Well, you did ask... An extract from the current PLA General Directions is below. I think in plain English this means (noting that the term narrow boat is not defined)
any narrowboat can transit between Brentford & Teddington (clause 1a), contacting VTS by telephone (3)
any pleasure vessel, not planning to fish, and less than 13.7m, can go anywhere without a radio (clause 1) - I agree with comments above about the wisdom of doing this
a convoy of boats over that length can go down as far as Bow Creek (1b), provided one of them has VHF, can speak English (clause 5d), and can communicate by phone, walkie talkie, shouting or semaphore to the others (1b iii), and that they give 7 days notice (4a)
I am not quite sure what the rules are for a 40 foot coal boat - that might count as bunkering .... In practice the third rule applies to well organised convoys going down through the Barrier. When we went to Gravesend we all had VHF and we a had a serious safety boat as well.
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4. USE OF VHF RADIO
(1) With the exception of General Directions 4.2, this Direction shall apply to:
• Reporting Vessels;
• Passenger Boats;
• Tugs;
• Bunker Vessels;
• Vessels engaged or intending to engage in fishing; and
• Vessels of 13.7m or more in length overall
except:
a) narrow boats greater than 13.7m in length overall navigating between Brentford
and Teddington;
Pleasure Vessels greater than 13.7m in length overall navigating to the west of
Bow Creek, provided that:
i) they are travelling in company or a flotilla;
ii) they are not the lead vessel of that company or flotilla; and
iii) there is a lead vessel, which complies with the requirements of this
Direction and is able to communicate immediately and effectively with all
other vessels in the company or flotilla; or
c) vessels under oars.
(2) On all vessels fitted with VHF radio, the Master shall ensure that VHF channels
utilised by London VTS are used only for reporting safety of navigation, emergency
and urgent communications and for no other purpose. All such VHF
communications shall comply with the guidelines contained within IMO Resolution
A.954/23 (proper use of VHF channels at sea).
Note: London VTS Operates on the following VHF channels;
Outer Limits to Sea Reach No.4 Buoy – Channel 69
Sea Reach No.4 to Crayfordness – Channel 68
Crayfordness to Teddington – Channel 14
(3) A narrow boat excepted under Directions 4. (1) a) above, shall call London VTS by
telephone and report it’s estimated time of departure from the point of departure and
estimated time of arrival at it’s destination.
(4) Any vessel or group of vessels planning to exercise the exemption under
Direction 4. (1) above, shall either individually or through the lead vessel:
a) provide at least 7 days notice to the Harbourmaster of their intention to navigate
on the Thames;
comply with any conditions for their passage required by the Harbourmaster; and
c) report, through the lead vessel, to London VTS prior to commencing navigation
on the Thames, providing details of the vessels involved, their destination and
estimated time of arrival. Upon completion of the passage the lead vessel shall
inform London VTS of their arrival.
(5) On every vessel to which this Direction applies, at all times when underway or at
anchor there shall be:
a) an operational VHF radio capable of communicating with a Harbourmaster at the
VTS Centres;
an effective, continuous listening watch maintained on the VHF channel
appropriate to that part of the Thames in which it is navigating or lying;
c) compliance with the communications requirements set out in these Directions for
the use of VHF radio; and
d) manning and operation of the VHF radio by a suitably qualified person, capable
of communicating effectively in English.
(6) Prior to a vessel’s departure from a berth, pier or anchorage, the appropriate PLA VHF
channel shall be monitored for information that may affect the safe navigation of the
vessel, including the routine half-hourly VHF navigation information broadcast made
immediately prior to the intended departure time.
Note: Notwithstanding that only Reporting Vessels routinely report their movements
(see General Direction 13), other than in the Thames Barrier Control Zone
(see General Direction 27), other vessels to which this Direction applies
should generally “listen and learn” from VHF radio traffic. They must
however, report in an emergency and when required by the Harbourmaster.
(7) Reports by Specified Vessels navigating in the Thames shall always be prefixed with
the word ‘SPECIFIED’ in any VHF communication with a VTS Centre or other vessel.