Need some advice on how to fix this...

[Islandtrader]

Both gunnels toe rail and rub rails are badly stressed cracked and or impact damage The whole length. Some of this was due to the amount of pressure by down riggers and such.

What is the best way to fix this so they don't show up again?

I was thinking of using 6 inch 9 oz. tape and then fairing the whole thing...any opinions out there would sure help. This is going to be time consuming so I want to get it right.

Gunnel Hairlines



Toe Rail



Rub Rail





Fix? Run the tape the whole way down.

[Bushwacker]

Terry - I'd say those cracks running across the gunnel perpendicular to the toe rail are stress cracks; it looks like they don't turn and run up into the coaming, so it's probably much stiffer than the side decks. The primary stress direction is typically normal to the crack, or parallel to keel in this case. Bending loads from winching boat up on a trailer might do that. That circular crack around the pop rivet is caused by bending stress from the rivet pulling the cap into the hull. An impact load such as from dock walloping will create radial cracks like a spider web. My neighbor, the composites expert that Skip & Carla met last weekend, said that the old polyester is very brittle, so it probably doesn't take much stress/deflection to crack it. The layer of cloth with some epoxy would probably fix it, since epoxy is so much stronger than polyester; just make sure you orient the glass fibers in the direction of the stress like in your picture. You might want to sand thru that brittle gel coat any place that it's cracked however, so the new cloth is bonded to glass instead of the old gel coat. A layer of foam core material bonded underneath the gunnel would provide a lot of stiffness to the side decks and is what he recommended for attaching their Seafari top to the deck. Probably overkill for what you're seeing however. He also said you don't need to use any mat if you're using epoxy. Will ask him about those cracks next time I see him. Denny

[Islandtrader]

Denny, I agree with your assessment.

However I am looking for glassing suggestions from folks out there that have tackled a similar problem...it appears it will take some real work and I want to do this job once.

Help...

[Bushwacker]

I agree that's a job I'd only want to do once! I think Strick had to fix a lot of spider cracks on his 20, so you could probably follow his lead. Not sure he used epoxy (maybe vinylester?), but I'd stick with epoxy due to higher bond strength.

Saw my neighbor this morning, and he said those cracks running across the side decks could be caused by a couple of things, one of them being an impact to the gunnel from dock walloping. Deck would try to bulge upward locally adjacent to the impact, so you'd get a membrane type stress that would produce those cracks. He confirmed that max stress direction is always perpendicular to the crack. There does appear to be some impact marks along the rub rail in the pictures, but don't know if that pattern repeats at every place there is a side deck crack. If cracks are due to impact loads, he said what you've proposed would fix it, provided the new glass is bonded direct to the old glass, not the old brittle gel coat. Might want to wrap the glass up into the coaming if the cracks go up there, and definitely around the toe rail. Sounds like lots of sanding involved!

The other possibility could be a buckling failure, since the side deck is probably not nearly as stiff as the coaming and the overlapped toe rail/hull joint. This is what happens to an I-beam where the vertical section or web of the beam is much thinner than the top and bottom plates. As you increase load on a beam like that, the web tends to buckle well before you reach max load capability of top & bottom plates. Same thing can happen to stringers if they're too thin or are not braced by enough bulkheads. In this case, the I-beam is shaped more like a Z laying on it's side, but the basic issue is the same. The fix for that would be to laminate a core underneath the side decks; he said it's important to taper the thickness where the core stops, otherwise it'll just crack where the core stops because of the sudden change is stiffness.

[muddywater]

I have been working on exactly that for months. I have one of those boats where the owner apparently thought that to stop the boat you run it into the dock

In some places the repairs were minor, but in several places the cracks went completely through the glass and I had to grind it all the way down. I could not really tell how bad the damage was until I hit it with the grinder. I rebuilt it with 1708 biaxial and used 6 or 9 oz stuff on stuff that wasn't as bad (simply takes too many layers to build up with the light stuff). It is a real pita and time consuming. I would love to hear how others have handled it.