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

On Thu, 08 May 08, (Geoff Miller) wrote:
It obviously
had some advantage over a conventional hull, but what
was it? And why did the design fall out of favor with
manufacturers?

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

On May 9, 10:07*am, wrote:
On Thu, 08 May 08, (Geoff *Miller) wrote:
It obviously
had some advantage over a conventional hull, but what
was it? *And why did the design fall out of favor with
manufacturers?

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

They beat the hell out of you and they were heavy. You needed a good
size engine to push them around.

lid wrote:
On Thu, 08 May 08, (Geoff Miller) wrote:
It obviously
had some advantage over a conventional hull, but what
was it? And why did the design fall out of favor with
manufacturers?

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


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.

On May 9, 10:19*pm, harry krause wrote:
wrote:
On Thu, 08 May 08, (Geoff *Miller) wrote:
It obviously
had some advantage over a conventional hull, but what
was it? *And why did the design fall out of favor with
manufacturers?

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

I remember when they first came out. My father carried a few from one of
his fiberglass boat lines.

Well of course!!!! That's probably what your dad took on his trans-
Atlantic trip and got a fireboat welcome for, huh, liar?

wrote:
..

Well of course!!!! That's probably what your dad took on his trans-
Atlantic trip and got a fireboat welcome for, huh, liar?


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.

On May 15, 11:26*am, "Reginald P. Smithers III" "Reggie is Here
wrote:
wrote:

.



Well of course!!!! That's probably what your dad took on his trans-
Atlantic trip and got a fireboat welcome for, huh, liar?

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.

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!

wrote
most people simply don't realize that
all cathedrals do NOT ride alike.

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 Scribbler writes:

My 77 Thunderbird rode no rougher than any equivalent
conventional hull:

http://blizzard.zmm.com/thunderbird/starboard.jpg


Nice boat. Looks like it's in great condition.

According to one of the photo captions, the stainless steel
prop reduces the top speed by 5-7 mph despite both props'
being 14.5" diameter and 21" pitch. Why would two props of
identicial specification have such different performance
characteristics because of one being steel and the other,
aluminum?

My father's 95-hp 1966 Mercury outboard, mentioned in an
earlier post, had a two-blade aluminum prop. I remember
my father telling me that a three-bladed prop would've
given our 16-foot Crestliner day cruiser a lower top
speed, but would've had more pulling power (like for
towing another boat, or pulling water skiiers).

I can certainly understand why a three-bladed prop would
give a boat more pulling power than a two-bladed one. That's
intuitive. But why would a two-bladed prop offer greater
speed? I'd have thought that the more blades, the greater
a boat's pulling power *and* top speed.

It occurred to me that maybe the explanation had something
to do with more blades rendering the prop less efficient by
creating more cavitation, but it seems like that would have
a detrimental effect on both aspects of performance.



Geoff

--
"The sky was low and heavy, like the brow of a retarded child."

"Geoff Miller" wrote
According to one of the photo captions, the stainless steel
prop reduces the top speed by 5-7 mph despite both props'
being 14.5" diameter and 21" pitch. Why would two props of
identicial specification have such different performance
characteristics because of one being steel and the other,
aluminum?

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.