Joining the Deck and Hull and Taping the Inside Seam

Joining the Deck and Hull

One of the more frequent questions I get is; "How do you put the deck back on the hull? How do you get the fiberglass all the way up into the end?" My standard answer is "I have a small child I send up in there." but the real answer is "Brush-on-a-stick." But, obviously there is a bit more to it than that.

The first thing I do is make sure the sheer/gunwale edges are cleaned up so the deck will fit tightly to the hull. Beveling the edges slightly so the outer edge is higher than the inner edge will help assure a tight seam.

I then place the deck on top of the hull and align the ends. As I do this, it is not unusual for the the deck to fall off the edges of the hull a little near the middle, but as long as I get the ends secured down I don't worry about the middle yet. The ends do not need to be tight yet, but I put a little bit of fiber-reinforced "filament" strapping tape around the ends to keep them in place. The 3M 893 tape works well, with good adhesive and clean removal.

I then move to the middle and use the strapping tape to start to pull the deck and hull together. It is not unusual for the deck and hull to be different widths at this point. It is fairly inevitable that they spread or curl up slightly while they are off the forms and it is too much to expect that they do this equally. However, the parts should still be flexible and it should be pretty easy to bend the hull and deck to meet each other. Especially in the middle where the boat is at its widest.

I use a metal tape dispenser that helps me pull the tape tight. It is important to pull the tape as tight as you can because this creates the friction between the deck and hull that will hold the seam in alignment. The tape dispenser has a integrated brake in the handle, the metal external flap and internal ring can be squeezed together to slow down how fast the tape comes off the roll. By squeezing this roll tightly I can pull heavily on the tape, putting a lot of tension across the seam.

First fold over the top end of the tape. This will help you later when it comes time to remove the strapping tape. Next stick the tape down on to the deck.  I find at least 6" of tape on the deck is needed to keep it from ripping off when I pull on it. Press the tape down on to the deck to assure it is well adhered. Then squat down next to the boat so your arms are below the seam. Squeezing the dispenser brake, pull down hard. With your other hand, get the seam aligned. Then pull the tape down across the seam and press it down onto the surface of the hull. Do not slack up on the tension until you have adhered the tape to the hull. Then the tip of the tape dispenser has a knife that allows the tape to be cut off with a quick twist of the wrist.

At the cockpit you can now reach inside if you need to tweak the alignment of the edges a bit. I strive for a perfectly smooth transition across the outside seam. Due to slight variations in smoothing and fiberglassing, the interior seam may not be quite as smooth.

After strapping down one spot on one side, I walk around to the other and repeat the same process on the middle of the other side. From there I will split the difference between this middle taping and the end of the boat, working on one end and then the other and both sides. Reach inside the boat to help align the seams where you can. Continue to split the difference between taped spot until you have straps of tape every 6 inches or so.

Near the ends you may find that the differences between the widths of the deck and hull become harder to overcome because you can not reach inside as easily to align the seam. I will use a thin, flexible putty knife as a lever to pry the seam into alignment. Insert the putty knife into the seam a little ways away from the spot you are working, and lever it up of down to force the deck and hull edges into alignment. Sometimes this will feel like you need 5 hands to control the putty knife, the tape, and the seam all at once. If you have a friend, now may be a good time to invite someone over to lend a hand. I will add some spring clamps to the knife handle to add weight or push on it with my head as needed.

Do your best to avoid wrinkles in the tape as it crosses the seam. Any irregularity will probably get filled up with resin later on and that will be epoxy you must sand off. Burnish down the strapping tape to be very sure it won't pop off.

After the seam was all aligned and held firmly in place with strapping tape, I chose to add some suspenders to the belts I had in the form of spot-welds of CA Glue in case the tape should give way for some reason. A small dot followed by a quick spritz of accelerant does the trick. A seam that comes out of alignment while you aren't looking is a real hassle.

I then run a strip of masking tape along the seam to prevent resin from dripping through the joint and on to the floor. Again, no wrinkles and rub the tape down to be sure it is properly adhered.

Taping the Inside Seam

When the seam is secure, turn the boat on edge and tie or tape it in place it so it will not fall over.

On some boats I have "cheek-plates" in the cockpit that I can hide the ends of the seam tape behind, but not on this one, so I chose to run one continuous piece from bow to stern. I'm also using a narrow ( 1 inch ) Kevlar™ tape instead of fiberglass so the results are more visible.

I measure out the length of the seam tape by rolling it along the outside seam. I marked a point inside the boat on a length of masking tape and transfered a similar mark to the outside. I then included this mark on the seam tape. This will serve as a center mark, but also mark which end goes towards the bow. In this way I will be able to get the tape to fit inside the boat at the right location without one end being too long and the other too short. I kept the tape slightly shorter than the seam on the outside to account for the stems.

After measuring, marking and cutting the tape I transferred it to work bench covered with waxed paper and brushed the tape down with epoxy resin. The goal is to fully saturate the tape before putting it in the boat. While this resin is soaking into the tape I brush more resin along the inside seam to help hold the seam tape when I roll it in place.

Starting at one end of the seam tape I rolled it up into a tight, smooth, even coil working towards the middle until I approache the center mark I had established earlier, then I roll the other end down to the center mark.

I now transfered the tape to the inside seam. Placing the center mark in alignment with the mark inside the boat and centering the width of the tape on the seam.

At first all you must do is simply unroll the tape along the seam by hand. As the seam proceeds under the deck, reach as far as you can up along the seam to continue unrolling. Eventually you will need longer arms, a small child or a brush-on-a-stick.

The stick just needs to be long enough to reach into the end from the cockpit, with the tip cut at a 45° angle and the brush is a chip-brush screwed on to that end. Cut off any excess handle from your brush and you are good to go.

Use this brush to gently unroll the seam tape coil along the seam. Use the brush to steer the coil as it wanders off center. The seam shown in this video is about as easy as it gets because it is straight and the deck-hull joint is flat across the seam. Other seams that curve and have a sharp angle across the seam are more difficult, but the same process works.

If you mess up, and the seam tape wanders off center you may be able to brush it back into place, but if it does not go easily, your best bet is to pull the tape back, re-roll it and give it another go.

When the tape is rolled all the way out to the end, smooth it out with gentle brush strokes and then brush on some more resin.

Let the first side cure before flipping the boat and doing the other side. Let the second side cure well before peeling off the tape. If you are having trouble lifting the ends of the strapping tape it is probably because you didn't fold over the ends like I told you.