Fighter pilot, Royal Navy 1945, Hydrographer Iraq 1947-52 India 1952-53, Canadian Hydrographic Arctic explorer 1953-1960, Writer-producer Canadian National Film Board 1961-72, Freelance journalist, audio-visual producer 1972-2009, National Press Club of Canada 1961 - 2006

Sunday, June 7, 2009

India Pale Ale

The secret superiority of India Pale Ale

Forty years ago I read in the New Scientist scientific journal, that during the heyday of the Imperial Raj in India many shiploads of beer were sent out from Britain for the Imperial army.   Often, for various reasons, when only partially unloaded the beer-carrying sailing ships had to leave on other urgent business and months later might arrive back in UK with much of their beer cargo still aboard.  At first, it was sold off at a discount to local dockside pubs and inns, but later it was found that this beer was of a superior quality and was then sold in England as a premium ale.  Even today brewers label many of their ales as being IPA.  Anyway, some chemist fellow experimented and found that the long sea voyage and the constant rolling motion of the ship imparted a special flavour to the beer in the shipping barrels.  So he rigged up a rolling machine in his laboratory and rolled some barrels for a few weeks and sure enough he found it tasted better.  Well, he would.  Wouldn’t he?  After extensive testing, I mean.

Another aspect of how the rolling motion of vessels and strong waters interact was demonstrated years ago by the small vessels that brought casks of sherry to Britain from Spain.  The Spanish seamen learned by experience that if they laid the elongated casks fore and aft, or parallel with the length of the ship they could expect to roll their innards out while crossing the stormy Bay of Biscay.  But if they stowed the casks athwartships the rolling motion of their vessels was considerably dampened and they arrived in UK in good enough shape to enjoy some fine IPA.

Post-war ship designers incorporated this phenomena into some of their largest ships in the form of flume tanks.  Two tanks were built into  the ship, one situated on the extreme port side the other on the extreme starboard side.  They were connected by a tube or pipe and partially filled with heavy oil.  As the ship rolls to port the oil begins to roll to port also.  If continued this movement of ship and oil would result in an extreme movement.  But what happens is that as most of the oil is flowing to port the ship starts its roll to starboard.  But the weight of the oil now on the port side tends to act against this motion thus dampening its motion.  Now the oil flows to starboard just in time to dampen down the roll to port.  And so on.  The oil acts just as the sherry in the casks acted.

A few years later I was in a ship in the Bay of Fundy during a storm when the flume tanks were turned on and off to see how effective they were,  The rolling motion of the vessel was reduced tremendously.  Yet these tanks are of comparatively small size.

Today, modern ship designs incorporate other vastly improved concepts of stabilizing.

No comments:

Post a Comment