Yes,lets assume that Hitler cancels the invasion of the Soviet union in 1941 and launches Sealion MkII and it succeeds

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Without going into ihq daa teinix (that's NetFinnish for usual Sealion reaction) , I think it would be interesting, for change, to ponder whether a Sealion in 1941 might have had a chance of succeeding:
Following factors for German benefit come to my mind:
-Kriegsmarine has had time to recuperate from Norwegian campaign and also has expanded. Taking a quick count, by mid-summer 1941 Kriegsmarine has (tadaa!), 16 destroyers and 23 torpedo boats (not MTB's), 2 heavy cruisers, two Panzerschiffe, 2 battle cruisers and 1 or 2 battleships. While still not a match for RN, it's not an insignificant force either
-Torpedoes which explode
-Expanded U-boat force, which by employing effective weapons is a farce no more. Even small Type II's could be used
-Expanded mine warfare force for both minesweeping and minelaying
-Vastly expanded MTB-force
-German Navy and Luftwaffe (!) have operational landing craft
http://www.german-navy.de/kriegsmarine/ships/landingcrafts/index.html
-Luftwaffe has had time to ponder the lessons of 1940 air campaign.
-Luftwaffe has proven capability of hitting enemy ships with deadly effect
-Luftwaffe has Ju-88 in widespread service as well as Me-109F. By late summer Fw-190 is also entering service.
-Recuperated 7th Parachute Division and 22nd Luftlande Division
-Mediterranean Campaign, even in ATL form, has had a effect upon RN strength. AFAIK, much of the war emergency production was to enter service in 1942. Taking a quick count, by summer of 1941 RN has (with taking into account shipping losses up to end of April 1941):
-4 QE-class BB
-4 Revenge class (secondary operations?) BB
-2 KGV-class BB
-2 Nelson-class BB
-2 Renown-class BC
-1 Hood-class BC
-6 carriers
Cruisers (not counting C,D,E and Hawkins-class)
-2 Crown Colony CL
-7 Town-class CL
-4 Arethusa class CL
-8 Leander/Perth CL
-3 Dido-class CL
-13 County class CA
-2 York class CA
-Total of 24 CL, 15 CA
-15 J & K class DD
-13 Tribal class DD
-13 G&H class DD
-15 E&F class DD
-7 C&D class DD
-5 B class DD
-A total of 68 destroyers (Towns and V&W were in escort service by that date). Some of these have to stay in the Far East and Mediterranean.
In OTL, a very large number of these ships were sank or crucially damaged by U-boats and air power during next OTL year. The experience of Crete should be noted. RN suffered extremely heavy losses due to airpower alone within few days. In Sealion-1941 scenario the Kriegsmarine, complete with mines, MTB's, U-boats and surface ships should be added to mix.
British benefits compared to 1940 include:
-Fortifications
-Rebuilt Army
-Expanded RAF and Army AAA. RAF is still weaker than Luftwaffe, especially as it cannot ignore Mediterranean and Far East.
http://www.tsj.net/avstats/strength.html