"Ron, if I'm reading you c
"Ron, if I'm reading you correctly here you are asking if say you only require 12 feet of cable and you have 18 will it affect the way the motor operates?
If I have that right, the answer in short is no. You can "coil" the cable to take up the slack as long as you don't try and coil it too tightly.
It is not optimum, because you have to either find somewhere to hide it or risk tripping over it at the stern end. Additionally, it does put added stress on the cables and they can wear out more quickly - but will work.
As to shortening them - not something you could attempt in the garage or basement. Besides, cables in themself are relatively economical.
Personally, if you can live with the extra length, I would use them until either they become a hinderance or they begin to seize/bind on you.
But I'm cheap [img][/img] and that costs less than replacing them..."
A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)