The good thing about a full size lofting is that when you are done, you
can easily "lift" patterns for each part directly from the lofting.
Also, lofting allows the builder to correct the designer's mistakes
before cutting wood. Happens all the time.
Plus, the lofting gives the builder a better concept for how the boat
"feels". Much better than a little drawing can or even a cad drafted
drawing. Unfortunatlely people unaccustomed to creating large drawings
seem to shy away from it.
If I was building a little canoe though, a minor mistake in the lofting
is not a big deal. I'd draw horizontal water lines, then plot the
section molds directly from the table of offsets. Then I'd draw the
sections out and tranfer the lines to the material (particle board) to
cut. Success in doing this will depend on whether the table of offsets
is lofted to the inside of the planking or to the outside as is
sometimes the case. Also, different designers work to different
tolerances and some tables of offsets are not very accurate or contain
too few sections to have the plotted section lines come out fair when
set up.
I've built boats from different designers and the accuracy of the
original design goes a long way toward getting a boat that resembles
what the designer had in mind.
Assuming your table of offsets are drawn to the inside of the planking,
here is what I'd do.

1. draw a horizontal line the width of the boat representing the
baseline in the lofting.
2. Erect a perpendicular line that intersects the baseline representing
the center of the boat.
3. Draw the waterlines relative to and parallel to the baseline.
4. Plot points along the waterlines based on the table of offsets.For
instance, if the sheer in the plan view for the center section at water
line 8", is 1-6-0, put a dot on the appropriate waterline one foot six
inches from the center line.
5. draw a line through each point to establish the cut line for the
section. Use a flexible batten and finish nails to hold it the batten in
place so the line goes through each point. A 1/8 x 1/2 inch thick piece
of plexiglas 36 inches long makes a good batten.
5. Continue plotting each section but do only one half of each. Either
the right or the left. Usually the foward sections are on the left and
the aft sections are on the right.
6. Do each section and figure out how you will set up the sections on
the strong back so you can also mark the bottom of the section mold
where it connects to the strong back. Various methods are used.
7. You now have a full size pattern of each section of the canoe and can
transfer the lines to particle board and cut them out.
Extreme accuracy will help in producing a fair hull as will placing the
section molds exactly where they need to be on the strongback.

If the boat is lofted to the outside of the planking, you will have to
loft the boat and subtract the planking to establish the sections. A lot
of work. That is what you buy when you purchase a design.



sebastian wrote:
hi im planning on building a canoe. Specifically, I would like to
build the 16 foot 'prospector' from moore's 'canoecraft' book, but the
design is in the form of a lofting table.

I know there are many books out there on lofting, but i have found
them to be more convoluted and complex than i need for a simple little
symmetrical canoe. The full size plans are available for purchase,
but I would I like learn how to loft. Can anynoe provide a brief
tutorial on how to loft canoe plans or maybe provide links to any
known web pages which *clearly* and as simply as possible methodically
describe how to loft -ideally canoes and specifically from the tables
in canoecraft- or other small simple boats?