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Whatever Happened To "Cathedral" Hulls?
When I was a kid in the late Sixties and my family
was just getting into boating, "cathedral" hulls
were all the rage. In case anybody doesn't know
what I'm talking about, that's the term for that
pseudo-trimaran hull design like the boat the
father character drove in the TV show "Flipper."That particular boat was a 22-foot Thunderbird
Iroquis. Thunderbird, the precursor to Formula,
was one of the biggest users of the design. Both
Johnson and Evinrude sold cathedral-hull boats
under their own names in those days. I go to my share of boat shows, and I haven't seen
a boat with that hull design in decades. It obviously
had some advantage over a conventional hull, but what
was it? And why did the design fall out of favor with
manufacturers?
Geoff --
"The future stretches before us, brown and sticky, like the
broad smile of a mongoloid eating peanut butter off a spoon."
-- snide |
geoffm
May 8
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| Loogie,
The best thing you can do with Harry is ignore him, he sent you the
email, because he knew it would stir up a new string of posts about him.
Don't play into his games, and lets improve the posts and eliminate the
inflammatory posts in rec.boats. |
Reginald
May 15
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| I agree that I should ignore him, but my post was in no way
inflammatory, he's made those accusations about the trans atlantic
trip! But, I will ignore him from now on! |
LoogyPicker
May 15
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| Ernest Scribbler <replies@newsgroup.only.please> writes: |
geoffm
May 15
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| It's the other way around, the stainless is faster. I believe it's primarily
because the blades of the aluminum prop are much thicker (in order to get
sufficient strength from the weaker material) and this reduces its
efficiency. |
Ernest
May 16
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| _NCnbDVnZ2dnUVZ_rTinZ2d@posted.lavanet: > http://blizzard.zmm.com/thunderbird/starboard.jpg The note says the aluminum prop is the slower prop. It is normal for a
steel prop to have faster top speed than aluminum, all other numbers being
equal, because steel allows for thinner blades and thus less drag. The
steel prop may have slight efficiencies due to shape as well, such as rake
and cupping, which are easier to do with steel and seldom seen with
aluminum. |
Reno
May 16
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| Aluminum is easy to machine, not true of stainless steel. Bronze is
easy to work with, and has long been a favorite material for props.
Stainless is quite good, aluminum is cheap. Casady |
richardcasady
May 16
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| I have one - it's a 16 foot 1969 Vanguard made in Canada with a
85hp.Evinrude. It has a stepped hull like the Regal fast-trac. It is quick
to plane and goes 41mph with a 17" pitch prop. I wonder how fast it would
go with a 19" or 21" prop. I think the shape and the steps help get air under the hull and boost
speed. It pounds like crazy in even small waves. I once made a sharp turn
at full speed and the inside corner dug in and it cornered like an F1 car -
scared the hell out of me because I figured if it let go part way through
it would have flipped. If I would have had a passenger they would have been
thrown out, the turn was that sharp. I guess that's neat but I haven't
tried it again. It goes and handles well with just 2 passengers but when I have a total of
5 people aboard it uses over twice the gas and handling is very sluggish,
more so than other boats. Maybe that hull is more sensitive to load then
deep-V's. |
Reno
May 13
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| Hence the previous replies to your post. My 77 Thunderbird rode no rougher than any equivalent conventional hull:
http://blizzard.zmm.com/thunderbird/starboard.jpg |
Ernest
May 14
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| Well of course!!!! That's probably what your dad took on his trans-
Atlantic trip and got a fireboat welcome for, huh, liar? |
LoogyPicker
May 15
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| We had a 70 bowrider with one of these. 'BeachCraft" was the
maunfacture. I beleive they were suppose to be more stable. At speed it
was ok, but going for a slow cruise waves that came in from the bow
would "thump and spit" water foward from the boat due to the pockets
that were formed in the hull. Some of the deck boats appear to have a modified version of it. Capt Jack R.. |
Jack
May 11
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| They beat the snot out of you in choppy water but I still see some bow
riders using that design |
gfretwell
May 8
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| Side to side stability was noticeably better. It also gives you much
more room forward than a standard hull which creates numerous design
layout options for storage, casting deck, larger cuddy, etc. Most were
relatively flat bottomed aft so were able to operate in thinner water.
As to ride, the original idea was that the upward spray created by the
center hull would be trapped under the outer sponsons which would then
cushion the ride a bit. That theory held water (ugh... sorry) in some
of the Thunderbird models but most manufacturers modified the design
to a great extent and wasted that advantage. Becasue of that,
eventually, the stereotype reputation of "rough ride" developed
because most people simply don't realize that all cathedrals do NOT
ride alike. Fact is, even though the oldest Thunderbirds were rough,
they were very strong, safe and seaworthy in rough weather but you
just had to slow them down quite a bit.
Before their demise (or sale rather), Thunderbird was building
cathedrals with a deeper center hull with much smaller sponsons. Those
boats rode as well as any of their deep V counterparts. But it was too
late. The market had already concluded that cathedral = rough ride,
and even the easiest riding Thunderbirds didn't sell well.
My first Thunderbird was a 1964 (+/-) model which served its purpose
well. I was very young and could take a beating without much thought.
I later ordered a 1971 T'bird Commanche. That boat rides like a deep V
and still has the advantages of the cathedral. Since then, I've bought
and sold more boats than I can track but I've never found one as
versatile all around or one I like better than that 1971 Thunderbird. Rick |
PhantMan
May 9
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| They beat the hell out of you and they were heavy. You needed a good
size engine to push them around. |
Capt
May 9
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| I remember when they first came out. My father carried a few from one of
his fiberglass boat lines. Don't remember the brand name. I do remember
that we both thought they rode hard and sometimes had an incredible
amount of bow rise in certain head seas. Most of the outboard runabout boats in those days were not deep vee, but
had rounded chines, like the Lymans, Cruisers, Inc., and Wolverines, and
many other brand news. These boats rode pretty well. The Wolverines had
"clipper" bows and rode drier than the Lymans. |
harry
May 9
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