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Topic: PT 761 Class |
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TED WALTHER |
TOP BOSS
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Posted on: Apr 29, 2018 - 10:49am
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Andy;
The stuff you are finding proves a thought I have always had, while the books say the ELCOPLANE died with the tests of PT 560-563 RON 29 Brooklyn to Miami, the info you are finding suggests the Navy told them to fix the problem, The speed an maneuverability were just too good to ignore. So they moved on to the ELCO SLIPPER(which was there version of trim tabs). I read in your previous research that PT 613 also sported new design rudders:
http://www.ptboatforum.com/cgi-bin/MB2/netboardr.cgi?st=10&nd=20&fid=102&cid=101&tid=3324&pg=4&sc=20
in this thread is also mention of a strake being installed on the keel somewhere between frames 20-35. I wonder if they were looking at a combination set up combining the aft rudders with what was termed a smaller bow rudder(which was actually on the keel amidships), as in the 1932 design of Miss America X.
The Irwin Chase Hydroplane boat diagrams of June 1911, that Jeff posted, were very interesting too. This diagram was the forerunner of the stepped hull design has been incorporated into the high speed offshore designs used by Cigarette, Fountain, Halter/USMI, Formula, Donzi, and many more,
Take care,
TED
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bubbletop409
MASTER
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Posted on: May 15, 2018 - 12:30pm
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Just an observation on the benefits of a stepped hull. I have a 26' Miami Vice style deep v speed boat with two small steps in it's bottom. The hull was originally designed without steps, some time later the design was changed to include the steps. The factory stated the speed of the boat with the steps increased by 5+ MPH all else being the same. In light of the fact the boats speed increased at any given RPM, I fail to understand why the PT's showed an excessive amount of fuel and oil consumption.
Larry
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Jeff D
Moderator
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Posted on: May 16, 2018 - 11:33am
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As a total guess, the design may have suffered from a lack of refinement Larry. The steps had a relatively steep straight angle that may have made it more difficult to push and keep up on plane. Here's what the steps looked like:
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mcgovern61
New Member
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Posted on: May 16, 2018 - 12:39pm
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PT-487
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Former crew member of the Big Blue Sightseer ex-PT 486 |
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bubbletop409
MASTER
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Posted on: May 16, 2018 - 7:02pm
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Jeff, after looking at your illustration I can now see the major difference between the Elco steps, and the configuration of the modern day steps. Thanks for the info.
Larry
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Andy Small |
MASTER
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Posted on: Jun 6, 2018 - 8:39pm
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Did Elco boats before the PT761 class have the additional longitudinal bottom planking in the Fuel Tank Compartment (1/2 mahogany) and Lazarette (7/8 mahogany)?
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Jeff D
Moderator
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Posted on: Jun 7, 2018 - 2:51pm
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It looks like it Andy, here's from a bottom blocking drawing for PT 163 and on courtesy of Dick Washichek. Section B-B is at frame 64-65:
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Andy Small
MASTER
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Posted on: Oct 19, 2019 - 3:00pm
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Completed drawing of PT-761 class. Weapons arrangement was supposed to be the same as that used by the PT-613 class, but I don't see how the 5inch rocket location would have worked. Radar is the SO-5. I included the Elco Slipper since they seem to have liked the adjustable kind since they were still on the boats (except PT-616) when they transferred them to the ROK.
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TED WALTHER |
TOP BOSS
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Posted on: Oct 19, 2019 - 3:43pm
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Andy;
Thanks! I like it, and this would make a great "What if" model of a RON 44 or RON 45 boat, (PT 766,) if Operation Downfall ( Operation Olympic and Operation Coronet ) actually happened in 1945-1947.
Take care,
TED
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Jeff D
Moderator
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Posted on: Oct 20, 2019 - 5:17am
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Very nice Andy, as far as I know it is a first! Thanks for the view of what they looked like. Hopefully you'll dig up some photos in your research trips.
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