Thursday, December 6, 2007


Wind and current determine the direction for approaching the anchorage, the final heading after anchoring, and to some extent the ship's behavior while maneuvering in the anchorage.
The effects of wind and current on navigation and shiphandling increase as a ship's speed decreases. Accustomed to navigating at full sea speed where set and leeway are much less, you have to plan more carefully and make greater allowances for wind and current effects while moving through an anchorage at reduced speeds.

Don't fight the wind and current. Current can be a problem, setting a vessel toward other ships and shoals, but it can also move a ship away from hazards. Wind causes leeway but it can also assist the shiphandler, helping to turn a ship around short, for example, as a ship with sternway backs into the wind. Think ahead and use these to advantage.

Plan to pass downstream and to leeward of ships, buoys, and hazards to navigation, or, if that isn't practical, allow plenty of sea room and several degrees for set and leeway to be sure to pass well clear. The two or three degrees allowed for set and leeway at sea just isn't enough in an anchorage; think in fives and tens, when maneuvering at slow speeds. Do not, pass close upstream or to windward of buoys, obstacles, or ships at anchor. It is a most helpless feeling to be passing close across the bow of a ship at anchor as the current sets you swiftly toward her stem. There is little that can be done in that situation except come full ahead, put the rudder hard over to try to move your ship's stern away from the other vessel, and pray you pass clear and that maneuver isn't very effective if you are in real danger of colliding.

And how far is far enough to pass clear, that depends on current and wind strength, and the speed at which the ship is moving. In any case, particularly at the very low speeds at which a ship is usually moving in an anchorage, it is probably farther than you might expect. I use a 100' rule, the ship moves 100' in one minute at 1 knot. By using that rule, and the length of your ship as the basic unit of distance, you can estimate a safe passing distance.