What is the ultimate goal here? Self-Defense? Or are you an avid archer?
I'm playing out the scenario in my head.
1) Armed intruder boards boat.
2) One of the crew puts on a pot of coffee or tea
3) The other crewmember locates the recurve boat in a storage locker.
4) Someone digs and finds the quiver of arrows (You got tired of moving them 5,000 times,
so they slowly migrated to the back of the locker).
5) You Interlace the recurve between your legs in order to string the bow, while your mate serves the tea or coffee.
6) You knock the arrow
7) cream and sugar all around
8) You aim trying not to knock something over or hit a bulkhead because a cocked bow and arrow along with your elbow out back is around 4+ feet long.
9) advise the intruder that he can commence with the attack (or you'd be happy to wait while your mate shows him how the head functions......coffee/tea...you know).
10) Attack resumes.
11) Shot fired and miss.
12) Goto Step #6 and repeat
In all honesty, I do feel a bow and arrow are an ineffective weapon. However, I think you have alternate choices. I would either get a large fish-billy, or the absolute smallest baseball bat I could find. A child's bat that can be swung either one-handed or two-handed. Small, light and short will give you extremely fast head speed and allow you repeated blows in quick succession. It will be easier to swing on a small boat. When declared, call it a Fish-Billy for clubbing large fish (explain that you prefer it to the mess of stabbing the head because there is less cleaning on the boat).
You can get a few of them and place one in the cockpit, one in the cabin and one in each stateroom. A much safer, easier and effective solution. Don't bother trying to travel internationally with guns.