Email This Page to a FriendNotes on Boat Design, Part 1 — The Case for Going Slower
October 2, 2012
Off Center Harbor blogs seem like they might be a good place to try to discuss some technical issues in boat design. There are lots of books on these subjects, many of them written by people with greater credentials and writing skill than I possess. But still, the blog-and-comment format available here would seem to offer some advantages. I can ramble on about some issues that seem to constantly come up in conversations with customers who are interested in design, and respond to readers’ questions about stuff that they could never quite otherwise get—and they might even get an answer that makes sense. But I make no promises.
To the extent possible, I am going to try to avoid relying on numbers and formulas to explain technical points. Sometimes this may be impossible, but generally it will be a good challenge for me, and possibly a relief for readers. There are lots of books out there that are full of formulas, and anyone who wants to delve into a subject in greater technical detail should carry on! David Gerr is a particularly lucid and practical writer, and for those who wish to see the numbers behind my generalities, I can heartily recommend his books.
I should also state from the start that my approach to boat design could be described as low-tech meat and potatoes. Although many of the concepts discussed here can apply to anything that floats, from a toy boat to a supertanker, my comfort zone extends principally from dinghies to mid-sized pleasure boats. Anything I say on cutting-edge racers, submarines, or cargo vessels should be regarded with deep skepticism. I am very interested in the aesthetics of boating, not just of the boats themselves, but of the entire process. Even the most beautiful boats lose some of their elegance if they are used clumsily or aggressively, or if they are bogged down with unnecessary gear or technical gizmos. In their classic Elements of Style, William Strunk and E. B. White advise us to “omit needless words.” I would argue that a similar prescription should apply to boats: omit needless stuff.
There are countless boating magazines and on-line forums that tend to discuss the same issues ad nausium. I am hoping to discuss different issues here, and be forewarned that I plan to spend some time up on my soap box. To start, I’d like to discuss powering and fuel issues. For a second opinion on this subject, pick up a copy of Polluting for Pleasure, by Andre Mele.
PART ONE: THE FORCES FOR “MORE”
When it comes to installing power in boats, the forces for MORE are firmly arrayed. The engine manufactures, the boatbuilders, the maintenance mechanics, the fuel dock operators, the magazine editors – almost everyone stands to profit from installing more. With a chorus like this leading the hymns, it would take a confident individual with a secure ego to sing a different song. Toss in some testosterone, cheap fuel, fully-packed leisure schedules and fish that might get away, and you have a lobby that would make the NRA weep with envy. In the other corner, there is only Mother Earth and you.
One of my first questions for anyone asking about a power boat design is “what speed is required”. A typical conversation might go something like this; “Got to have twenty.” “You could get nineteen out of a smaller engine.” “Nope, got to have twenty.” “Why?” “It’s a safety issue. If bad weather comes up, I got to be able to get in quick.”
Now, ignoring the fact that we now have weather forecasts that allow us to avoid most bad weather, and the fact that in said bad weather you would be hard pressed to maintain 20 knots, and the fact that 19 knots is pretty darned close to twenty, what is wrong with adding a little extra horsepower? Well, a bigger engine weighs more – not only the engine, but everything attached to it. Higher speed boats need to have heavier construction in order to withstand the higher forces they create. And you’d better install more tankage, or else your range will head down the dumpster. All this extra weight, together with the immutable fact that every extra knot above hull speed is more difficult to achieve, means that your bigger engine doesn’t get you much. And, you pay the price for this extra weight, both in initial construction costs and operating costs, even if you decide to slow down. Then there are the environmental costs.
Others may disagree, but I have the feeling that the human race may survive long enough to regret roaring through a cheap and incredibly versatile energy source that took the earth billions of years to create.
(PARTS TWO AND THREE OF THIS SERIES TO FOLLOW SOON, SO STAY TUNED.)
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