The addition of a compass to Olympic and Britannic


Jim Currie

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I don't think so Jim. Under the W-Comp. heading there were two columns, one marked course and the other marked deviation.
Gyro repeaters don't have deviation error. I suspect that the W-Comp was originally for the magnetic compass on top of the wheelhouse.
There were also 2 pelorus equipped, one on each bridge wing.
If Olympic was originally supplied with compasses as was Titanic, then she would have had three main compasses:
1: The mid-ship Standard Compass.
2: The Steering Compass in the wheelhouse and
3: The Steering Compass on the captain's bridge located directly in front of the enclosed wheelhouse.

The Standard was as named. The other two would be used according to the situation...i.e. when under pilotage or when on ocean passage.

Perhaps that's what the three headings were?

PS. As young Cadets we were very much aware of "Lecky's Wrinkles" A lot of his pronouncements were taken with a pinch of salt. That non- sense about the compensators affecting each other was a wrinkle too far. The farmer's Almanac said it but I think he was the one who wrote "The Sun Always Shines at Noon"
 
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A standard compass is always a conventional magnetic mariner's compass. It doesn't matter wen the gyro was installed on Olympic, it would have always been "per gyro" and not "per standard compass."

Actually, I think the question should be, "Why was the standard compass on Olympic and Titanic placed where an observer had such an obstructed view?" The 1962 edition of Bowditch (Page 135, para 622) says "...The compass designated as standard is usually a magneticc compass installed in as exposed position having an unobstructed view of most directions, permitting an accurate determination of error." The last part speaks to using bearings of fixed objects to ascertain error. Another sentence in that paragraph speaks to pre-gyro days, saying, "...Before the development o a reliable gyro compass, the standard compass was used for navigation of the vessel and for determining the error of the steering compass."

Finally, Bowditch talks about the reasons for both types of compasses and keeping records of their performances "...the...gyro has largely superseded the compass...directional information is so important to a vesssel that the availability of a second method is conseered justified. ...both types keep a record of errors and the performance of all compass and to compare the indications of magnetic and gyro compasses at frequent intervals , as every half hour when underway."

Note those words were printed 50 years after Titanic's demise, yet they still explain why the officers of that ship mad half-hourly compass checks throughout the day. Good practices never become outdated.

-- David G. Brown
 

Bob_Read

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Hi David: I appreciate the distinction between the "conventional magnetic mariners compass" and the gyro compass. However, as a functional definition wouldn't the gyro compass be the "standard" against which all other compasses would be compared?
 

Jim Currie

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To elaborate a little on what Dave wrote:

A Gyro compass has the unique ability to constantly point in the direction it is set pointing in. Thus, if it is set pointing in the direction of the North Pole, every direction read from it is a true direction. However, it is a mechanical device and as such, can malfunction for a number of reason...principally due to loss of electric power. Consequently, a Magnetic Compass has always been retained on board a ship to provide back up. This magnetic compass is not a Standard Compass but simply another means of determining direction. It follows that after the gyro became the means of guidance and observation, the role of magnetism in ship navigation was shelved, but not abandoned.

By the way, the expression "Standard Magnetic Compass" simply means a compass which is constantly checked for correctness and subsequently used as a reference for all other Magnetic Compasses on board ship. If that were not the case, then each and every other Margnetic Compass would require to be individually checked for error. because part of the error of a magnetic compass is due to where it is sited on board the ship.

To answer Bob's question...there were no "other compasses" in use after the adoption of the Gyro. All other compasses were simply satellites of the Master Gyro. Any one of these could be used to determine the error of the Master Gyro.
As for the one remaining Magnetic Compass...it was infrequently checked for error but it's reading was recorded at the end of each Watch. thus, in the event of a gyro failure the then magnetic equivalent would be used to steer by. The Magnetic Compass was sited above the helmsman using a periscope-type mirror for 2 reason:
1: The OOW could at any time, check the difference between it and the True Gyro course and the helmsman could use it for steering and
2: In the event that the Magnetic Compass became the prime means of direction finding, then its exposed position on the upper bridge allowed the OOW to observe the error of the compass using the azimuth mirror when ever the opportunity presented itself.
 
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The Standard was as named. The other two would be used according to the situation...i.e. when under pilotage or when on ocean passage.
Perhaps that's what the three headings were?
So if you are right, then the W-Comp. would be the magnetic steering compass in the wheelhouse, while the Stg. Comp. would be the one on the Capt.'s bridge in front of the wheelhouse that was used under pilotage.
So after the gyro compass was installed, would the magnetic W-Comp. in the wheelhouse have been replaced by a gyro repeater by which the helmsman would steer by in ocean waters?
 
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Perhaps the installation of a Kelvin's patented standard compass on top of the wheelhouse while still leaving the one on the amidships platform on WSL vessels in 1913 was done to see if atop the wheelhouse was a better overall location for the "Standard"? It certainly would have had a greater unobstructed view for taking bearings than the amidships location between two funnels.
 

