Specifications

Chapter 6 – Mission Performance
Beam Seas, Following Seas, and Quartering the Seas
E.4. Beam Seas
Whenever possible, the coxswain should avoid steering a course parallel
(broadside) to heavy swells. Tack across the swells at a 30- to 40-degree
angle. If necessary, steer a zigzag course, making each leg as long as
possible, and adjust the boat speed for a safe and comfortable ride. Seas
directly off the beam of the boat can cause adverse rolling conditions.
When transiting parallel to the seas, the boat will tend to ride the contour of
the wave surface. This means that the boat’s vertical axis will remain
perpendicular to the surface on which the boat is operated. A wave face of
20 degrees will cause a 20-degree heel.
E.5. Following
Seas
Following open seas up to 6 feet can be negotiated at full speed as long as the
boat remains stable as it travels down the front of the swell. In bad weather,
Defender Class boats are relatively safe running before the sea due to their
speed. If caught in breaking seas, this advantage is used to ride the back of
the waves while adjusting speed as required.
E.6. Quartering
the Seas
Taking larger head seas slightly off of either bow can create a more
comfortable ride, as the boat may proceed more gently off the back of the
wave instead of slamming violently. The speed and angle of approach will
have to be adjusted as needed for the optimum ride. This is sometimes
referred to as quartering the seas, which is not to be confused with taking a
following sea on the quarter.
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