Posted by Matty
on June 21, 2009, 14:08:43, in reply to "S-BOAT: Details of Form and Fit, into WWII"
Message modified by board administrator June 21, 2009, 14:23:50
As with practically everything else throughout the S-18 class, the sails evolved through substantial modifications, applied in different variants and at different times, to the various boats.
The earliest sail, which was apparently standard throughout the entire class, was also one of the more complex-looking sails ever fitted to a sub:
Click on Image to Enlarge
In actuality, howver, the basic underlying structure appears to have been rather simple:
Click on Image to Enlarge
Note the streamlining of the "bridge can", including horizontal (fairwater) vanes on its sides, and fairwater around its upper rim, as well as upward-sweeping base, together give the impression of an open boat - and for exactly the same reasons, I am sure. Note from the overhead views that the "bridge can" has a teardrop-shaped plan, with its aft end fairing into a heavy vertical pipe, undoubtedly housing the main (air) induction; a primitive forerunner of the snorkel. The earliest pic of this fit is the one at top-right - showing S-37 - on May 4, 1923, while the latest is at top-center; showing S-40 in the early 1930s. At right, the sails of S-32 and S-33 are shown to have the same fit, purportedly as late as April, 1941, though 1931 would be a much more believable date for this pic.
Because the next sail modification - again, apparently received by all the boats - began to appear as early as 1924:
Click on Image to Enlarge
At right, pics of S-37 at top and upper-middle prove that this fit was present on that boat (at least) as early as October 29, 1924. At right-middle, a pic of S-32 proves she retained this type of sail (at least) as late as 1943, as also pics at left; showing at middle-left, -right and bottom-left, 1943 views of S-22, S-21 and S-18, respectively.
Of course, numerous minor field modifications - particularly once WWII had begun - were no doubt fitted as well. One of the more prominent among these appears to have been wind/spray sheilds, on the open bridges:
Click on Image to Enlarge
Within a year or two, the vast majority - perhaps all - of the boats in the class received the final, and major, refit to their sails:
Click on Image to Enlarge
Several apparently custom-variations are shown at center. At top, S-31 appears to have had only partial "foot" removal; its end raked aft and topped with a light platform, additionally supported by a single, heavy post, which is similarly - but not identically - observed on S-32, at upper-middle. Similar light platforms, supported entirely by latticework after complete removal of aft "feet", are likewise depicted for S-35 and S-28 at lower-middle and bottom, resepectively - though again they are not identical; S-35's platform (mounting, notice, a shielded-20mm - or possibly 0.50-cal - AA gun) being sited much lower than S-28's.
At right, more views of S-28 reveal that the aft platform was round and, especially when combined with flaring railing and other features of the new sail, created a strong resemblance to a Type VII U-boat, when viewed head-on (bottom-right). (Small wonder that WWII submariners were very wary - and justifiably so - of "friendly fire" aircraft attack.) This may indeed be a major reason why later refits (to other classes, at least), either omitted such platforms or placed them ahead of the conning tower, rather than aft. In any case, they did not appear substantial enough to support any really effective (i.e., 40mm) AA weapons.
So there (in general) you have it; an evolution in fit of the sails creating appearances ranging from civil war monitors all the way to Type VII U-boats! 
Cheers,
-Matty
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