Jim Currie

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So if you are right, then the W-Comp. would be the magnetic steering compass in the wheelhouse, while the Stg. Comp. would be the one on the Capt.'s bridge in front of the wheelhouse that was used under pilotage.
So after the gyro compass was installed, would the magnetic W-Comp. in the wheelhouse have been replaced by a gyro repeater by which the helmsman would steer by in ocean waters?
My bet is that the Stg (Steering) Compass was the one in the enclosed wheelhouse... the principal steering position on the ship.
The one on the Captains bridge would be used on 2 occasions:
1: When the ship was under Master's Command but following the advice of a Pilot
2: On passage... used by the OOW to periodically check the quality of the helmsmanship. This he could do in darkness without compromising his night vision by simply lifting the little inspection lid. He would do so during daylight hours if he looked astern and saw a "water snake" following the ship. (bad steering wake).

If a Gyro repeater was fitter retrospectively, it would have been mounted on a column pedestal to the immediate right of the steering compass and the latter would be helmeted. If an additional Magnetic Compass was mounted above the steering position without a reflector. they would have installed a two-way voice pipe so that the helmsman or a junior officer could participate in a compass check.
 

Bob_Read

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Sam: The only question I would have about such an experiment is how could one determine which of the two gave more accurate readings. I could understand how a magnetic standard compass could be compared to a gyro compass but if a standard magnetic compass is compared to another magnetic standard compass, which can be considered “more accurate”.
 

Jim Currie

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So why would there be a column for a magnetic compass labeled 'W-Comp.', and which compass would that be?
Well, Sam, if it is not the mid-ship compass and not the steering compass in the wheelhouse, there was only one other such compass left...the one used by the OOW and the Pilot.

Additionally. to determine a true bearing of an object using the bridge-wing Peloruses, they would obtain a bearing relative to the ship's head. This would entail 2 men...one at the compass on the Captain's bridge and one at the Pelorus. In that case, the steering compass would not be needed I suspect the procedure would have been as follows:
Before taking a bearing, Boxhall would go to the Pelorus and Moody would stand by the magnetic compass in line of sight on the captain's bridge.
At a given moment, Boxhall would measure the angle on the bow while Moody noted the ships head. The Pelorus angle would then be added or subtracted to or from the ship's head by that compass to determine the compass bearing of the object . Then, the error of that compass would be applied to the bearing to obtain the true bearing.
 
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Well, Sam, if it is not the mid-ship compass and not the steering compass in the wheelhouse, there was only one other such compass left...the one used by the OOW and the Pilot.
Then my only question would be why label it W-Comp.?
For use in channel waters, the Courses on board book page had columns labeled From and To and columns for listing the course on the Std. Comp., and the Stg. Comp. only. There were no columns for listing compass deviation, and there was no column for the W.-Comp.
 
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This question is a little off topic as far as Titanic but it does have to do with Compasses and is for some of you more seasoned mariners here. I've read and my Dad told me the same thing that during WW2 a lot of the ships compasses were filled with grain alcohol so they wouldn't freeze and were more stable. But they had a problem of getting drained if you know what I mean...LOL. Is this true or just a myth over the years? I know the US Navy did have an issue with torpedo fuel (also grain alcohol) that supposeldy they added chemicals to it to make it undrinkable. But the compass story sounds a little fishy because aren't they all on the bridge?
 
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Jim Currie

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This question is a little off topic as far as Titanic but it does have to do with Compasses and is for some of you more seasoned mariners here. I've read and my Dad told me the same thing that during WW2 a lot of the ships compasses were filled with grain alcohol so they wouldn't freeze and were more stable. But they had a problem of getting drained if you know what I mean...LOL. Is this true or just a myth over the years? I know the US Navy did have an issue with torpedo fuel (also grain alcohol) that supposeldy they added chemicals to it to make it undrinkable. But the compass story sounds a little fishy because aren't they all on the bridge?
If they were, Steven, then it was not done by crew members. Many of my friends were torpedoed during that war and the boat compass was a very precious thing. What I do know, though (still off topic) is that when they found themselves adrift in a lifeboat and opened up the stores container, the often found that the dockers had already been at the condensed milk and the barley sugar. The same thing happened with our food parcels from my family in Philadelphia... they were usually broached and the fags ans sweeties were missing. So you see, this generation does not have the monopoly on selfishness:mad:
 
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Doug Criner

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In the early 1960s, I served on an old WW2-era destroyer. There was a back-up magnetic compass incorporated in the helmsman's position. I can't imagine how anybody could drain the fluid without anybody noticing. And if the fluid were alcohol, I'd expect that it was denatured. Of course, we had a gyro compass that we relied upon and used for steering, gun/torpedo fire control, and taking bearings.
 
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Jim, Doug thanks for the replies. I kind of didn't think the story held much water. It might have happened once or twice but them being on the bridge it didn't make much sense. However, my stint as a ships Master at Arms educated me on the lengths swabbies would go to get booze onboard...:p
 

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