Crack in Kevlar and bowed in hull side.
Posted by: castoff on Jan-05-13 12:18 PM (EST) Category: unassigned
I am looking at a used Kevlar MR explorer with some damage in the stern. The gunnel and side just in front the stern seat is bent and bowed inward from a wind storm blowing the boat into a pine tree. A photo of the damage, seems to show a crack with light shining through the gell coat. It does not seem to make it to the outside of the boat but runs from the gunnel most the way down the side. It looks to me to be in the fabric on the inside not the gell coat.
I have some fiberglass experience having build a kit sea kayak by Shearwater. However I react very badly to the uncured epoxy even when being very carefully. Anyway, how should I approach a repair and straighten out the bend in the gunnel and the bowed in side.
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- Crack in Kevlar and bowed in hull side. - castoff - Jan-05-13 12:18 PM
put up some pictures|
Posted by: pblanc on Jan-05-13 1:56 PM (EST)
I am assuming the boat has aluminum gunwales. If crimped, aluminum gunwales are nearly impossible to completely straighten, at least in my hands. I have tried using pipe clamps or bar clamps that can also be used in reverse as spreader bars, applying a clamp across both gunwales either side of the bend to keep them from bowing outward, and using one between them at the bend as a spreader.
You have to use C clamps and wood blocks to hold the clamps in position to prevent them from sliding toward one end of the boat and you have to be careful not to damage the good gunwale. I have been able to straighten bent gunwales somewhat to a functional state but I haven't been able to restore them to a normal shape.
If the gunwale is not crimped I suppose it might be possible to drill out all the rivets securing it and lifting it from the boat to reshape it over some type of form that approximates the shape of the boat. I have never tried that. If you can't straighten the gunwale to your satisfaction you would have to obtain a replacement gunwale. You could probably do so from Mad River but the shipping rates are murderous. If there is an MRC dealer near you that receives canoes from the factory, you might be able to have replacement gunwales shipped when they receive boats, but you might need to wait a good while.
As for the hull damage, based on my experience the cloth is probably damaged under the gel coat. Years ago (back when they made my Kevlar Explorer) MRC used an all aramid layup with no core and no external fiberglass, just gel coat. Now Explorers have an external layer of fiberglass which facilitates repair. Back when, all composite Mad River boats had wood trim. If yours has aluminum gunwales I would guess that this boat has an external layer of 'glass. You could try calling MRC and giving them the date of manufacture from the HIN. If they don't know try asking openboater on this forum.
I have seen a number of cracked composite boats in which the external damage only looked like a crack in the gel coat, but after the gel coat was sanded off the fiberglass fibers could be seen to be broken. The aramid fibers in the inside will often not fracture, but any light colored line means that at least some of the fibers have separated from the resin matrix.
Without seeing the magnitude of the damage I can't say for sure what I would do, but I would almost certainly apply an aramid patch to the interior, probably 2 concentric layers. If I thought that the outer fiberglass layer was extensively damaged, or the hull still "felt soft" after patching the interior, I would sand off the gel coat in the area of damage and put a fiberglass patch on that as well, one or two layers, then paint over the external patch with a paint that approximates the color of the gel coat.
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I doubt the inner Kevlar would have |
Posted by: g2d on Jan-05-13 4:03 PM (EST)
split from the boat's side being pushed in from outside. Kevlar has enormous strength in tension. Probably the appearance in the seller's photo results from disruption of the resin/cloth laminate along the line of the fold. That disruption would represent mainly compression of the outer laminate layers.
But pblanc is right in saying that a couple of concentric layers (larger first) on the inside would help.
If you're super sensitive to epoxy, and think you can't get by just using gloves and great care, you may be able to find a source of quality vinylester resin. Just be careful not to buy more than you will use in 6 months, because it will slowly "go off" on its own. I've used vinylester for patching, and it works very well.
If you decide to use epoxy, you might employ a "helper" who can do things for you such as pulling off epoxy soiled vinyl gloves, holding mixed epoxy, or even dipping out mixed epoxy for you to spread into the laminate. Some "helpers" may be susceptible into being Tom-Sawyered into wetting out the laminate for you.
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I have a friend near Greenville who |
Posted by: string on Jan-05-13 8:12 PM (EST)
has repaired several boats for p.nutters, incl. me. Excellent work.
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Thanks for all the help!|
Posted by: castoff on Jan-06-13 1:50 PM (EST)
Y'all are great! Not sure yet I will get this boat, but currently still considering it. The gunnel isn't crimped in the photos. As sugested it could be the glass between the gel and Kevlar that is compromised.
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