Complete Guide to Boat Hull Types

Understanding different hull types is crucial for selecting the right boat for your intended use. Each hull design offers unique characteristics, advantages, and limitations that affect performance, efficiency, and handling in various conditions.

2. Planing Hulls

How They Work: However, as they gain speed, they lift toward the surface of the water, riding nearly on top with only a portion of the hull submerged. They behave like displacement hulls at low speed but pop up onto a plane usually around 15-16 MPH depending on the design and load.

Characteristics:

• Require significant power to achieve and maintain planing speed
• Can achieve high speeds by ‘skimming’ across the water surface
• More fuel consumption than displacement hulls
• Planes quickly/easily. Harder impacts can be experienced due to the fast moving nature of these crafts but shock can be mitigated by means of (1) good hull design and (2) shock mitigation seating and/or deck systems

Best Uses:

• Sports boats and performance powerboats
• Water sports activities
• Fishing vessels requiring speed to reach fishing grounds
• Day cruising powerboats where speed is important

Example: Technohull Omega 47. One of the finest planing hulls in the world, capable of speeds in excess of 80 knots.

Advantages:

• High speed capability
• Quick acceleration
• Exciting performance
• Creates high performance and lower fuel consumption in smaller craft

Disadvantages:

• Bigger horsepower fuel consumption in larger models
• Rougher ride in choppy conditions
• Requires more powerful engines

3. Semi-Displacement Hulls

How They Work: Some boats combine features of both displacement and planing hulls, known as semi-displacement hulls. These vessels are nearly as fuel-efficient at low speeds as displacement hulls while being capable of achieving higher speeds than their full displacement counterparts.

Characteristics:

• Combine rounded sections for storage with flatter sections for partial lift
• Semi-displacement hulls combine rounded sections for increased storage and tankage, and flatter hull sections to partially lift the forward part of the hull out of the water
• More efficient than pure planing hulls at cruise speeds

Best Uses:

• Larger cruising motor yachts
• Powerboats requiring both efficiency and moderate speed
• Long-range motor cruising with occasional higher speeds

Example: Nimbus 495 Flybridge – award-winning design specifically created for low fuel consumption and efficient long-distance exploration, representing the explorer segment.

Advantages:

• Good compromise between speed and efficiency
• Reasonable fuel economy
• Comfortable ride
• Good internal volume

Disadvantages:

• May require high horsepower to achieve maximum potential
• Can generate large bow and stern waves

Medium-V Hulls

Design: A yacht hull design that falls between a flat-bottomed hull (shallow vee) and a deep vee hull in terms of its V-shape angle or deadrise. There isn’t a precise standard for what constitutes a “medium” vee, although typically it refers to a deadrise angle ranging from approximately 15 to 20 degrees.

Characteristics:

• Balance between stability and wave-handling capability
• Suited to watersports activities 
• Reasonable rough water performance

Best Uses:

• Runabouts and day boats
• Smaller fishing powerboats
• Family recreational powerboats
• Ski boats and watersport craft

Example: Axopar 22. Winner of the Best of Boats 2021, ‘Best for Beginners’ category. Excellent example of an intuitively designed family day boat.

Advantages:

• Good compromise design
• Reasonable rough water handling
• More space than deep-V
• Versatile performance

Disadvantages:

• Not as capable in rough head seas as deep-vee hull
• Harder ridging in a chop

Stepped Hulls

How They Work: What the steps do is to break the customary single long hull surface into smaller sections (almost invariably three sections, using two steps) by channelling air into the steps. In place of a single long hull surface, which is generally about three times as long as it is wide, a twin-stepped hull forms three smaller lifting surfaces that are almost twice as wide as they are long.

Performance Benefits:

• Improved fuel efficiency and a higher top speed are the well-known headline benefits. To those gains we can add a more level ride, better forward visibility, less pitching, reduced slamming and typically less spray
• Typically, though, the builders I talked to said potentially up to 15% if it’s the former, and down to around 7% if it’s exclusively the latter. However, anecdotal evidence and our testing suggest that few boats stray far from a figure of 10% efficiency improvement

Ride Quality:

• At speed, driving through waves, stepped-hull boats invariably pitch and porpoise far less; their ride is more resolute, consequently they invariably slam less
• With more lift aft, they ride more level, so forward visibility is improved

Best Uses:

• High-performance powerboats
• Motor vessels requiring fuel efficiency at speed
• Applications where ride quality is important
• Racing and sports powerboats

Example: Scorpion Serket 90ST – Twin-stepped design demonstrating the efficiency gains possible with stepped hulls. Highly revered hull design, winner of countless offshore titles.

Advantages:

• Potentially up to 10-15% better fuel efficiency
• Superior ride quality
• Reduced pitching and slamming
• Better forward visibility
• Higher top speeds possible

Disadvantages:

• More complex to design and build
• Some designs can be more challenging to handle. Driving skills and knowledge need to be acquired for safe and effective boat handling
• Vee hulls with stepped bottoms can add driving complexity. Steps can present a ‘trip edge’ during some manoeuvres that change the bottom loading