When I play golf, if I drive off the tee and lose my ball because of an errant swing, why is it that my second attempt is always perfect making me wonder why didn't I swing like that on my first shot!
It's kind of like that when you build a second boat. The first attempt is full of small errors, air bubbles, lifted glass at the bow and stern, too much epoxy used, etc.
I started the second boat yesterday afternoon and unwrapped it this morning and what a beauty she looks. If you are interested here is what I did with a couple of pictures.
I started by repairing the old hull plug, patching up some damage when I cut the previous boat off the plug with a dremel. After a rub down and 5 coats of release wax it was good as new and ready for the layup.
I cut out 3 sheets of 124gm S glass from a paper pattern I made earlier. I acquired 3 sheets of brown paper which were from a delivery of an old flower arrangement (my wife's!). With care, I cut the glass cloth straight onto the brown paper from the paper pattern I made earlier. The cloth was cut with no mess. In addition to the cutting, I drew a centre line with a felt pen and perpendicular lines (to the centreline) for the bow, stern and edge of the foredeck. This is done to allow easy alignment (when laying down the cloth onto the plug) with a centreline drawn down the keel of the hull along with a mark to indicate the foredeck. The brown paper not only seperated the 3 layers of cloth but also allows the cloth to be rolled up and carried as well as protecting the edges, keeping the cloth flat and clean.
Last summer on the first boat build, I cut the glass outside on a table, did not use any paper or protective cover and ended up with strands of glass fibre all over the patio!
With the cloth prepared, I was ready to lay the hull up in the garden shed. Yesterday it was about 12 degrees which is just warm enough to work with epoxy. I needed a workbench to clamp the hull upside down, a piece of wood hanging from the shed ceiling to screw the plug support post to work on the deck, paper towel to wipe up mess, acetone for cleaning, nitril gloves to protect my hands, West System epoxy (slow cure), three plastic pots (I use fromage frais pots), a 2 inch paint brush and an aluminium roller for removing air bubbles, peel ply for wrapping the epoxy, screwdriver and electric drill for mounting and dismounting the plug.
With all the bits together on site, I was ready to go. After mixing the epoxy using the self measuring plungers that you screw on the resin and hardener tins (3 pushes of the plunger will do one layer of glass) I applied resin to the hull side of the plug, being careful to wet the curves of the deck. The epoxy will not lie smooth on the wax and will pull back into globules looking a bit messy but it won't matter. Taking the first layer of cloth and with the boat mounted upside down on the workbench, hold it over the hull aligning the centreline, bow, stern and foredeck marks before laying the cloth down on the epoxied plug.
Gently smooth out the cloth with the paint brush and work out from the centre until the cloth is flat all over. This is quite fiddly but by taking time and being patient the cloth will lay out perfectly. Next step is to go over the cloth with the paint brush (be very gentle) and wetting the cloth where dry, removing air bubbles as you go. Use the epoxy sparingly as excess resin just adds weight. Finally go over the hull with the aluminium roller to get any missed air bubbles.
Now remove the plug from the workbench and screw to the bar dropping from the shed ceiling. Initially fix the hull upside down and then carefully allow the plug to rotate down while supporting the cloth over the deck, until the deck is level. (In my first build last summer, I picked the plug from the workbench after wetting the cloth on the hull, rotated it so the deck was uppermost, raised it up to the supporting bar and the glass cloth fell off onto the floor. You have been warned!)
Before you work the cloth into the deck with the paintbrush, cut away any excess. On the first layer I used a 1 inch overlap. On the second layer, I butt the ends of the cloth (ie no overlap) and on the third layer use an overlap again. In this way you avoid too much weight along the centreline of the deck. On my first boat I ended up with 6 layers of cloth on the centreline which produced a strong boat but heavy in the ends.
Work the cloth into the deck with the paint brush in the same way as the hull, until flat and smooth. Sorry there are no pictures of this as my gloves were coated in epoxy at the time!
Check over the hull and deck in good light to make sure there are no air bubbles and the cloth is tightly bonded at the bow and stern.
Leave the plug until the epoxy remaining in your mixing jug starts to go stringy. When this happens, the first layer of cloth will be stuck nicely to the plug and won't move when you apply the second layer. The longer you can leave it between layers the better. Half an hour should be long enough.
Wash your paint brush, gloves and roller in acetone and mix the second batch of epoxy. Bin the 1st mixing pot.
For the second layer, drape the cloth over the hull taking care with the alignment marks and brush out as before using just enough epoxy to wet the cloth.
Repeat for the third layer remembering to clean tools in between. I use four plunges of epoxy for the last layer because I wanted the outer layer slightly wetter. Any excess would be absorbed by the peel ply.
Finally wrap in peel ply. I used 10 metres of 100mm wide. Overkill I know but it did an amazing job even though the hull look a bit mummy like.
I peeled the peel ply off this morning to discover a hull with no air bubbles, perfect adhesion at the bow, stern and foredeck.
In all the process took about 3 hours
All I need now are two coats of epoxy primer rubbed smooth and I am ready to pop the hull off the plug.
If it all looks good and I know that the hull is useable, I can pay the design fee and fit the boat out.
Updates to follow.