A Visual Guide to Hull Types (With Real Examples)

It's that season: everyone's out getting their boating licenses (or their new boats), and understanding the basics, like hull shapes and why they look the way they do, can keep a new boater from making mistakes — from landing in the water to wondering if another hull might've been a better fit.

In general, there are four types, and each has its own strengths and weaknesses:

FLAT-BOTTOM

Flat hulls are best in shallow, calm water, and you can commonly find them on fishing boats, skiffs, and other small vessels not intended for choppy conditions or the open sea. Their chief strength is their ability to maneuver in shallow areas like creeks, canals, and lagoons — hence their use for fishing — but their mortal enemy is waves, since they rarely have built-in stabilizing features.

V-SHAPE

V-shape hulls are just what they sound like — though in modern shipbuilding, many of them have v-shaped hulls that transition into flat sterns, which is sometimes called semiplaning or fast displacement. Speedboats, fishing boats designed for bays or near-shore waters, and many larger yachts, including superyachts, make use of v-shaped or semi-v hulls. They're a useful compromise between the planing ability of a flat hull and the wave-cutting ability of a deeper hull, and their greatest strength is typically speed. They're not intended for rough seas, however, where they risk losing stability if pushed too hard, and even smaller waves can cause an effect called slamming, where the bow of the boat becomes temporarily airborne, and the landing impact can be harsh.

The Pershing 70 is a great example of a semiplaning v-hull built for performance — note the pointed bow and the flat, wider stern.

ROUND-BOTTOM

A round-bottom hull is most common in very small vessels, like dinghies and canoes, and in sailboats. Round-bottom hulls are also called displacement hulls — that is, they don't plane, or sail on top of the water; much of the hull is below the waterline. In sailboats, their primary strength is resilience in most seas: because of their weight ratio and buoyancy-promoting shape, a sailboat with a heavy enough keel can right itself even if its mast is in the water (!), making them ideal choices for bluewater cruising and ocean-crossing (or globe-circumnavigating, which is on many a bucket list). Their added safety has two drawbacks, however: the first is typically slow speeds of perhaps 6 knots per hour (sail power doesn't quite measure up to multiple diesel engines), and the second is instability: sailboats are rarely completely upright at all times, and anyone aboard should always be ready to grab onto something (one hand on the ship and one hand for yourself, as the saying goes).

Although this Pegasus 50 has a pointed bow, note the shape of the stern to see the typical sailboat rounded hull.

MULTI-HULL

A "multi-hull" can refer to two types: a catamaran, which has two hulls, or a trimaran, which has three. The classic pontoon party boat is technically a multihull, but modern multihulls are larger, have more living space, may be sail-, solar-, or gas-powered, and are becoming increasingly popular for cruising. Their chief strengths are an abundance of space and stability, with trimarans being even more stable than catamarans; their weaknesses are rough waters — catamarans especially have very little self-righting ability, and should not be taken through rough waves — and a slowness to turn, especially when weighed down.

Below, the Leopard 53 shows both the hull shape (note the water in the center) and the amount of space the shape provides — enough to store a tender. On the right, the Dragonfly 40 shows the increased stability of the trimaran in waves, with one outrigger keeping the boat from heeling too far over.

Whether you're getting ready for a license exam or deciding what's right for your boating style, I hope this guide was helpful! Stay tuned for more boating basics in the future. ⛵︎