Making the frame for a 'paper' hull

I bought a 'balsa bundle' from the modelshop containing various sizes of balsa...

and got some tools out...

...and cut the widest strips in two down the centre to provide more strip for the frame...

I made two pieces for the 'bow' of the hull by cutting an angle on one strip and copying it onto another (I find it best to make both pieces at the one time rather than complete one side then try to make another 'mirror image' afterward) then sanding the cut ends smooth and level

After cutting to the required length (which depends on the size hull you want to make) in this case 150mm, glue and clamp both pieces together. This can be done with balsa cement but I'm using evo stick weatherproof wood adhesive - because I already have some!

A 'centre' section is made from two equal lengths separated by two cross pieces (which can be removed later if preferred). Rubber bands hold it together until set... ...and two more lengths to fit between the centre and bow sections, the ends are tapered slightly to fit between the other two sections. A similar arrangement is made for the rear. If you're making a 'barge' ( designed for towing in either direction) the rear can be the same shape...

...but I'm going to make a 'counter stern' so it will be need to be shorter and more rounded...

I've used small blocks of balsa to strengthen the joins but the long hardwood piece is attached temporarily to find the centre...

...before glueing the remaining pieces in place;

When it's all set, remove the clamps and sand the outside to give a smooth curve. If you have a large enough piece of balsa, the whole base could be cut from it, which would give a better result, but I only have strips and a couple of thin sheets (which may have a use later)

Two 'uprights' are added on each side plus one at the bow (which you can't see in the photo)

As I'm making a 'counter stern', the rear piece is cut with a taper so it leans back at the required angle then cut to the height of the side uprights;

A second frame is constructed to fit on top of all the uprights (in the same way as the base frame). If it is the same size as the first frame, the sides of the hull will be vertical. If it is wider, the hull will have a 'V'shape to it. I'm making it the same width at the 'middle third' of it's length but wider at the front and rear, like this...

For the counter stern it will also be longer than the base and I made a partial frame to support the extra-long curved surface of hull that will result...

When set, it is all sanded so that paper strips wrapped around the frame will lay flat against it. The base also needs to be rounded off to give a smooth transition from the sides to the bottom of the hull...

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