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 Author  Topic: PT 761 Class
  TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: Apr 29, 2018 - 10:49am
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

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of bubbletop409  Posted on: May 15, 2018 - 12:30pm
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
62 Bel-Air
260 Eagle EXP
79 Cole TR-2
2016 Corvette Z51

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Jeff D

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jeff D   Send Email To Jeff D Posted on: May 16, 2018 - 11:33am
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:

jhDrZ.jpg



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mcgovern61

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Post a Reply To This Topic    Reply With Quotes     Edit Message   Posted on: May 16, 2018 - 12:39pm
PT-487

[jhYla.jpg

Former crew member of the Big Blue Sightseer ex-PT 486

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bubbletop409

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of bubbletop409  Posted on: May 16, 2018 - 7:02pm
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
62 Bel-Air
260 Eagle EXP
79 Cole TR-2
2016 Corvette Z51

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  Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Jun 6, 2018 - 8:39pm
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

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jeff D   Send Email To Jeff D Posted on: Jun 7, 2018 - 2:51pm
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:

jhRs3.jpg



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Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Oct 19, 2019 - 3:00pm
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.

PT761-drawing.jpg


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  TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: Oct 19, 2019 - 3:43pm
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

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jeff D   Send Email To Jeff D Posted on: Oct 20, 2019 - 5:17am
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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