(based substantially on Appendix III on The Pyecroft Stories in the ORG, and edited for this Guide by Commander Alastair Wilson, R.N.)
Kipling & the Royal Navy
the Pyecroft stories
the Royal Navy in 1905
warships' boats in 1905
At sea, the senior midshipman of the watch had to “heave the log” every hour to ascertain the ship’s speed (primarily to establish the ship’s position by ‘dead reckoning’).Since the distance between knots was only eight fathoms, 48 feet, and the time a matter of 28 (or 14) seconds, the terms “knots an hour” would seem to be anomalous.
A mizzen-topman, i.e. a responsible man from the sailors who worked in the after part of the ship] had to hold the reel, at the end of which was the log-ship, a flat piece of wood in the form of a quadrant, with a radius of six to eight inches, the base of which (the arc of the circle) was loaded with lead to keep it in the water while the upper corner floated. The two lower corners had each a hole, presenting a firm resistance to maintain its place when once thrown into the water. A few fathoms of line called ‘stray line’, to allow the log-ship to perform its duty (i.e. to let it out of the eddy wake following the ship) was marked with a piece of bunting to commence the marking of knots which represent nautical miles. Between the stray line mark and the first mark was eight fathoms (48 feet), each knot being marked with a small strand through the line, with one knot in the first, two knots in the second, and so on to six, and between each knot was a half-knot [i.e. half-way between each marker, at 24 feet intervals, a knot was formed in the log-line itself.]
The quartermaster held the sand-glass ready as the stray mark went over the lee quarter, and the midshipman called out “Turn”. The log-glass was turned, and the instant the sand ran out the quartermaster called “Stop”, and the line was kept from running out further.
The mid reported to the lieutenant of the watch, “She is going five-and-a-half, sir”, or whatever it might be.
That officer, if judicious and painstaking in his duty, had watched through the hour the fluctuations of the ship’s progress by an increase or decrease in the wind, or other circumstances affecting her speed, and would reply to the mid who had to mark the log-slate, “Give her seven”, or it may be only four.
Above, I have said that the distance apart of the knot markers was eight fathoms, but I have not mentioned the length of the sand-glass. The long glass was twenty-eight seconds but there is a short glass of half that time, fourteen seconds, for this reason that twenty-eight seconds bears (very nearly) the same proportion to an hour as eight fathoms does to a nautical mile. [The exact time ought to be 28.42 seconds.] But when a ship’s speed exceeds five or six knots it would carry out such a length of line that, by using the short glass, the half knots equalled knots, so that four-and-a-half became nine.
The first description of a log-ship and a line, I have heard, occurs in Bourne’s Regiment of the Sea, 1573”.