Planning Out the New Dinghy

We have finally begun the planning process for our new dinghy. This dinghy will be stored on deck, between the mast, boom, and dodger while on long voyages. This will reduce the drag associated with towing a dinghy behind us.

Tooth is an excellent row boat, but on long trips, he can be a drag! At 13 feet long, he is too large to store on deck when sailing. This leaves us towing him along over hundreds of miles, which has led to a few snags along the way.

We are very good at dodging crab pots in the bay, but they have a way of getting hooked on the painter. The snagged crab pot will bring us to a halt until we free it from the line. A towed behind dinghy also adds resistance to the equation, making us travel along more slowly than if we were not towing. It's the same idea as clean bottom vs. dirty bottom. It might not seem like much of a drag, but its effects will add up considerably.

While the longer length allows Tooth to carry more weight and row more efficiently, we need a smaller dinghy that we can take on long voyages with us. This is where our new dinghy will come into play.

I stumbled upon a dinghy design that I really like (mostly) and plan to make only a few modifications to it. The design is rather old, appearing in an 1890 Forest and Stream. The designed skiff comes in at 8.5 feet long and 3.5 feet wide. This is close to the size I'm looking for, but still on the big side.

We have a maximum of 10 feet available on the deck, so I'm looking to occupy it with something around 7 feet long. Shortening the span between the stations will bring this boat down to size and give us the wiggle room we want and need around the stowed boat on deck.

I am also going to change it from a flat bottom to a slight Vee bottom. Tooth is a flat bottom, and Maddie and I both hate the sound of the waves slapping into it. The first time we launched it, we thought something had broken because it was so loud! To avoid having that happen again, we are going to add a bit of a Vee to the hull, allowing it to cut through the waves rather than smacking them harshly.

This design is around 126 years old, and there have been plenty of skiff designs between then and now! Why this design? Why not a more contemporary model? Most all contemporary designs are for prams (which look ugly to me) and plywood construction.

I desire something with a pointed bow, allowing us to row into surf if we need to, and a carvel plank construction using "real" wood instead of plywood. I went back in time to find plans for wooden dinghies, before playwood and "stitch and glue" had dominated the scene.

Stitch and glue construction is fast and rewarding, it's how I built Tooth; but it doesn't hold up as well as I would like it to. Tooth has had a rather rough life, being towed over 800 miles in his first year after launching. In one year, Tooth has also shown significant amounts of wear and tear.

I hope that a heavy carvel planked hull will hold up to these abuses a bit better.

As you can see, the plans are not very extensive (that single page is what I'm going off of). There are no scantling numbers given, or diagonals or buttocks, simply a very basic line drawing with a station view.

I took to Herreshoff's Scantling Rules to calculate the needed dimensions for the parts at play. I did upsize a few of the key points (keel, frames, stem, and planking) to give me a bit more strength out of it.

With the basic calculations in place, I set out to collect some lumber to begin construction. At the moment, the plan is to build the entire dinghy out of Douglas Fir (Oregon Pine); but the planking might end up being out of cedar if I can't locate clear stock at a good price.

Since I am changing the design a bit, I'm going to begin by building a mold out of 3/4" particle board. This will allow me to visualize the hull form better (and make sure it fits in its intended location on deck) before construction begins. From the molds, I can also pick up the frame bevels by running battens along the hull, making final fabrication of the frames all the easier.

Lastly, having particle board templates of all the pieces needed will make cutting out the actual pieces from the wood all the easier. Instead of doing proper lofting, I'm going to cheat and use the mold as my templates.

Storing the Sculling Oar

The sculling oar is very useful, and it is very big! At 16 feet long, this oar is a bit of a challenge to store. I have many lines running on the deck with all the sails and I always worry that the oar will foul a line. 

Getting the oar out of the way has become a high priority for us. I decided to tie it to the lifelines that way it is available for use when needed but out of the way when not. At 16 feet in length, finding a span that was straight enough and out of the way proved difficult. The shrouds were my first logical choice, but the curvature of the hull was too great in this region. The oar was also at great risk of getting hooked on a sheet and breaking! 

The next location was the stern, but it would get in the way of the winches and sheets if set horizontally. If set vertically, the oar might be too much windage.

