Back to the Boat - Cabin Fever

At last some free time to potter in the boatshed! Taking stock of where I last got to (it's been a while) I've been making some modification to Kees Prins "Far Fetch" plans.  The main mods done to date are lengthening the hull by 8 inches to 17 ft 5 inches, centering the outboard cut out and adding twin rudders. The remaining item I had not yet modeled was the cabin size and ergonomics. To do this I first built a "lining-off" jig out of quad aluminium tubing and plastic connectors. This sits on my workbench over the model and I can measure down from the centre bar into the hull to check all mods and also do final lining off of the whole model prior to modifying the original plans from Kees Prins and Iain Oughtred.  You will see a pic below showing me starting to use this with the work I am doing on cabin design.

First thing I did re cabin space was to add 2 inches to the sheer. You can see this in pic above - pretty rough planking with that gap there but I will fair it up later. This was a bit of a pain to do as I had already fitted an inwale on the previous sheer plank. Next I added deck beams at station 2, 3 and 6 (the main structural deck points where I would be playing with cabin shape) and then made a cardboard deck. I drew a preferred deck perimeter for the hull/deck joint and made (extended) focal point of these curves ending just in from the bow where the forestay is to be anchored (you will see this point used in later pic re cabin slope). I took lining off x,y,z's of these perimeters and played with them on Delft ship CAD to get fair lines then.  After many cups of tea and coffee sitting looking at various ideas I came up with the following cabin profile which gave me head space sitting up in the bunk and included an extended front cabin roof for a bit more airspace and dry storage (there will just be a deck beam there in the middle, not a bulkhead as in the mock up).

Now to make a more permanent cabin model which I have started in the next pic. I am making the whole cabin structure above deck as a separate item so I can lift it off and view internal space as more detailed internals are checked.

Here's an amended draft on Kees Prins plans to show the full extent of hull and sheer increase and the new cabin design (new profile lines in red). New cabin is (relative to waterline) 9 inches higher at rear, 3 inches higher at front (both include the extra 2 inches sheer) for main cabin section and the forward extension is 17 inches long.  Note that there will now be no anchor hatch - this will help maintain clear foredeck space given the extended cabin. I intend to keep the anchor and warp in a self contained box inside the hull.  I also have plans for a small dorade box in the front cabin section to improve hull airing in our hot humid climes here.

I suspect waterline will come up a bit with the added displacement from higher sheer and cabin profile and it is starting to look a bit more like a motor sailor but that's acceptable compromise for me.

Here's some more pics a few days later after adding some more realistic cabin facings. Umbrella pole is roughly where mast will be.

A view dead ahead from about waterline level....

...and side on at deck level with 15 degrees heel....on the wind.