A Weighty Question. . .

[DanL]

Eino,
Noticed you said you dive salt water. Where do you normally dive and what weight wetsuit do you use? Is your wetsuit at Cayman going to be different from your normal wetsuit?
Anyway - it all probably doesn't matter. EVERY dive operation I've ever dived with asks how much weight you typically use, tank type, exposure suit, etc and recommends a starting weight. The DM's are usually very close in their weight recommendations, and they will help you get your weight right on the mark within a dive or two if you ask them to help out. Also, the DM's carry extra weight. Pre-arrange a signal to get weight from your DM toward the end of the dive if you find you are getting too bouyant.
It's GREAT that you're thinking about this, asking advice and working it out in your planning. But don't worry - rely on getting assistance from your DM in getting set up right for the local diving conditions.
PS - by the end of a week, a good DM will help you work your weight down and trim you out. They are in the water every day and see every type of diver. They can really help you improve. You'll have a wonderful time!