about the type and thickness of the wood you used for the thwarts you added to your DS2, what you used to attach them to the seats and cb trunk, and any other details/suggestions you might want to share.