Talk:Self-propelled barge T-36

Help needed deciphering the deck log[edit]

https://catalog.archives.gov/id/179487474 page 27. Trying to decipher the abbreviations: 050°T (I understand 50 degrees, but what does T mean?), c/c, c/s

Also, this page only covers March 7th hours 00 to 16, but where are March 7th hours 16 to 24?

Also: on "weather observation sheet pages": option 4 for "position" is D.R. -- what does it stand for? And, why is position taken at 0800, 1200 and 2000 - in a rather non-uniform fashion?

-- Wesha (talk) 06:59, 2 November 2020 (UTC)[reply]

050°T - the "T" stands for "true" - i.e. the bearing has been adjusted for magnetic variation (and compass deviation). Bearing (navigation) seems to explain it reasonably well. Can't help on the missing pages. ThoughtIdRetired (talk) 07:24, 2 November 2020 (UTC)[reply]

Thank you. Of course I am not asking "where" the missing pages are, but from the looks of it (and from what I know of important documents like that, there are a lot of preventative measures against loss of information, like they pages are threaded together and signed, etc. On some other pages I certainly see the continuation on the reverse of the page if everything doesn't fit on the front -- but not here. So I was wondering if maybe the missing times are printed on some other page, that I am not aware where to look for (like, for example, "at the very end of the book", or a separate "appendix", or something). -- Wesha (talk) 15:48, 2 November 2020 (UTC)[reply]

P.S. I figured it out: it's the page file that is corrupt on the website, but of you download the complete PDF, the page is there. -- Wesha (talk) 05:51, 3 November 2020 (UTC)[reply]

D.R. = Dead reckoning. In Navigation you can find In marine navigation, Dead reckoning or DR, in which one advances a prior position using the ship's course and speed. The new position is called a DR position. It is generally accepted that only course and speed determine the DR position. Correcting the DR position for leeway, current effects, and steering error result in an estimated position or EP. An inertial navigator develops an extremely accurate EPThoughtIdRetired (talk) 09:17, 2 November 2020 (UTC)[reply]

c/c may mean "course correction", c/s is the speed, but I can't guess the precise interpretation. The observations are in two parts. 0800 and 2000 (morning and evening watch changes) and 1200 (midday). The former are marked as being 2 & 4, that is electronic and dead reckoning. The noon observation appears to be 1 & 4 (celestial and dead reckoning) but the writing isn't totally clear. The noonday fix is the special one. Using a sextant and with reference to the ship's chronometer you can determine the precise longitude, and by reference to the almanac the ship's latitude. From the noonday AP you can check that your EPs are reasonable. It's worth bearing in mind that this was in 1960, so navigation aids were minimal, and the ship was around 500 nm from Japan in mid-ocean. The electronic fix would be by bearing from shore stations, I'm not aware that there was any satellite support at that date and definitely no GPS! Martin of Sheffield (talk) 10:08, 2 November 2020 (UTC)[reply]

What I'm wondering is, why 0800, 1200 and 2000 (which makes intervals of 12 - 4 - 8 hours) - wouldn't it have made more sense to take a reading (whether electronic or DR) every 8 hours instead? -- Wesha (talk) 15:58, 2 November 2020 (UTC)[reply]

0400 is in the middle of the night! I suspect that this is a simple, practical, issue of doing things at the start and end of the day. Watches change at 0400, 0800, 1200, 1600, 1800, 2000 and midnight. Martin of Sheffield (talk) 19:31, 2 November 2020 (UTC)[reply]

Yes it is in the middle of the night -- and it's perfect time to pull out your sextant: stars are visible! Anyway, the ship never sleeps -- watches are going around the clock, and with the readings distributed uniformly, I would assume it would be easier and more accurate to do the DR calculations... -- Wesha (talk) 19:49, 2 November 2020 (UTC)[reply]

Electronic navigation for a ship of that size and type would have included LORAN-A. I do not think LORAN-C was generally available at the time. If I recall the AN/SPN-31 receivers started getting into the fleet in the early sixties. We certainly had them by the mid 60s. Even LORAN-A could improve DR positions depending on the hyperbolic configuration and range but errors of miles were not uncommon. Even LORAN-C had some interesting error issues as seen in this Loran-C User Handbook. As for DRs? Those could be wildly off. From some experience I can say Navy navigation was rather spotty depending on the navigators. Analysis of some records showed errors of many miles. Even with survey navigation errors could be quite large and absolute, geodetic position using the old Navy Navigation Satellite doppler system helped only by analysis and statistical corrections. No one satellite fix was really reliable and I've been tied up at a berth watching the plot of satellite fixes wander across the harbor in a shotgun patterns with a cluster effect within a few hundred meters of the ship.

