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What is the Importance of Hull Design?
There is a huge secret in the
boat building industry; Whether your boat is a small one or a large one, there
is nothing else that will make as much difference in your boating pleasure as
the design of your hull. And nothing else can make it go faster or perform
better.
This may come as
a surprise to many boat buyers who are used to owning cars of every type
without having the exterior conditions actually affect their driving pleasure.
However boat exterior conditions change constantly and widely depending on
wind, tides, and current.
At Twin Vee, hull
design is central to the design philosophy of Roger Dunshee, founder of Twin
Vee and one the best small boat hull designers in the world today. The planing
catamaran hull was picked because it offered the most complete package of
benefits over V-hull designs currently popular. The advantages of a softer and
dryer ride in heavy seas and chop was very important. Efficiency, stability
and safety advantages over V-hull designs made the design choice easier. Twin
Vee developed a super strong hull and because of it's design prowess in weight
and balance, was able to create these features in a cat that was also fast.
The result today is the best line of small boats on the market. These cats
have the ocean going capability of V-hulls 25-30% larger. The ability to go
through 4-5 feet chop at high speeds, comfortably, and safely, is a singular
accomplishment in the boating industry.
The dedication of
Twin Vee to hull designs is the reason that Twin Vee has developed strong
customer loyalty and proven performance from Bermuda to Kona, in the world's
biggest waters. An additional benefit that came with the package is that cats
have a shallow draft. Twin Vee Cats have drafts from 7" (14&17),
8-10" (19&20), to 12-14"(22&26). This allows Twin Vee to perform very
successfully in the shallow waters and flats of Florida, Texas, the Bahamas,
Cape Cod and bays everywhere.
Additional work
was done on the hull design to allow for single engine performance in Twin Vee
cats 19 feet and lower. This was a significant accomplishment that has since
become the industry standard.
Hull design is
central to performance, comfort and speed among other things. But how can a
potential buyer test the hull design? The answer is a test ride in different
sea or chop conditions. The average sea state in the Atlantic is about 3 feet
(higher from November to April). The average wind speed is about 10-11 knots,
again higher in the winter (in Florida). If the buyer wanted to be able to go
boating year round, then a test in 3-5 foot seas or wind speeds of around 15
knots or more would be called for. Any place where such conditions could be
duplicated would suffice for test purposes. In any case, a test ride in calm,
protected waters is inadequate.
Additionally, in
the case of twin engines, it is important to test the planing ability of a
boat with one engine turned off and tilted up. This test simulates an engine failure
off-shore. Over 90% of V-hulls will fail this test, even with large engines,
due to the inefficiency of the hull. By comparison, a 20 foot Twin Vee will plane with a single 50hp motor, and a 22
will plane with a single 70hp. The
failure of a single engine to plane a boat is a safety issue.
The boat
buying public has been kept in the dark about the importance of hull design.
Twin Vee is a manufacturer that can be trusted to fully understand the issues
surrounding hull performance and testing. It is proud of its pioneering
development of the best small boat hulls in the world today. It's customers can
have the most enjoyable boating experience at a most affordable price.
What are the Qualities and Concepts of
Power Catamarans?
It seems new
catamarans are entering the world of power boating every day. Numerous
magazines have featured "cats" on their front page. What is making
these boats so popular? By now, many know their qualities: soft ride,
performance, comfort, and stability. Those fortunate enough to have
experienced "the cat ride" swear they cannot go back to V-hulls.
We like to
introduce boaters to "the cat ride." The recipe is easy but you've
got to pick the weather! Sunny is nice, but not for demonstrating Twin Vee
Cats. Make sure the wind is blowing at least 15 mph, then make your way to the
inlet. Now you have the perfect mess that most boats (and boater's backs)
loathe. Ahead, a 5' chop with plenty of white caps approaches and the cat
smoothly slices the wave and moves up on the next one. The green face turns
toward you with a surprised grin. "How in the heck...???" Makes a
Twin Vee dealer's day every time.
Truly there is no
bad cat in terms of ride, and even an average catamaran will compare favorably
to a V-hull boat of the same size. However, to move a cat from average to
great requires a special touch. If we've learned anything from years of
testing multihulls, it is the great importance of reducing weight and creating
balance to create great performance, comfort and SAFETY.
