Thanks to a
of a chainplate
through-deck sealing method by Alan Berens and following
discussions on the Valiant e-mail list, I have sealed the
chainplate-to-deck interface on EGRET. Here's some pictures
of how I did it:
Fiberglass tubes and 4-part mandrel. The
mandrel was wrapped in plastic sheet, then wrapped
with fiberglass cloth and mat
in alternating layers and saturated with epoxy.
When it set up,
the bolts were removed and the center two pieces
driven out, freeing the tube.
The chainplate slot was enlarged and the plywood
"hogged" out. The lower fiberglass skin was not touched.
The chainplate was re-installed and pencil marks made
on the deck to help in centering the tube.
Ready to insert the tube.
A pencil laid flat on the deck was used to mark
a cutting line just above the deck plane.
Here's the cut-off tube with alignment marks
made on its top edge.
From the top.
The deck was masked-off. Duct tape was placed
underside. Then about a 1/16" of un-thickened epoxy
was poured in to attach the tube to the lower skin and
seal it for subsequent pours. When this epoxy set up
(2hr or so), epoxy thickened to catsup consistancy
with coloidal silica was poured in.
Since the deck slopes, the cavity was
not completely filled. After this
pour jelled, the hole was topped off with a thicker
layer of mayonaise consistancy epoxy.
Here, it's all filled, sanded and the lower
skin has been cut back to the size of the inside of
the tube. (Actually,
it's a different chainplate hole; I forgot to bring
the camera to continue the story on the next day.)
Here, we're ready to pack in the butyl rubber.
Actually, one side and the ends should be packed, then
the chainplate slid in and bolted in place. This will
smush the butyl rubber on one side and the ends.
Then fill the other side, half
from the top and half from underneath.
UPDATE: It turns out that the butyl rubber was really tough to work with. It sticks to the chainplate and doesn't want to be pushed down into the gap. We re-did the staysail chainplate and used a caulking compound that we got at a Home Depot. It was much easier to apply, as it sort of flowed down into the void. It's called:
Henry Elasto Caulk #289
"White elastomeric Acrylic Patching Compound/Roof Coating"
The jury is still out on how long it will last... 11/2005 gbf
Now the butyl rubber is in place and it's
ready for the decorative plate.
All done... Ready to start on the next one!
(Well, not quite done... someday we'll spray the
If you have questions, please e-mail me:
gary "at" gizmology.com