If you’re looking into buying a boat, you may be overwhelmed by the number of hull shapes and designs available. The shape of your hull will affect a great many aspects of your boating experience, from speed, comfort and maneuverability to storage and deck space. It’s important to carefully consider what you want from your boat before moving forward with your purchase.
Once you’ve figured out what your needs are, you’ll have to determine which type of boat hull will suit you best. Fortunately, Drive a Boat Canada is here to help! Find out about the pros and cons of every hull shape and design in this article.
Displacement hulls lie in the water and displace it when moving. This generates a lot of resistance, so boats with displacement hulls tend to be slower. Water resistance increases as the speed increases, creating a kind of built-in speed limit called hull speed or displacement speed.
Displacement hulls tend to have a deep draft. That means that more of the boat’s hull is in the water, which makes it easier to handle in waves and rough conditions. Most sailboats, cruisers and cargo ships that need to cross oceans have displacement hulls for this reason.
Most displacement hulls are designed with round bottoms because the rounded shape offers the least resistance and displaces water most efficiently. Round-bottom hulls provide a very smooth, comfortable ride. Their major drawback is instability—boats with round bottoms are prone to rocking and capsizing. A deep keel (often found on sailboats) can help improve stability.
Planing hulls are usually found on smaller, lighter boats that are built for speed. Planing hulls displace water when moving slowly, but as they go faster, the shape of the hull and the speed work together to generate lift, bringing the boat right out of the water so that it skims over the surface.
Boats with planing hulls can move much faster than those that displace water, but they make for a bumpier ride and are more easily affected by gusts of wind.
Flat-bottom hulls are designed to sit on top of the water and displace very little while underway. Boats with flat bottoms can go quite fast because of the lack of resistance, but if the water is choppy at all, the hull will pound against each wave, making for a very uncomfortable ride. Flat-bottom boats are quite stable in that they won’t rock or capsize, but the wind can easily blow them off course due to their extremely shallow draft.
Flat-bottom boats tend to be less expensive to build and require less power to operate because they don’t need lift to skim over the surface of the water. The flat bottom also maximizes space inside the boat. However, it’s best to use them on calm, inland waters, because they can be uncomfortable and unwieldy in more challenging conditions.
V-shaped hulls are designed to provide a smoother ride in rough water than flat-bottom boats, but it takes more power for them to reach the same speed.
This type of hull has a deep V-shape that runs all the way from the bow to the stern. The shape of the hull acts like a small keel, providing the boat with more stability and maneuverability than a flat bottom while maintaining very fast speeds. Unfortunately, the sharp angle of the hull results in less interior space for storage, boat safety equipment and accommodations.
Modified V hulls have a flat bottom at the stern that gradually transitions to a V shape towards the bow. The flat stern provides speed and stability while the V-shaped bow improves maneuverability. This type of boat hull is the ultimate compromise—it has a little of everything but doesn’t truly excel in any category.
Multi-hulls are boats with two or three separate hulls. They tend to be very wide, which increases stability and provides extra deck space but makes them less maneuverable.
Catamarans have two hulls with a deck stretching between them. While they are displacement hulls, they have a very shallow draft, meaning that not much of the boat is actually in the water. This makes them a great choice for navigating shallow waters and reefs.
The main drawback with catamarans is their width, which gives them a very wide turning radius and makes them very costly to moor at marinas.
There are two types of trimarans. One is similar to a catamaran, just with three hulls instead of two. The other, often called a folding trimaran, has one main displacement hull with two floats or pontoons, one on each side.
As its name suggests, the main advantage of a folding trimaran is that the floats or pontoons can be folded away when mooring or transporting the boat.
Pontoons are airtight, hollow floats that are extremely buoyant. Pontoon boats generally consist of a wide deck mounted on two or more pontoons. These are planing multihulls that float on top of the water. They are very stable, but tend to be slow and lack maneuverability.
When buying a boat, you need to consider the kinds of waterways you want to boat on and your requirements in terms of space, speed and comfort, and select your hull accordingly. Powerful motorboats with deep-V hulls and multihull pontoon boats aren’t made for the same kind of boating!
In Canada, boaters are required to take a boating safety course and pass an exam in order to operate a vessel, so before you can get out on the water, you’ll need to obtain a pleasure craft operator card. Go to Drive a Boat Canada today to get your official Canadian boating license online.