what does purchase mean?

[set]

Hi,

Sorry for the dumb question but what does purchase mean in the expression "extra cunningham purchase" or "2:1 purchase"?

Thanks a lot!

 

[mlemieux1978]

a 2:1 purchase, as in a block and tackle purchase, is an expression which indicates the power enhancing capabilities of the system. A 2:1 doubles your input, minus some small percentage for friction. friction gets to be more of a factor the more turning points in the system.

check here http://en.wikipedia.org/wiki/Block_and_tackle for info with pics for a better explanation, especially about rigging tackle to advantage/disadvantage and theeffects of friction on the system

happy sailing
Mike

 

[set]

Thanks a lot for your answer!