Crack in hull

[Carl]

I finally repaired a crack in my hull of my Day Sailer 1 that ran from the front of the center board trunk, forward about 2 inches. The crack was about as wide as a putty knife blade. Prior to the fix at the end of an afternoon of sailing I'd have about 3 gallons of water sloshing in the boat as a result of the leak.
A freind of mine wise to the ways of fiberglassing opened up the crack with a dremmel, we put in in resin with fiber, let it fix and then added the gel coat which I sanded it down. Looked great, my first effort at fiberglassing and I'm feeling good.

All seemed right with the world I took the boat out for a shake down and there appeared to be none of the leakage I had prior to the fix.

Failed to the cover the boat up after the sail and it sat on the trailer during the next deluge of rain. That was fine with me I wanted to rinse out the insides anyways. Today I was bailing out the boat and looked underneath to admire my handi work. Much to my surprise I noted several drops of water collecting at the site of the repaired crack. Crawling under the trailer I discovered a hairline crack had redeveloped in the repair site. This did not do my ego any good.

The boat is an old one sail #51. I have the original paper work and hull numbers it was built in 1959. Boat is on a trailer supported by two bunks. I have three rollers one under the stern near the transom, one under the center board trunk (about the middle of the trunk) and one along the keel about 3 ft back from the bow. The area where the crack has devloped is not supported.

I sail at West Branch which is NE Ohio, the lake is only about 15 min from my house so not a long distance to trailer.

The past several years I have been skulking on this forum and have learned much from you all, this is my first post. So wise members, any speculations on why this problem is reoccuring? Should I have some roller support for this area of my boat?

Apprecitate your insight or just commiserate with my problem.

Carl

[dsheer]

Some thoughts.

The crack is in a high stress area. The original construction almost certainly had multiple layers of glass cloth across the keel. The strenght of the cloth is what probably holds things together. In your boat, the cloth layers are cracked through, and motion in the crack will cause it to expand over time, so you must fix it, and fix it well. I doubt that glue, be it resin with fiber in it or a commercial glue, will hold, but if I was gluing, I would probably use JBWeld and not resin. It may be that a glue with a little flex when it cures would work. There was some flex in the cloth before it tore.

I'm thinking that the solution is will involve both glue and creating new layers of cloth across the crack, both inside and outside. I don't know how to do this on the outside without making a "hump" in the hull, ond on the inside there is a hollow channel that I think serves as a longitudinal stiffener. I don't know how to get a layer of glass underneath the channel without removing it and then replacing it. Perhaps others in the forum can help you out here. I tend to doubt that glassing one side alone will work.

I'd guess that there's a good fix for the problem, but you will need to find someone who has experience to tell you what works - and that's not me. All I can say is Good Luck. Keep that old hull afloat.

Dan

[Roger]

You must bridge that gap, not just fill it. From the outside, I would take off a the layer of gelcoat completely up to 2 inches on all sides and ends of the crack, right down to the cloth. Could use a dremmel for this, but a belt sander will get you there very quickly. Be very careful and apply the sander is short 1 to 2 second spurts, then check your work. Do not use an angle grinder, it will take it off too quickly, A belt sender is almost too fast as well, but a palm sander will take hours! You will now have a crater four inches across, by however long the crack is, plus another 2" on each end. Now with the dremmel and a small drum sander, take out the first layer of cloth about an inch on each side and ends of the crack.

If possible do this repair with the boat careened onto its side, or even better upside down so that gravity works for you. That may not be practical but working this kind of repair from under the boat is really challenging. Widen the crack to about an 1/8 of an inch, clean with acetone and let dry.

