The sons of Captain Abele in the Summer of 2006 initiated, with the help of a Japanese party and other sources, a search for the remains of the USS Grunion (SS-216) lost in 1942.
The web site http://ussgrunion.com/blog/attack-analysis/ holds a long anonymous discusson of the circumstances of the loss of the Grunion, in the course of which there was discussion of damage to submarines resulting from collisions with surface ships, particularly the shears. As evidence, the following discussion of the Irex's sail damage in February 1960 is included. This account appears to draw upon a first hand report by someone on a submarine accompanying the Irex in the North Sea at the time, and so it is worth including here.
Based upon pictures I have seen and stories I have heard about boats getting hit by surface ships it appears that it does not take all that much force to bend the shears over, especially when one considers that they represent a long lever arm. Perhaps, as a contrary view, is the experience of USS IREX (SS 482), a Fleet Snorkel boat, after getting a new fiberglass sail. In February 1960, after a big ASW exercise in the very rough seas of the Greenland-Iceland-UK gap my boat passed IREX which was then enroute to a port visit in Belfast, Ireland. IREX looked weird - the rough seas had knocked off the entire fiberglass sail so that all we saw was the periscope shears but they all looked upright and intact. Back in port she got a new sail but I never learned any details about what had happened although I am surprised that the periscope shears would not have suffered extensive damage. I think that I did hear, much later, that larger and stronger fasteners were used for the replacement sail.
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