Trawler Evolution

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The word “trawler” doesn’t have the same meaning it did 20 years ago.

Just a few decades ago, if you said you owned a trawler, I’d have a pretty clear idea about what it was you shoved off in. It might well be a converted fishing boat or a civilian, gussied-up version of one produced by the same builder in slack times. Its displacement hull would slip along, depending on its length, at somewhere between jogging speed and a brisk run. It would have a single, heavyweight, slow-turning, derated diesel that you could count on running perhaps 10,000 hours between major overhauls.

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Its refrigerator-sized fuel tanks would deliver a range of well more than 1,000 miles. It would be either an Eastern rig (pilothouse aft) or Western rig (you guessed it, pilothouse forward) design. And it would very likely sport a pair of paravanes dangling from 20- to 30-foot steel outriggers, ready to splash and hold you steady once past the jetties.

The windows would be small, 1/2-inch thick and pretty much impervious to wave impact; larger windows had storm shutters at the ready. The boat’s high freeboard forward and oversize deck freeing ports, and the small superstructure’s low topside weight and sail area all maximized seaworthiness.

Today, if you were to tell me you own a trawler, I wouldn’t have the foggiest idea what it is you actually go to sea aboard. The market category has broadened widely, and the word “trawler” doesn’t have the same meaning it did 20 years ago. The reason is that both builders and marketers have figured out that “trawler” connotes ruggedness, seaworthiness and reliability, and, perhaps more to the point, suggests good judgment and even a sort of derivative reliability on the part of its owner.

For better or worse, depending on your preference or prejudice, a trawler today can be almost anything a builder, marketing company or, in the end, you, the boat owner, want it to be. The trawler fleet includes everything from the original, authentic oceangoing displacement vessel to a full planing hull with a large deckhouse and sunroom-sized windows letting in boatloads of glorious sunlight.

There are several other examples of this “evolution” outside the trawler world. For instance, there are plenty of hard-chine, planing “Maine-style” boats that bear little resemblance (other than topsides styling) to an authentic round-bilge, semidisplacement Down East hull you’d find swinging on a mooring in Southwest Harbor. Different strokes for different folks — and different capabilities, too.

If you’re in the market for a trawler, you need to consider the limitations and capabilities of the various types. Here’s a start.

Evolution of the breed

There still are the originals — call them the denizens of the deep — out there. They will run along with very little horsepower, sipping fuel and moving as fast as an open-ocean wave of the same length (and no faster). By the way, that comes out to about 1.34 times the square root of their waterline length. So if you take a boat that is 36 feet on the waterline, it will run along on very little horsepower (around 40 hp) at 8 knots; a 49-foot-waterline boat would make about 9.4 knots on not much more horsepower, and so on.

These hulls are slack-bilged, which minimizes wave-making resistance at displacement speeds. And they’re deep in the water, with a very low center of gravity, which gives them a high range of positive stability — often more than 70 degrees and sometimes past 90. They’re tender through the first 15 or 20 degrees of roll, which is why they need to be stabilized, but that’s when they start picking up righting arm. Make no mistake about it: These are the safest boats to be aboard when you’re out in the middle of nowhere in a blow — say 500 miles off the Azores.

But these slow, full-displacement boats evolved to suit the demands of boaters who got tired of running along at 6 or 7 knots, waiting forever to get anywhere. To satisfy the demand, some builders that were already making hard-chine fiberglass semidisplacement trawlers just started adding more power, which turned boats that ran really well at 8 or 9 knots into wet fuel hogs that could make 15 or 16 knots down sea. (Note that a hard-chine bottom is still a displacement hull if the buttocks sweep up abruptly aft, preventing planing.) The only problems were frequent trips to the gas docks and wearing out wiper blades every other trip.

Eventually, builders started developing real planing hulls with entries, chines and flatter buttocks to help them run reasonably dry and comparatively efficiently (to other planing hulls). Weight was never a consideration, but since it’s the single biggest element driving planing hull fuel consumption, builders started paying a little more attention to this detail, as well. The result today is a crop of “trawler” yachts that will run along at 20 knots or more, with large deckhouses to accommodate all the trimmings.

Today

This decidedly brief history brings us to the present, which, by the way, includes quite a few twin-engine trawler offerings. Some diehards have a hard time putting “twin-screw” and “trawler” in the same sentence, unless it’s to say they don’t belong together, but I’ve long since capitulated on this point. Twins are popular now in some circles because people tend to value propulsion redundancy over range and efficiency, even though a single derated diesel with clean fuel will run without a burp for years without shutting down, except for the occasional oil change.

Twins also make docking a lot easier, though it’s a shame people won’t take the time to learn how to drive a full-keel, single-screw boat with a big, slow-turning tractor prop. They’re surprisingly easy to drive and predictable (due mostly to their draft) around the marina once you get the hang of it, even without a bow thruster. Personally, I’d much rather be graded backing a single-screw 65-foot dragger into a slip in a cross wind than a 20-foot outboard.

Planing trawlers usually have twin diesels, and like any planing hull, they can run as fast as their horsepower will push them — there are no wave-length restrictions here. The problem is that a planing hull, though much more efficient once up on plane, burns more fuel at displacement speed, since those hard chines create more form drag. And while they have a good deal more form stability, they could capsize in very rough water — conditions in which the displacement hull is still picking up righting energy. So you’re not likely to find a planing hull crossing oceans, even at 6 or 7 knots, unless maybe it is a very large planing hull with tons of fuel capacity.

Semidisplacement hulls are, as you might have guessed, right in the middle. They’re less efficient at displacement speed than a full displacement trawler, but they can get up and plane at 14 to 20 knots, or thereabouts. That’s because they have flatter buttocks along the aft half of the hull, which develops dynamic lift provided by water-flow pressure. At cruise speed, they’re partly supported by buoyancy and partly by dynamic lift, which is where the “semi” in semidisplacement comes from.

Note that if you want a really seaworthy boat, you will need to find one built with a long, moderate-beam hull, deep draft, and a small, low superstructure. But with considerably less volume for their length, these trawlers don’t sell, so they’re not offered as production boats.

Conclusions

There’s something out here for everyone. Displacement trawlers for world travelers who enjoy the journey as much as getting there, planing boats for coastal cruisers and goal-oriented Type As, and semidisplacement boats for those who want to be able to throttle back and go far, or speed up and get someplace close quickly when needed.

These are just a few features to look for, as picking a boat, especially a larger one, involves lots of compromise and insight. In the meantime, there are plenty of trawlers to choose from these days, so enjoy the hunt.