Planing Hulls

Planing Hulls Can Perform Better at Every Speed

Many boaters grew up around planing hulls—after all, this is the design used on skiffs and outboard-powered runabouts that many of us used to discover our lifelong passion for boating and the fun of being on the water. Planing hulls are the most efficient way to go faster on the water: Once they reach a certain speed determined by hull shape, they hop up out of the water—or climb out of the hole—and ride on the surface. Because the hull is on the surface of the water, less of the hull actually touches the water, so there’s less friction to overcome with horsepower and fuel burn.

It’s this combination of speed and efficiency that inspired the team at Summit Motoryachts to design a planing hull for a cruising yacht. While performance is a key factor in these yachts, it’s not the only consideration: We knew our buyers would expect a certain level of robust construction, smart use of interior space with plenty of stowage, a fine interior finish, and plenty of proven equipment.

The Most Efficient Hull Design?

All of these features and benefits are accommodated with good hull design. “You want to get up on plane without going through a great transition between displacement and planing,” says Michael Peters, of Michael Peters Yacht Design, the firm that designs all Summit Motoryachts, widely considered to be the industry leader in all aspects of yacht design. “What we try to do is create a hull that goes through that transition zone without much fuss.” The result is a hull without a perceptible hole or hump.

This is the issue with many planing hulls on the market today. They have a noticeable transition zone, where the bow points to the sky and the stern drops as the boat tries to get over the hump. At this point, the boat is burning more fuel, the engines are working harder, the boat handles poorly, and the ride is uncomfortable. As a result these boats have a zone of speeds in their acceleration curve—usually in the area of 12 to 18 knots—that the driver learns is best to avoid. Not so with our hull. “You can cruise really any speed that you want, you don’t have to avoid sort of a 12- to 18-knot range because the boat is, you know, a pig at that point,” Peters says. “We concentrate on hull shape so that it’s narrow enough not to suffer going through that zone.

The Fastest Hull Design Can Be the Most Comfortable

There are other considerations as well. Since all Summit Motoryachts are designed to cruise comfortably, our design makes certain accommodations, while still maintaining the benefits of a planing hull. Speed and efficiency are goals, but at what cost? “Many planing hulls maximize efficiency with flatter aft sections, but sometimes it can be an absolute terror in a following sea,” Peters says. “I’ve always concentrated on making sure that a boat handled well in those kind of conditions. While a head sea is hard on a yacht’s crew, but the following sea is so dangerous due to broaching.”

For those who have never been through a boat broaching in a following sea, it occurs when seas approach the boat from the stern, and because of the hull design, the stern lifts as the wave passes beneath the transom, pushing the bow into the water, or “stuffing the bow.” Since the boat can’t readily move forward, it slews sideways to the seas, where it is in danger of taking a sea over the rail or swamping. There are two design features of a hull that can help reduce the chance of a broach: a bow that is less “sharp” and offers more flotation, and a stern that has more deadrise or V-shape to it. “Summit hulls are designed to have enough deadrise that they tracks well, and don’t want to get away from you in a following sea,” Peters says. “

Beyond hull form, another feature that Peters uses in the Summit designs is weight management and balance. “We try to keep the weight right on the boat—don’t let it get too heavy,” he says. “Weight and balance is everything. If you have a boat that is balanced too far forward it will help you at lower speeds, but it can be a real handful in a follow sea. And if you have the weight too far aft, it will make you suffer in the transition zone, where it wants to point skyward before it drops onto plane. Getting the balance right is where we always start.”

“Once we understand the basic layout of the boat, we draw the hull and then we force it to balance properly,” Peters says. “We don’t modify the hull to improper balance, we modify everything else so that it can balance properly.” It sounds like a no-brainer, but Peters point is well taken. Other builders seem to be intent on adding features and amenities that modify the balance of a hull, and cajole their designers into accommodating them.

A Word on Working with Michael Peters Yacht Design

As the longtime builders of pure-full-displacement Kadey-Krogen bluewater trawlers, we understand the importance of comfort at sea, and we understand how good hull design and indeed good overall yacht design can set a yacht and indeed an entire brand apart from the rest of the market. So when we set out to launch Summit Motoryachts, we wanted to build a faster yacht that would be comfortable, efficient, good-looking, and well built. We called the best in the business to give us the yacht hull design and indeed the entire design to set ourselves apart right out of the gate. Michael Peters Yacht Design delivered. As Steve Jobs said famously, “It doesn’t make sense to hire smart people and tell them what to do; we hire smart people so they can tell us what to do.”