FWIW you might find it worth reading through this thread: Cleaning Corrosion from High Tension Electrical Cables - Page 2 - Cruisers & Sailing Forums
. I went through the trials of installing a windlass just as you are now. A couple of thoughts:
1. ensure the lugs you order are the correct size for the studs on both your battery, the solenoid; and, your windlass.
2. Do not have the lugs installed before you run your wire. It is certain that the bends and curves in the wire will all but ensure that the lugs are not oriented in the correct direction for the studs. Schedule 4/0 wire does not like to be twisted, and in some cases, cannot be.
3. All this discussion of crimpers is of no use. Crimpers do not give a decent connection between the lugs and the wire and particularly 4/0 wire. Instead, I used a "Swage-It" tool which completely compresses the lugs around and into the wire. By adding your adheasinve shrink tubing beforehand and then sliding it up and over the ends of the lugs, you end up with completely water tight connections. And the Swage-It tool is inexpensive and very usefull aboard.