I think that the Uboats that operated in the Indian/Pacific ocean isn't a "first priority" to the HQ, as Adm. Doenitz says ("we have to concentrate the attacks on the British navy, the atlantic war, the tonnage war", or something like that).
The Snorkels were a great strategy gadget, specially at the end of the war. So then, sending snorkels to the japs subs bases is not a good idea to win in Europe.
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