Don't know what else you could do for boats in slips, but it would seem to me rather simple to install sprinkler systems in boathouses. May not save the boat that was the original cause of the fire, but could certainly make a difference on adjacent boats. Water damage shouldn't be an issue on unaffected boats.
Ted
Here are a couple of things you'd do.
-Wiring of the boats and docks
-Storage of propane tanks on the boats
-No wood docks, all concrete.
-Venting of any boathouses. Typically this is with center opening of even with multiple vents. Better selection of roof materials.
-Certainly sprinkler systems is a possibility. The only place I've seen them is in a concrete boathouse for larger yachts
-Alarm systems
-On site fire boats or hydrants and hoses. Fire boats preferable.
-Electrical inspections
-Full slips with long fingers on both sides, wider fingers
The problem is that all these things cost money and the customer often isn't willing to pay so most have to be dictated by law. Then we see the customer resistance to something like GFCI. And that's before even discussing all the older facilities.
I haven't been to the Great Lakes yet. However, in the PNW I did notice how many boathouses would not have been allowed on the lake we lived on previously. The dock in the photo shown in this thread wouldn't be allowed in many areas today. I've not seen a lot of docks with fire hoses outside of Fort Lauderdale.
Then of course if you have the equipment at the marina, you need to train some people to use it.