See full version: Boat Buying Tips: What Hull Shape is Best
Having said that, we occasionally come across boats that are designed to go 30 knots in coastal work which are a little too full forward, or ones that have a wide chine taken to the stem, and they tend to pound in those conditions. In these cases, bow shape is more important than the deadrise at the transom.
One variable that's easy to see, and one the buyer should consider before choosing one boat over the others, is deadrise -- a most important factor in the bottom design. Deadrise is the angle of the bottom sections relative to a horizontal baseline at the keel -- in other words, it's how sharp the V is. more
Until the post-World War II years, most planing-boat bottoms were flat, or nearly so, in the after sections. This is great for speed -- flat-bottoms are fast -- but make for a bone-shattering ride in rough water. After studying the research of naval architect Lindsay Lord, and experimenting with many bottom shapes, designer C. Raymond Hunt developed the "prismatic" hull, with a constant 23.5 degrees of deadrise from amidships to the transom. more
Describing a hull as "planing" or "displacement" isn't really accurate in the first place. Hulls operate in displacement or planing modes, determined by their speed vs. waterline length. That's the speed/length ratio, calculated by dividing the speed in knots by the square root of the waterline length.
Planing boats with angular bottoms can run 50 or 60 knots or more, depending on how much horsepower is available, but are less efficient at low speed. Who cares? For these boats, and for their buyers, it's all about speed.
Offshore fishermen who go out in all weather, high-performance speed freaks, and others who want to go as fast as possible as often as possible should choose a deep-V. Since they don’t care about fuel consumption or anchoring out and rolling, they should preserve their back bones and go deep-V. [links]
HYDROPLANES
Hydroplanes come in both full body hulls as well as outrigger hulls. Here we will touch on the major differences between them.
Let us start with the body of water you will be running on. Most racers like myself tend to stay away from free flowing or very large bodies of water, but with the proper hull, speed and power system one can run their boat quite confidently on large bodies of water. Large bodies of water can build large swells and upset the fun you could be having with your boat. The ideal body of water is one that is protected from winds as well as having a good area from which to launch and retrieve your boat safely. It is extremely important that when running your boat, swimmers and full-scale boats are not in the immediate running area.
TO SUM IT UP
Hydroplanes: Although the fastest hull design, they are limited to smooth water and only turn well one direction. [links]
CATAMARANS
Most RC catamaran hulls are based on the looks of full-scale catamarans. Performance is no less spectacular as they too can reach great speeds. Cats, like hydros, are also air suspended hulls, but the main difference is the length of the sponsons. The sponsons on a cat run the full length of the boat. As the boat races across the water, air is trapped and passes under the center of the hull. The faster the boat goes the more air it packs. As we learned with hydros, the cat too is susceptible to blow overs, but will run in slightly rougher water than a hydro. Catamaran hulls turn very aggressively and do so quite well both right and left. Catamarans are a good choice for sport running and are also a great choice for racing in some of the offshore lasses around the country. here
Before we dive into the world of hulls, let’s get a few things straight.
Now I mentioned that canoes are typically round hull, but depending on the degree of curve, the width of the body and so on, it can morph itself into more of a planing hull design. The same is true for kayaks. When researching kayaks, I found that they can be obtained in basically 4 hull designs, only one of which fits into this rounded hull category. here
“The friction resistance of the water on the hull of a moving ship, one of the functions that are used to determine the ship’s potential speed.”
The two appendages you see running fore and aft on this hull are strakes. more
There is one truism here: no boat design does everything well. In some cases, you may want to sacrifice stability for speed or vice versa. Weight may be a prime factor for trailer boaters, while strength may be more important to skippers who venture far offshore. In the end, each boat buyer has to make choices based on a particular set of needs. Let's take a look at the strengths and weaknesses of different hull shapes.
The Carolina Skiff 2480 is a flat-bottom fishing boat. more
How your boat's hull is shaped will have a huge impact on how happy you are with the way it performs. Photo © Dieter Loibner.