Do Instructors Know Your Buoyancy Without Checking?

Diver in advanced diving class struggled due to excess buoyancy. Instructor failed to recognize and correct the problem.

Reported Story

I chose to do my Advanced PADI course on a liveaboard, after logging about 20 dives. My previous dives were in various conditions and I used a 5mm wetsuit, a 7mm wetsuit or no wetsuit accordingly. I recorded the amount of weight I used in each dive and never had any problems being under or over weighted. During the liveaboard dives, I wore a 3mm wetsuit; after the first dive, I told my instructor that I felt underweighted. I had to completely empty my BCD even at 15m (49ft) to prevent ascension and although we completed a safety stop at 4m (13ft), I had to arch my back and fin down to do this. I told all this to my instructor but she insisted that I had perfect buoyancy throughout the dive and would be overweighted if I added more. She said that she prided herself on being able to weight people correctly. I then completed the next 5 dives over the course of two days. After each one, I had back pain as I had to fin down almost continuously at 15m (49ft) or shallower. In retrospect, I should have insisted on having more weight, but I felt pressured by the instructor to ‘just get on with it’ and despite being a confident diver, she made me feel very unsure of myself. I also didn’t have a chance to perform a buoyancy check as my instructor told me I didn’t need to, and told me to start the descent. During the whole trip I felt as though she was rushing to fit in all the dives with planned departure/arrival to and from the dive-site.


Proper buoyancy control is essential for pleasure and safety of diving. Buoyancy control skills reflect best the level of training and proficiency of divers. However, even the most experienced divers (instructors) cannot reliably guess the optimal weight required for each diver without checking it. The buoyancy balance check must be standard procedure of a pre-dive check at the surface before descent. Divers who do not practice it are at risk of running into an incident and instructors who do not require it are negligent. This diver seems to understand the significance of buoyancy control and she wanted to get it right but the instructor wouldn’t listen to her. It is not easy for beginner divers to take responsibility for their own safety against advice of their instructors. While instructors do have responsibility towards their clients, remember that the prevailing attitude out there is that responsibility is on the diver. When you feel that things are not in favor of your safety, the ultimate responsibility is with you to ask for corrections and not pursue diving until it is corrected.

Petar Denoble, MD, DSc