HMS Conway (school Ship) - Loss of The Ship

Loss of The Ship

By 1953 another refit was due. This could not be done locally so the ship had to be taken back to Birkenhead dry dock, passing back through The Swellies once more.

The operation took place on 14 April 1953. There were the same two Liverpool tugs which had shifted her several times before, "Dongarth" forward and "Minegarth" aft. The new Captain Superintendent, Captain E Hewitt RD RNR was in command, with two Trinity House local pilots, Pilot R D Jones (junior) aboard the head tug, Pilot R J Jones (senior) advising Captain Hewitt, with Blue Funnel Liverpool Pilot James Miller overseeing the towage.

High Water Liverpool that morning was 1118 am, height 32'10" and the highest tide that year (Admiralty Tide Tables) Lavers Almanac quote HW Menai Bridge as 28 minutes before HW Liverpool (L.pool -00.28). What is termed High Water 'Slack' in the Swellies is actually a brief period of uneasy equilibrium between two opposing flood streams which typically occurs 1 hour 42 minutes before local High Water. (L.pool - 2.10, or 0908 that morning - (Caernarfon Harbour Trust) Owing to the strength of the SW-going ebb, which Admiralty chart 1461 states runs at 8 knots at Springs producing a confused complex tidal flow among the numerous rocks and islets generating many powerful eddies (Anglesey Pilot p17 para106) on a big tide in particular it's vital for an outbound vessel to be through the Swellies before the tide turns against her, a point which cannot be over emphasised. It's therefor the local practice to start the outward transit with the last of the NE-going flood 20 minutes before the 'Slack'. (L.pool -2.30, or 0848 that morning) (Caernarfon Harbour Trust)

The least depth in the principle channel through the Swellies, the South Shore Course, is the depth over Cheese Rock, which is the 4 ft sounding shown on the chart 270 ft east of Britannia Bridge. Since the chart title clearly states that soundings between the bridges are reduced for the same 22 ½ feet rise and fall as Menai Bridge, it would be a very easy mistake to add the height of the tide at Menai Bridge to soundings to figure the depth at that time at any given point between the bridges. But the title also states that when the tidal range is 22 ½ feet at Menai Bridge it's only 19 feet at Britannia Bridge(Pwllfanog). So while the depths at the N-Eastern end of the Swellies are figured on the tide at Menai Bridge, at the S-Western end depths must be figured on the tide at Pwllfanog. Using the familiar sine formula, the graph on the Conway site shows the red curve (b) which is the depth over Cheese Rock correctly calculated on the tide at Pwllfanog. This shows the ship would have her 21' 10" draft over the rock 35 minutes before the 'Slack' (0833) and this is confirmed by Caernarfon Harbourmaster Richard Jones' physical measurements taken 22.02.2000 (see his graph) But the blue curve (a) on the Conway graph shows that erroneously working the depth on the tide at Menai Bridge would give the false result that the ship would not have the water over the rock until L.pool -2.00 (0918). So, it being a rising tide, Capt. Hewitt decided he would have to delay the transit by half an hour until 0920, (Subcom p1 line 14 although the aforesaid graphs and measurements show the ship did have the water at 0833.

The streams in the Menai Strait are affected by winds outside in the Irish Sea. With a strong North or North-westerly wind both the rate and duration of the Southwest-going ebb are increased, and the Southwest-going ebb may begin quarter of an hour earlier. (Admiralty Pilot vol 37; p 315; line21) The 0600 synoptic chart showed a stationary deep depression west of Norway with a secondary Low in the North Sea, and a High steadily closing the west coast of Ireland, which could be expected to result in an increasingly strong NW'ly wind in the Irish Sea. But in the shelter of the Plas Newydd mooring there was no indication of this. At 0800 as the wind was being recorded in Conway's logbook as northerly force 1-2 (2 to 5 knots), only 13 miles away on station off Point Lynas it was being recorded by the Liverpool Pilot boat as NW force 6 (22 - 27 knots) (Subcom p4 line 7) and her noon entry was NW force 7, (28 - 33 knots) (Beaufort wind scale) while during the morning Bidston Observatory was recording gusts up to 49 knots (storm force 10).

