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 The
Hull You Say by
Cap'n Jack Perdue
We're going to talk about hulls.
After all, a boating rig is made up mostly of a hull with an engine
attached that will push it through or over the water. How fast and
with how much stability depends to a large extent on the hull itself.
So forget for a moment how pretty it is to look
at, and instead examine its functional features: how roomy and safe,
how much storage space and sleeping area, what shape is the wetted
surface and how functional is the superstructure?
The bottom, where the rubber meets the road, will
decide what kind of boat it really is: how stable, how fast and
how comfortable. So first we'll look at round, flat and V-bottoms,
or a combination of some sort.
Trawlers and most other displacement hulls are
usually a combination of round and flat on the bottom. The chines
are rounded, with a strong curvature that is carried almost to the
keel, with only a small strip on either side of the keel that's
flat. This provides a gentle, rolling motion and a more comfortable
ride at slow speed than you'll get from an off-plane deep-V hull.
But it is a displacement hull and it doesn't go very fast.
A flat-bottom boat, such as a jon boat, barge
or planked boat of some kind, is limited to its practical use while
V-hulls are ubiquitous and efficient. So if you're still looking,
you would be wise to concentrate on a boat with some degree of V-bottom.
A deep-V hull has a deadrise at the transom of
18 degrees or more while a modified deep-V deadrise falls between
10 and 18 degrees. Less than 10 degrees is considered a semi-V hull.
All deep-Vs have increasing deadrise forward, providing the soft
entry that is the hallmark of a well-designed V-bottom and a blessing
for all aboard. (But it's not famous for coming onto plane swiftly.)
Its main feature is that it's a planing hull that travels across,
not through, the water, is fast and frugal on fuel.
Now we should decide what the boat of your dreams
should be built of.
Most recreational hulls up to, say, 50 feet in
length, are constructed of wood, aluminum or fibreglass. Let's look
at each one briefly.
At one time, up to about 50 years ago, almost
all boats were built of wood. Some still are and a well-maintained
wooden hull will provide a warmth, a flexibility and a softness
of ride that is seldom matched by other materials. However, wooden
hulls require more continuing maintenance than any other material.
In fact there's so much maintenance that you really have to have
a passion for wooden boats if you plan to own one.
Aluminum boats have come a long way since they
were first introduced to the pleasure boating market. They are relatively
lightweight and require very little upkeep. If they get shabby looking
you can paint them or repaint them. But they are somewhat noisier
than wood or fibreglass boats and they lack the infinite compound
shapes available to fibreglass hulls and superstructures.
And that brings us to fibreglass, the material
that revolutionized pleasure craft less than half a century ago.
You can build fibreglass into just about any shape of boat, inside
and out. It won't leak, it will look spiffy, it will be of reasonable
weight and strength, it will require little maintenance and can
be readily combined with wood for decks and cabin work and finishing
trim.
So there you have it. The choice of materials
is yours.
Here are a few things to remember that might affect
your choice. A boat that has a fairly flat bottom immediately forward
of the transom will get you onto plane faster with a load than most
other practical designs. A hull that has a well-defined chine will
give you a cleaner turn at high or medium speed than one that has
little or no chine at all. (This is best illustrated by racing hulls
that rely on chine-hook turns.)
Here's something else to think about. An outboard-powered
boat designed for a transom bracket brings with it some definite
advantages. They include far more room in the open cockpit, and
a better-performing outboard operating in clean water back of the
hull. A transom bracket can also provide good, built-in boarding
platforms with direct access to the open rear cockpit.
There is a considerable variation in the amount
of freeboard provided by runabouts. Some, built for a rakish appearance,
have as little as 12 inches of freeboard. Others, designed for family
use, provide a deep, open cockpit, difficult for children to fall
out of. The deeper models also lend themselves to more creative
seating and storage. Some of them, with camper tops and sleeper
seats, can provide quite acceptable overnight facilities. Your major
problem in Ontario is providing a marine toilet. The law says that
the genus porta-potti is forbidden.
If you are aiming a little higher and are considering
the extra delights of a cruiser, there are some positive parameters
to be considered when dealing with permanent berths that can change
nighttime discomfort into blissful sleep.
In our society the accepted bed sizes are 39 by
75 inches for a single, 54 by 75 inches for a double. Not overly
generous but certainly more roomy than you can expect on most cruisers.
But there are limits.
Accept, or maybe construct, nothing smaller in
a single berth than 27 inches of width at the shoulders which can,
if necessary, be tapered to 18 inches at the foot. For a double
berth, the width can be as little as 50 inches at the shoulders,
with a narrowing at the foot usually subject to the shape of the
bow. (This is commonly known as a "toe tickler.")
The next important bunk dimension is length and
you should try for a couple of 74-inch berths aboard. But women
and children are usually somewhat shorter so most bunks need not
be longer than six feet or, if necessary, as short as 5'6".
Now for the height. Statistics indicate that 95
percent of Canadian males have a sitting height of 39 inches or
less, so boat companies aim for a 40-inch clearance. But this is
not always practical on a boat so we suggest you aim for a 36-inch
clearance and pad the frame above the bunk.
Finally, to encourage restful nights and alert
crew members, always plan on a five-inch slab of polyurethane mattress
foam. Just remember, you'll be laying it on unforgiving plywood,
not coil springs.
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