Model Forum / Radio Controlled / Water Models / May 2005

Thanks for the links. I'm familiar with the Scale Shipyard - in fact, I
was reading an article on how they prepare their plugs and molds
the other day. (Hadn't thought to design in some allowance for
shrinkage of the mold and molded hull - that was useful info.)

I've lusted after their 1/96th scale U.S.S. North Carolina for many
years. (My parents took me to visit that ship in Wilmington, NC,
several times as a child when we lived at Camp Lejeune.)

But the hull I'm planning is a 1/48th scale U.S.S. Olympia and I
don't think anyone's got one of those. (Besides, I can build it
myself for 1/3 the cost of a commercial hull - maybe 3/4ths
the cost if I go the molded hull route instead of using the built
up one. Also, I rather enjoy the work.)

The link to the Warship Models Underway site is really interesting.
I'll have to peruse that one quite a bit.

This project is actually easier than the last one of this size I did;
a 1/24th scale patrol gunboat, about 15 years ago. (Here's the
type: http://www.gunboatriders.com/theboats/general_spec.html)
I didn't have a set of cross sections so I had to scale up
drawings made from a 15" long plastic model. Hand-drawing each
bulkhead lost its appeal after about the tenth one. (I'm considering
scanning them this time and having them laser-cut, but that does
seem like a cheat.)

The neatest thing about that one was the beautiful bow wave it
cast when running at speed - a perfectly solid sheet of water
peeling off the bows. The Olympia's not going to have that
effect, I'm sure - all those rivet heads and plate seams :-)

Thanks again for the links. -Wm

Very nice!

Similar in lines to the patrol gunboat hull I built but that didn't have
the "bulb" at the bow - different scale, but similar finished size.

You're much braver than I, though. I didn't trust my carving skills to
do an entire bow that way. I used stripwood up to the last inch or
so and only carved that last bit. (And cheated on some of that, using
Epoxolite putty smoothed to nearly the final shape with a wet finger.)

I'm glad to see someone else thought heavy poly tubing could be
useful as a universal joint.  (The propellors are gorgeous, by the way.)

I lucked out with a set already to scale for the tricky bits (and half-scale
for the rest). Just need to adjust for sheathing thickness. (Probably 1/8"
thick - that gives me some sanding and support margin.)

Mainly I wanted a hull without too many bulkheads (and, maybe, the option
of making a backup copy just in case). I figured to gain structural strength
by adding fiberglass "box beams" following the curve like bulkheads,
but needing to intrude less into the spaces than flat bulkheads. (I'd start
by gluing flexible foam "bars" to the hull, then fiberglass over them,
perhaps
with a ribbon of graphite on the inner surface for rigidty.) Maybe also use
four full bulkheads and some stringers to add strength fore-and-aft. (The
stringers could serve as supports for equipment trays too.)

Yeah, the same way I'd make the interior ones, probably, but maybe
releasable from the mold's shell so I can flex it a bit to free the hull.
(I'm thinking it might pay to experiment on a smaller, simpler hull first.
I've been looking around to see if I could find a steam tug of about
the right period - it'd be useful as an accessory and a rescue boat
as well.)

I'm a little concerned about getting it out since there are some reverse
curves to deal with. I thought the silicone layer would provide a little
wiggle room, literally. I believe I can smooth it out by working carefully,
using a thin first coat and a second, heavier, coat. Smooth-on's got
a variety of types, curing times, etc. (It will stick to itself, but I'd
have
to test to see if it resists delaminating - that would kill the two coat
idea right there.)

Even at that I may end up having to do a two-part mold, port and starboard
shells. (Although a joint across the beam might be easier - much shorter
seam and probably easier to brace - and that would work about as well
in terms of release.)

I don't expect to decant a perfect hull - I'd anticipate some filling and
sanding to get the final finish. Being non-commercial that's no problem.
That does mean I wouldn't even think of trying to mold all the rivets :-)
(I am thinking the hull plate seams themselves might be worth trying for,
though.)

Just thinking about it all makes me tired :-)  -Wm

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