If the 40.5 is designed for a windlass in the anchor locker, which Wes can answer that question, then yes, I agree that welding cable should not be used. However, on the 37.5 which is not designed for an anchor windlass in the anchor locker, as I installed it all wiring connections are located in the people part of the boat where it is not exposed to the salt environment of the anchor locker, welding cable is just fine as all connections are not exposed and significantly cheaper and can actually handle more current per size. If you want to spend all the extra money on marine grade wire, by all means. However, 80% of the wiring used on your production boat is off the shelf wire purchased in bulk from the lowest bidder. Do not take my word for it, just look at the wiring on your bought and you will see that this is pretty much the case. I do use marine grade tinned wire on any application that is exposed to the outside elements. In fact most production boats, even though they carry a NMMA sticker are not wired in accordance with ABYC standard. Just open up your electrical panel and look at the connections, if you know the ABYC standards, and I do, you will see that they are followed only some of the time. If you doubt my wisdom, here is my background. I was in the Navy for 30 years. 20 Years as a Missile Technician (this is an electronics rating) on submarines. Then I was a Submarine Ordnance officer for ten years. I worked as a Chief Test Engineer at Newport News Shipyard where we build Navy submarines. For the last 8 years and present I work at the submarine training facility in Norfolk, VA. So you could say I have been around the block a bit with the marine environment and wiring. However, I will never tell you not to use tinned wiring. All I am saying is look at you application, where it is needed. It is not always required on a boat. By the way, the Navy doesn't use tinned wiring per say. remember my statement about highest bidder. That is a business decision and the Navy has been doing fine with it for more than a few years. I am very comfortable with my decision to use welding cable. I did give it a lot of thought before using it.
Scott.