Re: Progresive insurance won't cover my trailer.
Now you know how they save you hundreds of bux. They don't pay any.
They pay lots of claims every day. COVERED causes of loss claims, to be exact. Your inclusion of the word "any" is a false statement.
As a couple fellas have already pointed out,
Mechanical damage alone is almost NEVER covered by any insurance policy. When your transmission goes out in your car, do you think State Farm pays for it? Heck no. It's excluded in every auto/boat/home/commercial policy I have ever read. It's even excluded in Yacht Policies.
Now if the broken spring had resulted in a collision that damaged the boat, the collision damage would be covered.
As far as the towing bill, do you have towing coverage on your policy?
As usual, the answer to all this is to read your policy and understand it. If you can't understand what's covered (this does get confusing, I know) have someone explain it to you.