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Discussion about the dimensions of the pilot jack

Border = one-third of union height (1-3-1): The Pilot Jack according to one interpretation of the 1833 Kings Regulations

5:8 image by Martin Grieve

Border = one-fifth of union height (1-5-1): The Pilot Jack according to the Warrant of 1823/24

7:12 image by Martin Grieve

Border = one-third of union height (1-3-1), stretched to 1:2 ratio: The Pilot Jack according to current usage
(shown here as used in the Queen's Harbour Master flag)

1:2 image by Martin Grieve

See also:

It would appear from Christopher Southworth's personal notes, that the "officially correct" overall ratio of the flag should be 5:8. The overall ratio of the 5:8 version is achieved by adding a white border around the Union, this border being one third of the hoist dimension of the Union, which in turn has an overall ratio of 1:2. This flag was first introduced in 1823 as a signal for a pilot in Marryat's Code of Signals for the Merchant Service, and had come into use as a Civil Jack by the mid-Nineteenth Century. It was formally adopted by an Order in Council (which abolished squadron colours in the Royal Navy) of 9 July 1864, and was last regulated by article 4(a)(iii) of the Merchant Shipping Act (1995). The specification given here is based upon the provisions of the 1894 Merchant Shipping Act, however, later legislation is less specific and current practice is to make the flag's overall proportions 1:2, thus distorting the Union.
Martin Grieve, 28 November 2003

It would appear that the flag with dimensions 5:8 is not made (both as to width of border and details of the Union) according to the original regulations which established it, with the relevant section of the Admiralty Warrant dated 8 July 1823, published in London Gazette No. 17938. and effective 1 January 1824 reading as follows:
"...should have an entire white border, such border being one fifth of the breadth of the Jack itself, exclusive of such border",
and this is apparently confirmed in a slightly truncated form by the "Instructions to Consuls etc..." which accompanied the 1854 Merchant Shipping Act which states:
"A British Union Jack with a border of White of one fifth of the breadth of the Jack."

As far as we can see, this can only be interpreted to mean that the border should be (or was originally regulated at) one-seventh the flag [giving dimensions 7:12], rather than the one-fifth which is currently used. However, it strikes me that this latter statement, whilst perfectly clear if viewed in conjunction with the previous regulations, if taken in isolation could possibly be the source of the mistaken interpretation commonly seen [i.e. the 5:8 flag].
Christopher Southworth, 12 October 2004

The problem here seems to come with the very ambiguous, and therefore poor, English that was issued from the powers-that-be at that time, and the confusion would perhaps come from the term "Jack". Are they (the Admiralty) talking about the UNION Jack or the PILOT Jack, i.e., the flag itself in this instance? If we assume that it is the Union Flag that they are talking about, then the dimensions down the hoist would be:
    1: White border
    5: Union FLAG
    1: White border
The Union to remain at 1:2 presumably. This means that the white border is is at 1/7th the overall hoist width [and yields a flag overall of 7:12].

But if we are to assume that the term "Jack" means the flag (pilot JACK) in its entirety, then:
    1: White border
    3: Union FLAG
    1: White border
The Union to remain at 1:2 presumably. This means that the white border is 1/5th the overall hoist width [and yields a flag overall of 5:8]! And this is the version that Chris, David and myself are talking about.
Martin Grieve, 13 October 2004

This is the problem. The 1823 Warrant is specific and exact in that it states the flag "should have an entire white border, such border being one-fifth of the jack itself exclusive of such border", and there can be no doubt that in this instance the "jack" referred to by the Admiralty was the Union itself (therefore a flag of 1-5-1).

The "Instructions to Consuls" issued following the Merchant Shipping Act of 1854, however, give "A British Union Jack with a border of White one-fifth of the breadth of the Jack" which is, as been suggested, open to differing interpretations. If we bear in mind however, that the flying of this flag as a jack was not one of its authorised uses, then in using the term "Jack" we may be reasonably certain that the Admiralty were once again referring to the Union. I say "Admiralty" advisedly, because while the "Instructions" were (in fact) issued by the Board of Trade, the wording given above was actually a repeat of those in the 1833 revision of the King's Regulations for the Navy.

It is, of course, entirely possible that the confusion with regard to the width of the border may stem from this flag being itself used as a jack, when a casual reference to the Admiralty instructions would lead to proportions of 1-3-1?

As I see it the situation is this: the flag was originally regulated with a border equal to one-seventh the flag, but this has (for whatever reason) become one-fifth over the course of time. The flag was originally regulated to have that border surrounding a Union Jack whose proportions were (and are) 1:2, but over the course of time this has been mutated into a flag whose overall proportions are 1:2, with a distorted Union within the border.
Christopher Southworth, 13 October 2004

To the two versions above, one may easily add two versions with the overall flag proportions set to 1:2. It may well be that all four have been used at some time, but if I understood Chris correctly, there is indeed only one possible correct reading, even if it was not always observed - and, of course, all real flags deviate from the ideal pattern more or less, so any of the above variants would be acceptable, more or less.
Željko Heimer, 13 October 2004

I think I've got it, the point at which the border of the Pilot/Civil Jack definitely became one-fifth the flag. My only excuse for the delay is the sheer volume of paper involved and the relative obscurity of the source concerned. However, The Schedule, "Signals to be made by Ships wanting a Pilot", which forms part of an Order in Council of 12 December 1894 issued in accordance with Article 615(1) of the Merchant Shipping Act of 1894) states
"1. To be hoisted at the fore, the Union Jack having round it a white border one-fifth the breadth of the flag"
Christopher Southworth, 14 October 2004

