‘Building’ the perfect powerboat
Posted on 24 February 2009
Written by Eric Sorensen
Page 2 of 2
Just as many boats today have too much deckhouse for the hull, they also try to cram too much into a 5-pound sack. My philosophy on accommodations is to avoid the temptation to cram too much into a limited space. Many boats have too many berths for their size, with the result that none of them are big enough to actually comfortably sleep an adult. With this in mind, my 46-footer would have a single stateroom forward with a 78-inch-long berth that’s 60 inches wide for the majority of its length. Overhead would be a big hatch to serve as an escape route in the event of fire or flooding aft. The stateroom has private access to a split head — the head and sink to one side and the shower on the other — and there would be access to the head from the main cabin as well.
The galley would be a few steps up at the companionway, which brings it closer to the pilothouse without intruding. It takes full advantage of the interior volume below the windshield, and its raised position creates extra storage space below. Also at the galley would be large windows to provide a good view from the sink. I would avoid some of today’s trends like the plague, such as those cute bowl-shaped sinks that toss their contents at you the first time you hit a wake.
Hand-holds would be liberally provided throughout the interior, and there would be no hard corners to get hurt on. Headroom in the cabin at the companionway would be 6 feet, 8 inches, same in the pilothouse. The companionway opening would be 24 inches wide and the stairs evenly spaced, with a gentle rise and run for safe and comfortable passage.
If you think of a sedan-style boat as being divided between forward, lower cabin, pilothouse and cockpit, the majority of my boat’s length would be given over to the pilothouse. That’s because I like sunlight and the cheery view through large windows. This would be balanced by a clearly conflicting goal to situate the helm station farther aft in the hull, where the ride is better. The pilothouse — or saloon, if you insist — would contain a pull-out bed for the occasional guest, along with a couple of inflatable mattresses stowed away for the grandchildren. A companion seat opposite the helm would be up nice and high so my co-pilot has just as good a view ahead as I do at the wheel. Besides being a thoughtful touch, this comes in especially handy when coming into an unfamiliar harbor and trying to pick out buoys or other aids to navigation.
The boat would have its primary helm station in the pilothouse and a second on the flybridge. The windows would have narrow mullions to minimize obstructions to horizon visibility, and the height of the deck at the wheel (along with the boat’s running trim and bow height) would be carefully engineered to provide an unbroken view of the horizon ahead, including when the boat is coming up on plane. Steering will be an effortless three turns from lock to lock for excellent responsiveness. Running lights would be up high where they can be spotted from vessels farther away.
Electronics flats, angled so they face toward the operator, would be close enough to reach without the contortions and stretching needed on most boats. The design would comfortably accommodate a seated or standing operator. The dash area under the windshield would be a dark, flat color to eliminate windshield glare, and the weather decks would be light gray or tan to minimize glare in sunlight. Depending on how the initial sketches worked out, I’d also consider having a Western-style, forward-sloping windshield, which give a big advantage in visibility ahead, especially when running at night. Red lighting would be provided to maintain night vision in the dark. An adjacent watertight door would provide quick access forward.
Access to the bridge is via open stairs from the cockpit. The bridge will be minimalist in size, in keeping with the boat’s beam, with seating for four. It would be situated well aft atop the pilothouse, since farther aft is where pitching motions are less pronounced. There’s no substitute for driving the boat from the bridge on a beautiful day or when you just want the added height of eye for improved visibility.
Seaworthiness and safety
The boat would be hard to sink, with compartmentation and use of foam creating positive buoyancy if the hull is breached in one area. The cockpit would be well above the waterline at full load, providing plenty of height for the diesel, along with a good measure of reserve buoyancy in the event of a boarding wave. Very large transom scuppers would be sized for — and the bottom of the transom door designed to supplement — rapid deck drainage.
Touching here on horsepower (underscoring how propulsion impacts seaworthiness), selecting a drivetrain according to the desired hull speed is an excellent starting point. But anyone who has spent much time in heavy weather (loosely defined here as when the seas are noticeably higher than the boat) knows that brute power can mean the difference between returning home unscathed and not.
If my boat needs 260 hp to achieve its optimum cruise and top speed, I might opt for an extra 25 percent margin, say 325 hp, so I have a better chance of being able to accelerate out of harm’s way or stay comfortably on the back of a wave running an inlet. As we’ve discussed elsewhere, speed definitely affects seaworthiness; it’s tough to dodge a breaking wave at 9 knots.
My boat would have a single common rail diesel, such as a 330-hp Volvo Penta D6 (think low noise, smoke and vibration), with a joystick controlling the engine, steering and thrusters for precise docking. A large, efficient, slow-turning propeller in a shallow pocket will be fitted to reduce shaft angle and overall draft and allow a larger prop.
If you’re wondering about pod power, the hydrodynamic drag of pod and sterndrive propulsion are not significantly lower than a well designed inboard at this boat’s cruise speed, so a well-designed inboard can be just as efficient. At 16 or 18 knots I would much prefer the traction of a large, slow-turning inboard prop; I’d just make sure the grounding skeg, shaft struts and rudder are carefully faired to minimize drag and propeller water flow disturbance. For a 25- or 30-knot cruise boat, pod power becomes a strong candidate for me.
A noisy boat is unpleasant to be on board, so acoustic insulation would be designed to keep noise levels to 74 dBA or less in the pilothouse when running at full power. This job is made easier because the common rail diesel is quieter and smoother-running than older technologies. With wave noise against the hull minimized by the cored construction, this will be one quiet boat at cruise — think sailboat quiet. A fixed fire extinguishing system would be installed, along with bilge alarms and an engine-driven emergency pump.
So there you have it — a quick sketch of my ideal boat. I might even become pleasantly irrational momentarily and have a varnished teak transom or natural teak washboards, since a little wood adds a lot of soul to a fiberglass boat. This boat will be easy to own, environmentally friendly and economical to operate, and safe and extraordinarily comfortable to be aboard, with a versatile layout and timeless beauty. See you offshore!
Eric Sorensen was founding director of the J.D. Power and Associates marine practice and is the author of “Sorensen’s Guide to Powerboats: How to Evaluate Design, Construction and Performance.” A longtime licensed captain, he can be reached at
This article originally appeared in the March 2009 issue.