I think that some experimenting will be called for when I start on the light unit.

I have made a start on the construction of the model by cutting out all the hull frames.  I developed a method of marking out the shape when I did my Humber Sloop and have used the same method for Spurn.  The hull sections are shown below with the original drawing being 3/8 inch to a foot or 1:32 scale.  My model will be 1:24 scale.

The drawing is scanned in two halves, either side of the centreline with a couple on inches overlap.  Each of these images is then flipped in the computer so I have a mirror image.  Each image is then printed with an appropriate magnification to give me a complete 1:24 size cross section at each hull station, but taking account the thickness of the hull.  There is a bit of trial and error involved here with several test prints but it worked out at about x1.28.  The two parts of the section at each hull station can then be taped together and cut round just outside the line for each frame.  They are then stuck on the 5 mm plywood I used for the frames with Spraymount adhesive.  There are a few sample frames below.

The right hand image shows my first mistake, which I will explain in the next post.  The frames are cut out using my scroll saw and then trimmed to size using a disk sander

The frames were all cut out and fixed onto battens which can then be fixed to the building board, initially just using spring clamps.  I could then plan which area of the frames to cut away to allow access and space for the 12 V lead acid battery, servos and other electrical parts.  I drilled three of the frames to take the prop shaft as its much easier to drill accurately through 3 frames clamped together rather than spaced 5 inches apart. The bottom of each frame was notched to take the keel which is made from 3 pieces of 2mm ply laminated together.  There are three sections of keel which are joined in a mortice and tenon fashion for strength and stiffness.  Once I was satisfied everything fitted together the frames were bolted to the building board which had the hull centreline marked on it.  In addition I used a laser level to shine along the keel to ensure everything was straight.

The model will also incorporate a carrying handle in the centre of the hull.  This can be removed or slid backwards for access underneath it to fit the battery.  I first did this on Shemarah, a 1:24 scale Scottish trawler I built some years ago which weighed about 65 lbs when complete.  I discussed this with Dave Milbourn at the Warwick Model Show at the time and he told me it was a daft idea as the bottom would fall out of the boat if I tried to pick it up.  I sent him a photo of me holding the model, ballasted with bricks temporarily and he reluctantly conceded it might work.  I have now used this approach on three fairly heavy models and it makes carrying them much easier, if no lighter.

In the fourth picture you can see the mistake I make in drawing the frames.  I did not make the extension above deck level high enough for the stem of the hull to clear the building board so I have had to cut a slot to accommodate it.