Today, we have many years of R&D on our several hulls. It is this R&D investment that has
allowed Twin Vee to be the technological leader in developing the most
affordable, softest riding, fastest and safest power catamarans on the market today.
What are some of the Definitions used in
the Power Catamaran Industry?
Tunnel
All cats have one, although some are
specifically called the tunnel hull. It's the space between the two hulls and
the underwing or bridge deck, and is relied upon for lift.
Slamming (Called "pounding" on
V-hulls)
Occurs when a wave is trapped inside the
tunnel and hits the underwing. A lightweight, good design, and sustained
speeds prevent slamming.
Sneezing
Exclusive to cats, it's a spray from the
front of the tunnel back into the boat. Air compresses the water and creates a
cushion. The air cannot escape out the back of the tunnel and thus is forced
forward. Poor design and /or balance usually cause sneezing, and weight can
sometimes be a factor. Thanks to our great hull design and attention to weight
and balance, Twin Vee PowerCats are practically immune to sneezing.
Banking ("Leaning" for some)
The lateral attitude of a vessel,
applicable to moving vehicles as well. V-hull boats, bicycles, and motorcycles bank
into a turn. Powered catamarans on the other hand, are more similar to cars.
They tend to bank out of the turn, and it takes a little getting used to!
If
you think of your car as riding a bus standing up, it's the same idea.
Can you Explain Catamaran Hull Design
Theories?
There are three types of hull
designs for catamarans. Each design relies on the tunnel effect to some
degree, and each can have innumerable variations within its type:
Tunnel Hulls
As the name implies, these boats rely on lift to operate from the bottom hull
when compressing air into the tunnel. As you can imagine, this can only happen
at high speeds, and this means that a lot of power is needed to bring the boat
up to plane. A tunnel hull performs poorly at lower or trawling speed. Also,
due to their mostly flat-paneled bottoms, the ride can be rough in waves.
Displacement Hulls
Displacement hulls depend on buoyancy. The volume of the hulls is a major
contributing factor; the boat slices waves instead of punching them, and it
does not come up on a plane. This accounts for the smooth ride. Some factors
such as friction from the wetted area can limit the top speed and can also
cause both slamming and sneezing.
Planning Hulls
These are hybrid hulls combing features of both tunnel and displacement hulls.
They provide a smooth ride and top speed for less overhead. Twin Vee's
proprietary asymmetrical bottoms do just that, plus control the amount and
flow of water in the tunnel that the center propulsion requires.
Why is Weight so Important?
The catamaran hull shape, by nature,
is easily driven through the water. It requires less power to attain the same
speed as a V-hull. The largest single negative is weight and its location. It
will impact comfort and safety since a heavy cat is low in the water. It will
then suffer from underwing slamming, sneezing and slow steering reactions. A
heavy cat also needs more power and more fuel (which adds even more weight!). The Domino
effect is hard to stop. And since we are talking trailerables, the heavy cat
will also need a heavier trailer and a bigger vehicle to tow the whole
package!
Why do Twin Vee's 17 and 19 Footers Utilize
a Single Engine?
Because they can! The real
answer is multi layered, and will depend on how you intend to use the boat. A
day trip within 5 miles of land does not call for twins. A Florida/Bahamas
crossing, Channel Islands, Catalina or Dry Tortuga trip will usually call for
a twin setup. Single engine catamarans are asked for, and we have made it work where
others have failed.
Isn't all this "State of the Art"
Expensive?
No! Twin Vee's design
philosophy is affordable power catamarans. If you want performance, strength,
comfort, economy, dependability, durability, low maintenance and resale value all in
one package, then isn't it nice that it's also affordable?
What is the Best Decking Material?
In many respects, wood is actually
stronger than any material known, even so called space age material.
How can wood be stronger than Kevlar and graphite fibers? It is stronger, strange as it seems. The answer lies in understanding "strength."
There are two critical types of strength: tensile and stiffness (the modulus
of elasticity, or Young's modulus-E). Both are measured in pounds per square
inch (psi). Following is a comparison of space age materials in order of
"strongest" to "weakest".
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