Highlights From the Forum October 29 through November 4, 2000 |
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Contents:
(click on the number to go directly to that message) |
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35 | W40K | Don Neumann |
36 | Manta Boards | Rick Seapin |
37 | Birch Matthews | Ric Gillespie |
38 | AE and the Hams | Mike Everette |
Years ago, when I was into S.C.U.B.A., I had the opportunity to use a torpedo. No, not the kind that is shot from a sub, but an electrically driven unit which pulls a diver along the ocean floor. They were cumbersome and heavy. However, I’m sure that nowadays, the propulsions devices must be state of the art and light weight. From Ric Would the same concerns apply to a “torpedo?” From Van Hunn In response to some warnings posted by forum members concerning Manta Boards, I offer the following: The Manta Boards we used in the 1997 lagoon search were part of the dive equipment belonging to the live-aboard SCUBA ship Nai’a. These Manta Boards are made of plywood about three feet wide by two feet. There are holes to attach a towing rope, and two slots for the diver’s hands. The diver is in complete control of ascent and descent by either tilting the board up or down. While being towed, if the diver turns loose of the board, he/she will stop while the board continues on and soon floats to the surface. These boards were excellent equipment because: A. The diver did not have to do any navigation over the grid area to be searched. The boat driver did the navigating by visual sighting of buoys outlining the grid. B. Propulsion was from the boat instead of the diver’s legs, making it easy to search much more of the grid without exhausting the diver. Divers were towed at about swimming speed in order to see more and to make it easier to avoid coral heads. I am happy to no diver was injured; however, the Manta boards had a few scars from bumping coral heads! Is towing a SCUBA diver as dangerous from an embolism standpoint as some have said? Yes and No. For an uncertified or inexperienced diver, Yes. For an experienced diver, No. I cannot imagine an experienced diver ever holding his/her breath while ascending--whether being towed or ascending for any reason. Additionally, divers all over the world use other devices for towing. One of the most popular is the battery operated diving Scooter – these could actually be more hazardous than boat-towing because the can take a diver much deeper. Also, we have all seen TV diving shows where a diver is being towed by manta rays, whale sharks, or other creatures. Again these are not for the inexperienced divers. Since this subject surfaced (!) a few days ago on the forum, I called two friends each of which owns a dive shop. Both said essentially the same thing – experienced divers only. By the way, our local fire department does employ towing of their experienced SCUBA divers when doing bottom searches. What about the experience of the TIGHAR Team divers? Both the owner/operator and the chief instructor of Nai’a are Master certified, instructor certified and have years of experience. Another diver, Tommy Love, is a medical doctor with specialties is decompression sickness and a lot of SCUBA experience. I am Master certified, Open water instructor certified (emeritus), and NACD Cave Diver certified. I hope the above helps forum members with the Manta board question. LTM, Van |
It is with great sadness and regret that I must tell you all that our friend Birch Matthews died suddenly and unexpectedly this past weekend. I don’t yet know what happened. I have just now received an email from his family informing me of his passing. Birch was a fine gentleman who was always eager to share with us the Lockheed 10 data he had collected over the years and his impressive knowledge of aircraft and engine performance. We will miss him. I’ve told the family that I will forward to them whatever messages of sympathy the Forum may wish to express. |
AE would have contacted ham operators by transmitting on either 3105 or 6210 KHz, and listening for replies on frequencies in a ham band. This is called “crossband operation” and is still practiced in some circumstances today... notably, during the Armed Forces Day period when hams “work” military stations like WAR, AIR or NSS (HQ of Army, Air Force and Navy) among others... WAR, for instance, might transmit on 4020 KHz (outside the 75-meter band) and advise that they are listening for replies on, say, 3850 KHz which is inside the ham band. As for how Carroll may have worked her (notice I said MAY), a number of problems arise. The WE 20B receiver AE had only tuned HF freqs from 1.5-10 MHz. This includes the 160- 80- and 40- meter ham bands. Phone operation was allowed in the 160- and 80- (75 meters is the actual term used for the voice portion of the band, 3800-4000 KHz) bands, but in 1937 there was NO phone operation in the 40-meter band (7000-7300 KHz)... it was CW only. Therefore the only bands AE could have heard hams TALKING on, were 160 and 80/75. I have doubts that 80 meters could make it to Niku... and 160? 99.9999999% sure, NO WAY. AE’s receiver could not tune the 20 and 10 meter bands (14-14.4 MHz, 28-30 MHz) which are the best possibilities for a stateside signal getting to her.... UNLESS: She was not using the WE-20B, but.... ANOTHER TYPE RECEIVER. One that had a wider tuning range. I know Ric and I disagree on this point, but this event, IF it happened (and we do not know it did, yet) MIGHT be evidence that she had a “second” or a “different” receiver... as Joe Gurr claimed, remember? But let us PLEASE not get a tangent going yet, on this...!!! As for harmonics working “both ways” (!?) I doubt it... But, if she could hear hams on 20 meters, she and Carroll MIGHT conceivably have encountered a scenario where some hams (including Carroll) operating on, say, 20 meters, were discussing hearing her, on some harmonic (but neither AE nor Carroll may have realized the AE transmission was on a harmonic)... and AE heard this conversation. AE, realizing she could be heard, may have in fact been able to establish a roundabout crossband contact... but here’s another factor that throws doubt on this. It would likely mean that one of the hams involved had to be listening on both the ham freq AND AE’s harmonic at the same time. Remember, NONE of AE’s possible harmonics fell into any ham band. There were no “scanners” in 1937, so that means the ham would possibly need 2 receivers to accomplish this.... Not many hams in the 30s had more than one receiver... could not afford it... but it is POSSIBLE. I don’t know how PROBABLE, though. LTM (who overhears
EVERYTHING) and From Ric All true, I’m sure. The odds seem astronomical – and yet – what are the odds that a series of letters and numbers written in Betty’s notebook just happen to match a ham call sign that just happened to belong to someone who lived on the same Great Circle between Gardner and St. Pete and that this person just happened to have made the comment that he “talked to her?” This is very strange. |
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