Post Description

voor de liefhebebrs van submarine tactics :)

Anal. of the Advantages of Changing Speed, Course (Submarines) [website capture] (ONI, 1918) WW
1 pdf

ANALYSIS OF THE ADVANTAGE OF SPEED AND CHANGES OF COURSE IN AVOIDING ATTACK BY SUBMARINE.

1. It has been generally recognized that high speed and frequent changes of course by vessels within the War Zone are desirable; this analysis has been undertaken with a view to indicating the relative value of speeds and the most advantageous amounts and frequency of changes of course in avoiding torpedoes fired from submarines.

2. The value of speed for this purpose can be demonstrated mathematically or graphically and is indisputable. The value of changes of course can not be proven mathematically and such is therefore dependent on conclusions drawn from an analysis of the operation of the enemy submarines previous to and during an attack.

ANALYSIS OF THE VALUE OF SPEED IN AVOIDING SUBMARINE ATTACK.

3. The first factor to be considered is the number of hours of daylight, or moonlight, spent in the submarine danger zone, and it may be said without question that this number should be reduced to the smallest possible amount consistent with obtaining the most advantageous conditions. This will be accomplished by arriving within safe waters as near daylight as possible and by using maximum speed on the straightest course. Special conditions may in cases make it inadvisable to arrive off a port at daylight; i.e., when submarines are known to be concentrated near shore. The principle stated above assumes a uniform density of submarines in the so-called "War Zone," an assumption which information may make untenable.

4. The greatest amount of submarine activity today is close to shore and in location where the convoy system is difficult of execution. The procedure should, therefore, be modified so that vessels shall arrive in this zone, after daylight. The analysis of the value of speed and zigzag courses should first be made from the point of view of a vessel acting singly.

5. The effect of speed is great in reducing the time within the danger zone, but even greater in reducing the chance of being attacked by submarines even if the vessel is seen.

6. It is assumed that a submarine cruising on the surface may sight a vessel at a maximum distance of 10 miles while she herself
...

Thanks to Rockhound57 :)