Several comments.
Lately I have been diving either in:
A) 3mm top, no pants/trousers, and 2kg neck weight
B) no suit, 2kg neck weight
C) no suit, no weight
In each case, the monofin is heavy, and my legs are extremely heavy, and so I end up in a vertical position, breathing through my snorkel. This makes breathing a bit hard, and I have to pack just to get a normal inhale. Reaching a full pack is impossible, which is why I do a little trick. Once I can barely pack anymore, I flick my ankles, pushing the monofin forward, which pops my legs to the surface, putting me in a flat position. My lungs are now so buoyant that I stay in that position long enough to finish a full pack.
Concerning diving heavy or diving light, it depends on the target depth. Imagine it this way. Suppose you choose a terminal velocity of 0.8 m/s in Case A, or 1.2 m/s in Case B. In case A, you need to use much more energy to get down. In case B it is very easy to get down. Now, suppose the target depth was 60m, and terminal velocity is reached at about 35m. In one case you must overcome a 'negative' buoyancy equivalent to 0.8m/s (case A), the other case you must overcome a negative buoyancy equivalent to 1.2m/s (case B). Of course, the ascent in case A is easier than in case B, but that ease only lasts from 60m to 35m, and after 35m the ascent is pretty easy in both cases. So the penalty for the heavy dive is a difficult 25m in the start of the ascent--no big deal.
On that note, I have found that doing a 55m dive is easiest with an insane amount of weight -- 5kg or more, doing one monofin kick and sinking the whole way! However, for obvious reasons this would not work for a deeper dive.
Imagine now that the target depth was 100m. In the earlier example, in case A the whole ascent is easy, and in case B the ascent from 100m to 35m is hard (a distance of 65m). So in case B, you must have a hard ascent for the immense distance of 65m--why? Why are you putting yourself through such a torture? Because you wanted to save a few kicks in the beginning. In case B, being heavier, you probably only saved about ?3-5 kicks with the monofin...? And yet you have to pay the penalty on each of the 60+ strokes on the ascent.
So, the deeper you get, and the longer you sink for, the more important it is to have a terminal velocity below 1 m/s. You can imagine in the extreme case of a 1000m constant weight dive, saving a few kicks in the beginning would not make up for being very heavy on a 965m ascent.
In that sense, the deeper you go, the less weight you should use. Pelizzari probably recommended little weight because he was diving quite deep himself, and maybe it never occurred to him that shallower divers need more weight.
The question now is this: for an immensely deep dive, say 200m+, what is the ideal terminal velocity? At 0.8m/s, the ascent is easy, but the descent takes longer, and at 0.9m/s, the ascent is a bit harder, but the descent is a little faster... etc... For such a deep dive, you can neglect any extra energy in the beginning of the dive, because the dive is so deep those few kicks are of no consequence, and all that matters is the terminal velocity. Of course, the ideal terminal velocity also depends on the stiffness/shape of the monofin and the technique used on the ascent.
Eric Fattah
BC, Canada
