It's a touchy subject in this forum. From the experience of people who have actually cruised to foreign shores, it seems that guns
are a lot of hassle to have on board. Legally anyway.
They usually are required to be handed in at each port of entry, and picked up again at the port of exit. Getting the guns moved from one to the other can also be a problem.
Of course you could choose not to declare them - but if you are caught with undeclared firearms you could end up in jail. In some places this could be seriously life-threatening.