Archive for March, 2008

Epoxy coating the bulkheads

Thursday, March 13th, 2008

The ballast tanks will each hold 290 litres of seawater. The plywood MUST be PERFECTLY waterproof. Epoxy resin is the man for the job. Here the bulkheads and inserts are on the workshop table, sanded, dusted, cleaned with acetone. The table is covered with newspaper, but also several large sheets of acetate (from a friend’s printworks). Epoxy will not stick to the acetate, meaning we don’t have to worry about drips or overflow 0r the newspaper stuck to the underside after coating.

Epoxy coat 1

A plastic squeegee is used to spread the epoxy evenly over the surface. The panel at left has been coated. Room temperature of 20 degrees C permits three layers in a single day.

Epoxy coating 2

It is good practice to heat the plywood using a hot air gun to prevent “outgassing.” The gently heated plywood will draw the cooler epoxy resin into itself as it cools. Otherwise, bubbles will form as trapped air molecules in the ply try to escape.

Epoxy coating 3

The mixed epoxy is simply dribbled over the ply and then spread with a stiff squeegee.

Epoxy coating 4

The squeegee in use, after coating, wait a couple of hours and do the second coat, then after two or three hours (20 deg C) the third and final coat.

Epoxy coating 5

Making forward tank bulkheads

Wednesday, March 12th, 2008

Patterns for the bulkheads were drawn with light cardboard and then transferred to fibreboard which was then checked on the boat for a good fit. Tracing the contours on the underside of the deck and the inside of the hull was not easy.

Here, the fibreboard templates are being laid out on the ply for tracing.

cutting ply 1

Tools used to cut the plywood bulkheads. Jigsaw, steel straight edge and razor knife to scribe the straight lines for cutting, panel saw for the straight lines, drill with 8mm bit for tight curves where the jigsaw cant turn.

cutting ply 2

The two bulkheads, port and starboard, cut and ready for sanding on the surface and to round off the edges.

Cutting ply 3

These two inserts are needed to fill in the “rubbish bin” (clever builders those French) storage lockers on the after bulkhead.

Cutting ply 4

Progress Report 1

Monday, March 10th, 2008

Attached are some views of the first few weekends work on Dinah. The transformation steps up a gear next weekend…

Picture 41

(click to enlarge)

Friday off work to grind away half the thickness of the entire floor, seen in the picture above, with an angle grinder. It’s a bit disconcerting to wield a grinder at the very skin of the boat. It reminds me of tunnel builders hoping not to see any moisture coming through their tunnel walls! After the dust has settled (quite literally!) fibreglass guru Paul is coming over from England to spend a few days building reinforcement and strengthening the whole subfloor assembly. That should make her stiff enough to stand up to the sort of loads than can be expected dropping the boat off a proper Atlantic wave.

Picture 40

In the background of picture, that big space behind the chart table is where the starboard ballast tank will be fitted. They’re being built in Bob’s shed at the minute, whenever he’s not busy updating his website that is . Hopefully we’ll be able to start offering them up by the end of next week.

With two long weekends in a row coming up, I expect some serious progress on the structural side of the project. Then comes the electronics fit out. Although I did have a little start as you can see below.

Picture 30

I’ll post a few pics anytime a milestone is passed.

Picture 36

Plywood for the ballast tanks

Monday, March 10th, 2008

Bloody expensive stuff!

Three sheets, 12mm, from Waller and Wickham in Baldoyle.  We could have used cheaper BS1088 waterproof and boilproof board, but potentially the plys have voids, allowing water ingress followed by de-lamination.  WE are taking a “to be sure to be sure” approach.

Robbins plywood