What will this cost me?

[Roy in TO]

Link to a thread from a couple of years ago talking about getting the shine back. There is some discussion on repairs and I provided a link to a video that was available on gel coat and repairs. The video talks about various problems encountered with gel coat.

[Roy in TO]

not sure what to call it

Neither am I Ken, that is probably why you may not have gotten too many responses initially.
The picture you provided looks like blistering (almost like water got underneath and froze) but it also looks like various forms of impact marks there are small dents of multiple sizes. Then there are the 1/2 circle indents looks like something was banging into the gelcoat. It almost looks like the end of a bolt or something. It is really hard to say if there is a single problem or multiple. My guess is the latter.

Is the whole trailer like what you posted, or only one specific area?

Roy