Boat model planked up

1:12 scale model with 1:12 scale 6 footer sitting in what will be the galley area

I have learned a few things from making the model. I have a human scale (1:12) fi gure about the equivalent of a six footer that my Grandmother knitted for me when I was a kid back in the 1970s. It is a 'Dad's Army' type character - my Grandfather was in the Home Guard in the UK during WW II - and can be posed because it has a skeleton made of pipe cleaners. Using this manikin I quickly determined that a mocked up galley 2 feet deep would leave no room to stand in front of it, so I shrunk the galley width to 18 inches. I also noted that the passageway on the other side of the main cabin was a bit narrow, so I shrunk the bunk/settee a couple of inches. Finally and most importantly a 2 foot wide toilet with solid bulkheads either side looks like a really tight squeeze so in the design I shifted the aft bulkhead 4 inches back to give some more room for my larger potentially claustrophobic guests.

 

The other purpose of the model was to see how the hull planks would fit to each other and conform to the bulkheads (they should all join together without gaps). I was also worried that there would be too much twist needed at the very front in the lowest panel. The twist does appear to be an issue true as I had to torture the thin sheet of basswood so I think this plank or at least the first section of it would have to be made of 2 layers of 1/4 inch plywood. 

 

You can see here where I experimented with joining planks. I used a simple butt joint backed up by a butt block inside.

 

The planking does sort of fit but not exactly. The planks fit fairly well to each other but not as well to some of the bulkheads. They also come up too high at the transom. Part of the problem is probably that when I built the bottom I did not put enough curvature in it because it sprang back to a flatter shape when I took it off the strongback after building it upside down. Still, I think the transom angle and match between planking height and transom are off and I need to figure out what caused this. It could be an error in the CAD software or more likely a mistake I made.

I also scaled down the bulkheads using the design software by a percentage where I should probably have taken the time to draw them out as the CAD software projected them and then subtracted the plank width before marking them out. Finally, I did not place the bulkheads with enough exactness fore and aft so the planks do not lay fairly against a couple of the bulkheads.

I think though that despite these issues, the over-all design could work when built in full scale. I would build the whole thing upright to ensure the bottom curvature is correct and turn the boat over only after it was all planked up to add the keel at that point. I would also template the planks before I cut them out to check that the designed versions would exactly fit the bulkheads as laid out. Finally, I would be more careful in reducing the bulkhead's dimensions to allow for plank thickness.

Working with the model has been a bit frustrating. The basswood is light and forgiving but breaks easily across the grain and the lighter bulkheads were patched together many times during building. My full size tools (circular table saw and oscillating multi tool) are pretty heavy handed and cutting fine shapes in 1/16 thick wood is tricky. I managed to take a chunk out of one of my fingers using the table saw for this purpose. Ideally I would use a Dremel type tool and sharp exacto knife for this work.

I am now not so sure I will proceed with building the actual boat. Rani has made it clear that long trips on a 22 foot sailboat are not her idea of a perfect holiday. So, I must weigh the fact that what I will be doing will be a fun creative project against the likelihood that I will be sailing it on my own and might need to keep a second larger boat at the same time if I want to cruise with my wife! After reading more account of home builders creating similar boats, I have also re-estimated the time to build upwards to a (hopefully worst case) time of 4000 hours/4 years. At least this has been a great learning process even if I never get to sail in a boat I designed and built...

When I carry on with the model, I will build the cockpit seats and floor and then fit out the galley and settees.