The Hull Story

When’s the last time you thought about hull innovation? Now’s the time.

Many people who buy a boat focus on the amenities and features, such as the layout of the deck and helm, the type of propulsion system, and even how many speakers and cupholders it may have. One area that is often overlooked, despite being more critical than any other, is the hull. I don’t mean the above-the-water portion that will feature the buyer’s favorite color or graphic signature. I’m talking about the below-sea-level section, the wetted surface, the part that interacts with the H2O.

Hull types vary by shape, displacement, construction and other attributes. Just like boats are designed for different uses, so are — and should be — hull configurations, for bass and flats boats, bowriders and cruisers, center consoles and ski/wakeboard boats, and jet- and pontoon boats. Let’s see what makes the hull so interesting.


Build It Right

Hull construction may vary from process to process, but for the range of boats discussed, the material of choice is fiberglass. Sure, pontoons are made of aluminum, and that’s great, especially since additions or changes to the pontoon just require some welding. And wood in most cases has gone away. Fiberglass is a durable and lightweight material. Mixed with the proper amount of resin, the combination bonds to create a hard laminate, suitable for pounding the waves.

The layup of a fiberglass hull is critical to the desired results. With fiberglass, woven glass-fiber sheets or mats are laid up in a jig or mold, usually on the previously applied gelcoat or outer surface. Mats are laid out at 45-degree angles for improved strength, with additional mats used at points of higher stress and through-hull fittings. Resin is rolled into or drawn through the matting to create the hull structure. Stringers are added for increased rigidity and mounting points.
Chopped-strand construction includes short pieces of fibers sprayed onto a hull mold through a gun that includes resin. It’s not as strong as matting in general, but it is equally strong in all directions.


Boat Types

Jet Boats

Yamaha 242 Limited S
Jet boats are unique in that they can offer a modified V forward and a shallow draft but need to flatten out aft. Why? Because the jet drive sucks water in through an opening on the bottom of the boat, and that intake needs to be in contact with the water all (or most) of the time. The hull does offer speed thanks to the flat surface and is perfect for beaching.


Pontoon Boats

Larson Escape
Many pontoon builders make their pontoons with V fore sections for wave slicing, as well as with strakes and spray knockdown rails. Pontoons are typically made of aluminum for durability and ease of repair, but more importantly, aluminum is non-corrosive. Also made of steel, older pontoon boats are usually less expensive to build but susceptible to corrosion.


Bass & Flats

Nitro Z-18
“Bass is for glass” is what I say. Built for chasing fish in a flat to light chop and likely in skinny water, flat-profile or bass boats are basic fishing platforms. The draw is that they can be fast, with up to a 300 hp outboard engine, to get out and back in a hurry. The hull surface is fairly flat, with a small V for cutting the chop and strakes to lift it out of the water, adding to the speed factor. They are not built for open-ocean or rough conditions.


Bowriders & Cruisers

Glastron GTS225
With modified-V hulls, bowriders and cruisers try to offer the best in many aspects, such as efficiency, handling, speed, comfort and seakeeping ability. A modified-V hull will have hard chines, strakes and usually a shallower deadrise than a deep V, which make them suitable for cruising and even fishing.


Center Consoles

Regulator 31
With a pronounced sharp entry forward, significant deadrise carried aft and longitudinal strakes to provide lift, these boats are designed to run fast. When getting to the fishing grounds and back is important, such as during a tournament, a deep-V hull can make the difference between placing or going home empty. The deep V allows for better tracking in choppy waters, slicing through the waves and maintaining speed as conditions change.


Ski/Wakeboard Boats

Super Air Nautique G23
For skiers and wakeboarders, it’s all about the wake size, as in height and width, and that is a product of the hull and/or tabs. Many entries in today’s market offer systems that can vary the size of the wake, to attract wakeboarders and skiers alike. These are purpose-built boats, to create large wakes in inland lakes or coastal waters.

Strakes and other appendages on a hull have to be built into the hull mold, so the entire hull component is formed together for maximum strength. It is near-impossible to add strakes or knock-downs to a fiberglass hull after it has been produced.


Feature Presentation

Today’s hulls include many features that are designed to help a boat run more efficiently and safely.

A stepped hull is a hull that has an aft-angled channel or vent in the hull, dividing the running surface and allowing a cushion of air under the running surface. Benefits are improved efficiency and boosted speed on the higher end.

