High Wire nailed it!
Once the fibreglass gets burning, it is mostly about trying to stop the fire from spreading to other boats, the docks, boathouses, etc. without putting life at risk.
Marina fires (boats tied up in a marina) are often very, very difficult to deal with. Long set up times (to advance hoselines from shore to dock location), often only one way out to the fire location and therefore one way back (without going in the water which is not good in fire protective gear). Don't get caught (trapped) on the "water side" of the fire.
My advice for those without the necessary knowledge, tools, and equipment is (if the fire gets a good foothold) "run away" and leave it to the firefighters! Life safety is first and foremost! Oh, and by the way, call the fire department first thing!!! Seen the "I'll try to put it out first" method, and the results! Usually not good!