During ancient times when ships had beer to drink for the crew since water would spoil, how was the matter handled on muslim ships since the religion bans alcohol.
I am not an expert on this but I did recently do a bit of reading on the Ottoman navy and in a book I was reading they discussed the importance of the availability of drinking water. The main subject was arranging fresh water for the city of Alexandria but one line does stand out as relevant
"sufficient supplies of drinking water were clearly essential for the sustenance of sailors aboard Ottaman naval ships" (i)
Which I would assume means they would tended to survive on water. Beyond that from what I can gather their navy rarely extended its field of operations too far from shore. I have read that twice the navy reached the East coast of the Americas but that appears to have been a voyage hopping across the North Atlantic stopping at all the smaller islands (Faroe Islands, Iceland to Newfoundland) in 1627 (ii) rather than a voyage straight across the Atlantic. I am looking for a source but that to me would suggest that voyages were limited to the length of time they could keep fresh water.
I did also find the abstract to this paper which could shed some extra light on the issue
Altintas, A & Yaman, D "The technique used by the sailors for converting sea water into drinking water". It mentions a technique known as "the amelioration of waters" which is best described in a text from the 17th century known as “Gâyetü’l-Beyân fi Tedbîri Bedeni’l-İnsân”. It suggests that running out of drinkable water was a common problem for Ottoman sailors, which I would again read as water was their source of liquid aboard their ships. (iii)
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(i) Mikhail A, M "The nature of Ottoman Egypt: Irrigation, environment, and bureaucracy in the long eighteenth century" 2008 pp226
(ii) http://en.wikipedia.org/wiki/List_of_Ottoman_conquests,_sieges_and_landings
(iii) Altintas, A & Yaman, D "The technique used by the sailors for converting sea water into drinking water" 2012
I'm not sure I understand the premise to this question. Alcohol will dehydrate you further, so why would ships' crews rely on it? Also, I'm not sure if the correct word is "spoil" because water isn't like milk or juice. As long as you boil it, it should be good to go in almost every situation.