When cruising, every sailboat needs its own sports car, a little dinghy. I wanted to purchase a 9′ Montgomery sailing dinghy, but could not find one on the used market. So why not build my own? Ok, I had a friend whom also needed a dinghy, so the dinghy project percolated up the extensive to-do list. Last fall I re-drafted plans for a 9′ lapstrake dinghy that could row, sail or power with a small outboard motor and we began construction of a building form. It took a couple months to construct the building form, a male plug.
As we were only going to build a couple dinghies, the process of making a female mold from the male plug was eliminated and we just laid up a 9′ dinghy on top of the form, constructing the dinghy from the inside, out. My friend did not have room to carry a 9′ dinghy on his davits, so we planned to make sections on the form to cut and contort into a 6.5′ dinghy. Notice the seat bases are filled with 3lb density marine flotation foam. The seat is a “U” shape allowing for good position to row or sail. A dagger board will extend through bottom of boat. The centerboard trunk has not been fabricated yet but will bond to the hull in the approximate location of the blue masking tape in bottom center of boat.
The bottom pieces were laid up a a glass mirror in two sections, then bonded together to form a 5 degree deadrise. This process allows us to make a finished outer surface very quickly with only the joints requiring gel-coat touch up.
Originally, the narrow lapstrake bottom was too unstable, so we cut out the bottom and redesigned a flatter, wider bottom with a lower center of gravity.
I am sorry to say that many of the pictures of the process were lost when my hard drive died last fall.
The small dinghy project is now complete and a wonderful success. The narrow, deep bottom was cut out and a new wider 5 degree deadrise bottom was glassed into its place. The seat was lowered about 2 inches as well, lowering the center of gravity. Static stability tests at the dock demonstrated increasing positive righting moment to the point of heel that would allow water to enter over the gunwale. 3 lb density flotation foam fills the side seats and make the boat unsinkable.
Friends were eager to take to the oars and give her a spin. The dinghy is a delight to row and maintains a straight course when rowing.
Jan enjoyed rowing too and wore an ear to ear grin when he returned to the dock.