A handsome planing boat that’s a model of efficiency
Posted on 30 November 2012
Written by Eric Sorensen
More than a few discerning boaters have been looking for yacht designer Steve Weiss, but they haven’t known it until now. They lack only an introduction. His background comprises a thorough grounding in conventional sail- and powerboat design and CAD technology, and his aesthetic sensibility reflects a sympathy for the environment and consonance with nature. It overtly permeates his work.
Weiss is a 1983 graduate of the Yacht Design Institute and has worked for Lazzara Yachts in Florida, Morris and Hinckley in Maine, and Oyster Marine in the U.K. After three years as a yacht broker he started his own design firm in Trenton, Maine, in 2008 — of all years to strike out on your own. Working in 2D and later 3D CAD since the early 1990s he is now a CAD whiz who, despite his classical roots, clearly enjoys the computer-aided creative process.
Looking through Weiss’ portfolio when we met at a marine industry event in October, I was struck by how his 3D computer boat renderings bring them to life in a way not possible just a few years ago. Such is the power of computer modeling programs such as Rhino. Like the characters in a play or book that flow from the pen of genius, it is hard to remember that the boat portrayed does not actually exist … yet. The result is a boat that can be thoroughly visualized, tinkered with and refined before the first pattern or mold is cut.
Looking through his designs at www.weissyachtdesign.com, I see a kindred spirit at work, a man who values economy, quiet, comfort and elegance above the modern trappings of speed and bulk, which can come at high cost to the purse and the environment. His powerboats are designed to cruise in the mid-teens on a single diesel. The hull is of modest beam, though only by comparison to modern full-planing designs. This moderate beam/length ratio offers both comfort in a seaway and low resistance for that single modest-horsepower diesel to overcome.
The hulls are designed to minimize resistance at a speed/length ratio of 2.5. His 38 DayBoat, for example, measures 36 feet, 7 inches on the waterline, with a waterline beam of 9 feet, 11 inches, for a waterline length/beam ratio of 3.7 and a displacement/length ratio of 130 — the lower this number, the more efficiently it will be propelled. The boat will cruise at 15 knots — s/l of 2.5 — efficiently and is expected to make 18 knots with a 320-hp diesel.
The displacement/length figure is particularly important in a boat operating in the semiplaning (or semidisplacement) range since it combines in one number a useful summary of both the boat’s bottom loading and its ability to get on top of and past its own bow wave — in other words, its ability to get past displacement speed without a lot of power.
A boat with a low d/l, such as the 38 DayBoat, will slide up on and past its bow wave — semiplaning, with both buoyancy and dynamic lift supporting the hull — without dragging half the bay behind it. Very little fuss at hump, so to speak. Round bilges work well in a boat that cruises below 16 knots; above this speed, however, hard chines work to separate water flow from the hull, reducing the amount of wetted surface and the associated frictional drag.
Weiss’ website shows all of the 38 DayBoat’s details, so I’ll keep my comments short. The boat has a low center of gravity with a short, elevated bridge deck that’s installed flush over the engine. The cockpit and cabin soles are low to the water, which also makes life comfortable for anyone seated in those areas, as they are subject to very low accelerations when the boat is rolling. The entry is fine, boding well for a comfortable ride in a head sea; the spray rails forward will help, as she lacks chines and flare to knock down spray at speed.
The 38 DayBoat has a skeg aft that, with her flat hull sections aft, will help with coursekeeping. She will assuredly lay with her quarter to the wind when drifting with that skeg and her high freeboard forward, and her big rudder will help when running into the wind at low speed. A semiplaning boat such as this doesn’t have to worry much about the skeg’s added drag — it would be prohibitive in a 30-knot boat — and she benefits from the grounding protection provided to the running gear.
“I take pains to reduce wetted surface on these boats in comparison to the typical skeg, or ‘built-down’ lobster boat hull, with their full-length skegs,” Weiss says. “It’s one of the ways I aim to advance the semiplaning powerboat beyond the lobster yacht paradigm.”
Weiss’ objectives for his 38 DayBoat reflect the low-impact functionality of the rest of his designs. He wanted to create a space where people will naturally gather and talk to each other while enjoying both nature and each other’s company, including that of the nearby helmsman.
