Impressment was eventually dropped in the early part of the 19th century in a move to encourage seamen to volunteer for full career employment in the naval service.
This was fine for the numbers required during peacetime when many vessels were laid up in reserve but it meant that some means had to be provided to produce the extra men needed when the fleet expanded in time of war.
[1] The Register of Seamen was supplemented in 1853 with the creation of the Royal Naval Coast Volunteers (RNCV) comprising boatmen and fishermen who would undertake limited (geographic) service in the Navy during a conflict.
[1] The new force was named the Royal Naval Reserve (RNR) and was originally for ratings but in 1861 this was extended to officers who wore distinctive rank lace consisting of interwoven chain links.
Officers spent longer periods of up to one or two years training in shore establishments and in ships of the fleet at home and abroad to acclimatise themselves with naval practice.
At the start of the 20th century with a period of rapid naval expansion taking place it was realised that the RNR could not supply the required number of trained men and a scheme was introduced that allowed men in civilian shore jobs (unconnected with the sea) to train on a part-time basis at special shore establishments, and provided the valuable experience of real time with the fleet for a few weeks a year once a certain level of competence had been achieved.
This was the Royal Naval Volunteer Reserve (RNVR), known as the 'Wavy Navy' on account of the rank stripes (rings) on officers sleeves being wavy rather than straight.
In the late 1930s, The Admiralty realised that the numbers available would not meet the needs of the fast approaching war and created the Royal Naval Volunteer Supplementary Reserve (RNVSR).