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 Author  Topic: Speed of PT Boats?
  Jerry Gilmartin

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jerry Gilmartin   Send Email To Jerry Gilmartin Posted on: Jul 15, 2013 - 12:33am
Bob,
It was Maury Hoopers story. PT238. They intentionally disabled the overspeed cutout on the engines and the engines were turning 3300 rpm. The Packard engines were so overbuilt they could easily handle that much rpm over their limit. I have also heard that some boat motor macks would spray a water mist into the carbs to mimic "war emergency" power like on an aircraft engine. (Overspeed trip setpoint is 2950) Frank, your speed test data on the Higgins Hellcat was limited to a top engine rpm of what? 1850 rpm? I know on the boat acceptance INSURV trials that is the maximum rpm they would test the engines to. There is your improper assumption. These guys racing the boats were in it for some serious bragging rights, plus a little cash I would imagine, So you figure it out, 3300 rpm using 26x26 inch props. All Maury knows is that the 10 mile course was completed in 8 minutes. OK all you doubting thomases, do the math! Higgins rule the seas! Way faster than those slow barely turnable Elco boats! Jerry

Jerry Gilmartin

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Bob Butler

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Bob Butler  Posted on: Jul 15, 2013 - 9:16am
I really didn't mean to open a bag of worms, well maybe just a little...


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Bob Butler

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Bob Butler  Posted on: Jul 15, 2013 - 9:16am



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  Frank Andruss

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Frank Andruss   Send Email To Frank Andruss Posted on: Jul 15, 2013 - 12:14pm
Jerry, I really have to dig out Montgomery's other notebook from when he was conducting speed trials in Miami. Let's see here, in one entry in the book, he used PT-295 and PT-552, both using W-14 Packards. PT-295 is using 29/26 Props, while PT-552 is using 28/29. Three runs are made with a full war load and 2,000 gallons of fuel.

Run 1 PT-295 44.010 Knots PT-552 45.113
Run 2 PT-295 43.690 Knots PT-552 45.000
Run 3 PT-295 44.227 Knots PT-552 45.456
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There was no RPM's given for this one test. In anther entry Montgomery writes down he also conducts a test with PT-487 using three runs with different RPM'S. For instance at 2,786 rpm, the boat produced a speed of 52.13 knots for the first run, the second run at 2,832 rpm. produced a top speed of 54.17 knots, and the third run at 2,695 rpm's produced a top speed of 51.30. I will not argue the point that in the war zone the motor macs were always trying to gain more speed, but I still never heard of any of the boats doing 75mph. Test's do not say altogether if they were carrying a full war load or how much fuel. Montgomery writes down in yet another entry in his book PT-487 doing 52.98 knots at 2, 670 rpm's. The boats never gave you the same speed in each run.


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