----- Original Message -----

From: htmills@bright.net

To: For and about Montgomery Sailboats

Sent: Thursday, April 10, 2003 1:33 AM

Subject: M17 line drawings

Honshells wrote:

 

Does anyone on the list understand design well enough to take the lines off a 17'?  Except Jerry, of course, who probably wouldn't want to (and who no one should expect to) invest the time on a purely volunteer basis.

 

Craig, I'm sure quite a few of us know how; it's more likely a matter of so many things to do, so little time...

There are two components to it:  collecting measurements, and actually making the drawings from the measurements.

If you are feeling ambitious, there are a number of good books that describe lines drawings and the significance
of waterlines, station sections, buttocks, and diagonals.  I used to have a copy of "Skene's Elements of Yacht
Design" by Francis Kinney until someone who borrowed it neglected to return it.  That's pretty good and understandable
for the layman, but there are others I'm sure.  Probably your local library could round one up for you to borrow.

In the early days of naval architecture, a model would be made to suit the builder's eye (the bigger the better) and it
would be sliced not unlike a loaf of bread and the resulting slices measured for laying out the frames.  If you ever
get over to Ann Arbor, see if you can get a tour of the naval arch. facilities.  For a virtual tour, visit:
http://www.engin.umich.edu/dept/name/

There is a model shop and associated laboratories and towing tank on the main campus and classrooms and stuff on the
north campus.  The towing tank is pretty large, 360' long and with a several-ton carriage that rides on rails that actually
have a curve in them (to match the earth's curvature). Some of the models that they make there are over 20' long.

On the North Campus, there was a drafting room full of drafting tables and carts laden with lead "ducks".  A beautiful
velvet-lined oak box of Copenhagen Ship's Curves could be checked out.  I expect those are mostly gone, replaced by
computers.  The walls were lined with half-hulls of all sorts, some yachts, mostly ships.

The model shop consists of the wood shop and the machine shop.  Models are made bread-and-butter style of one
inch thick clear sugar pine lifts.  The lifts are rough-cut on a band saw to approximate the waterlines.  After they
are all stacked and glued with the hull upside down on a specially made precisely flat table, the corners on the lifts
are cut off with a handheld power plane.  Then the hull is shaped carefully at each station with a spokeshave and
checked with a template.  After the hull is shaped at each station, the hull is faired between stations.  It is a lot of
work but the master craftsmen they have there make it look quick and easy.  There are racks of hundreds
of all sorts of clamps and strongbacks.  In short, it's a boatbuilder's heaven.

The machine shop includes a cabinet with all sorts of propellers on pegs.  These propellers are all scale models of
propellors you would see on ships.  Some of them have all sorts of odd rake and skew, some with 5 or 7 blades, very
different from what we have on our outboards.  Each propeller is worth several thousand dollars.

Then there's electronic testing equipment out the wah-zoo.

Every now and then they get more models than they can store.  There are some people who probably have very
interesting coffee tables in their living rooms!  I managed to only lay claim to a seven foot fiberglass mold that
was used to make a model of a sailboat, "Golden Daisy", which was an epoxy/wood boat that won the Canada's Cup
back in the late 70's I believe.

Fascinating place if you get the chance....

:-)

Tod