Manoeuvring and berthing The seaman’s eye
The seaman’s eye is hard to define, but if you don’t have it, your exercises are doomed to failure in strong winds or tides. The success of any manoeuvre depends on the vessel going into it from the right place at a suitable speed. Unlike road vehicles which operate on a stable surface, a boat in a beam wind is stalled and skidding from the moment she leaves her berth until she has gained enough way for her keel to start working (see page 63). If the water is tidal or subject to currents, the whole ‘road’ is in motion, so she is not going where she is pointing even after she has gathered way. Understanding how much she will slide, how to use the tendency, how to prevent it, and knowing which is best, is half the battle. The rest is being able to judge any developing situations by eye.
Wind awareness and apparent wind
Knowing the wind’s direction is always important. When a boat loses most of her way and it’s blowing hard, it becomes vital. Everyone knows that you can find the wind direction by looking at a handy flag, but while this is true for bunting hoisted ashore or a burgee aboard an anchored vessel, on a moving boat it will give a false reading because of ‘apparent wind’.
A boat motoring through still air generates an apparent
wind across her deck, equal and opposite to her motion through the air. If a wind is blowing over the water, this combines with the wind created by the boat’s motion to form a resultant apparent wind. Unless the boat is on a dead run, the apparent wind usually blows from forward of the true wind direction. Apparant wind is the wind registered by every flag or wind arrow on board, or by any electronic instrument whose readout has not been modified by a processor to deliver true wind speed and direction. Being able to sort out true from apparent wind is important for sailing boats manoeuvring, but it can also be useful for high-speed motor boats taking off way in preparation for an awkward arrival alongside in a strong crosswind.
In the absence of direct evidence from the shore, the best way of detecting the true wind is by reading the small ripples it puffs onto the water — not the waves, which are subject to other forces. But like the ripples on a bowl of soup when you blow to cool it, the wind ripples run at right-angles to the airflow. Recognising them takes time and practice, but the time taken is very well spent.
Spotting the current or stream
Wind due to forward advance.
True wind
‘Mark 1 Eyeball’ is the best instrument. Only resort to the tide tables when all else has failed. Moored or alongside, just look over the rail. Manoeuvring free, note how moored vessels are lying. This is generally ‘head-up’ to the moving water, although a strong wind may modify their attitude. In the absence of other craft, check the ‘bow waves’ on piles, buoys or anything else attached to the seabed. If there aren’t any ‘bow waves’ and the shore is reasonably close, lay the boat as nearly across the suspected current as you can. You’ll spot your drift by noting how the immediate shore line appears to slip sideways against its background.
62 | MANUAL OF SEAMANSHIP
Apparent wind
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