Will my boat catch fire?

[Windseeker]

At the end of past season, I noticed these burn marks on my electrical cord. I know they were not there for the past 6 years. The difference with this past years is that I was using a Honda EU2000 portable generator. The burn marks are only at the boat connection. The other end is fine. I've included a picture of the adapter I use for the generator and 120v 20 amp shore power connection. It does not have any burn marks.

What's causing this?
What to fix it?
How to prevent it?

I would rather not just replace parts if there is some underlying electrical problem that needs to be addressed. Feedback would be most appreciated.