Blockship

A block ship is an old, decommissioned ship, which was sunk alone or together with another in a fairway channel or in front of a harbor entrance to prevent the passage.

When the sinking of several ships block things to consider, thus the best possible blocking effect is achieved.

• It is (for example by tractor use ) ensures that the block ship comes across are for traffic direction and is not subsequently turned by tidal effect from his position. If necessary. anchors are applied.
• The vessel used must be large enough that it is only so far flooded even at spring tide, that no passage is possible.
• If a body of water so wide that it can only be disabled with multiple block ships, the largest of which is the center sunk to the lowest point of the passage. More block vessels to prevent Avoid is, overlapping sunk with the smallest possible lateral distance to the others.

Block ships are almost always used in conjunction with other blocking agents, such as anti-submarine nets, bar locks and sea mines. Their disadvantage is that they are only effective against larger vehicles while frogmen and certain small ordnance of them are not affected.

In 1918, the Royal Navy tried the German bases Ostend and Zeebrugge in Flanders to block with block vessels and so prevent leakage of torpedo boats and submarines to their missions. The company failed, however, because the schedule was not adhered to and in this area extremely strong ebb tide had already begun, as the sinking was initiated. Thus, the already partially flooded ships drove off to the edge of the fairway, where they could exert almost no blocking effect and the arrival and departure of the German boats practically non-disabled.