Making Merlin Engines

--Saw one a couple yrs back at the Vallejo model engineering show; complete with scale prop. Will look for photos..

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 :).

H.

I'll bet. Here on our Rogue River, the jet boats have triple Chevy

454s. They're definitely a hoot, especially when they get up to speed, whip the wheel, and we spin around fast enough to get hit by the rooster tail it threw up. It's best on 90F+ days.

These are big, 50-person cattle boats, but they _m o v e_!

The older, smaller ones.

-- One word frees us of all the weight and pain of life: That word is love. -- Sophocles

TWIN Merlins!!!??? Now we're talking about my dream boat. Dave

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... :)

When I was in the Royal Air Force 1959-64, I was on Gan in the Maldives. There were two AVRO Shackletons Mk 1 on permanent Search & Rescue duty. I was there to fix the airborne radar. Also we had a couple of Target Towing Launches (TTLs), they had two marinised Griffon engines. These Griffons were used in the Shackleton and were quite a bit bigger than the Merlin. The Shackletons had contra rotating props to absorb the extra horsepower. I had the enviable job of looking after the Sarah Beacons that alll the aircrew carried and and the receivers that were in the TTLs and the Shacks. We used to abandon a little Sarah beacon in a dingy, shoot off 50 miles or so, in any direction and then come back and find it. Sometimes the Indian Ocean was like a millpond and boy - did these boats go! We never lost one Sarah beacon. They were started by explosive cartridges and when these two huge engines were put to work, the fairly light TTL would really fly! They were made of wood - so as to be non magnetic, and about 50 ft. and I dearly, dearly wanted one. There were quite a few based around and Lossiemouth in Scotland springs to mind. Being wood they did not last long, especially in the tropics, but what craft these were. 4000 gallons of aviation fuel would be a bit hard to handle nowadays, but it wasn't a problem then.

Regards George.

There was a book called Rumrunner (ISBN 0-920501-94-X) that is full of stories from a guy that was a rumrunner up around Puget sound and a little south. It was written by the guy's niece (Marion Parker), based on verbal stories. If nothing else it is an entertaining read.

There were a number of stories about outrageously powered boats.

BobH

Have you seen the coast gaurd's little go fast boat. four four stroke outboards on a light boat under thirty feet.

They decided to stop us once. I KNOW they were doing over seventy on the water coming up behind us doing 24 knots. Looked like we were standing still. The captain held a M16 while the mate boarded us. We got a citation for a non conforming life ring. And a story to tell the grandkids.

Karl

You might want to look up some things about the rum runners that were built during Prohibition. A famous one was built around 15 miles from where I now live. Her name was "Fleur de Lis." 52' long (IIRC), she was clocked at 55 mph with a full load of illicit booze aboard. She had three Liberty aircraft engines, the predecessor of the Allison that powered the early P-51s. The Coast Guard chase boat that was built to go after her had two Liberties. That's why Fleur de Lis had three -- an advantage of the flexibility of free enterprise over government bureaucracy.

We had some fantastic rum runners built around here, on the shores of the Raritan Bay. My uncle made pin money tuning and maintaining the engines on Fleur de Lis -- when he wasn't teaching shop in a local high school. d8-)

I'll bet I'd enjoy that. I'll have to keep it in mind.

Fleur de Lis is described in a book that was published by Rutgers Univ. Press a few decades ago, _The Sea Bright Skiff and Other Shore Boats_, which contains a photo of her. But I preferred my uncle's accounts of how she evaded the Coast Guard and snuck up the creeks in Staten Island and New Jersey, after running in the 12 miles from booze pick-ups, which they got from Canadian ships that would just park offshore.

It was a long time before small ocean-going boats would go over 50 mph again. I recall seeing one of the first, Bertram's original prototype, the Blue Moppie, running in the Miami-Nassau powerboat race in the early '60s.

Miss Supertest III only had one when Bob Hayward won the Harmsworth Trophy three times in a row. Gerry :-)} London, Canada

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:

(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 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.

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.

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.

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.).

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

Supposedly the War Department told Elco to use the quadraconic after the sea trials on their prototype. There was some other Huckins technology that was licensed to the other manufactureres as well.

If you look at the drawing on pt-boat.com you'll see that the entry is indeed concave (note though that I'm not clear on his source for that drawing--did he have access to an original Elco from which he could take dimensions?).