Aidi
Thank you very much for the build log - clear and interesting
I too would not use pins/nails, but every other clamping device known to personkind.
Don't forget the humble rubber band, and its larger brother the strip of model aircraft elastic (6mm x 1mm approx) ~A metre length of this will wrap 50 times round a hull and apply pressure over a length of plank - and it can "reach" into difficult areas if you trap a block of something (balsa, hard foam) to transfer the force to where you need it - like the lower planks of a hulll near the keel.
Also remember the inner tube - bicycle, motor bike and car (and lorry). Available free
from tyre places.
Heat resistant to about 200deg (stick it in the oven with the parts)
Slice across the tube to make small rubbber bands
Use as a long , strong bandage
slice round the tube to make strip (see above)
Stuff inside something and inflate gently to apply pressure in difficult places
watching and applauding on the square leg boundary
andrew