Kindly Old Dr. K’s Hydrosphere

Finally, we get to the last major step: seaming the hull and deck together.  This step is a bit of a pain, as it requires a bit of contortion to lean inside the boat the apply the inside seams.  In this case, the type of  mold we used adds a bit of extra work.

With a classic mold, the halves are left in the mold until the seaming step.  The mold halves have been precisely matched, so we merely bolt the mold back together with the new halves still inside and you have the seams precisely aligned for application of the seam.  Since this mold has the cockpit hole closed, for vacuum bagging, we can’t do that since there is no opening through which to apply the inside seams.  We popped the halves out of this mold early in the process, so aligning the halves to apply the seam has to be done by hand and eyeball.  This is a bit of a pain, but on the other hand, having the pieces out of the mold makes some parts of the process easier, such as preparing and installing the customized cockpit described earlier.

Another price of popping the halves out of the mold early is that they cure into slightly different shapes.  In this case the hull is slightly narrower than the deck at the seam line.  This must be dealt with during the seaming process with a combination of muscle, finesse, and lots and lots of masking tape. Some pictures of the process of installing the right-side inside seam are below.

Aligning the edges is done an inch at a time.  As each bit is aligned properly, masking tape is generously applied to hold it in place.  The blue hacksaw blade in the foreground is helpful in levering the edges into position.

The right seam is completely aligned and the boat is turned on its edge so the seam tape will lie flat as it cures.

The inside seam for this boat consists of two layers of glass tape.  Back in the day we used to cut our own tape from glass cloth, but the loose strands on the edges were a nightmare.  Ready-made glass tape is a great improvement.  The tape is carefully measured to fit the length of the boat, in two pieces, and will be rolled from the cockpit to each end.  The rolls above are ready to be impregnated with resin.

Looking inside the boat toward the bow.  The first layer of impregnated tape is rolled up and lying on the seam, ready to be unrolled.  The stick in the middle is a broomstick with a disposable foam paint brush taped on the end.  We will use this tool to push the tape roll down the seam to the end of the boat.  The droplight on the left is essential to see what you’re doing.

Looking down the stern from the cockpit.  Both layers of tape are laid up on the seam and the operation is complete.

Now it’s time to go away and let the seam cure.  In a couple of days we’ll flip the boat over and repeat the process on the left seam.

Next step: the outside seams.