The addition of a compass to Olympic and Britannic


Jim Currie

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One thing I do agree with Dave about is that there can only be one standard compass. It is the standard to which other compasses aboard are adjusted. There are a number of things I want to set forth as what I understand. If I am wrong then I welcome correction:
1. I can possibly understand the designation of a standard compass on the wheelhouse roof of Olympic which would render the midship compass to an unknown role.
2. What I can't understand is that while the change in compass locations on Olympic was a retrofit, the same cannot be said of Britannic.
3.While Britannic was being planned for mercantile service, her Specification Book lists both a wheelhouse roof compass and a midship compass.
4. This Britannic compass configuration can be confirmed by photos of HMHS Britannic.
5. It is obvious that the wheelhouse roof placement of a standard compass would be more convenient.
6. It is most likely that the midship standard compass location would have the least magnetic interference.

These observations still don't explain why if the wheelhouse roof compass was the standard compass then what purpose would the midship compass serve? The opposite statement would also hold true. Attached are two entries in the Britannic Specification Book. The one specifies all compasses aboard but does not designate which would be the standard compass. Another interesting side note is the description of the midship compass platform. In the Shipbuilder journal for Olympic it describes the compass platform as "brasswork". In the Britannic Specification Book the compass platform is described as galvanized ironwork.



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I can offer the following:

While all three vessels were built from essentially the same plans, the effect of the earth''s magnetic field on the so-arranged mass of ferrous metal relative to the position of the Standard Compass would not be known until the first vessel went into service. Titanic went into service less than a year after Olympic consequently, data on induced Standard Compass errors and the positions of compensating magnets on the binnacle was still being collected. You may be surprised to know that the run these ship's were on also had to be considered/
The siting of a standard compass binnacle mid-ship on Titanic was an indication of the shortage of understanding as to how induced magnetism by the earth's field effected the compass combined with the normal practice on standard vessels where the navigation and control center was traditionally amidship or nearly so. In fact. it was found that judicious arrangement of the compensating magnets in the binnacle would allow the standard binnacle to be sited anywhere on the deck. The next big problem was the changing of generated electricity-carrying cables near the compass from DC to AC.
In 1913, the Sperry Gyro Company began producing gyro repeaters for ships in the UK. The RN already had them.

The year following the Titanic disaster was a game-changing one with regards to ship's steering and navigation compasses.
 

Bob_Read

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Jim: So What is the answer to my question:
On post 1913 refit Olympic and HMHS Britannic which was the standard compass: the wheelhouse roof compass or the midship compass? And whichever was the standard compass, what was the purpose of the other?
 

Jim Currie

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I thought I had answered that earlier? However, there is no practical need for 2 standard compasses an any ship. In fact, in the case of a multi-funnel vessel, a mid-ship one is inferior to a "monkey island" mounted one...i.e... above the main steering position. The purpose of retaining the mid-ship one is anyone's guess. However, if it was retained as a back-up. it would b e subject to periodic compass adjustment ... probably at the quadrennial drydocking. In addition, as In have pointed out. Gyros were being installed in many ships and the master gyro would also be close to the steering and standard compasses. Hence, keeping everything up to date and accurate was much simplified.

A little bit of extra info for you...All British MN Masters Mariners were intensively trained and subsequently examined in compass management and adjustment. Consequently, a person so qualified could easily change professions to that of a Compass Adjuster.
 

Bob_Read

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Jim: Is it possible that the wheelhouse roof compass of Olympic in 1913 was actually a gyro compass which they were experimenting with and the midship standard compass readings were being compared with the gyro readings?
 

Jim Currie

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A gyro compass system consisted of a master and repeaters. If there had been any Gyro equipment on the monkey island it would have been a bearing repeater. Normally when a system was fitted , the master was installed in a separate room on repeaters were located at the side of the Helmsman, on the bridge wings and on the monkey island. By 1913, the British and American Navies had Gyros fitted as standard. I suspect that ship's like RMS Olympic would have been earmarked as naval auxhiliaries in the event of hostilities and that it is just possible that a gyro system was installed by the Navy. In saying this, it should be borne in mind that the first non military, commercial version installed was aboard the Cunarder, RMS Aquitania which was built in 1913 and had her maiden voyage to New York the following year...1914, but I don't know if she had a gyro when launched at Clydebank.
 
