Just a comment on the alarm system idea. I think it is a good idea. However, be aware that under such an alarm, due to monitoring costs, the alarm like are in many existing buildings is for "local alarm" only, and unless someone calls, does not notify the FD (unless the Marina owner decided to pay for 24/7 monitoring).
It is a bit of a mixed bag, some buildings are monitored by a private company (Like ADT for example), while others are just local. Most Fire Departments do not provide alarm monitoring themselves (directly). Even for a building (or location) that is monitored, call the FD anyway if the alarm sounds and provide any additional eyes on scene to them that you can.