lofting on cardboard or foam to prevent waste

[kormorant2]

I an about to commit myself to the construction of my first boat and was wondering if it would be " good practice" to loft my parts onto cardboard or foam to prevent wasting a pefectly good $125 sheet of okume (sp) plywood? I am currently trying to decide between a super skipjack or a triad and have plenty of time to practice. I downloaded the plans for the mini cup as a practice design. I will construct it in cardboard to learn lofting. ANY tips would be appreciated.

Thanks,

Joe aka Kormorant

[Greg Luckett]

On small boats I loft directly onto the plywood.  On bigger boats, such as the lapstraked lobster boat, I use the Luan 1/4 cheap plywood for pattern making (lofting).  Incidently, I pay about $55 for 6mm Okume.

[Barry Pyeatt]

I've always done the lofting on small boats directly on the plywood as well.  But when it comes to making patterns to fit spaces I too will use an inexpensive sheet of Luan or even pressed hardboard to make the patterns.  I will seldom use cardboard or a foam board simply because it is too soft an edge and generally not thick enough to hold shape well over any span that is critical.

The key to lofting is to have good light, a sharp pencil,  a good quality single tape measure to use and a  good consistently straight grain length of wood to use as a batten  I have several in different lengths to use up to 20' and in varying dimensions from 3/4" X 1/2" to 3/4" X 1 1/4".  All but one of the battens I use are clear, straight grain, quarter sawn sitka spruce and the other one is clear,  straight grain quartersawn western red cedar.  They all take a wonderfully fair curve no matter which way I lay them down and push to the offsets.  For the major part of laying things out stick with the one tape measure for everything, that way any small errors in the overall length of the tape won't be different with a differen tape measure. 

Measure twice, and on large parts, it is good to have someone else work with you, one reading and the other marking the spots.  Then reverse the roles to check the work.

A fair curve is simply one that will follow a natural curve of the batten when laid down and pushed into the curve.  If you have to force it into one portion or another to get it to follow the shape, go back and check to be sure the offsets are correct. 

Understand just how you are going to cut and cut to within about 1/32" consistently on the same side of the lines all the way thru.  Take your time, and have a new, good quality saw blade going into this.  Practice on a scrap of plywood if you aren't used to cutting curves with a circular saw.  It takes a little practice to get good at it.  If the blade is set at an angle, then be sure you are cutting from the correct direction on the line or the piece may be larger than needed or smaller than needed.  Just pay attention to those things first.  You'll do fine.

[Greg Luckett]

Good advice, Barry.  I agree with you completely.

I have found that those plastic moldings, the ones sold at HD or Lowes, work pretty good for battens less than 8 feet.  I use the 1/2 quarter round.  On longer ones I have used mahogany, sassafras, and oak.  I wish I could get the Sitka Spruce locally and at a reasonable price. 

Incidently (small thread hijack) I have some sort of an Oak growing on the back of my property that is about 4 or 5 foot at the base and about 100 feet tall.  No limbs for about 50 feet.  That species is common here abouts.  I would not cut down that beautiful tree, but if it falls or dies, I will hire a local mill to cut it to lumber.  There are local mills with piles of these trees cut into random lengths of 10 to 20 ft, 3 to 6 feet in diameter.  I think it is either white or red oak.  Time to get the book out and determine the species.   It will make for some good battens.  Local Cherry trees get pretty big around here too.