This is provided by Peter H Scholes.
Extract from 'John Schoales of Hatfield, Gunner, R.N.'
The Ship's Gunner
The gunner was one of  five standing  officers on  board ship:  the
others  were  the  boatswain, purser,  carpenter and  cook. In  The
Wooden  World,  N.A.M.Rodger  explains  that  these  officers  were
permanently attached to the vessel normally for the lifetime of the
ship. At the end of a `Commission', when  ships paid  off the  crew
and  were  placed  in  `Ordinary' and  lay at  their moorings,  the
standing officers stayed on board, with a force  of 'shopkeepers'
under their orders to maintain the vessel. This meant that standing
officers had a fairly secure job until retirement from the Navy.
  The gunner was responsible for the ship's  guns and  ammunition,
for which he was accountable to the Navy's Ordnance Board. Gunners
were assisted by, and usually recruited from, gunners' mates,  and
their subordinates also included the armourer, the yeoman of the
powder room, and one  quarter gunner,  or seaman  layer, for  each
group of four great guns.
  The  ship'  gunner  was  a  warranted  `sea  officer'   directly
responsible  to  the  captain  for gunnery  and to  the Board  for
keeping  accounts  and  drawing  stores.  Before  qualifying as  a
warrant  officer,  John  Schoales  would  have risen  to become  a
gunner's mate or an armourer, and have been rated  by his  captain
as a petty officer for a period of some years. But we have not yet
found any records of John's career on the lower deck.
  The gunner was the one man whose carelessness could destroy  the
ship. According to Dudley Pope in Life in Nelson's Navy, this  was
well recognized by the Admiralty in Regulations and Instructions.
'No person shall be warranted as a gunner before he has passed  an
examination before a mathematical master, and  three able  gunners
of  the  Navy,  and  from  them  procure  a  certificate  of   his
qualification'.  There  were,  in  fact, 33  instructions for  the
ship's gunner: they ranged from swabbing a gun with water `when it
grows hot, for fear of splitting' to coating guns  with a  mixture
of tar and warm tallow if they had to be carried in the hold.  The
boxes of gunshot and hand-grenades had to  be kept  in dry  place,
and he `was not  to load  the guns  with `unfit  mixtures (of  gun
powder), which greatly endanger their splitting'.
  The gunner `had to keep  good order  in the  gunroom and  suffer
none to lie there but such had a right or whom  the captain  shall
direct'. He presided over the senior warrant officers -  boatswain
and carpenter - and petty  officers such  as sail makers,  armourer
and master's mates, as well as the  the captain's servants,  young
gentlemen not yet  rated as  midshipmen. His  pay at  the time  of
Nelson ranged from about £3 to £5 per month depending on the  size
of the ship. By comparison an  ordinary seaman  received about  £1
and a lieutenant £5 to £7 per month. Pay might well be
supplemented by prize  money  from  the  capture  of  an enemy  ship
with  warrant officers sharing one eighth of the total  value of  the
prize.  In addition, there was `head and gun money'  based on  the
number  of men aboard the captured vessel.
  Promotion for a gunner meant being transferred to a bigger  ship
for which he received more pay. But once having obtained a warrant
from the Ordnance Board the gunner would always  remain a  warrant
officer.
  Guns and gunnery on sailing warships have been described in many
publications. The following is taken  from The  Frigates by  James
Henderson and The Line of Battle edited by R Gardiner.
  The standard armament of a frigate was the 18 pounder (Pdr) gun,
nine feet  long, weighing  about two  tons, requiring  ten men  to
handle it. On firing the force of the recoil sent the gun  running
inboard on its carriage to the full length of its breeching tackle
which secured it to the ship's side; it was then sponged out  with
a swab to remove any smouldering  remains of  the previous  round;
the powder in its cloth cartridge rammed down with a  wad on  top,
followed by the shot and another wad. The cloth  of the  cartridge
was  pierced  and  a  little  priming  powder   poured  into   the
touch-hole. The gun crew then ran the gun  out by  heaving on  the
breeching tackle, after which the  gun captain  adjusted his  aim.
The gun was fired by flintlock and lanyard.
  Elevation of the gun was a relatively easy matter but any degree
of traverse needed much effort to lever the carriage around. There
were no sights and aiming was, to say the least, very approximate;
the motion of the ship had an obvious effect, so battles had to be
fought at close range to  have any  chance of  frequent hits.  The
management of the gun was heavy work, especially in rough weather.
Under good conditions, with a well trained crew, a shot every  two
minutes was a very good rate of fire.