Designing the New Dinghy

Our plan to build a dinghy from set plans has been changed somewhat. The plans will build a dinghy that is 3.5 feet wide, 8.5 feet long, and have a plumb bow with an angled transom. This will make for an efficient rowboat, but this no longer fits our needs.

Maddie wants to have an outboard motor as a backup in case we end up anchoring miles from the nearest shore. We decided that we will buy a propane powered outboard and use it as a backup to the oars for as long as the outboard lasts. The moment it starts to die, we are going to throw it out and not bother repairing it (I have talked to outboard mechanics and they all tell me that the propane units don't work well once the repairs begin). 

Change #1: The outboard means that we need a vertical transom to hang the outboard. 

I measured the space on the deck, and 3.5 feet is a bit wide for where we want to store the dinghy. 3 feet would be much more comfortable on the deck. 

Change #2: The beam needs to be reduced from 3.5 to 3 feet.

The dinghy will live on the deck between the mast and the dodger, but it can't cover the chimney and it needs to cover the salon hatch (the salon hatch leaks). The space available on the deck to comfortably hold the dinghy is 9 feet, and the smaller the dinghy is, the easier it is to build, hoist, and control. I personally need 4 feet in the dinghy (I have long legs) and Maddie needs more space as well. Quickly, the length kept being bumped up until 7 feet seemed reasonable and comfortable (in a small sense). 

Change #3: The length needs to be reduced from 8.5 feet to 7 feet.

As you can see, these are some rather drastic changes that we are making to the design of the dinghy, so much that I decided to scrap the plans and design one myself!

I began sketching out the design of the dinghy on a 3/4 inch piece of particle board. I marked 1 foot increments on the panel, and then marked the boats centerline, bow, and stern. I decided that the bow would rest at Station 0, and the beam of the boat would be around Station 4 (3 feet), with the transom being 24 inches wide at Station 7.

I then set small nails into the board marking the bow, stern corners, and desired beam at station 4. These nails set into the particle board and will hold the batten in place while I trace the curvature of the hull. Once the curvature of the hull is traced, the nails and battens are removed and the design is complete.

This sketch will provide a rough idea what the footprint of the dinghy will be and lets us verify that the dinghy fit before I build it!

Measurements were taken from the sketch and then transferred to the deck of the sailboat to make sure it will fit all of our requirements for the dinghy. It turns out that it did not! The transom was covering chimney which means that the dinghy would need to be removed from the deck if we want to start the fire or risk covering the inside of the hull with soot! Then some creative thinking led me to measure the dinghy in reverse on the deck and set it at an angle, this seems that it will fit and work. The transom hides behind the dorade vents and mast, and the beam of the dinghy covers the hatch while the chimney sits next to the bow. This will probably lead to a soot stain on the starboard bow of the dinghy, but I can live with that.

Our next step will be to trace out a paper template of the dinghy and set it on the deck and make perfectly certain that it will fit on the sailboat. The design process continues as we figure out what our ideal dinghy will be before the first piece of wood gets cut.

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