The Signal/Pilot Jack was a signal flag, not a jack. The basic shape was more nearly square than oblong. Marryat suggested that signal flags used by merchant ships should be 6 feet x 8 feet. As a signal for a pilot, British merchant ships were thus using a Union Jack with a ratio of 3:4. The Signal Jack with a white border that was required in 1824, would probably have been constructed by adding a white border to an existing Signal Jack resulting in a flag with a ratio of 4:5, but no doubt as new suits of signal flags replaced old flags White-Bordered Signal Jacks would have been made in ratios of 3:4. The White-Bordered Signal Jack was adopted as a signal flag by the Royal Navy in 1826 and continued in use until 1948 when the white border appears to have been about 1/7th of the breadth of the flag, as seen on this image showing International Mike over Signal Jack on HMS Comus, August 1946.

White-Bordered Union Jacks that were used as jacks were unofficial and therefore did not need to conform to any specifications. Since the intention was to have a flag that looked like a Union Jack, without actually being a Union Jack, you would think this best achieved by having a Union Jack with a ratio if 1:2, and adding a small border, giving a flag with an overall ratio of about 6:11.

The King's/Queen's Harbour Master flag is specifically a crown and initials on a White-Bordered Union Jack, and not on a Signal Jack, which would have had the proportions of a signal flag. The latter was considered for the role but thought to be too insignificant.
David Prothero, 14 October 2004

Assuming that the merchant service actually adopted a 3:4 unaltered Union as signal Jack during the two years before 1824, and a white bordered Union in the same proportions during subsequent years, then that scuppers yet another theory (or at least puts it into serious question). We now know when the one-fifth border was regulated for the merchant service (1894), but are however, still left with the mystery of when the overall proportions of 1:2, and consequently distorted Union, became standard practice? We know from the Flaggenbuch that it had become so by 1939, but when and how did a signal proportion of 3:4 become a standard sea-going ratio of 1:2?
Christopher Southworth, 14 October 2004

In the early years of the 19th century the Union Jack was the signal usually displayed by merchant ships wanting a pilot. The Admiralty Warrant, of September 16th 1822, includes:
"... His Majesty's Jack, commonly called the Union Jack, a Jack made in resemblance thereof, hath been the usual signal displayed and kept flying for pilots to come on board merchant ships and vessels on the coasts of this United Kingdom; ..."

Based on very limited information I have come to the tentative conclusion that soon after 1901 the white-bordered Union Jack (roughly 3 : 4), probably went out of general use as the signal for a pilot, and that the elongated version, which continued in used as an unofficial merchant jack, retained or acquired the name 'pilot jack'. Later, the fact that the flag, as a pilot signal, had been more square than oblong was forgotten, and it was assumed that it had always existed in its elongated form.

In 1900 the International Code of Signals Committee wrote:
"At present the single-flag signal to be used by British vessels requiring a pilot is the Union Jack with a white border. This flag is not suitable for international use, and there is a great diversity of practice amongst foreign countries in regard to the signal to be made by vessels wanting pilots. Some countries use their jacks with a white border as a signal for a pilot; while other countries use their ensigns or jacks without a white border, or the blue peter, or a special flag; and others seem to have no single-flag signal for a pilot, and use the flags P and T of the International Code, which mean 'I want a pilot.' We gather that foreign maritime powers are generally agreed as to the desirability of there being an internationally recognized single-flag signal for a pilot, and we are of the opinion that flag S (blue centre with a white border) is well adapted for this purpose. We therefore recommend that the Board of Trade should obtain an Order in Council making legal the use of flag S as a signal for a pilot."

The white-bordered Union Jack was still a legal signal for a pilot, and remained so until 1970, but I doubt that many ships bothered to carry a special flag, that could be used only as a pilot signal, when one of the International Code flags could be used instead. It is strange that the Flaggenbuch featured national pilot flags at all. They were not included in the Admiralty Flag Books. I suggest that in the case of the British pilot flag, they were unable to discover the correct form, and assumed that it had the same dimensions as the flag of the King's Harbour Master.
David Prothero, 18 October 2004

The only official merchant jack is the white-bordered Union Flag which you list. However, others are used by some smaller passenger ships. The ferries of Caledonian MacBrayne have for several decades flown the Scottish Saltire from the jackstaff. The preserved paddle steamer "Waverley" has often flown the Saltire too, but I have also seen her fly the St. David's Cross, and I have a postcard of her flying the White Horse of Kent in that position. I wonder if there are other similar examples?
Kenneth Fraser, 24 August 2011

I can confirm the use of the St Andrew's Cross by the 'Waverley', and I have also seen on other vessels the Welsh flag ('Y Ddraig Goch' - the Red Dragon, as opposed to the St David's Cross) used as a jack (and, indeed, an ensign). Expanding this across the English Channel, Brittany Ferries ships fly as jacks either the Breton 'Gwenn ha Du' or the Norman two lions, depending on which route they are on.
André Coutanche, 24 August 2011

Discussion about the dimensions of the pilot jack

Border = one-third of union height (1-3-1): The Pilot Jack according to one interpretation of the 1833 Kings Regulations

Border = one-fifth of union height (1-5-1): The Pilot Jack according to the Warrant of 1823/24

Border = one-third of union height (1-3-1), stretched to 1:2 ratio: The Pilot Jack according to current usage (shown here as used in the Queen's Harbour Master flag)

Border = one-third of union height (1-3-1), stretched to 1:2 ratio: The Pilot Jack according to current usage
(shown here as used in the Queen's Harbour Master flag)