Hi dan,
Since you already have an existing coaming, this can be a fairly easy project. To make it failure proof, completely cover the entire coaming with packing tape layed as overlaping strips from under the coaming wraped radially over the lip and on to the deck. Cover the deck and the inside bilge area with plastic sheet or vinyl wall paper, so no drips touch anything.

You now have a form that you can lay bias cut strips of carbon and glass around your form. Let each layer hang straight down into the cockpit,don't wrap under, and don't worry about excess carbon/glass till it cures.
Squeegee the excess eopxy and let it cure over night.

Because you protected the coaming with packing tape (2"wide clear) you can remove the entire lay-up, probably 6-8 layers total from the boat. This new coaming can then be cut to shape with tin snips and sand paper.add some more epoxy coats till you have a smooth piece. The new coaming can then be epoxied to the existing coaming.
You could do the same lay-up directly on the existing coaming, however, you don't have a second chance.
If you mess up my suggested method, the only thing lost is time, epoxy, glass, and carbon. No damage to the boat.

This all sounds fairly straight forward, but it is probably better suited to someone with experience with glass and carbon layup or you could waste some time and money.

I once repaired a friends K1 race boat coaming that had cracked coaming lip by adding a layer of carbon to the under side of the coaming lip. The boat was white, so I protected the riser part of the coaming and the top with tape. I epoxied narrorw bias cut strips to the underside of the coaming only, and trimed after cure. It was amazing how much this stiffened the fiberglass coaming of this boat. I only used one layer of carbon. If you don't want the look of carbon on the top, this could be an easy fix that won't show.

You must protect non work areas from contact with epoxy. I like using vinyl faced wallpaper I readily find at Dollar stores. I cut the 20" rolls with a band saw to the most useable length (6-8") and tape them in place to protect the areas from epoxy that I don't want touched. The wallpaper is easier to work with than plastic film, and cheaper. I make sure all area are covered with someting, just in case my gloved epoxy coverd hand touches another part of the boat. Think ahead, and "Work Clean"

Check out One Ocean Kayak site for Carbon coaming layup details.

The Pic is a Carbon/kevlar, red/black coaming I used. The world is not just black and white........

Larry C.

: I have some...what appear to be stress cracks in my Explorer
: coaming. Even with pressure they don't open up so I'm not
: thinking it'll break but i do want to add something to it and
: spiff it up at the same time.

: I am looking to do something like this if possible and if it will
: maybe help prevent the hairline cracks from becoming breaks. Got
: it from redfish

: If it's a bad idea, shoot it down quickly :)