Why DO Keels Fall Off?

by Sail-World Cruising on 6 Feb 2007 An investigation is being launched into an English Channel yachting tragedy in which a man died on Saturday. The crewman was believed to be in his twenties, said the police. Four other crew were rescued in a major operation when the 35 ft Solent-registered yacht, Hooligan V, capsized off the south Devon coast after losing its keel.

Four of the five crew from the yacht were found in a liferaft and taken aboard a lifeboat, then to a hospital in Plymouth, where they were found to be suffering from slight hypothermia.

Later, RNLI Coxswain at Salcombe Chris Winzar said: 'We went to the scene to pick a lifejacket up and sadly found the body of the missing person.'

A Department of Transport spokeswoman said: 'The Marine Accident Investigation Branch (MAIB) is sending a team to Devon to conduct a preliminary examination of the incident.'

As the basic integrity of any yacht depends on the counter-weight of keel against the mast structure, it is a given that when a yacht loses its keel, it will capsize and not right itself. With this as a given, the structural integrity of the keel is one of the most crucial elements of the yacht’s structure.

Many of the most publicised yachting disasters in recent history have involved the keel falling off a yacht.
Probably the most famous, or infamous (depending on your point of view) was that of Tony Bullimore, who was saved from the Antarctic after a massive Australian Navy operation.

Then there was the Moquini, lost with all its six crew during the Mauritius to Durban yacht race in late 2005 due to a lost keel.

In 2003, after racing yacht Excalibur sank after losing its keel near Port Stephens in Australia, four of the six crew were lost.

The list goes on . . . . .

But what does make a keel fall off a so-called structurally sound boat? From the perspective of a yacht designer, boat builder or a surveyor who has give a boat the ‘ok’, what are the possibilities?

1) It’s possible that the original structure of the keel was insufficient and had fatigued over time.

2) It's possible that the hull-keel joint was originally adequate, but was weakened over time by repeated groundings, possibly by a number of different owners.

3) It's possible that the keel bolts may have corroded and failed, especially since drawing them for inspection or replacement can be a major undertaking.

4) It's also possible that the boat was both structurally sound and in good condition and simply failed due to the circumstances it was placed in, intentionally or unintentionally.

Points 2 and 3 are the ones that may bring the surveyor out in a cold sweat, as they're both things which a good survey should be able to guard against. Point 1 brings up the whole question of yacht design and manufacture

So, assuming that the boat was in good condition, what circumstances could precipitate a parting of the keel?

a) Collision with the bottom. This is unlikely in the current case in the English Channel.

b) Collision with a floating or submerged object. This is always an unknown, with whales and lost containers coming in for most of the blame. Floating containers generally just break the surface at best, and are almost impossible to see in daylight, let alone at night.

c) Rough water conditions. This would have to be exceptional conditions – maybe as severe as hurricane conditions to warrant inclusion, as the integrity of yachts is meant to cope with most sea situations.

As many of the known incidents have had ‘reasonable’ conditions, c) can largely be discounted from the discussions. Any enquiry should be able to quickly substantiate, by examination of the hull, whether it has suffered a severe collision. Once this is discounted, one must return to the first set of numbers for the answer, and it’s 1) which gives cause for most concern.

The keel must rate as one of the most problem prone areas of modern boat design.

One can only hope that when marine architects get together later this year (see Sail-World story by clicking http://www.sail-world.com/news_w_f.cfm?Nid=30622&SRCID=4&hasFlash=1!here!same ) to discuss future yacht design that they will be using all of the data gained from keel loss over in recent times to guide their thinking.