CHAPTER 18


squall’s influence, but unless you are in a super-fast craft the loss will be more than offset by the reduction in general unpleasantness. In certain specific areas, line squalls can be lethally powerful, such as the isolated cold front that can run up the Eastern Seaboard of the US generating 60-knot winds out of a calm afternoon. It therefore behoves all skippers to make enquiries when cruising strange waters, either by consulting sailing directions or local knowledge.


• The thunderstorm - A thunderstorm not directly associated with a travelling front behaves much like a squall, although it may last somewhat longer. Along the coast, these are commonest late in the afternoon when the land has heated up. Offshore, they are more prevalent at night. Try to avoid them if convenient by steering so that the bearing of the closest edge alters. If you’re caught, thunder and lightning are alarming at sea, especially as the mast of a sailing yacht (particularly a metal one) is likely to be a focal point for a lightning strike. Disconnect antennae and other masthead equipment to protect your electrics, and keep your crew well away from the mast and shrouds. Strikes are mercifully rare, but if you are unlucky enough to take one, this offers your best chance of keeping them from harm. The worst winds under thunderstorms are best avoided by steering to leave the big cloud to port (starboard in the southern hemisphere).


• Isolated squalls - These can occur anywhere in generally windy weather with a comparatively clear sky. Assess an approaching squall by noting whether or not you can see the horizon underneath it. If the cloud has a complete ‘skirt’ of rain, it is more likely to produce wind than not. If you can see rain underneath the cloud but the horizon remains visible, you may be fortunate. In any case, prepare for the worst and steer to avoid passing under it if you can.


• Waterspouts - A waterspout is the aquatic equivalent of a tornado, or ‘twister’ seen mostly in the tropics, but it can also venture into higher latitudes. In the right conditions it will appear at first as a funnel descending from a heavy squall cloud. The water beneath the finger becomes disturbed and finally the whole column joins with the sea. Assess the direction of its motion and steam as hard as you can at right-angles to this. Except over open ocean, the greatest danger appears to come from flying debris, so if a hit seems unavoidable, either go below and hold on or, if things look really desperate, attach yourself to the boat with a long line and jump overboard until the danger is past. Although one US authority suggests swimming underwater for as long as you are able, this manual is more inclined to recommend wearing a good-quality lifejacket.


MANUAL OF SEAMANSHIP | 153


Wind and wave


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