A ship left in a seaway will more than likely fall off until she has the sea abaft the beam, the propeller will act as a drag and hold her stern-up. in this position, she will roll deep but easily and will drift to the lee.
If the ship starts to roll heavy you can make turns just fast enough to give her steerageway. From experience, a ship may safely run with the sea either aft or quartering, provided she runs very slow. I have heard statements from masters who have tried this slowing down or stopping when running before a heavy sea, that this maneuver, so far from resulting in the disaster that many seamen would expect from it, had an effect of easing the ship and keeping her dry.
Rolling and Pitching another point that comes into the handling of a vessel going before the sea is that as she rolls and pitches, she buries her bow first to one side and then the other, increasing the pressure on the bow. If she is being driven through the water, her head will be forced off, first to one side and then to the other, causing her to yaw badly with a tendency to broach to. This situation cannot be helped by the rudder because, at the very time the bow is buried, the stern is lifted more or less out of the water, and the rudder loses its steering power. As the stern is lifted, the propeller begins to race, a danger at high speed. There is no question that the dangers are reduced, if not altogether removed, by slowing or stopping.
But it should be understood that in this matter, as in all others connected with seamanship, regard must be given to the individual ship and that the maneuver that is safest for a majority of ships may be dangerous for others. Once again I feel a person on the bridge has to have a feel for the ship and whats going on,every situation is different.
For every ship (in a given condition as to trim, etc.), there is a definite rolling period in which she will make a complete roll. Just like seaway, there is usually a fairly regular interval of time between wave crests passing a given point. If the point is a ship in motion, her motion may increase or decrease the interval between the waves but this will not change the interval. If this interval coincides with that required for the ship to complete a roll, each wave as it passes her will add its rolling to the accumulated effect of those which have preceded it, and the ship will roll more and more deeply until she reaches the maximum roll of which she is capable. She will not capsize (if properly designed) because there are forces at work to resist the rolling, and these increase as the depth of roll increases until the rolling forces and the resisting forces balance.
You can make this break, provided the ship has headway, by changing her course or her speed. By running more nearly into the sea, meeting the waves the apparent period is shortened; by running more nearly before it, the period is lengthened. The same effect can be made by a change of speed.
A ship making high speed in the direction of a heavy sea or swell may take a sheer and roll very heavy. A moderate following sea, accompanied by a less obvious swell from a slightly different direction, can occasionally produce a very large sea astern which, if the helmsman is not alert and experienced, can produce the sudden roll mentioned above.
The length of the ship as compared with that of the waves is also a important factor in the behavior of the ship, especially when she is running more or less with the waves or meeting them. Sometimes a smaller ship rides better than a larger ship. The larger ship has one end on the crest of one wave and the other buried in the adjoining one.
