I have always taken that"gap" to represent the thickness of the stem post, keel and sternpost.i.e. the backbone of the ship.

if you are using a solid "backbone" including all three items mentioned above, it would be represented in a piece of timber such as ply, it would be the thickness of that "gap" on your plans.

then if the "bulkheads" or "frames" as some call them are being fixed to the back bone they can be fixed in two ways.

The first is to photocopy all your numbered frames at least once in one whole piece.

I then, myself ,fold each piece of paper down that centre line and one  different frame is cut from each photocopy following the respective numbered line so that the 2nd half is cut at the same time giving total symitry. If you have 14 frames you end up with 14 cut out paper frames, all of different shapes. they can then be glued to the timber prior to cutting.

Then they are attached to the backbone using a half housing joint. ie. half the slot is cut from the bottom end of each frame to the thicknes of the backbone, and the corresponding half slot ( the thickness of the frame) is cut from the top end of the backbone.

If you go the other way and attach the "frames" to the backbone in two halves and not a whole frame, the "gap" represents the amount of frame that has to be taken off in order to give the true "beam" of the ship rather than an exagerated beam which you would get if you cut the frame straight down the centre line.

Hope this is understandable.

Neil.

Hello Peter

Both Bob and Neil are right in saying that the lines are representations of the keel or to be precise half the width of the keel for as Neil points out the drawings are intended to identical sides along a center line.

The reason for showing the thickness of the keel is to give the builder correct instructions as the builder’s job is to build and not to have to make uninformed assumptions about the design.  

If you wish to use 2mm ply for the planking then you will have to draw out the plans to scale and include the areas that are affected by the 2mm planking, at this point you have to make adjustments to the drawings to allow for the 2mm planking (but without changing the overall dimensions of the design) and then create a new set of templates. 

Its not to difficult to do as long as you work all of you measurements from the center line, but if you get stuck drop me a line and I will help you sort it out.

Paul

Peter

You`re tying yourself into needless knots!!

Just follow the drawing…ie…Don`t change NOWT!….and just get with it!

Bob

Peter

You could use a pair of dividers or a drawing compass…just set the 2mm and follow the outside line but Neils "finger" guage has always worked for me.

Paul