OK, well I think MOST of know that it all a matter of degree. There is no way one can makes one's self 100% safe and secure 100 % of the time (even with the G word). That said, how can one involve the odds.
As other's have mentioned (here and elsewhere), fear is big factor but this is a hugh subject and I am not qualified to delve into it so will leave it aside for others to discuss.
Dog's can certainly be excellent protectors, especially if very well trained (not necessarily as "attack" animals - just as loyal protectors). The bad guy(s) are never sure how dangerous / unpredicable dogs are so that unnerves them somewhat and balances up the situation. Of course some downsides on having dogs onboard!
Self-defence courses vary from forgettable to excellent (IM -very humble- O) but if one wants to travel down that road and really commit to becoming very well trained in "martial arts", I am sure that would be a great help in some (many?) situations.
Sound is a reasonable "non lethal" weapon, very easy to generate on board (and in large quantities). This could vary from an attention seeking external siren (and say strobe) to an absolutely ear splitting shrieking alarm below, just operated by a "panic switch". All the components are easy available off the shelf and are simple to rig up.
The electric fence idea of the lifelines are doable and could offer some significant deterrent to unwanted boarders.
A Wyoming woman should be familiar with the electric cattle prod but that borders being a weapon but again it is a matter of degree (IMO).That also goes for all the other existing "weapons" on board; flares, spearguns, kitchen knives, frying pans, etc.
I hate to say it but it seems to me that the old adage "attack is the best form of defence" is an inconvenient truth.
So get some dogs, wire up some sound alarms, sort out the electric lifelines and watch some Bruce Lee movies
