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Reflections:
Discovering The "Hull" Truth
(20-1)
by Dusty Miller
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 They
say there's nothing new under the sun, whoever "they"
are, but in the boating industry change is the only
constant. When I was young (now I am dating myself)
boats like my father's cruiser had one deck and were
wooden with planks of mahogany or oak. Runabouts were
also made of wood, often lapstrake cedar with clinched
copper nails. There was no fibreglass. In the 1960s
we began to see small runabouts made of glass and as
soon as that door was opened, fibreglass took over as
the favoured boat building material and wooden hulls
became collectors' items.
When this magazine splashed onto the boating scene 20
years ago, I was selling 30- to 60-foot fibreglass cruisers.
Mind you, they still had a lot of traditional hull designs
- displacement and semi-displacement hulls were
common - but they were soon changed to sleeker and
faster styles as manufacturers realized the flexibility
of this modern building material.
Smaller boat hull designs changed from a deep vee from
bow to stern to a modified vee - a vee at the bow
that quickly gives way to a large flatter area from
amidships (or farther forward) that extends to the transom.
This hull allows the boat to ride on the top of the
water, with just the flat area of the hull getting wet,
but the designers kept modifying. The flatter hull had
a harder ride, tended to dive into the waves and slide
away from sharp turns. So manufacturers added more strakes
at the bow to slow down the entry into the waves and
help it get up on plane faster. Straight chines gave
way to reverse chines for sharper cornering. Breaks
in the chines created a layer of bubbles next to the
hull to further reduce the wetted surface for even faster
top speeds. Shark fins on the centre line of the hull
helped to make the fastest boats go around sharp turns
as if they were on rails. Engines changed, too. The
development of the I-O brought the weight of the engine
forward so all the weight wasn't resting on the
transom. Outboards evolved to develop more power with
less weight and higher revs. Boats could now skim across
the top of the water at unprecedented speed.
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(Read full article in the magazine.) |
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