On Sun, 14 Aug 2005 18:20:15 -0500, Reynaud said:
I would like to build an replica of an old Chestnut canoe. I have the
full size boat to refer to but am not sure how to take off proper
measurements . Could someone suggest where to find information or clue me
in. Help would be much appreciated.

I've often wondered at how casually John Gardner, for instance,
mentions he "took down the lines" from some boat he'd come across,
as though it were a thing you can just do in a moment. I believe
that he could do just that, and the world is poorer for his passing.

I also would be very interested to see replies to this question.
I do suspect that watching an experienced boatbuilder do this is
probably the only way to learn, and it's an art as much as a skill.
I have seen it done once, and not done ideally at that.

A quick summary of my understanding:

1) You need a safe, level floor or other surface to work on,
and it's a bonus if you are able to scribble all over it.

2) Setting up the boat is important, but the only critical
part is that it must be level athwartships (relative to
the floor). Fore and aft trim is only important if you
want your measured waterlines to be real waterlines. Then
you have the problem of working out where the real DWL is
and probably the easiest way to do that is put it in the
water.

3) You need to make your own jigs and large squares from
scrap lumber. These do not need to be precision gear,
for the most part you can work out a way to set up
so that errors either cancel out, or are consistent
across all measurements and as such can be ignored.

4) You take down buttocks as distances up to the outside
of the hull from lines on the floor at fixed intervals,
if the boat is set up right-way-up, or else you do some
more complicated arrangement with a jig if it's upside
down. This is where drawing a grid on the floor helps.

5) You take waterlines with a jig that can be set to a fixed
height and either moved or adjusted to give the distance
from points on the hull to a reference line. Again, a floor
you can draw on is an asset. You would draw your reference
line parallel to the centreline of the boat, and just outside
the point of maximum beam, then draw a series of lines that
represent stations, at right angles to it. Your jig, then,
would resemble large calipers: a set square with an extra,
sliding arm that can be set to intervals marked on the upright.
All you'd need to do for each waterline, would be to set the
height, then move the jig from station to station with the end
of the top arm butting against the hull, quickly scribing
half-breadths away from the reference line directly on the
floor.

Like I said, I'd be interested to see discussion on this subject,
especially from the old hands. I've only seen it done once and while
obviously I've got my own ideas, this is the sort of thing where the
voice of experience is called for.

--Damian