Ouzo Incident - Response to Report

by Nancy Knudsen on 18 Apr 2007 The disappearance of the yacht Ouzo, and the discovery of the bodies of the three crew a day later has been a high profile story, particularly in Britain, where the incident occurred, ever since that night in August 2006 when it was suspected that the ferry the Pride of Bilbao had struck the yacht.

Now finally, the official enquiry has been completed, and the MAIB (Marine Accident Investigation Branch), according to the official report, ' is of the firm opinion that the yacht was Ouzo and that Pride of Bilbao had collided with her, or passed so close that she had been swamped or capsized by the vessel’s wash.'

The report makes a number of recommendations, and several of them are worth a discussion. However, this article will only deal with one of them, the recommendation 'that yachtsmen should check their masthead tricolour lights for crazing on the plastic lens, which may reduce light intensity. Also you should check the power rating of the bulb is correct.'

While the report spends some time discussing the issue, with great respect to the institution of the MAIB, this lonely recommendation could be seen as verging on the puerile, and fails to address the real issues of visibility of yachts by ships.

In March, 2006, long before the Ouzo incident, Sail-World printed an article about the difficulties of ships in regard to the presence of small yachts in the ocean, for both day and night sailing, and we repeat the extracts from the article here:

Day sailing:

Due to the curvature of the earth’s surface, the distance that can be seen in clear weather, neglecting such things are refraction, is dependant on the height of the eye(HE) of the observer. The formula for this is: Distance in miles to the horizon = 1.15 X square root of HE in feet i.e. 10 feet HE horizon is 3.6 miles, 100 feet 11.5 miles. So, if the watchman on a bridge of a ship at a height of 100 feet is looking at a yacht with a mast height of 40 feet, he should be able to see it at a distance of 19 miles. However it probably could not be seen due to its small size at that distance.

As the vessels approach, the yacht itself, at 11.5 miles, would be exactly on the ship’s horizon. However, if there were mist or clouds on the horizon, the ship would still not see the yacht. With blue sky and clear weather, the yacht would then be visible as a silhouette on the horizon.

As the two craft continue to approach each other, the yacht would drop between the horizon and the ship so that the silhouette effect would disappear and the yacht would merge into a back ground of white horses and once again be very difficult to see – even more so if close hauled in an end aspect to the bridge. In overcast weather or with a sea haze, detection would be even more difficult.

It would be much more practical if sails were made of bright orange or red, or any other colour but white.

A container ship watchman would advise any yacht owner NEVER to paint their boats white, black, blue (specially mid blue) grey or green. Yellow, red or orange would be ideal.

Poor visibility from ships’ bridges is another consideration to take into account for the cruising sailor. Quite frequently there are derricks, Sampson posts, a forest of masts, cranes and wires, not to mention containers in some areas cluttering up the view forward, particularly on the opposite side of the ship from where the watchkeeper is standing. This means that it is usually the port side of the ship which is ‘blind’. Containers are a particular problem, and sometimes the watch keeper has to move from side to side to check that all is clear. If the watch keeper’s attention is taken by a large object on one side, he might very well miss a smaller object on the other side. This is not always the case of course. Some ships have very good visibility.

So you can see that there are many aspects making it difficult from the watch man’s point of view.

One further point I would like to make is that the International Regulations for Prevention of Collisions at Sea say that a vessel, including yachts, must have a lookout at ALL times. This actually means that single-handed sailors are constantly breaking this rule.

Night Sailing:

Sailing vessels less than 20 metres and more than 12 metres (that’s many cruising sailors) must carry red and green side lights and a stern light visible for 2 miles, OR a tri-light arrangement at the top or near the top of the mast - red and green side lights combined with a stern light, making a 360 degrees total. If the vessel is less than 12 metres, then the lights need only be visible for one mile. If less than 7 metres, the same applies, with the additional provision that if the boat is not equipped with these, a light should be shown ‘in sufficient time to prevent a collision’.

However, you don’t have to be in bad conditions to be pretty sure that a container ship won’t see you at night. Why?

First, the focal plane of any normal yacht’s navigation lights is + or – 5 degrees, and the loss of effective light outside this arc is 50%. This is a staggeringly large loss of effectiveness.

Let’s take the case of a yacht less than 12 metres, showing the regulation lights visible at a one-mile range. (Remember this requirement is stipulated to be for a dark night, with no background lights, and clear air.) However, anywhere near land there are often lights around or the glow of cities to reduce visibility, and if there is moisture in the air, this will also reduce visibility again. There is also likely to be salt on the yacht’s lights, and, if she is sailing, then she is almost certainly heeling more than 5 degrees.

The original one-mile visibility is therefore reduced as follows:


Original light visibility distance: 1.00 nm = 1,852.0 metres

Salt on the lens reduce by say 10% 0.90 nm = 1,666.8 metres

Moisture in the air, reduce by say 10% 0.80.nm = 1,481.6 metres

Interference surrounding lights say 10% 0.70 nm = 1,296.4 metres

Reduction due to heeling, say 50% 0.35 nm = 648.2 metres

So the resultant actual light visibility distance is .35 nm, or 650metres, or less than half a nautical mile.



Neglecting the speed of the yacht and assume a ship’s speed of 15 knots (one mile every four minutes) and assuming the watch officer sees the light at this range and acts instantly (unlikely) then the ship has less than two minutes to act to avoid collision.


To put the rudder hard over takes about 15 seconds. For the ship to answer her helm and make any significant alteration of course takes at least another 40 seconds, so that, of the available time, 55 seconds may have now elapsed. Let’s assume the officer has acted immediately and put the wheel ‘hard a-starboard’, the troubles are not yet over if the ship is large and deep laden and especially if the depth of water is less than twice the ship’s draft.

Once the ship starts swinging, the bow may clear the yacht, but the speed of the swing will be increasing. To check this, once the bow is clear, he puts the rudder ‘hard a port’, but the swing will continue to starboard against the port rudder for about 40 degrees, depending on how fast the ship was turning when the rudder was changed, This is due to the tremendous inertial forces generated by the turn and the length of the ship.

This means that although the ship misses the yacht with its bow, it has an excellent chance of giving it a swipe with the stern as the radius of the stern’s swing is greater than that of the bow. This is because a ship pivots about one third length from the bow, so that the bow is inside the turning circle, but the stern is well outside it.

Even if