How to "Repel Boarders for Dummies".

Water (non lethal, doesn't cost anything)
Water pumps; one for the starboard and the other for the port side of the ship; usually installed on a ship to fight fire and empty the bilges.
Good hoses, connections and spray piece.

When pirates or Israelis come near enough then spray through one of the water overflow holes, using the protection of the sides to protect one from "HER" (Human emotion and reaction or Anti-semitism).

Against Helicopters, I would aim at the small rotor at the back of the helicopter, and the landlubber that slides down the ropes from the helicopter.

I don't recommend landlubber hand weapons. It would be nice to see the pirates floundering in the see, uncoupling their Ammo pouches, gas bombs, rifles, bullet proof wests, prayer books so they don't sink.

Oh! So is life at sea. Neptune has his own Talmud.