When the unimaginable happens, what should you do next? That was the question posed to me late Saturday morning by Alan Taylor upon discovering his forward starboard ama beam was snapped nearly in half. After some consideration and consultation, it was agreed bringing the boat to our warehouse in OBX and fixing it that weekend was the only way we could get this fixed for Alan to sail next week. Derigging at Kerr Lake was put on hold and a 4 hour trip was undertaken to meet up and formulate a plan. What follows is an account of our process and what we would have changed for next time:
The first step was to cleanly saw through the remainder of the crack to separate the beam into two pieces. When working with carbon or fiberglass, dust and splinters are a major hazard, so we employed the use of respirators, gloves, and a shop vac as PPE. We then cleaned up the two ends of our newly halved beam using 80 grit sandpaper, ensuring we tapered the edges down towards each other. This ensured when we added material on top, it wouldn't all get sanded away when leveling the surface. The interior of the beam was reinforced with a carbon tube made by Weta we just happened to have lying around the warehouse. The repair tube was approximately 12 inches long, and we made a mark at 6 inches to center it in the crack. After ensuring we had properly sanded and cleaned with acetone, we felt the time was right to get the first layer of epoxy down. We mixed 2 pumps of West Systems epoxy, and looking back should have slightly thickened this initial epoxy. We covered half of the tube in this epoxy and inserted it slowly into the ama end of the beam. The tube was slowly twisted down the tube so as not to drag air bubbles along with. With half of the tube inserted, we coated the other half with epoxy and placed the short end of the beam on. The non thickened epoxy was quite runny, and caused the the tube to want to slide all the way into the beam, I believe thickening it would have solved this problem and removed its' mobility. The two halves of the beam were brought together, and we ensured we realigned them to their original orientation. the squeeze out of epoxy was controlled by a rag wrapped underneath the joint, and wiping with acetone on paper towel to dissolve excess.
We should have stopped to take some photos and videos at this moment but the pressure of curing epoxy took all of our focus. Later steps have more photography to supplement my descriptions.
Another 2 pumps of epoxy were mixed and this time thickened to a peanut butter consistency. This inedible foodstuff was then generously applied into the remaining gaps. It was important we didn't change the total length of the beam (which is 132 cm for anyone curious). Our initial sanding removed just enough material to account for the extra epoxy. Immediately we cut a 2" by 8 3/4" strip of carbon fiber weave and fully imbued it with our thickened epoxy. This was wrapped around the entire circumference of the crack and pressed into place to remove air bubbles. The remaining thickened epoxy was roughly spread around the beam about 3 inches to each side of the crack. The final carbon addition was a cylindrical carbon weave sleeve supplied by Roger of Weta Marine. We cut a 6" segment of this sleeve, then slid it over the end of the beam. This sleeve acted sort of like a chinese fingertrap, it's diameter shrank as it was stretched and grew as it was compressed. This allowed us to bring it all the way down to the crack and then wring it out with our hands to shrink it to fit the beam as well as absorb the epoxy. A final pump of epoxy was mixed with no thickener and then painted over top of our carbon sleeve, not allowing too much excess. The key to the whole job was wrapping the whole segment in surface finshing tape. This clear, non-adhesive tape compresses the carbon to give it its strength and can be peeled straight off of cured epoxy, as long as squeeze out doesn't cover it. We coiled the tape down the length of the tube keeping a 1/2 overlap the whole way down. Keeping the tape flat was difficult, but necessary to minimize ridges and bumps. We noticed the beam wasn't perfectly straight so we affixed a splint and a line to hold as close to straight as possible while it dried. We called it a night there.
The next morning, the tape came off and it was time for sanding. Basically all of the tape came off, except for a couple areas were the epoxy formed a bridge over it.
We segmented off the new epoxy with blue tape on either end, and sanded in between for about 30 minutes with 80 grit. This got us to close enough to flush to be happy with.
At this point I realized I had no plan to refinish the surface. After some discussion and googling, we decided to go over this again with a thin layer of epoxy and another round of finishing tape. In hindsight, working up to 800 grit sandpaper from here probably could have produced relatively similar results. Although I do think the way we did it looks better, it maybe wasn't strictly necessary. 1 pump of non thickened epoxy was enough to thinly spread over the whole surface, and extra care was taken to assure the tape lied flat, which was easier with a rounder shape.
We also did this process to the end of the beam that inserts into the hull as it had an obvious wear mark.
We let the epoxy set for about 20 minutes before taking off the tape and letting it dry.
After about 2 hours of waiting, We touched up the finish with 800 grit sandpaper. And with that, the boat was packed up and started its long trip home.
I think your technique was spot-on for this job, with the sleeve insert paired with the fiber over-wrap. Great advice on the finishing aspects, particularly the finishing tape. Thanks so much for such a thorough and clear description!