Judging distance at sea by eye – a how-to

Distance judging at sea 5


How far is the mudbank opposite? Half a mile? A mile and a half? On board sailing barge Lady of the Lea in the Swale

Each year I tell myself I will now memorise the ways old fashioned used to judge distances by eye to improve my ability to navigate by eye. Perhaps this will be the year I manage it.

Anyway, it would be a great skill for all of us to have and so when I found this little chapter in The Yachtsman’s Weekend Book  I thought should share it…

Distance judging at sea 1 Distance judging at sea 2 Distance judging at sea 3

Distance judging at sea 4


Some things I mean to try to remember are the following:

  • ‘For the man with his height of eye at 8ft, the sea level horizon will be about 3 1/4 miles.’
  • ‘Anything with its base just touching the horizon line, or a power vessel under way and showing her bow-wave just above the horizon – all these objects would be approximately 3 1/4 miles away.’
  • ‘Had his eye been between 5 and 6 feet above sea level, this distance would be about 2 1/2 miles.’
  • ‘At two miles distance (from the 8-foot observer) a large navigation buoy should be visible, in smooth water, but its shape and colour will as yet be indistinguishable to the naked eye’
  • ‘At a distance of 1 1/2 miles small-sized navigational buoys can be made out in smooth water.
  • ‘At a distance of 1 mile to 1 1/4 miles the shape of the smaller buoy can be made out… as also can the colour and markings of the large type of buoy.’
  • [At a distance 1 to 1 1/4 mile]’A man moving to and fro on board of a ship or on shore shows up… as a black mark but his limbs and features are, of course undistinguishable.’
  • ‘At 600 to 800 yards a moving man… resolves himself into a featurless vertical mark. At 400 to 500 yards distant the movement of a walking man’s legs are noticeable, and the rower’s arms in a dinghy can be seen working… ‘





The rule of the road told in verses

SS Metapan sunk by the SS Iowan

SS Metapan sunk by a collision withthe SS Iowan; image from Popular Mechanics magazine published in 1915. Image placed on the Wikimedia by Pmcyclist


I found the following useful navigation rhymes in a book that Mike Smylie was kind enough to give me at the weekend – it previously belonged to his father. I’ve heard them before, notably from old Sam Larner, but haven’t seen them printed out. And as a bonus they came with some extra verses relating to sailing vessels.

The book is titled The Yachtsman’s Week End Book, written by John Irving and Douglas Service, and I think it’s a gem because of the way it opens a window into the different attitudes of the past. For example I particularly liked this quotation: ‘Four things shalt thou not see aboard a yacht for its comfort – a cow, a wheelbarrow, and umbrella and a naval officer.’

But back to the rhymes – they may be wrong in the current age, so please don’t take them as gospel. I can’t accept responsibility if you do!

Two steamships meeting:

When both lights you see ahead

Starboard wheel and show your red

Two steamships passing:

Green to green or red to red

Perfect safety, go ahead

Two steamships crossing:

If to your starboard red appear

It is your duty to keep clear

To act as judgement says is proper

To port or starboard, back or stop her

But when upon your port is seen

A steamer’s starboard light of green

There’s not much for you to do

For green to port keeps clear of you

However, all ships must keep a look-out and steamships must stop and go astern if necessary:

Both in safety and in doubt

Always keep a good look-out

In danger with no room to turn

Ease her, stop her, go astern

But these rules don’t work so well for sailing vessels. Instead, the following rhyme is proposed:

Now those four rules we all must note

Are no use in a sailing boat

As we’re dependent on the wind

Another set of rules we find

A close-hauled ship you’ll never see

Give way to one that’s running free

It’s easier running free to steer

And that’s the reason she keeps clear

With the wind the same side, running free

One’s to windward, one to lee

The leeward ship goes straight ahead

The other alters course instead

Both close-hauled or both quite free

On different tacks we all agree

The ship that has the wind to port

Must keep well clear, is what we’re taught

At other times the altering craft

Is the one that has the wind right aft


Foghorns on the BBC

Foghorns on the BBC

This is a typically quirky and entertaining BBC Radio 4 piece celebrating the foghorn’s place in music, literature and film, and in sailing. If you can, hear it here: http://www.bbc.co.uk/i/yqp5z (If you’re outside the UK you’ll probably need to find a proxy or some other technical fix to hear it.)

Here’s what Auntie Beeb’s blurb says:

‘The foghorn was invented in 1855 by Robert Foulis, a Scotsman living in Canada who heard the low notes (but not the high notes) of his daughter’s piano playing whilst walking far from the family’s fog-shrouded coastal cottage, thus inspiring the first steam powered fog horn. But beyond the sea, it’s “whale-like” sound has inspired artists, writers and musicians to use the foghorn both as symbol and instrument.

‘[Programme maker]Peter Curran hears from foghorn composer of Maritime Rites Alvin Curran, Jason Gorski, aka The Fogmaster, who used to conduct guerrilla foghorn concerts in the Bay Area of California, and takes a tour of Portland Bill lighthouse in Dorset, with keeper Larry Walker, taking the opportunity to set off an almighty Victorian foghorn. He also joins James Bond film music and future 2012 Olympic theme music composer David Arnold, who tries to digitally recreate the foghorn’s cry, and Dr Harry Witchel, who analyses Peter’s yearn for the sound as a child.’

Stand by for the usual BBC mix of inspiration and nonsense!

PS – If you can’t hear the programme itself, you might enjoy the following – though I think they’re best enjoyed with a pair of headphones rather than the tiny speakers you get with many computers: