Help with hull repair

Hi you'all,
Down in Mexico and need to repair a gash in the hull of my 2004 nacra F18. It's a 10'' horizontal gash, 4' back from the bow, in the middle of the hull. Lucky it's a clean gash and only through the outer skin and a bit into the foam. Would greatly appreciate some help with a few questions and any suggestions.

a. are these boats built with polyester or vinylester resin ?
b. anyone know what the laminate schedule is ? how many layers and what weight ?
c. would you grind and taper the existing laminates for the repair ?
d. what resin would you use ?
e. anyone know whoes gelcoat best matches the standard nacra white ?

thanks for the help

send a PM to Jake - he's done some pretty extensive glass-work on beachcats.

There are several others building and/or working in boat repair yards who have plenty of advice to contribute...

How deep does the scratch go into the foam? And how wide is the opening itself?

I'm here...I don't check this forum that often. If the fibers of the glass are broken through into the foam (which it sounds like they are) I would grind the hull with a side-angle grinder and a flapper sanding disk to remove any damaged glass / gelcoat or foam and get a tapered shape into the good foam. I would then start laying glass cloth (~5 oz fabric) starting with big pieces and graduating to smaller and smaller pieces to fill the tapered depression in the center. Fine finish with premium bondo car filler (or pay lots of money for the marine filler and use that), sand and fair down to a 220 grit sandpaper before you gelcoat.

The nacra boats are vinylester so you can repair them with polyester, vinylester, or epoxy resins. Although the ester resins do tend to work a little better with gelcoats (since gelcoats are ester resin based) I've had no problem getting gelcoat to adhere to epoxy repairs.

I'll see if I can find some pictures of similar repairs I've done in the past...or you can go to flickr and search for Team Seacats. You should be able to find some stuff in my "composite works" photo set.

show 'em Tad's repair...

Here's that gallery with a bunch of fiberglass repair documentated:

Composite Works

And a few sequence shots of a similar type repair (from that gallery). Although the damage was significantly different than yours to begin with. The final seam I did on the exterior was the same process I would recommed for your repair.











[img]http://farm3.staticflickr.com/2392/2332279630_c50d6ecb72.jpg[/img]

[img]http://farm4.staticflickr.com/3180/2331464021_def08cbfe0.jpg[/img]

Hey,
Thank you'all for the help, will check out that info.

Hi you'all
Thanks for the help with this.
the gouge is about 1/8'' wide and pretty clean, goes about 1/4'' into the foam.
I had assumed you fill up the tapper with the smaller pieces of cloth, ending with the largest, but you are suggesting the opposite ?
Do you recall how many layers are in the outer skin ?

There are normally two to three layers (if fiberglass) in the outer skin but you'll need more than that to bring the repair close to the surface since you are digging into the foam but this won't really come into play for this type of repair. The fiberglass/resin repair should come out close to the surface so you are not using much body filler. Body filler should not be more than 1/8" thick (I usually try to stay less than half of that if any at all).

It's not that critical but it is my theory that you start with the larger piece first for two reasons:

1) The connection between the foam and the fiberglass skin is the important link. Starting with a large piece ties in the freshly exposed foam to that skin and makes a more unitized repair. After the first few layers of your repair, the fiberglass is just filling the indentation and isn't make as much structural connection.

2) If you start with small pieces, it's harder to guarantee full contact with the foam throughout the radius of the repair Lower layers of fiberglass may hold outer layers of fiberglass proud of the foam and leave a void around their enlarging perimeters.

Jake, in your sequence of steps, you forgot to add your finger print at the end

SMH in shame.

Still one of the funniest times we had that year. I could tell by the look on your face that you were going to put your finger in it but I was frozen and just watched you do it. Then two of us screaming at the same time as Jamie had just thrown the epoxy mix in the trash...Jamie quickly reaching in the trash can digging for the mix...and you quickly trying to smooth it out with no success because it was already setting. Good times buddy. Thanks for the laugh.