When to tape exterior seams for abrasion resistance?

I currently have the 'glass wetted out on my MC 16.5 and am preparing to put the next coat of epoxy on.

I intend to put an additional layer of fiberglass tape on the bow and stern, as well along the base chines near the ends to help with abrasion from beaching, plus bumps, etc.

When should  I add the layer of tape? Now, after I've applied the'glass with it's 1st coat of epoxy? After I fill the weave? When?

 Thx,

 

The Ranger


4 replies:

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RE: When to tape exterior seams for abrasion resistance?

I'd consider using regular 4 oz. glass in two layers, one draping over the keel and  running maybe 4 to six feet back and overhanging maybe 6 inches on each side. Then a second strip of 4 oz along the keel running 3 to 4 feet back with lesser degree of overhang.This would give a larger area of protection and be easier to fair than tape.

If you are thinking about using the tape that is used for seams (9 oz typically), that stuff would be more difficult to feather in nicely along the edges. The tape I have tends to have a kind of a bead along the edge that would make feathering especially annoying.

The dynel fabric/graphite powder rubstrips, for which you can purchase a pretty inexpensive kit from CLC work well also. I have also heard of people who have experimented with something called helicopter blade edge tape with some success but I haven't tried that myself.

--

Ogata (eric)

RE: When to tape exterior seams for abrasion resistance?

Eric,

I have extra 6 oz fabric as well as the 9 oz tape you mentioned. I see the bead you refer to on the tape and agree that it would be a pain use it and then have to sand that away.

I figure that some of the 6 oz cloth, cut on a bias, would be my best bet. I will cut it to shape the areas in question & feather them in.

 The question I still have is when to add the 2nd layer. After wetting out the first layer of glass? (& 1st epoxy)

Or after completely filling the weave on the first layer of glass?

OR, somwhere in the middle of the "Filling of the Weave" process.

 I'm trying to figure out which is best/recomended .

Thanx,

 The Ranger

RE: When to tape exterior seams for abrasion resistance?

Maybe one extra layer of 6 oz glass running back along the keel and just overlapping the chines near the bow and stern would be good enough? The shearwater designs use multiple layers in this manner but are layed up with 3 layers of 4 oz glass. You can cut the layers to size and then wet them out all at once, or do one layer at a time. Don't worry about filling the weave except on outermost layer and if you do the layers separately, don't wait too long between layers. Perhaps do the entire hull late in the evening, then cut and wet out the extra layer the next morning, while the original layer is still a little green.

Good luck,

--

Ogata (eric)

 

RE: When to tape exterior seams for abrasion resistance?

The best time to put on the tape would have been before the main glass. The selvedge (bead) could have been quickly hit with a scraper or sander while in the green stage (cured soft, rubbery and not tacky), easily removing it. Then there wouldn't have been a fairing problem after the main layer was put on. Keep this in mind for the next boat.

For this one, put the tape on before filling the weave in the main glass. In general, you never want to fill the weave on an inner lamination. Doing so results in a heaveier and weaker lamination. This is because you'd end up with a relatively thick and brittle epoxy layer sandwiched between the inner and outer glass.The good news is that for our low speed boats the reduction in strength won't hurt anything, but it's still a waste of epoxy and a source of excess weight.

Have fun,

Laszlo

 

 

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