During my time working for the yacht builders McGruers and Silvers on the Gareloch I was asked to make several half models, sometimes as presents for the clients we were designing and building for and at other times for exhibit at boat shows.
I enjoyed making them so much that I obtained the lines for some very early yachts and produced these as half models for sale - I used scrap Pine which had a fairly wild grain and delineated the waterline with a layer of plywood as you will see. The top six half models adorn the Selway Fisher Design office.
Because I did not have pine stock of the correct width, I had to use 2 pieces side by side to make up some of the layers and you will see that this automatically gives you buttock lines.
I love the way the grain works on this example of Yolande.
Note for the newest half model built this way see the 26'6" Tancook Whaler model which features in the Model Boat Building Manual.
Cheri II was designed for a German shipping magnate but never built - for the half model I made half section moulds reduced in size for the planking and glued to a backing board. the space between the section moulds was then filled with scrap wood before the hull was planked with Mahogany veneer - doing this gives a large gluing area for the planking which is then less likely to 'move'.
I worked on several 3/4 Tonners at McGruers - this was my first, Nippie Sweetie for Ninian Sanderson which was exhibited at Earls Court and took part in the 1976 World 3/4 Ton Championships. The half model is Mahogany plank over frame.
Amoress is another 3/4 Tonner designed by Peter Norlin but which I did the interior and deck plan for. This model is around 20" long but I did another one for the owner which was twice the size - both used wood from the same tree used for the full-size yacht and paint and varnish from the same tins. you can see the Mahogany diagonal veneer outside planking.
Sadly Caitlin of Ashton, a lovely 8 meter Cruiser racer designed by James McGruer foundered off the coast of Ireland - just a couple of planks were salvaged and I was given one to make into this half model for the grieving owner.
Below is a small selection of some of the half models I used to develop the plank shapes of some of the early Selway Fisher Design before the advent of computer software that could do the job more efficiently - for those familiar with Selway Fisher Design, see if you can identify them or go to www.selway-fisher.com to see them.
To the left is the Highlander 18 and Petrel designs and to the right, the same again plus Ptarmigan 15, Hawk catamaran, Henley 16 slipper and Simplicity 20 amongst others. These are true 'working' models of multi-chine boats - the hull was first drawn to a small scale and altered until it's hydrostatics (displacement volume, LCB, Pc etc) were correct - a half model was then carefully made to these lines, often to a scale of 1"=1' (1/12), tracing paper was then pinned to each plank and the tope and bottom (chines) of the plank traced. The traced plank was then transferred to a grid and the dimensions for the plank at stations marked at 6" or less intervals were taken using a scale rule.
Finally these plank shapes were transferred to cardboard and the planks cut out and taped together - this new model was then checked for dimensional accuracy against the original lines plan and if it was within a 'gnats' whisker' all was fine - the trouble was, scaling dimensions off meant that you could easily be 1/2" or more out and then in 1990 I bought a computer and software and overnight the process became so much more accurate and the time taken to get to the stage of developing hull plank/panel shapes dropped from 2-3 weeks to 30 minutes!!