The next option was to set the oar up in the bow area. Tying it to the lifelines, stanchion, and bow rail seemed to get the oar out of the way while being clear of all sheets. It also lays lower than the foot of the headsails, so it would remain completely out of the way.

The oar is neatly stowed on the bow, out of the way but also ready for deployment when needed.

Sheathing the Tiny House

The plywood sheathing that wraps the house serves many purposes. It helps keep water out of the structure as construction progresses but it also provides stability to the tiny house. Plywood is composed of three sheets of wood oriented with different grain directions.

Some plies have vertical grain, others horizontal grain, and the rest have diagonal grain. This gives the plywood strength in all these different directions. A square of 2x4s can easily collapse, but when it is sheathed, it will hold its shape under incredible loads!

Sheathing the tiny house in plywood enables us to remove the wooden stays as stability is introduced tot he structure. 

My dad and I would position a sheet of plywood and tack in a few screws to hold it in place, then we would add a few more to keep it well attached to the house. Later, we would run around the house placing a screw every foot in each stud of the frame. This ties the house together with such great strength that we felt confident enough to stand on the tops of the walls while working on the roof.

The problem is, there are lots of studs and tons of screws to drive in! I highly recommend using a drill with a driver on it, as it makes the process proceed incredibly quickly. Light weight is another wonderful feature, as the drill will begin to feel heavy and make stabilizing the unit hard as the work progresses.

Even with the ease of power tools, driving in each screw is very time consuming. Maddie spent an entire afternoon sheathing the "no door" side and front of the tiny house!

Lastly, cordless battery powered drivers are amazing! You never have to worry about the plug separating or the cord not reaching. Lastly, have fun while you do it because you are building your tiny house!

Chainplate Fabrication: Part 3

To properly radius the holes of the chainplate, I use a carbide bur in a high speed hand piece followed up with an abrasive cone in a low speed hand piece.

These burs will result in a smooth and rounded transition from hole to chainplate, reducing the risk of point loading on the fasteners near the corners.

With lots of water flowing over the work site, I am able to keep the whole system cool while rounding up the corners. After the course reduction was completed, finer polish was achieved with the slow speed hand piece, smoothing it all up. This step could also be completed using a dremel tool, but as a dentist, a drill is second nature and I know I can get the exact result that I need!

Now the chainplates are finished and ready to be installed with new hardware and beeded into the deck to seal out any water intrusion.

Chainplate Fabrication: Part 2

The chainplates are mostly polished after running them on the lathe. The grain in the metal is still apparent but the surface is very smooth. Further polish can be achieved if the client desires a mirrored finish. 

The corners have been radiused to reduce the risk of injury if you bump into them, now it's time to drill the holes in the chainplate.

Careful measurements have been taken and the centers of the holes have been transferred to the blank chainplate. The holes were verified by stacking the chainplate under the old template and the marks lined up with the center of the holes, proving that everything is accurate.

Once everything is confirmed perfect, the drilling may begin! There are a few important points to remember when drilling through stainless steel:

• It is very hard
• Heat will kill your drill bit
• You need to keep everything lubricated
• Drill slowly
• Drill with very light pressure

Heat from trying to drill through stainless will cause the drill bit to lose its hardness and dull. To avoid this, you must keep things cool while drilling. To keep it all cool, set the drill press to its slowest speed and keep the drill bit lubricated.

I use transmission oil to lubricate the drill bit because it will begin to smoke if I am pushing it too fast. The oil also keeps the system from creating too much friction (and heat) and helps keep the drill bit sharp for longer. Having a shop vac at the site of drilling also helps keep the metal shavings under control. 

As soon as you start to see smoke or the area runs out of oil, stop and add some more transmission fluid to the site. 

When drilling the holes, be sure that the old chainplate is securely connected to the new chainplate with at least two C-clamps at all times. Having a third clamp will allow you to re-position the clamps without going below two clamps.

Since the old chainplate is your acoustic guide (if you are slightly off center, the drill bit will scrape the side of the old chianplate and alert you that you need to re-center the unit below the bit) you need the old chainplate to maintain itself in the exact same position. You need at least two clamps to avoid any kind of movement; if the template shifts the slightest bit, the holes will be out of alignment!

At the end of it all, you will have yourself a set of new chainplates with properly oriented holes! The next step in the manufacturing process will be to radius the holes to reduce stresses on the corners of the fastener holes.