Using polyester resin (not epoxy) fill the crack and saturate the bottom of the crater that is 1 inch wide on either side of the crack, add a saturated fg cloth strip the same size (2 inches wide, or slightly wider 2 1/2" then before it cures, saturate the whole area, and add a 4" wide strip on top the same size as the crater. Let this cure, then the next day clean off the amine blush with acetone and cover the whole area with gelcoat, or if you are planning on painting the repair, just with polyester resin until the repair is at least level with the surrounding area. After four days, (cured and final hardening) use a Palm sander with 80 grit, knock down the high spots and get an initial flat finish, move up to 120 grit, then 320 or so, and finally finish off with 400 or 600 to match the finish of the surrounding area. If you are painting wait four days.

This now gives you a base to start working on the inside if you can access the crack from there.

You want to beef up this area as much as possible, so yes you will have a hump, but it will be on the inside, where it will not affect bottom performance.

On the inside, clean out the crack with your dremmel tool to about a 1/8" V shaped groove. You will not be creating a crater like you did with the outside. Give the surrounding four or five, even six inches a good sanding with 80 grit, but basically just to get a 'tooth' on the surface. You want to keep as much existing fiberglass here as possible. Clean with acetone, let dry and again fill the crack with polester resin, paint the area with resin, place a fiberglass cloth saturated with resin over the area but short of the edges of the sanded area by about an inch and a half. While this is still wet cover with a second layer of cloth, this one extending to about a 1/4 inch from the edge of the sanded area.

Do all of this work on cooling temperatures, ie after the heat of the day. If you do it as temps are increasing, tiny bubbles will appear in your work from heat expansion. If you do it on cooling temps, the resin will actually soak into the toothed area better, and you will get a better mechanical as well as chemical bond.

If the crack goes right up to the centerboard case you may also want to strap the lower end of the cb trunk just above the crack to reinforce it. Do it the same as the first repair, but just add 2" straps of saturated fg cloth on to the similarily sanded and cleaned area. Make sure your straps wrap around the front of the trunk and extend back at least 6 inches on either side.

It will definately look reinforced on the inside, but at least you should not get any leaks.

This is likely a minimal fix. If you were wanting a stronger fix you may extend your repair up to 9" on either side of the crack.

One further item, to make sure to check. Although you think the visible crack is only two inches long, assume the hairline crack goes another inch at least. Groove it out while your are doing the visible crack and repair the whole area as one.

Finally when using fg cloth, do not use the woven stuff, get chopped strand matt. It saturates better, and is more water proof than the woven cloth.

If you have never worked with fiberglass, do a little bit of reading first to familiarize yourself witht he process, but after you've done it once, you will not hesitate to do it again. Use a mask, protective clothing and latex gloves. Use disposable containers, mixing sticks, foam brushes, etc. Resin kicks best at about 60F degrees, so for a few days before you do your repair, watch your daily temps and id the time they peak. This is when you want to start your repair. Also if you are working outside, work in the shade, the direct sun makes it kick faster and may create bubble. One trick with moveable work is to let in sit in sun, under a green garbage bag, then move it to the shade to do the work.

Hope that helps.

[Peter McMinn]

Wow, nice work, Roger! I think I would go with a wider area, just to be assured of the bond.

Carl, send us some process pics and contribute to the fun!

[tedsojka]

I opened the boxlike structure between the mast and forward part of the centerboard trunk. There I found a mouse nest that was just above the crack, and assume as it was very damp, that it cracked the previous Winter when it froze.

I dremeled out the crack, held it open and shoved glass fiber and resin mixed with filler material to the consistency of peanut butter and forced it in the crack, held open with a screw driver.

It sealed fine, I sanded and it remains a fixed item.

Mine is an old three number boat.

I WONDER ABOUT SEALING THE FRONT OF THAT STUCTURAL BOX UNDER THE MAST STEP TO KEEP THINGS FROM BUILDING NESTS IN THERE? Some told me that this was meant to collect a little water during sailing and dry out later???

Anyone got a thought, at the National this Summer said it needs to breath under that four by fourish structure that supports the old style brass screw and disc that tensions the mast.

I have left the top cut out on this box like member caulked on to the rest of the structure in case I ever need to get back in there. It is like a flap between the mast step and the centerboard trunk, about 6 inches long.

Ted