Leaky 73...

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Leaky 73...

Postby Palmer4th » Tue Aug 09, 2016 3:44 pm

A month ago I went to vermont and purchased a oday ii from another member on this site. The boat was named suluhu by jkfinity. I'm a first time sailboat owner who knew nothing.. The add was pretty true except I would say it was not in good condition. The part that was not true said "I Resurfaced, painted bottom 1/3 of boat (below waterline). Three coats oil-based paint. Did not use ablative, per local marina recommendation, since the boat was trailering not moored." However somehow during that he missed the big crack in front of the keel?? I'll try to post a picture.

All venting aside I'm still excited about owning my first boat and I can't wait to get it on the water. My plan is to cut a 6" how in the cuddy and patch the hole from above. Then fiberglass the bottom as well. It will take a good bit of glass and epoxy to get things right. There is also a 18" crack that was just filled with epoxy so I need to put some glass on that to make it stronger.
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Re: Leaky 73...

Postby Palmer4th » Tue Aug 09, 2016 6:11 pm

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Re: Leaky 73...

Postby GreenLake » Wed Aug 10, 2016 3:20 am

Generally agree with your plan. There are some ways you could make this less messy.

a) you could lay up an interior patch on a sheet of plastic (or even on a sheet inside a plastic bag). Then you can transfer it (still wet) to the repair sit, slide it out and have the plastic sheet as backing to allow you to put some pressure on it (bag of cat litter) while it cures. Definitely less messy than trying to lay laminate through an access hole.

b) if the hull area you are trying to reinforce from the inside is flat (or curved only in one direction, like a cylinder) then you can even let your patch cure to the green stage before gluing it in place. Working through an access hole, you may have to divide a larger patch into two strips, so it fits.

I used method (b) for a hull repair after a collision, because tension in the hull had forced the edges out of alignment and I needed a well defined surface to bond to. That required a patch that already had some stiffness.

c) for a larger crack it should be possible to use a modified method (b) where you push a stiff patch through the crack from the outside. Then use sheet metals screws or something to hold it in place while gluing it from the inside. Remove the screws and finish the repair from the outside, taking care to fill & fair the screw holes in the process.
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Re: Leaky 73...

Postby Palmer4th » Wed Aug 10, 2016 10:28 am

Those are great tips! So I am planning to cut a 6" round port in the cuddy, then remove any loose fiberglass, sand with fien tool sander, then clean clean and clean. I was thinking about taping wax paper to the bottom of the hull and filling with west systems epoxy and 403 microfiber. Then let that set up a bit and start glassing the inside and underside. someone had obviously tried to fix the crack already because i had to remove a lot of fiberglass when I sanded it down. I don't know why their fix did not hold? I'm hoping that by patching inside and out i will gain more strength?
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Re: Leaky 73...

Postby GreenLake » Wed Aug 10, 2016 12:04 pm

Your photo shows some brown color. That's not what laminate normally looks like, so I wonder whether someone simply used Bondo.

Now, the main reason to reinforce the repair from the inside is to make it easier to do the layup from the outside. This applies if the hole has a significant diameter (so that any laminate would sag badly if not supported) or, as in the case I mentioned, when there's tension in the hull and the sides of the repair do not line up properly.

A well executed repair from the outside should otherwise be strong enough to stand on its own - especially given that the laminate for the DS hull is perhaps a bit stronger than minimally necessary.

I would start by grinding away on the outside until you hit clean laminate (without any signs of damage). Damaged laminate will look white (from broken fibers), good laminate will be transparent, so look dark. You want to leave shallow edges, about 1:12, for a strong repair. You'll want to fill that repair with layers of fiberglass cloth.

There are two techniques: start with a small piece and layer ever larger pieces. Or, do the reverse, start with a piece that covers the whole repair, and then add smaller pieces to fill the center of the depression. The second technique seems counterintuitive, but has the advantage that that first layer of cloth is well suspended. If the actual "hole" in the center of your damaged area (after grinding) is small, the cloth may well "bridge" it without support from the inside.

If you do decide that the unsupported area is too large, then you will have to cut a port and prep the inside. You need to remove loose fiberglass and any paint, but you are not going for a perfect surface. Something like 60-80 grit is totally fine.

Your damage is at the corner of the CB trunk. If you add reinforcement anyway, it might as well serve to strengthen the hull/trunk connection in addition to providing support for the outer repair. 2-3 layers of cloth, tapered, so the inner overlaps the outer by and inch (ideally). I would do the layup in reverse order on a piece of plastic on your workbench, then, still wet, transfer it, with the plastic acting as backing, to the repair.

As you will need to fit it through a 6" hole, perhaps laying up two narrower strips of laminate might work best. You can apply them like an X across your repair. To transfer them, you'd roll them up like tape and then unroll them, with the plastic acting like backing tape.
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Re: Leaky 73...

Postby Palmer4th » Wed Aug 10, 2016 12:33 pm

great tips! I sanded off both layers of bottom paint in the area around the whole and crack. So is that the down color your talking about?
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Re: Leaky 73...

Postby GreenLake » Wed Aug 10, 2016 1:51 pm

What does it looks like? As in the photo? Then I doubt you've hit laminate.

In this image you see a repair I made 1041.

(Described here: http://forum.daysailer.org/forum/viewtopic.php?f=11&t=3785&start=15&hilit=gored)

What you see is the hole, ground out for repair, with a backing plate being glued from the inside (top) and partially filled (bottom). The exposed laminate, being transparent, normally looks dark, but may show through a bit of the color of what's behind it (often the paint).

It does not look opaque and chocolaty brown. It also shouldn't have little voids, and where it's cracked, there should be visible fibers (it'll look torn). The cracking that appear in your image don't look that way.

Compare to this image: 1035.

So, I'm very much afraid that what you are looking at is simply filler. Don't count on it for strength.
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Re: Leaky 73...

Postby Palmer4th » Sat Aug 13, 2016 11:52 am

I see what you mean, it does look like its not all the way down to glass. if you zoom in you can see the fiber. so its getting pretty thin in the area around the crack. is that ok? what is the best prep that can be done so the fix is nice and strong?
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Re: Leaky 73...

Postby GreenLake » Sat Aug 13, 2016 4:24 pm

For a strong repair.
  1. You need to grind away anything that isn't solid laminate. Damaged laminate, filler, whatever.
  2. You need to grind the sides of the repair at a shallow angle (12:1).
  3. Use epoxy and cloth (as described above).

Usually, following these three main steps (and making sure the epoxy is measured accurately(!) per maker's instructions and mixed well (including scraping the sides, corners and bottom of mixing container and scraping the mixing stick), you should be able to get a repair that's just about as strong as the original. Even without a backing plate.

Adding a backing (if it is easy to do) can make a repair simpler, because you have a flat surface onto which to laminate your repair. In my case, it was crucial because the hull side had shifted with the sides of the repair no longer lining up (unlikely in your case). The benefit of adding strength come in when you're not sure you found all the damaged laminate, or the location is tricky, or may be highly stressed, so it's nice to have a safety factor. (That might be the case for any cracks that separate hull from centerboard trunk).

But, if the spot is small, you may be able to insert a stiff plastic sheet and screw it in place from the outside. Then do your layup with it closing the back of your repair site. Later, remove the screws and fill the holes.
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