We took our older (5 and 6 yr.) mini-schnauzers with us when we were cruising the
Caribbean. If your dog is adaptable and smart as I have heard Jack Russells are, you should be able to tray train it for when the
weather is bad, or teach it to go out past the
mast on the foredeck on a piece of astroturf or take it to shore every time it needs to go. We generally walked our
dogs on shore twice a day. Do NOT even consider a
passage until the dog has adapted to going somehow/somewhere designated on the
boat. Some dogs just won't do it and will make themselves very ill. Our dogs almost died on our first
passage because they refused to go on the pee pads we tried to train them to. Also, you should be aware that there is an enormous amount of paperwork, vet visits, and
inspection fees involved with taking your dog with you. Go to Noonsite and on each countries page is a very basic amount of info on what is required to bring
pets to each country. We took our dogs to the
BVI, St. Martin (French side), Antiqua,
Guadeloupe,
Dominica. So many people tried to buy our dogs we were afraid they might get stolen. Also, on
BVI there is active underground dogfighting and dog thefts. We had the most trouble in BVI and
Dominica. Basically, anywhere formerly a British colony. There is less trouble with the former French colonies but even one or two of those is off limits.