On Wed, 22 Sep 2004 12:10:21 -0700, engsol
wrote:

Now that I have a boat, I need to replace a couple of
gate valves used as seacocks.

Nigel Calder et all recommend using a wood block and bronze
bolts to secure the seacock to the hull, rather then simply
screwing it to the through hull. Makes sense to me.

The diagrams all show a perfectly flat hull, but as we all know,
real hulls are generally curved. My question is: what's the
best way to contour the wood block (actually a ring) to conform
to the hull? Any hints?

I have used three variations on this theme, depending on where on the
curve of the bilges I've needed to "degate" something properly.

1) Simplest: Use simple bedding material, but of course make it 5200
or something equally tenacious. Drill up through the block/ring from
the outside, bed, screw, tighten, wait for cure, tighten a bit more.

2) Make a radiused ring by drawing a chord of the area and sanding it
on a bench grinder or belt until it matches. Bed as before or glass
in.

3) This is the one I thought was clever of me G. Make a wood ring
pad of desired thickness. Using a fine blade on a band saw, cut into
fine "slices" (how fine depends on the wood type). Steam slices into
desired curve. Laminate together with epoxy and glass into place.
Guaranteed not to rot, either, if you use the "epoxy plug" method
mentioned lately for deck core isolation.

My .02 and congratulatations on your new old vessel.

R.

engsol wrote:
Now that I have a boat, I need to replace a couple of
gate valves used as seacocks.

Yep. I did that too.


Nigel Calder et all recommend using a wood block and bronze
bolts to secure the seacock to the hull, rather then simply
screwing it to the through hull. Makes sense to me.

Why wood? It makes far more sense to me to build up a pad of fiberglass
& resin with some filler. This produces a strong, faired,
non-water-trapping non-dirt-trapping block. Also, it will not split or rot.


The diagrams all show a perfectly flat hull, but as we all know,
real hulls are generally curved. My question is: what's the
best way to contour the wood block (actually a ring) to conform
to the hull? Any hints?

Make a template using a couple of pieces of cardboard.


rhys wrote:
I have used three variations on this theme, depending on where on the
curve of the bilges I've needed to "degate" something properly.

1) Simplest: Use simple bedding material, but of course make it 5200
or something equally tenacious. Drill up through the block/ring from
the outside, bed, screw, tighten, wait for cure, tighten a bit more.

The problem with this method is that the contact pressure between the
hull & the valve will be uneven. It may also distort the valve body. It
does not distribute the load, if any, from the valve & piping over an
area of the hull.


2) Make a radiused ring by drawing a chord of the area and sanding it
on a bench grinder or belt until it matches. Bed as before or glass
in.

That works. You can use a Dremel tool, too, although it takes longer.



3) This is the one I thought was clever of me G. Make a wood ring
pad of desired thickness. Using a fine blade on a band saw, cut into
fine "slices" (how fine depends on the wood type). Steam slices into
desired curve. Laminate together with epoxy and glass into place.
Guaranteed not to rot, either, if you use the "epoxy plug" method
mentioned lately for deck core isolation.

Shucks, you didn't start soon enough. It's a good way to build a whole
boat


My .02 and congratulatations on your new old vessel.

My congratulations also.

Fresh Breezes- Doug King