Save Our Ships! Navigation on the High Seas
SCILLY NAVAL DISASTER OF 1707
The Isles of Scilly, a small group of islands (some only the size of large rocks) just off England’s west
coast, was the site of one of the Royal Navy’s worst maritime disasters. A British fleet of 21 ships, under
the command of Admiral Sir Clowdesley Shovell, was headed home to Portsmouth from duty in the
Mediterranean Sea as a part of the War of Spanish Succession.
“It was a dark and stormy night” describes the evening of October 22, 1707. The British fleet had been
sailing in foggy and rainy weather since leaving Gibraltar, making navigation difficult. In the 1700s,
navigation at sea was an inexact science. Longitude was determined by “dead reckoning,” which is
determining location based on how far you’ve travelled from your last known location based on
landmarks or the stars. The bad weather compounded the problem by limiting visibility and blowing the
ships off course.
Shovell called a conference of the ships’ masters to determine the fleet’s exact location. The consensus
of the sailing masters was that the ships were close to Ushant, France. Only one master disagreed,
stating that they were nearer the Isles of Scilly. Shovell, believing that he was at Ushant, headed west,
thinking he was headed into the English Channel toward Portsmouth. Unfortunately, he was many miles
further west and north than the inexact calculations predicted—near to the Isles of Scilly. His flagship,
the Association, ran aground on the westernmost part of the Scilly Isles. By all accounts, the Association
sank rapidly, quickly followed by the Eagle and the Rumney, losing all men on board. The Firebrand sank
shortly thereafter. Various accounts of the event list the number of sailors lost between 1,400 and over
2,000. At that time, few sailors could swim. Various logs and journals from other vessels in the fleet
show that it was miraculous that no other boats wrecked. The remainder of the fleet made it to
Portsmouth on October 25, 1707.
Oct. 23. At 6 Sir Cloudesley Shovel made ye signal to wear, at the same time we all made saile,
hauling up E. [east] by S. [south], E.S.E. [east southeast] and S.E. [southeast] At ½ past 7 fell in
with ye islands of Scilly; the Genll fired one gun, as we plainly saw, and immediately lost sight of
him; then Rear Admiral Noris fired four guns, hoisted several lights and wore, and put all his
lights out, at ye same time made the light on St Mary's under our lee bow. At 7 a.m. (on 23rd)
saw seaven saile wch I judg'd to be some of ye separated fleet.
The Shipwreck of Sir Cloudesley Shovell, on the Scilly Islands in 1707. From Original and Contemporary
Documents Hitherto Unpublished (Read at a Meeting of the Society of Antiquaries, London, Feb. 1, 1883)
By James Herbert Cooke, F.S.A.
The Scilly naval disaster in 1707 prompted the British Parliament to pass the Longitude Act in 1714. It
included the Longitude Prize, which offered £20,000 to anyone who invented an accurate method of
determining longitude at sea. Sir Isaac Newton helped write the Act, including a list of methods of
finding longitude that had already been tried but were not effective.
Teacher Gazette October 2014
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Save Our Ships! Navigation on the High Seas
Navigational Tools Chart
What challenges are there to
finding where you are in the
middle of the ocean?
What problems did the fleet
encounter on its voyage in 1707?
What navigational tools could
have helped them? How?
Answer the following question in the box below. How did mariners use navigational tools to solve the
challenges/problems of early transoceanic travel? Be sure to include 2-3 pieces of evidence to support
your thesis, and write in complete sentences.
