The Smuggler Stealth is a true deep vee with 27 deg deadrise at the transom.
HOW DEEP DO YOU GO?
You’ve probably read “Its deep-V hull has a smooth, dry ride” a thousand times over in brochures and marketing materials. The biggest problem with this marketing-talk isn’t that this boat or that one isn’t particularly smooth nor very dry. No boat is perfectly so, and we have to look at these traits comparatively.
So, what exactly makes a hull a deep-V? Part of the reason why so many builders and brokers get away with selling everything from dinghies to dreadnaughts as deep-V boats is because most consumers don’t have a good handle on basic hull design. What’s worse is that while the term “deep-V” seems self-explanatory, it’s not.
Contrary to what those marketing folks may say, most boats are not deep-Vs, nor should they be. It’s ok to have a boat that is a modified-V or even a shallow-V, depending on the intended use and body of water where the boat will be used. Deep-Vs can roll at rest and lean over when underway. Flatter bottom boats are generally more stable at rest, and more likely to need less tab when running.
When describing just how much V-shape there is in a hull, which is called its “deadrise,” the most telling figure is found at the transom of the boat and is called “transom deadrise.” The greatest deadrise you will find there is 27-degrees, as in the case of the Smuggler Stealth and the Highfield 700 Series RIBs. But that is not often found. They are the deepest of the deep-Vs.
21 to 25-Degrees
Many more boats are designed with a 24-degree deadrise at the transom. Still, more are built with a transom deadrise angle of 21 or 22-deg. It is generally recognised that all boats from 21 to 25-degrees are deep-Vs. Bear in mind that deep hulls are generally harder to push. So, they are not as fuel-efficient and take more horsepower at certain speeds. At high speeds, if they are light, they may rise and reduce wetted surface to some degree, thus mitigating drag. They are also more trim-sensitive.
From 21-degrees down to 17-degrees are modified-Vs, but all of this is simply arbitrary dividing lines. Below 17-degrees at the transom, the boat is getting flatter at the stern, which is just fine and is desirable in many applications.
Many consumers think that the best boat to have is a deep-V, but that may or may not be true. It depends on the application.
HULL BASICS
Why should you care about all of this? Because the next time you’re shopping for a boat, you want to make sure you pick the best one for your purposes. A good understanding of the boat’s hull design will play a huge roll in just how satisfied you ultimately are. So, here’s a quick run-down on basic hull designs, and the deadrise you’ll find in each.
Flat bottom boats are incredibly stable, have low draft and excellent weight-bearing characteristics. They also plane easily and usually require less power than similarly-sized boats with V-hulls. It’s something you will find with a lot of the small alloy dinghies.
However, a flat bottom is not going to ride very smoothly. Flat bottoms provide about the bumpiest, wettest ride on the water.
Semi-V or Modified-V
Smaller trailerable cabin runabout boats from 5m to 6.5m fall into this category. A semi-V hull is one with some V in the hull, but not enough to qualify as a deep-V. Most range between 17 and 20-degrees of deadrise measured at the transom, though there are some boats out there with less deadrise which could still accurately be called semi-Vs.
These are middle-of-the-road hulls. They aren’t the smoothest nor are they the bumpiest. They aren’t the driest nor are they the wettest. They aren’t the most stable nor are they the least stable. They are almost always more fuel-efficient than the deep-V hulls and they are more comfortable than boats with a deadrise angle at the transom from say 16-degrees to 10-degrees.
By focusing on the in-between, semi-V hulls are generally designed for certain bodies of water or certain boat types and sizes. They may be a compromise, but they may also be the best hull shape for the application. Their builders think they are.
Variable-Degree Deadrise
Summary
When shopping for boats, consumers should ask the sales people the deadrise angles for the bow, amidships sections and at the transom for any boat being seriously considered. Then, they should consider the sea, lake or river conditions where they will be boating, and finally the kind of boating they will be doing. Any one of the hull shapes might be best for the intended application.