A little oddity of the transition to GPS was an increase in accidents for a time. Even with the best navigation sane mariners gave many miles of avoidance to hazards. That cost money and time but was damn cheaper than a grounding or sinking. Even survey ships crept up with lots of eyes in good visibility and on the echogram trace in trying to pin down an isolated reef or rock. Then came this amazing GPS thing. Hey! I can cut hours off by cutting closer to that bank or reef or rock I've been passing with ten miles of space! Oops! GPS was just fine. It was just lots better than the survey that had "fixed" that danger and the hazard was a few miles off from where it was supposed to be. Most people still do not realize that many islands were miles "off" from their actual positions when geodetic teams started tying things together with modern systems and a common datum. An idea of the state of things can be seen in The Importance of SHORAN Surveying. Take logbook positions with at least a small bag of salt. Palmeira (talk) 14:01, 2 November 2020 (UTC)[reply]

LORAN-C came in in 1958, so by 1960 a USN ship might well have it. NAVSAT was the first satellite system and came in during 1964, so couldn't have been used in this log book. Martin of Sheffield (talk) 14:43, 2 November 2020 (UTC)[reply]

The driver of Loran-C was the FBM (Polaris) program so the priority for both the shore stations and chains and at sea receiving was given to associated platforms. I have not searched for the exact operational date for WESTPAC coverage but it was later than Atlantic coverage which had operational chains by then. I'd expect Kearsarge to have been on a priority for Loran-C, particularly with involvement in Project Mercury. I know a Pacific transit had quite a few vast Loran-C "not so good" areas (geometry problems, particularly between chains) that had to be worked around very expensively when there was a requirement. The ranging capability (solved geometry problems by ranging on masters and slaves but required early "atomic clocks" synchronized with the station clocks) was one, expensive, difficult and quite complex in its early stages (around 1967-68). Palmeira (talk) 21:47, 2 November 2020 (UTC)[reply]

Hey, I do understand that. Of course the purpose is more historic/illustrative than trying to be exact. Right now based on the accounts from the media the area of interest ends up rather large -- and now we will be able to narrow it down. -- Wesha (talk) 06:06, 3 November 2020 (UTC)[reply]

Decodes: I suggest "c/c" is change of course and "c/s" is change of speed. The aircraft being launched: "HSS" is Sikorsky SH-3 Sea King and "S2F" is Grumman S-2 Tracker. One could perhaps deduce that it was one of the aircraft that made the initial sighting of the drifting barge, since the log says "received report of sighting" and range is given as 15 miles when the weather report for the same time is 14 miles visibility. "LCM" - "Landing Craft Mechanized".ThoughtIdRetired (talk) 12:08, 3 November 2020 (UTC)[reply]

We already know that HSSs are HSS-1 Seabat from the Kearsarge video. Also, the rescued guys reported that they were indeed spotted by two airplanes, flown by Glen Conrad and David Mericle(sp?). -- Wesha (talk) 18:08, 3 November 2020 (UTC)[reply]

Decode for 14th March "TF" is Grumman C-1 Trader (carrying press and news correspondents).ThoughtIdRetired (talk) 12:55, 3 November 2020 (UTC)[reply]

Any idea what the item "Secured from flight quarters." means? It appears multiple times throughout the logbook, and it looks like it is somehow related to aircraft. -- Wesha (talk) 23:22, 5 November 2020 (UTC)[reply]

"Secured from flight quarters" meant that the flight deck (and other) crews were not needed for duty as they had no aircraft in the air or about to take off. "Secure" in this context means finish the job, tidy up and put away all the equipment and hands can then go off duty or on to other assigned duties. An aircraft carrier has a myriad of crew members with jobs associated with flying off and landing aircraft - most obvious is the Landing signal officer, but there are fire fighting parties, aircraft controllers (for the aircraft still in the air), the crews that operate the arrester gear (the wire that the Tailhook connects with), etc. Modern United States Navy carrier air operations lists the modern method of organisation and the people involved.ThoughtIdRetired (talk) 07:41, 6 November 2020 (UTC)[reply]

Thank you everybody, behold. If there is interest and somebody would like to help me with adding more details to the article in English that we collected in ru-wiki, I would appreciate that. -- Wesha (talk) 22:09, 5 November 2020 (UTC)[reply]