The Investigating Subcommittee was later to express its "surprise" that Captain Hewitt had left the Plas Newydd mooring without a weather forecast, and "had no knowledge of the stormy conditions prevailing at sea at the time Conway was to make the passage" since it was local knowledge that in such weather "abnormal conditions might be encountered." (Subcom p4 para 5) In addition to the tide generated streams in the Menai Strait there is also a non-tidal current, the Southwest Residual a dynamic reaction which directly reflects wind stress in the Irish Sea. Dr Toby J Sherwin, Estuarial research Menai Bridge, referring to a formula in Simpson et al page 252, explained how the North-westerly mean wind speed of 16 meters per second at sea that day would enhance the Residual by 15 cm per second, increasing the strength of the SW-going ebb at Plas Newydd by 3 knots, "And quite obviously by a lot more than this in the narrow sections of the Swellies." (loss p9 para 2)

Conway's logbook shows she left the mooring at 0822 and arrived at Britannia Bridge at 0850, which was the locally recommended time for starting the outward transit and Pilot Jones naturally advised keeping her going with the last of the northeast-going flood tide behind her. Instead Capt Hewitt had the ship brought up for half an hour to await his 0920. The severe wind in the Irish Sea caused the stream in the Strait to turn to the westward earlier (Anglesey Pilot p17 para 104) which eliminated the brief slack water period. Capt F J Durrant, Marine Manages of the towing company, observed "The anticipated ten minute slack water did not materialise. The ebb set in immediately the flood ended at 0920" (Durrant p4 para 1) With the ship far too late and sensitive to the adverse conditions Pilot Jones advised going back, instead the logbook shows Capt.Hewitt passed the ship under Britannia Bridge at 0923 even though the ebb tide was already setting against him which was quite contrary to all local practice.

Only 17 minutes later, "At 0940 ..... the forward tug "Dongarth" was towing at full speed against the tide but making no further progress." (Durrant p4 para 4) By 1010am, 47 minutes after passing under the bridge, the tow was still in much the same position having made good only six tenths of a mile from the bridge, (Subcom p5 para5) giving the tide another half an hour to develop further, yet it was not until then that Capt. Hewitt had the stern tug slipped and sent forward to assist the head tug, (photo) when "headway became slight but noticeable" (Durrant p5 para 4) By 1020, already a full hour into the ebb, the pilots had worked the ship across the tide and into the eddy which Anglesey Pilot p17 para 106 states forms near the Anglesey shore close westward of the northern pier of the Suspension Bridge, (photo) and intended holding her there in the safety of this until the strength of the tide had abated. Instead, with only 750 feet to go to the bridge, Capt. Hewitt ordered that the ship be put back in the channel and this was done. Almost immediately, at 1030, she was suddenly caught by an eddy of overwhelming strength which drove the ship ashore over The Platters. "This disastrous sheer occurred and was concluded in a matter of seconds" (Durrant p5 para 5) (photo) (see chart which also shows the position where the ship finished up, which was 'inked in' by Capt Reece-Thomas who was Caernarfon Harbourmaster at the time) Contrasting with the 18 minutes she had taken to complete the inbound transit, the outbound ship had been 1 hour 7 minutes covering the 1200 yards from Britannia Bridge where the pilot had advised going back.

After both tugs on full speed for ten minutes had failed to make any impression they were instructed to stand bye at Menai Bridge Pier for another attempt to re-float her on the evening tide when there would be a better opportunity if the weather at sea moderated. (Durrant p6 para 2) But a third tug, "Grassgarth", sent out at 1430 to assist in towing her off was forced to put back to Liverpool through stress of weather. (Durrant p6 para 4)

While her fore part planted firmly on the shelving shore her stern was floating in 30 feet of water. As the tide fell the stern lost its support (photo) causing the ship to become severely hogged which opened up her seams, and about her midship sections the height between decks was reduced from over 6 feet (1.8 m) to less than 4 feet (1.2 m). (photo) "Conditions on board were very bad with the after end of the ship from the mainmast sagging downwards, and the continuous sound of cracking, twisting, rending timber and rushing water below" (photo) (Durrant p6 para 7) When the next tide made the stern failed to lift and the ship flooded freely through her open seams. Being evident that further attempts to tow the ship off would be to no purpose, the tugs were discharged and left for Liverpool the following morning. Two days after the grounding, in the evening of 16 April 1953, surveyors declared "HMS Conway" a total constructive loss. The ship was not insured.