The Pirate Crew

[Salty Dog]

LATITUDE
Three forms of instrument were available in 1700 to ‘observe’ the sun at noon; the time the sun was highest in the sky. Once you’ve used an instrument to measure the altitude of the sun, ‘nautical tables’ printed in an almanack could give you your latitude so you’d then be able to draw your north-south line on your chart and if you were reasonably skilled probably accurate to somewhere between ten and fifty nautical miles of your actual position north-south.

LONGITUDE
To calculate longitude, you need to know the time of the port you sailed from and the time at the point you are currently at - the sun moves 15 ° to the west every hour every day, so in simple terms if you sailed from London and from your ‘nautical almanack’ you knew that the sun rose in the east in London at 6.00am on the calendar date your ship is on but viewed from your ship on that date the sun rose at 8.00 am on the same date, you would know that you were 30° to the west of London ( 2 hours x 15°) and that would give you your east-west line. But - and this is the great ‘stumbling block’ in the year 1700 and would remain so for another seventy years until the invention of a reliable mechanical clock - Longitude is governed by Time and the only ‘clock’ you would have aboard ship to maintain the time in London would be a sandglass. You could ascertain ‘local time’ by using your compass and the sun - but if anyone forgot to turn the sandglass that was recording London time or even if they did remember and the sandglass was running just one second an hour wrong over just a few days your longitudinal calculations would become seriously wrong and using them for positional reckoning useless (you could be as much as 250 miles in error within just one week). Of course, navigation was undertaken aboard both merchant and pirate ships : but the more skilled you are and the more reliable your instruments were and the less rum you drank - and the more navigators there were aboard the merrier, as they could all compare their individual calculations daily to ascertain a ‘mean average’ - hopefully you then have something like a true position of the ship. A Royal Navy fleet of five ships after twelve days at sea in fog sought ‘a mean average’ from all their navigators in October 1707 which later resulted in four of the five ships running onto rocks near the Scillies and two thousand seamen drowned…

[Salty Dog]

As you may have already gathered, very basic instruments deal with measuring speed and direction and some means of keeping a record of these and any changes. A ‘logbook’ and a pencil would enable a navigator to keep records if he could read or write : other than that, in some form of scribbles or scratchings that he could understand when referring back to. Pending his individual skill, he could make his own chart as he sailed by taking bearings on any coasts seen. A compass will tell you in what direction you are sailing in relation to Magnetic North (which is not the same as the ‘True North’ you would plot if you chose to use the stars to navigate). Compasses came in many forms and sizes - a variation is the ‘Bearing Compass’ used for taking sights of coastlines or other landmarks such as rocks or reefs.

A ships’ speed needs to be measured quite often (at least every 30 minutes when under way as the wind that is driving your ship will rise or fall in strength and speed increase or decrease in the same way). To do this one can easily create and use a ‘log-line’ (which will also give an idea of ‘leeway’ the vessel is making) : there is a simple equation between how fast a line tied to an object in the sea pays out from a ship as the vessel moves away from it - using a sandglass as the log-line pays out from a spool, a navigator can calculate how fast the ship is moving in terms of nautical miles per hour (or as this became known, ‘knots’). As a navigator has to eat and sleep sometime, the job of taking these notes would be shared with at least one other person on an ‘alternate watch’. Without making these notes, you will never know - to within several hundred miles on a long voyage - roughly where your vessel is on a chart (if you had a chart).

[Salty Dog]

What happens if you are unsure where you are - lost ! - or when after a storm your ship is blown some way off course ? You can always make an ‘educated guess’ here but if you are wrong you may pay for an error with your life and those of the rest of the crew, so the capacity for must be reduced as much as possible. You can see from the above that Latitude can be calculated from the deck of a ship using an instrument to measure the height of the sun in the sky : many positions in the early 18th Century are given in latitude only because of the problem in calculating Longitude - this necessitated the logic of sailing north or south until you reached the ‘parallel of Latitude’ your destination actually lay on then steering east or west until you reached it. Without going into too much detail, the height and position of the sun (or other celestial bodies) for every day of the year including allowances for seasonal variation were printed in ‘nautical almanacks’ which by 1700 were widely available. He would still have to be recording ‘calendar time’ to fix a date, but if he had an instrument such as The Cross-staff or The Davis Quadrant and knew how to use it correctly, an observer aboard ship can fix the height (altitude) of the sun at noon and take off his reading from tables printed within the almanack (you can do this without tables but the calculation is a tedious one). Having fixed his latitude, he would then know his east-west position on a chart or relative to the given latitude of a destination or a home port - but - some ‘guesswork’ still remained in him fixing a position on the east-west line as in fixing longitude before the introduction of a reliable maritime key-wound clock in the latter half of the 18th Century, performing a set of very complicated calculations lie before him (and these calculations took some hours and would be beyond all but the very skilled navigators).

[Salty Dog]

The reader may be thinking that arriving roughly at a destination is perhaps enough ( perhaps then thinking to send a boat ashore to ask for directions from someone ! ) but arriving just twenty miles downwind from your destination could then see you spending a week ‘beating upwind’ to make port and many destinations for pirates were islands - and some relatively small islands at that - not lengthy coastlines. At least three occasions are recorded in pirates ‘missing’ islands they were sailing for and then wasting a long time trying to find them !'

Pirates often stole not just ships and cargo but members of a ships’ crew and the master or a skilled navigator of a prize - along with his charts and instruments - would be a primary target for any pirates !