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Mar 22, 2003
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The purpose of retaining the mid-ship one is anyone's guess.
I agree. It is clear that the two compasses that were equipped for Britannic were of the same make and model, one for each of the two locations. The only question is which one was considered "the standard compass" on board the vessel? Each would have suffered from some deviation errors, and deviation error for a given direction will change somewhat over a period of time. In fact, one of the things that Boxhall was doing the night of the disaster was taking stellar bearings to check deviation error of the amidships compass, and it was an IMM Co. rule (253) that compass deviation error should be checked often and compasses were to be compared with each other every watch.

"253. Steering and Compasses.-- He [the officer of the watch] must pay particular attention to the steering and the course the ship makes. He must steady the ship on her course by standard every half-hour, and must compare the compasses every Watch, the comparisons to be entered in Compass Comparison Book for reference. He will also ascertain the deviation as often as possible."
 

Bob_Read

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Sam: I am considering a new possibility. On both Olympic and Britannic in 1913 it may have been that they were experimenting with a gyro compass on the roofs of the wheel houses of both ships and compared them to a standard magnetic compass amidships. Since the gyro compass required power, the possibility of a power interruption to the gyro compass would have made the retention of a standard magnetic compass as a back-up prudent. The year 1913 seems to be a watershed year for mercantile applications of gyro compasses.
 
Mar 22, 2003
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Ah, just found something in my personal notes from years past. This one was from Dave Gittins that may be of interest.

"It may be that whoever planned it was aware of the thoughts of Captain Lecky, in his famous Wrinkles in Practical Navigation, which was hugely popular in Britain for many years. Lecky was very interested in the antics of the compass and warned against the common practice of mounting the standard compass on top of the wheelhouse. He feared the influence of the correcting magnets in the two compasses, which would interact with each other in weird ways."

There was a "Courses on board" book for Olympic that I have seen that contained three columns: One marked 'Steering compass' another 'Standard compass' and the third marked 'W-compass'. Each of the three compass columns actually consisted of two columns, one for the course and another for the deviation error. Course were (for example) always written as N 82° W, and deviation (for example) as 2.5° E. In the 1920's the column marked W-compass was crossed out and the word 'gyro' was put in. In that column they recorded gyro headings in modern notation such as 270°T.
 

Bob_Read

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Sam: I know the book but the only problem in this case is that the year of the entry is 1930. I looked at the Andrews Notebook and it reflects 1913 refit changes. The problem is that it lists 4 magnetic compasses. The one odd thing is that all the compass entries are underlined except the one for the wheelhouse roof. Since the wheelhouse roof compass eventually was replaced by a gyro compass, I wonder if it was actually done late during refit.
 
Mar 22, 2003
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For what its worth, the "Courses on board" book used for Olympic in the years following her refit had three column pairs pre-printed in it for the transatlantic part of the voyage. The three column pairs were labeled: Std. comp., Stg. Comp., and W. Comp. Each compass had a column for writing down both the compass course and the compass deviation. There were also in the book a column for writing down the magnetic variation labeled Var. W'ly., and a column labeled True Course. There were also columns for the ship's Lat. N., Lon. W., the Day, Month, Date, Hour From and Hour To for a particular course run. When filling out a given row for a particular run, values were entered into all of these columns.
However, for use in channel waters, the page only had columns labeled From and To and columns for listing the course on the Std. Comp., and the Stg. Comp. There were no columns for listing compass deviation, and there was no column for the W. Compass. It was only during the the transatlantic part of the voyage that courses and deviations on all three of these magnet compasses that were logged.

