Home . Articles . Columns & Blogs . On the Wind . It floats! Thanks to a degree from the North Lawn School of Design

It floats! Thanks to a degree from the North Lawn School of Design

2007 January 17
I like naval architects. I really do. In fact, two of my best friends are naval architects, and when I think about high points in my sailing career, some of the best were spent in the company of the vastly amusing naval architect Gary Mull.

But naval architects take a beating. If they design a slow boat, then it's always the naval architect's fault for losing the race.

"This dog just won't go upwind/downwind/heavy wind/light wind/etc." It is never, ever, the skipper or crew's fault.

On the other hand, when a naval architect designs a brilliant boat, it is always the skipper and crew who win the race. It's generally agreed that when Dennis Conner lost the America's Cup, it was against a yacht that was so vastly superior that he probably wouldn't have been competitive even with an engine. The Australian crew was able to recover from tactical errors that would have been terminal with a slow boat, yet the naval architect got more abuse (for his winged keel) than attaboys for his clever design.

This comes to mind because I recently undertook my own foray into naval architecture, albeit on a much smaller scale than the America's Cup. I decided to build a Christmas tree, and in the process, it became a challenge of yacht design.

We live on a waterway and I decided, for reasons now forgotten, that it would be pretty neat to have a floating Christmas tree out in front. It didn't seem such a major mission but, in the end, it was one of those five-minute projects that take a week of trips back and forth to Home Depot to accomplish.

To get a Christmas tree to float on the water, I needed a float. I started looking at the floats under docks with clinical interest and I guessed that a 4-foot-by-4-foot float would not only carry the 12-foot Christmas tree I had in mind, but it would also be economically sized to require only a couple of 4-by-8 sheets of plywood.

But then I started worrying. Terms like "center of gravity," "form stability" and "righting moment" started to nag at me. All I wanted to build was a four-foot square box with two-foot sides, but what if it tipped over the moment it hit the water?

Niggling in the back of my mind was the name Vasa, the mighty 17th century battle galleon designed as the largest ship ever built by the Swedish king (like me, a self-proclaimed naval architect). It capsized and sank within a mile on her maiden voyage.

Knowing that naval architects are careful about the weight of the materials used in their boats, I started fretting about the weight of the 3/4-inch plywood, plus the 2-by-4s that I planned to use for corner reinforcements. I hefted the box of wood screws, and wondered what difference a pound of metal would make. I planned to fiberglass the bottom of my float, and I even put the gallon of polyester resin on the bathroom scale to see how much it weighed.

Of course, knowing all these weights was pointless, because I didn't know what to do if the float was too heavy or too light, so I simply set to work turning wood into sawdust. I finished up the woodworking portion of the float, discovering that "too light" was not going to be one of my problems.

Next came waterproofing. Since moving to Florida, I hadn't done any fiberglass work and quickly discovered the effect high humidity has on curing times. The phrase "watching paint dry" is nothing compared to walking out every hour, tapping my newly fiberglassed float, and finding it not just tacky, but still liquid.

While watching the fiberglass cure, I also had another frightening thought that I hadn't considered: windage. Putting up a framework to support the Christmas lights would not only affect the center of gravity, but would add considerable windage. And we get not just steady trade winds, but occasional squalls with some oomph in them.

My original fears of waking up one morning to see the top foot of my Christmas tree above water in front of our house now turned to a more graphic image of the tree heeling gently in a gust of wind, heeling, heeling, heeling. I realized that, technically speaking, my Christmas tree float would have even better form stability upside down than it had right-side up.

Obviously, I needed ballast. It was too late in the design and building process to add a keel, so internal ballast seemed the solution. A pair of concrete blocks were about the right weight (and price), and I centered these in the float, thinking perhaps I should put a gold doubloon under them for good luck. But it hadn't worked for the Swedish king, so it probably wouldn't work for me, either.

The fiberglass finally dried, a framework for the lights was erected, and string after string of lights was hung with care. I forgot, however, that naval architects also have to carefully calculate the electrical loads. Of course, the first time I plugged in the lights, all the fuses blew just as my wife arrived on the scene.

"I don't think you're supposed to plug that many strings of lights together," she said helpfully. I defused all the lights, wired them together, and tried the lights again. The tree lit up spectacularly, although it may have accounted for that late November brown-out in south Florida.

The next problem was logistical: I had built the tree in the driveway, which is on the opposite side of the house from the water. Sigh.

The final solution was to drag it to the water's edge with our sport ute, tearing up large portions of grass in the process. "Yes, dear, I should have built it by the water's edge." With no small amount of trepidation, I pushed it into the water and-voila!-it floated. If I were really a naval architect, I'd say it floated on its lines although, and in the absence of a boot top, I could say anything I wanted. Best of all, it floated level.

That night, we had the lighting ceremony. Since the electrical system is Mickey Moused illegality at its best, we all stood well back as the plug went into the socket. But the tree lit in a blaze of Christmas glory, although one of my neighbors suggested that anyone with a pacemaker probably shouldn't swim in front of our house.

There are naval architects who are graduates of the Westlawn Institute of Marine Engineering. I'm pleased to be a graduate of my own North Lawn School of Design.

I anchored my tree offshore with a concrete block, and the next hurdle will be to retrieve it after Christmas. I know it's going to be tough to tow it behind my rowboat back to shore: the thing doesn't go to windward at all.

Damn naval architect.