Part One - Part Two - Part Three - Part Four
In the last installment we looked at Construction and Offset Plans for a simple motor hull. Now we get to look at a sailboat with cabin and interior. Usually the plans you buy don't have much in the way of details because designers leave cabin interiors to the builder and the owner. Some yards even build the cabin house before the hull is finished, then when the hull is ready the cabin top is lowered onto the deck, secured and done.
We'll look typical plan sheets for a 15 foot Sam Rabl sloop Titmouse as a guide. By the way when Sam Rabl designed Titmouse, the estimated cost was $475. That's not a misprint, that's where you cry.
Our method if building will be the same as with most boats. First, the keel with stem and stern. Then the frames are made. The planking can go on before or after the centerboard trunk. This is possible because the boat is small and simple. The deck goes on, and then the sailing gear is made.
What this means is the plans sheets should be organized by the order of build - keel, stem, stern, frames, deck, board and sail gear. Sam Rabl made some sheets simple and clear by putting some of the details on other sheets.
Here is our profile in full sail. It would be decorated as a promotional page, especially in the days when sailing magazines carried new plans every month. This is page 2 of the original plans.
Here is page 3, the framing plan with stem, frames, deck beams, and floor beams. The stern knee is showing, although its' exact size is not specified. This page needs to have the details of how the deck beams are joined to the sheer and how the chine is backed.
I have simplified the frames, keel, and stem and stern. The frames and deck beams (parallel to the frames) are in black, the sole and joists are red, the carling is blue and the stern framing is put in also.
What this page shows us is the importance of the breasthook - as small as it is - and the quarter knees. The stem has a metal strap, rather than the cutwater of the previous motorboat. This boat also has a centerboard, which when anchored to frame 2 and 3 will strengthen the hull.
This page can tell the builder how much lumber is needed for the framing, deck beams and sole joists. The dimension of the hull frames is important, as the builder has to have enough room on the framing to anchor floor joists, bed frames, and galley supports.
The significant factor here is the weight of all these frames. Above the waterline, lightness is everything.
Now here we get some details, page 4 of the plans. These frames require a great batten or more than one to get the beautiful curve right. The frame measurements come off this page and the page of offsets. This page also gives dimensions for the centerboard trunk in frame 3 and 4. If you build the trunk before putting the deck on, have page 5 handy. You'll be working back and forth between page 4 and the offset page. Ordinarily, an interior framing sheet would have more details, and some designers fill up every space with measurements, type of wood, bevel angles and anything they want. William Garden is known for filling his drawings with all kinds of details which nearly amount to modern art. But Sam Rabl has kept the measurements and notes to a minimum. For me, filling up the page with details and notes is an obstacle, like trying to bowl in a phone booth.
The last page is even more detailed. It has the stem bevels, the rudder measurements and the centerboard house. When you see diagrams of the stem bevels like this, you know it was meant for the builder to do this work by hand with chisels. That means, whatever wood Rabl specifies needs to be used without exception.
Another point is that you will have to use this page with page 3. The stem will be cut early in your build. The board trunk can be made outside the boat but you'll have to decide whether to cut the floorboards around the trunk or to cut a space for the trunk in the floorboards. I don't know which is better, but either way how close the fit of the sole to the trunk is not that important compared to the fit of the trunk top to the frames.
This is the aft section of the cabin at the bulkhead, showing the scantlings used and the joinery. The framing plan shows brass angles in the corners of the cabin top. It also shows the position of the transverse framing members of the cabin top.
Old style plans for a simple weekend cruiser.
What I have not mentioned in all of this is the strip planking. Rabl's instruction sheet has the method of planking described in detail. I think this shape of hull, narrow flat bottom with curved sides might be the ideal sailing shape in a small boat. It's not an instant boat, but when you finish you could handle anything but my mother's meatloaf.
Paul is also publishing his books on Amazon.