It depends where you are. In the Northeast, where your first respondant dives and works, it's customary for the diver to bring everything he/she needs with them. The boat is generally your taxi to and from the dive site, and only that. (There are exceptions everywhere, of course, but that's why I use the word 'customary'). In Oahu, where you (and I) are, the dive shop running the charter will bring weights for you, providing you give them a heads-up in advance. They'll usually bring spare weight, so if you're short a pound or five, it's not the end of the world. When you travel abroad to dive, bringing weight's obviously a difficult matter, what with airline restrictions and all...the dive resort that's probably your destination will have all the weights you need.