"J. Clarke" wrote in message
in.local...
In article ,
says...

"J. Clarke" wrote in message
in.local...
In article ,
says...

Jon Anderson wrote:
On 7/9/2011 3:06 PM, Howard Eisenhauer wrote:

The RCMP used to have 50' coastal patrol boats with twin Merlins,
those puppies wouls MOVE. They had even faster speedboats that fit
into the back of the patrol boats, they'd kick'em loose at full
speed.
Must have been a Fun Ride .

Don't know about the boats you reference, but I remember reading
that
the PT boats the US Navy was running in the Pacific, had a rather
punishing ride in choppy or rough water when running at speed.


Jon

Yeah, but that was THREE engines...

Not Merlins, alas. Perhaps with Merlins they'd actually have been able
to pull off those 70-knot dashes that the press thought they could do.

There were several US PT boat designs, but most, if not all, had a hull
shape like that of sports boat planing hulls of the time, which is still
the
prevalent hull shape today: a "shallow V" planing hull which had an
almost
flat run aft, for speed (and fuel efficiency, in sports boats), combined
with a fine entry. If you read hull drawings, you can see it here, down
the
page:

http://www.pt-boat.com/ (click on "Redrawn Original Hull Construction
Plans")

Those things pound in rough water and their speed in limited when the
water
gets rough. But they're very fast. They were used in ocean racers until
around 1962, when Bertram introduced the deep-V with longitudinal lifting
strakes. The deep Vs suck up power and fuel but you can plow them through
waves at very high speeds without pounding the fastenings out of the
hull.

The hull was actually the Huckins Quadraconic, which reduced pounding
compared to other similar designs--Huckins licensed the design to the
War Department. Incidentally I met Pembroke Huckins once--I was just a
little kid and don't remember anything about the meeting except that he
was a lot taller than I was and seemed nice. Used to drive past the
Huckins yard regularly.

Aha. Huckins were pretty rare among PT boats -- just 18 out of roughly 600
PT boats built by the end of the war. Most were ELCOs (Electric Boat Co.).

http://www.ptboats.org/20-01-05-ptboat-001.html

Those developed-cone plywood shapes, based on the Quadraconic, remained
popular through the '60s, and their concave entry did reduce the slamming
into waves.

--
Ed Huntress


The engines were Packard 4M-2500s. These were not re-badged Liberties
that
Packard made before the war, nor were they the Merlins that Packard made
under license later in the war. They were a Packard design that produced
up
to 1,500 hp in the PT boat version. This was as much power as most
Merlins
made, except for the special versions made for the de Havilland Hornet
and a
few others. The Merlin's big advantage was at high altitude, because of
its
very effective two-stage supercharger. The low-altitude Merlins used a
single stage.

So I don't think the PT boats lacked much in the power department.

Still, one can dream. Of course if I could scrape up 3 Merlins and a
million bucks or so I'm sure that Huckins would be happy to build me
such a vessel.