BoatsExplained.com tells us how to avoid it

AtheY set off on a round the world race, a well known skipper told his crew "if
you fall overboard, I'm not coming back." It caused quite a stir at the time, but serves to highlight two important points. The fIrst is to impress on any crew that they have a responsibility to stay aboard. Secondly, it recognises that our attention is best directed to prevention rather than cure.

The boat
A great deal can be done at the design stage, and the degree and nature of risk will vary from boat to boat. For example, size-for-size, traditional heavier displacement vessels tend to have an easier motion than lighter craft and in general are less likely to capsize. Cockpits which are small and deep - or even enclosed - offer better protection than those which are spacious and exposed. Ideally, decks should have a good non-slip surface, with generously proportioned bulwarks or toe-rails to provide a secure foothold on the leeside. Very narrow side decks should be avoided at all costs.

The gear
But whatever the basic configuration of your boat, more preventative measures are necessary. The most common are physical restraints in the form of life-lines and rails. Again, compromise is inevitable. The cruiser may cheerfully accept the weight and windage penalties of such things as solid rails, taller than usual stanchions, 'granny bars' in way of the mast and robust pulpits and pushpits - all in the interests of optimum crew security. The racing boat will probably see advantages in having the minimum - say 4mm guardwires and the lowest height stanchions the racing rules allow.
Most modern cruising yachts strike a happy medium - typically having pulpit and pushpit fore and aft, with side decks guarded by twin wires (often PVC covered) supported on 2ft 6 in (760mm) high stanchions.

To be continued.......