four Rev 8's and a HT4 amp

I just purchased a used 2012 boat from a dealer, the boat came with 4 rev 8's powered by a HT4 amp. By the looks of it is was not a dealer install (unclean wiring).

The issue I have is they seem very under powered, we were surfing yesterday and it was very disapoingting. My old kicker coaxials were louder and clearer at surf range then the rev's. so something is obviously wrong.

Is there anything obvoius I should be looking for with respect to how the speakers were wired?

Thanks everyone!