Glue Stitch Sabot - help reading plans please

Hi there,

i am currently building a cedar strip canoe so evidently have heaps of time spare, as such I have promised my daughter I will help her build a small rowing dinghy.
Having found some plans which look ok, however, on closer examination, I am having problems working out some dimensions, or rather, problems with measurements on the drawings. Specifically with the way
the lengths of bow and stern edges project against the elevations for the side and bottom ply planks.
Is it simply that I follow the set out dimensions in full scale, cut and all will be good. or is this where the dark art of lofting comes into play and i need to do some sort
of conversions to get true lengths of edges for side and base panels. on the enclosed drawing the edge lengths of the base and side panels simply don't measure as the
same length as the edges on the bow/stern panels?

Any suggestions would be greatly appreciated/
Roy.

G'day,
Could it have something to do with the curve of the timber. When stitching together the pieces may join up???
Post a pic when finished.
John.

Perhaps, I will be doing a full mock up in 3mm mdf to start with.

Both transoms (bow and stern) are shown "projected", which is one way to present them if you want accurate measurements. I do it a little differently on my plans, by simply showing the transom dimensions as a station mold, with the term "projected" in brackets. The reason it's shown this way, is because it's hand drawn and this is the mechanical way of drafting an angled surface. Just take the provided dimensions as they appear (heights and half breadths) and make the transom or transom mold to these dimensions. If you used a ruler and scaled directly off the drawing, you'd have different measurements, unless you "project" the transoms (as shown on the drawing) first. It's just a technical drawing thing, just use the provided dimensions.

As a reminder, these dimensions are not the planking dimensions, but the exterior surface of the hull dimensions, from which you'll make station molds. In the process of making station molds, you'll need to subtract the thickness of the planking, from the actual mold dimensions.
Attachment 374015
This is a round bilge I recently built, during the station mold erection stage. The molds are shaped to the inside of the planking, so that when you apply the actually planking, the exterior dimensions are what the design calls for.

If you drop me an email, I can send you a PDF that explains all this more completely, than I have here and it shows a hard chine hull (like yours) being done like this.

@PAR Thanks for the reply, I'm older school so I understood the reason for the projection and that the transoms were true shape as per the dimensions, what confused me was the mis match on the drawing.
As I am glue stitching, therfore not needing station moulds, ill just have faith in the drawings, set out and cut.

Cheers

Roy.

Roy (again) those are not panel dimensions, but instead are "heights" and "half breadths". If you make your panels to those dimensions nothing will fit (not even close in some areas). To get actual panel dimensions you have to "develop" the drawings, which isn't an easy thing for the novice. In the old days, these developments were done by hand "triangulating" areas, until the panel was mapped out. Now we use software to address this quite tedious task. There are lots of plans available for taped seam 8' prams, where the developed panels are already figured out for you.

I'd recommend the "D5" from bateau.com. It's a 7' 10" sailing pram (just like yours), designed for taped seam (stitch and glue) construction. It's plans are cheap and available as a digital download too.

http://bateau.com/boats/D5/slides/BotaduraD4104.jpg
http://bateau.com/boats/D5/slides/D4_iso.JPG

Thanks PAR, I re read what you said then had another think about the drawing, totally understand now! I'll look at the drawings you suggest. Really appreciate the assistance and wisdom.

Those Sabot drawings look very old.
Might be the original MacGregor drawings.
All Australian boats for the last 50 years or more have buoyancy boxes front & rear.
Sabots are a still a popular junior racing class.
The skeg is long gone, and kick-up or dagger rudders are the norm.
If you really wanted a Sabot, the AU Sabot Association might be able to help with plans.
Although it looks like the class has gone to f/glass hulls & c/f spars. :(

Thanks Alan,

I found some other plans which have worked really well.

Cheers
Roy.

Alan, Given that you are in Hobart, you might want to talk to Lindisfarne SC about 8 footers. They sail Firebugs and Optimists, they built the Bugs and target them at kids who then move on to Sabres or Laser 4.7s.

They threw a terrific event for Firebugs on 16/17 April.

Lindisfarne - April 2016 - THE FIREBUG DINGHY - IN AUSTRALIA