Skip to main content

The Physics of Boat Design

Michael Peters

Sightlines - October 2016

There Was This Guy Named Archimedes...

NDAs? CEOs? When it comes to designing a boat, some people still have much to learn.

Whenever I get a call from a potential new client and he starts the conversation with, “First, I need to have you sign an NDA,” I’m skeptical. For starters, I’m supposed to be the professional in this conversation, and I suspect I have more to disclose than the caller, and second, my experience tells me that he more than likely has nothing novel to share with me. The fact is, we work with some of the largest boat companies in the world, and they never start off with a non-disclosure agreement. Those proud inventors seeking to disclose their grand ideas to me often don’t even understand the most basic of physics pertaining to boats.


I often marvel at how few people know about this guy named Archimedes—he has been dead a while now, since 212 BC, to be precise. Well, he’s the father of hydrodynamics. He figured out displacement, and why things float, while sitting in his bathtub. Upon this discovery, he went running through the streets naked, screaming “Eureka!” thereby inventing that word at the very same time. He was a brilliant Greek mathematician, who, among other things, discovered the mathematical unit Pi. “Pie,” as most people know it, was, of course, discovered by his rotund cousin, Atetoomuchedes. It seems Archimedes lacked a good public-relations agent, because an awful lot of folks don’t seem to know his principles to this day.

Offshore Class I racing rules limit the maximum engine displacement to 1,000 cubic inches. Back when we were designing racing catamarans, we had an Italian client that wanted to use four small-displacement Formula One engines at 700 horsepower each, instead of the standard two big-block engines. The F1 engines were billed as weighing an ultra-light 300 pounds each, giving us a total of 2,800 horsepower for an amazing 1,200 pounds. When I pointed out the additional 1,600 pounds of remote coolers and accessories mounted in the engine room and included that all in the engine weight, the engine builder went ballistic. This guy could never get it through his head that if this stuff couldn’t stay on the dock, it had to be included.

We’ve entertained several electric-boat projects. The most bizarre came to us from a group that had a concept that would eliminate the need for heavy batteries. Three guys arrived at my office and proceeded to describe a light-displacement, fully planing, long-range boat with a large tank full of rechargeable electrolyte. They reasoned that the boat didn’t suffer the added weight of the electrolyte, because its specific gravity was exactly the same as seawater. When I persisted in including the weight of their electrolyte in our calculations, they were incredulous that it added displacement. Where is Archimedes when you need him?

The most alarming discussions sometimes involve the CEOs of large boat companies. The title of chief designer often rests on the shoulders of these men—just ask them. I once worked with such a gentleman who believed that his race boat porpoised because we had used a rubber-like putty compound for the lift strakes. I guess if rubber bounces on concrete, and water is like concrete at 100 miles per hour, then it’s only logical... After a year of discussion and refusal to implement our solution, he finally relented and let us add a wedge to the running surface. The boat lost its porpoising problem, gained four miles per hour, and won the next world championship.

Worse than a CEO without much technical knowledge is one that actually has a degree in naval architecture, but forsakes it. After once meeting with such a person, I voiced my concern for his lack of educational application to design problems. He stated that in his present position he was now a reformed engineer, and seemed to believe that any actual knowledge of the subject only stood in the way of his developing a good boat. It seemed that his most brilliant move as a young naval architect was to marry the founder’s daughter.

Prior to writing this column, I read over several NDAs that I have signed during my career. I think my disclosures herein are safe, but if you recognize yourself, please read with a chuckle and be glad I saved you tons of money when we took a pass on your project. Archimedes is surely laughing at all this blissful ignorance.

History tells us that Archimedes never signed a non-disclosure agreement. Should Michael?
Share your thoughts with him in the comments below.

This article originally appeared in the October 2016 issue of Power & Motoryacht magazine.