Ellis Downeast Semi-displacement Hull Design

Ellis 36 Lobster Boat

True Downeast boats trace their legendary performance to a long line of ocean-proven work boats dating all the way back to Friendship sloops and Muscongus Bay schooners. For generations, Maine fisherman have relied on these rugged boats to take them to sea, function as stable, dependable work platforms, and then bring them home safely, burdened with the trip’s catch — in weather that most of us wouldn’t venture out in, 12 months a year.

Downeast boats, in general, are sea-kindly and safe in all kinds of weather. Stability is inherent in a design that includes a skeg to protect the underbody, propeller, steering gear, and drive train. It’s simply a very comfortable ride.

When Maine fishermen began switching from sail to power, the Downeast hull configuration evolved from a true displacement hull to a longer, wider, semi-displacement hull. In this long transition from sail to power, the builders shortened up the keel slightly, but kept the long and narrow hull. It was an easily driven shape with excellent sea-keeping characteristics. In fact, the early boats, with a ratio of three feet of length to one foot of beam, could be driven to hull speed with just 3 hp.

Semi Displacement Hull

True Downeast hulls features a large keel, flat aft sections, and a fine entry, allowing them to slice cleanly and comfortably through the waves without significant loss of speed.

As engines became more readily available, and horsepower and displacement increased, the fisherman built their work boats with flatter aft sections to support the weight and bulk of the bigger engines, yet retained the boat’s traditional fine entry. The keel of the traditional Downeast hull is similar to a sailboat’s keel. Although it’s not ballasted, the keel performs two important functions: First, it helps steady the boat in a seaway, especially a beam sea, limiting side-to-side motion. More importantly, the keel and skeg serve to protect the vessel’s running gear in the case of accidental or deliberate groundings. The configuration allows lobstermen to come right up on a ledge at slow speed and ground–or “tunk” as it’s known on the waterfront–without damage.

V-Bottom Hull

Planing hulls tend to ride on top of the water at speeds where they pound in any kind of a sea. At slow speeds, forward visibility is restricted until the hull gets up on plane.

Today, with a single engine, Ellis boats can duplicate the performance of most deep-V boats with twin engines, but with single-engine efficiency and economy. The common hard chine or planing hull must utilize a great deal of power (with a corresponding leap in fuel consumption) to drive the boat up out of the water and onto a plane. Once on top of the water, the hull will pound and slap the waves, and has little lateral resistance to wave motion and, as a result, will pitch and roll, often lifting the props out of the water.

At slower speeds, these hulls point their bows high into the air reducing forward visibility to a dangerous level, and making for a very uncomfortable ride. In bad weather, then, the planing hull must either travel at a bone-jarring rate of speed to stay on plane (if the hull and crew can withstand the punishment) or reduce its speed to a crawl to maintain a relatively flat attitude.

Ellis 36 Lobster Boat in Downeast MaineThe Downeast semi-displacement hull behaves in an entirely different manner. The fine entry of the forward section slices through the waves cleanly and without pounding. It’s an exceptionally dry ride, with the flared bow effortlessly tossing aside the bow wave as the hull slips through the water without a fuss. The flat after section tends to squat slightly, keeping the propeller and rudder deep in the water for a solid bite and excellent steerage. At the same time, the full length skeg and keel resists side-to-side rocking, while helping the boat track effortlessly–even in a following sea. The Downeast hull, even in nasty chop and heavy swell conditions, can cruise comfortable all day long at 12 to 20 knots.

Today’s true Downeast hulls use horsepower to get them up beyond displacement speeds, and yet these boats are still true to the central issue of providing predictable stability. They are simply about as stable a platform as you could ever want–and that means stable at 8 knots, stable at 20 knots.

ChinesA more subtle aspect of the Downeast hull design are the soft chines (the gradual curve where bottom and sides meet). The sound of waves slapping against a hull can be surprisingly disruptive to those who sleep aboard. Soft chines eliminate the noise of waves against the hull entirely. Many of our customers find this single feature to be of real value when tied up to a mooring or alongside a dock.

Each Ellis hull is manufactured in our state of the art two-piece molds (with the exception of the Ellis 20, which is constructed in a single piece mold due to its more manageable size). These two pieces are hand-laid with stitched biaxial E-Glass and vinylester resin for superior strength and then fit together to form a one-piece hull while still in the mold. The center seam is filled with twelve layers of fiberglass which fuse the two halves together creating an extraordinarily strong keel. With the exception of the solid fiberglass keel and skeg, the hull is cored with vacuum bagged ATC Core-Cell® structural foam core to provide exceptional seaworthiness, impact resistance, sound deadening, strength to weight ratios and insulation properties.