The ships mentioned in his service record show that he enlisted in 1915 – first ship shown as SABRINA (ASTRUM SPEI) – this means that pay and paperwork were controlled by the Sabrina – the name of the Auxiliary Patrol base at Milford Haven, but he was actually serving onboard the Astrum Spei, which was a drifter from Banff in Scotland, although then at Milford H. In November 1915 he was MANZANITA (ASTRUM SPEI)
MANZANITA was a former Lowestoft trawler that acted as the base and depot for the ships on the Otranto barrage – this means that he was still serving on the Astrum, but pay and paperwork were administered by the larger vessel.
He is then shown under THALIA from 1916. This was the name of the base at Peterhead, Aberdeen. This was simply an administrative move – everyone in the Navy has to belong to a ship – as his had been lost, he was borne on the books of Thalia, but noted as being a PoW.
Later ‘ship’ entries, Nairn and President are again, simply for admin: NAIRN took over from Thalia as the base at Peterhead, and President is the base for Naval Reserves in London.
Background - The Austro-Hungarian Empire, which then controlled what is now Croatia, Serbia and Bosnia was allied to Germany in WW1. There was a threat from Austrian submarines in the Adriatic and Mediterranean.
In 1915 the British and their allies attempted to establish a blockade of the Adriatic Sea by establishing a line of fishing boats – mostly British drifters and trawlers, across the Otranto Straits, between Italy and Greece. The boats were manned by merchant crews – I would imagine on a T124 agreement – that means the boats and crews were kept on civilian rates of pay, but came under the control of the Navy and were subject to naval discipline
The barrage was raided by the Austro-Hungarians on several occasions.
One such raid was on 9 July 1916.
On that occasion the Austrian cruiser NOVARA attacked the line of drifters in the early hours of the morning. At 4am a ship was sighted approaching the barrage line, but was initially believed to be an allied vessel, but a few moments later opened fire. The cruiser initially concentrated her fire on former drifter from Buckie, the CLAVIS, which was sunk with the loss of three men. She then shifted her attention to a second drifter, the former Banff based ASTRUM SPEI, commanded by Skipper George Wood. She was also sunk, but eight members of her crew were picked up by the Novara to be taken prisoner.
See the wiki entries –
https://en.wikipedia.org/wiki/Otranto_Barrage https://en.wikipedia.org/wiki/SMS_Novara_(1913)
https://www.clydeships.co.uk/view.php?a1Dir=DESC&ref=59023&vessel=ASTRUM+SPEI