Teacher Gazette October 2014
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Save Our Ships! Navigation on the High Seas
Timeline of Navigational Tools and Legislation
13th Century
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•
portolan charts
first documented use of astrolabe for sea travel
15th Century
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quadrant
logbooks
16th Century
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•
•
•
chip log
traverse board
back-staff
cross-staff (first recorded date of use – 1514)
18th Century
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•
•
Longitude Act passed in Britain
logbooks used as official documents
marine chronometer
Teacher Gazette October 2014
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Save Our Ships! Navigation on the High Seas
Navigational Tool Cards
Mariners’ Museum images and more information can be found at http://ageofex.marinersmuseum.org
Navigational Tool: portolan charts—navigational
maps based on compass directions and estimated
distances observed by mariners
Purpose: useful near the shorelines to identify
and go to or avoid coastal features and ports
[Portolan atlas of the Mediterranean Sea, western
Europe, and the northwest coast of Africa]. Joan Oliva,
1590. Library of Congress Maps and Geography Division
[2005634035].
Navigational Tool: quadrant—a device that was
one-fourth of a circle, used by mariners to
measure the height of the Pole Star. By knowing
the height the Pole Star was when viewed from a
particular port, mariners used the quadrant to
help them navigate to port cities.
Navigational Tool: astrolabe—an anglemeasuring device for measuring the sun and stars
in the areas of astronomy and astrology, later
adopted for use at sea
Purpose: measures the angular heights of the
sun
Mariner’s Astrolabe, Portuguese, 1645, by Nicholao
Ruffo, The Mariners’ Museum (2000.52.1).
Navigational Tool: chip log—a basic
speedometer in which a line was knotted at
regular intervals and weighted to drag in the
water
Purpose: to determine the speed of a vessel
Purpose: to help mariners determine latitude
Quadrant, circa 1650, Peter Ifland Collection, The
Mariners’ Museum (1998.39.10).
Teacher Gazette October 2014
Loch à plateau [Ship log and associated kit from the
Musée de la Marine, Paris] Rémi Kaupp, Wikimedia
Commons.
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Save Our Ships! Navigation on the High Seas
Navigational Tool: logbook—originally a book for
recording the ship’s speed, the logbook became a
record of anything related to the ship or voyage
(i.e. direction and speed, cargo, weather, any
special event on the ship, and some included
drawings)
Navigational Tool: traverse board—a navigation
device consisting of a small board marked with
the four points of the compass with eight holes
bored at each point to represent each half hour in
a watch and used to peg the courses made by a
ship in each half hour
Purpose: to record the trajectory of the vessel as
well as to detail cargo and events that occurred on
ships
Purpose: used to track a ship’s course and the
distance traveled
Logbook entries August 11-13, 1774, from the Logbook
of the Snow Minerva, 1772-1776. The Library at The
Mariners’ Museum.
Traverse Board, Reproduction, Donated by L. Eichner,
1957, The Mariners' Museum (1957.19).
Navigational Tool: marine chronometer—a clock
that is precise and accurate enough to be used as
a portable time standard, providing a means of
navigation by the sun, moon, and stars
Navigational Tool: back-staff (also known as
Davis Quadrant)—a device that used the shadow
of the sun to determine the altitude of the sun
Purpose: to determine latitude
Purpose: to help mariner determine longitude
when at sea out of sight of land
Back-Staff, 1711, by Walter Hensaw, Peter Ifland
Collection, The Mariners’ Museum (1998.69.151).
Ferdinand Berthoud, marine chronometer no.3, 1763.
World Imaging, Wikimedia Commons.
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Save Our Ships! Navigation on the High Seas
Navigational Tool: cross-staff—an instrument
that helped mariners determine the angle
between the horizon and the sun, and used when
sailing to unfamiliar places
Navigational Tool: nautical almanac—a
publication containing a set of tables that use
accurate measurements of the angle between the
moon and known stars
Purpose: to determine a vessel’s latitude on the
open sea
Purpose: helps mariners navigate using the sun,
moon, planets, and stars
Back-Staff, Peter Ifland Collection, The Mariners
Museum, (1998)
Navigational Tool: The British Longitudinal Act—
an act that set up a Board of Longitude, which
established a £20,000 prize for the person who
could invent a means of establishing accurate lines
of longitude
Purpose: to examine how to gauge correct
longitudinal positions at sea
Teacher Gazette October 2014
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