With its slippery hull and 15-knot cruising speed, this single-diesel boat will be efficient, consuming a fraction of the fuel of a similar-size, beamier twin-engine planing boat. The smaller diesel will be quieter, interfering less with one’s ability to become immersed in and enjoy the landscape and the birds and fish busily at work around them.
Another important concept for Weiss is the hull-side door. “These doors make so much sense, making getting on and off the boat so much easier and more elegant,” he says. “Your advanced-age, non-athletic in-laws arrive at the boat in the dinghy and are told to climb on board, which is not as easy a task as it once may have been. This is not a happy experience. Think of the ergonomics of how people actually board the boat. The doors provide a natural way to step on without being athletic and without embarrassment.”
Since the 38 is primarily a dayboat, you could accomplish much the same result with a smaller hull, although a shorter boat of the same height would be hard-pressed to be as pretty. Of course, you would give up the deck space that a larger vessel affords, as well as the ability to use the boat as a comfortable weekender and coastal cruiser. The cabin not only allows the boat to be used as a cruiser, but it also comes in handy for day boating.
“Any time there is a kid under 12 years old on board for more than a few hours they will be down there napping, so the bunk is for kids as much as adults,” Weiss notes.
It’s obvious that his design philosophy is informed by the practicalities of being at sea, for however short a period. “On a typical planing boat you have to sit there like a schoolboy in a church pew since the motions are so violent,” he says. “On my round-bilge designs you can sit and walk around casually and safely. You can get up and go to the bathroom, have a face-to-face conversation in normal conversational tones, cook a meal and so on while you’re cruising along. You’ll find life aboard to be much more livable, rather than sitting in a line like pigeons on a telephone wire.”
You can read Weiss’ design philosophy on his website, and I encourage you to look at all of the material to see for yourself whether his views are in consonance with your own boating priorities. I think he presents a coherent and compelling counter-argument to the 30-knot crowd. He correctly points out that we spend precious little time at 30 knots, anyway, so why carry all the extra iron and fuel to support it?
His sailing background permeates his thinking, with an emphasis on the helm area being open to the fresh air with soft curtains aft “so you can hear a fish splashing or gull crying” and a high enough position for passengers so they can see outside the boat when comfortably seated. “Owning a boat should not be an exercise in sensory deprivation,” he says.
We discussed the importance of “visual mass”— how the superstructure relates to the hull in terms of their relative position and size, and the overall proportions. The boat should not only look proportional, but it also should be sleek and purposeful. Windows play a big role in defining the look of a boat, and they can also be used to disguise height and exaggerate length, which is especially important in a smaller boat. Owners of 40-footers aren’t shorter than owners of 60-footers, so there has to be just as much headroom, the berths have to be just as long, and so on. However, the necessary height can be hard to conceal in a shorter hull.
Weiss is surprised at the lack of offerings in the semiplaning powerboat marketplace. “Fifteen knots is fast enough to get you places in a reasonable amount of time,” he says. “In many cases it is the optimum speed for offshore conditions, anyway, without being strapped into the helm seat.”
His larger boats have layouts that aren’t appreciably different from a center-cockpit sailboat, with a walk-in engine room below and an aft owner’s cabin separated from the rest of the interior. He correctly points out the fallacy of buying a lobster boat hull to convert to a yacht, thinking it will be economical to operate. A modern lobster boat is designed to carry weight and turn on a dime, not to cruise as efficiently as a 38 DayBoat at semiplaning speeds.
Weiss begins a new design by sketching out a sheer, stem profile and height, cabin sole heights, initial engine placement and other key elements by hand. Once the outlines are established he transfers the sketches to Rhino, develops the section shapes and waterlines, and from there the program will calculate the hull’s displacement and hydrostatics, including center of buoyancy and stability. Thus the hull envelope is defined, and this starts the design spiral.
The decks and superstructure are sketched with deck camber and pitch, cabin trunk tumblehome, windshield angles and other details worked out to his satisfaction, and forward the process goes. I can only imagine the thrill of starting a conversation about a new design with a couple of sketches on a napkin and ending up a year or two later with a custom boat sitting at the dock, shiny and jaunty, freshly launched and eager to put to sea.
See related article:
- A semiplaning take on efficiency
December 2012 issue