After they installed a gyro compass on Olympic the Courses on Board book showed the printed words "W.Comp." crossed out and replaced with the handwritten word "gyro". For the channel crossings, the gyro compass values were written in the column for the Stg. Comp. But the "Std. Comp." columns for both channel courses as well as transatlantic courses were still being written in. And the the value written into the "True Course" column always equaled the Std. Comp. course after adjusting it by the variation and std. comp. deviation to a 1/4 of a degree. Thus you may see something like "S 43 3/4 W" written in the true course column while the gyro course in the cross-out W. Comp. column was entered with three digits, e.g., 224, and no fractions.
 
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The mariner's compass has never been "replaced" by gyro compasses. Yes, in many ways the gyro has superseded the mariner's compass, but the magetic instrument is still considered a vital piece of equipment. The time-honored devices keep right on working even in a power failure, fire in the gyro room, or other such incidents. Plan for the worst, expect the best.

The Grreat Lakes where I live has a fleet of old, retired ships built in and around Titanic's time. The older teak and bronze binnacle still is proudly queen of the wheelhous. The Gyro repater is most often on a tripod mount off to one side (usually starboard in my observations) at a comfortable distance not to interfere with the magnetic instrument.

I'm glad that Sam mentioned the compass book. No matter what the purpose served by the platform compass, it was aboard ship. As a navigation compass, its performance had to be recorded per company rules and common sense. Regular records meant that in the event that the new roof-top instrument failed, there was immediate backup. Belt, suspenders, and safety pins.

Note that the book was not reprinted immediately after adoption of gyro compass aboard Olympic. Instead an old column heading was scratched out and a new heading put in by hand. Parsimonious, those boys in the head office.

-- David G. Brown
 

Jim Currie

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I suspect that the letter "W" referred to a bridge-wing gyro repeater . These were so mounted to allow the officer doing the navigating or who had the con, to take gyro bearings of an object without the need to climb up onto the monkey island to do so. Gyros did have an error but it was very small, constant and in the order of a quarter or at most, a half degree. It was not easy to eradicate.
As Dave very rightly points out, the Standard Compass has never been replaced by a mechanical/electronic one. All ship still have a Standared Magnetic Compass fitted.
We must be careful when interpreting the WSL Rules... In particular the bit which states " He must steady the ship on her course by standard every half-hour, and must compare the compasses every Watch, "
Note that the word "Standard" is not capitalised. It would not be necessary to steady on the standard course until the error of the Standard Compass altered by at least half a degree. Titanic was on a Westerly course therefore the Westerly Magnetic Variation error was reducing by about half a degree every 6 hours. If the course was constant, then the Deviation error would remain fairly constant.
The "standard" course would be verified by compass comparisons every 4 hours, starting at 2 am. each day.i.e.. when the senior officers changed Watches. This would incorporate any changes in Deviation or variation calculated during the previous 4 hours. Discovery of any meaningful change before that time would result in immediate and appropriate heading adjustment
 
Mar 22, 2003
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I suspect that the letter "W" referred to a bridge-wing gyro repeater .
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.
 
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Mar 22, 2003
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Note that the word "Standard" is not capitalised. It would not be necessary to steady on the standard course until the error of the Standard Compass altered by at least half a degree. Titanic was on a Westerly course therefore the Westerly Magnetic Variation error was reducing by about half a degree every 6 hours. If the course was constant, then the Deviation error would remain fairly constant.
Good point! The course board in the wheelhouse was marked with the standard compass course and the steering compass course. The rule required compasses to be compared once per watch, that is every 4 hours.
 
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No matter how the columns were headed in the compass book, the question still amounts to, "Why two standard instruments, a practice which would negate the whole concept of having one standard reference for all navigation?"

-- David G. Brown
 

Bob_Read

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David: I agree with you about having two standard compasses. What I’m trying to investigate is when a gyro compass was installed on Olympic. If a gyro compass (or repeater) was installed on the roof of the wheehouse, that could explain it being the standard compass and the one amidship being a back-up in case of an electrical power failure to the gyro compass.
 

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