Look. It works this way. The only thing worth someones life - yours, theirs, whoever - is your family. Protecting anything else with force is guaranteed to get you investigated, interrogated, possibly arrested, and possibly charged. Even if you are acquitted or not charged, I promise it will be the worst experience of your life. The court system is heartless, as it should be. Someday, I want one of you who touts firing a weapon to stop and talk to a veteran officer who has killed in the line of duty - or a vet - and ask them how it felt.
If that blatant appeal to reason did not work, try this: Tell me in three sentences exactly how your dock or your boat is your castle?