Double or twin stepped hulls are hulls with two channels in the hull, adding more efficiency as the hull lifts out of the water (water is a drag component) and reducing the amount of running surface in contact with the water.

The Z stepped hull is a product of SeaVee Boats. It’s a cross-ventilated hull with twin steps, coupled with SpeedRails (lifting rails).

Reverse chines take the edge of the chine and turn it downward, offering improved stability, a better “bite” of the water and a drier ride.

Keels — even on mid-20-footers — improve straight-line tracking, help to reduce rolling and can protect running gear.

From The Builders

Tigé Boats specializes in wakeboarding boats, with innovation at the heart of what it does. The patented Convex V hull curves up toward the transom, working the flow of water out and up from the transom to generate a surfable wake. Taking the laws of physics and the properties of the Coanda Effect — where a fluid jet stays attached to a convex surface, basically the water trail following the shape of the hull — Tigé adds in its TAPS 3 system, which is a series of three trim tabs (two outboard and one center tab) adjusted independently to help the Convex V hull attain maximum wake style by adjusting the list, yaw and draw of the hull.

Wave riding is about riding the wake behind a boat, and Nautique Boats is another builder that excels in this space. The Nautique Surf System (NSS) allows users to dial in customizable waves on demand. Nautique’s custom system of six set points on the Waveplate and Nautique Configurable Running Surface results in 36 combinations of height, shape and length of the trailing wave.

Tigé and Nautique have unique systems that dynamically change the running surface of the hull, delivering wake options for wakeboarding and skiing.

Pontoon Envy

Pontoon boats have come a long way, and Sylvan knows a thing or two, having been in the business since 1948. Its RPT tubes (Revolutionary Planing Technology) are structured with a V nose and running surface along the bottom, allowing for sharper entry, more lift and improved fuel efficiency over round pontoon tubes.

Sure it builds sport- and fishing boats, but did you know Larson Boats also builds pontoons? With its TTT (Tapered Tube Technology), each pontoon acts like a wave-piercing hull, thanks to the V nosecone. Added to each tube are keels and reverse chines.

Not to be Forgotten

Catamaran-style boats are a unique breed. With twin hulls, they offer more stability than standard hulls. One builder, Larry Graf of Aspen Power Catamarans, has been building dual-hulled crafts for 30 years, but Aspen takes innovation to another level. Its cats have one engine, not two. Placing the powerplant in the starboard hull and making the port hull 35 percent thinner, Aspen’s patented Power Proa Hull and drive system allow for the asymmetrical shaping of the hulls to offset thrust and torque, creating a straight-running vessel. And with fewer appendages in the water, drag is reduced and efficiencies are increased.

Hull design plays a very important part of the boating lifestyle. Buyers need to know what’s happening below in order to boat the way they want. A flat hull isn’t good for wakeboarding, and a displacement hull may not offer the speed one needs.


Understanding Hull Shapes

Generically, we know hulls should have a V-profile, for the most part, which starts sharp in the bow and flattens toward the stern. That does change with the intended use, desired comfort level and need for speed. There are some terms everyone should know up front.

Displacement hull

Displacement hull

  • Pushes water ahead
  • Hull likely rounded
  • Limited in speed

Planing hull

Planing hull

  • Pushes water, or plows, at slower speeds
  • Rises up and rides on top of water as power is increased
  • Usually V or flat-bottom boats

Deep V

Deep V

  • Sharp bow entry
  • Sharp V carried aft
  • Smooth ride in rough water
  • Fast design but may be unstable at rest

Modified V

Modified V

  • Sharp but broad bow entry (offering more interior space)
  • Flattens a bit aft
  • Not as much rocking as deep V Pontoons
  • Flat-deck boat supported by pontoons, or sealed tubes

Pontoons

Pontoons

  • Flat-deck boat supported by pontoons, or sealed tubes

Chine

Chine

  • The edge that turns up from the hull bottom to hull side
  • Can be wide or narrow, hard (right angle) or soft (rounded)

Strake

Strake

  • Hull-length (or partial) rails that provide lift and increased speed for planing hulls
  • Help to knock down spray and improve cornering

Deadrise

Deadrise

  • Amount of V angle in the bottom of the hull, typically measured at the transom
  • The larger the deadrise angle, the more V in the hull

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