trim issues

[Banyan]

You're describing someone who is badly overweighted. An overweighted diver swims at an angle with their head up, in order to keep off the bottom. An underweighted diver swims at an angle with their head down, in order to keep from floating to the surface. As herman notes, he's spending energy trying to keep off the bottom and then he's also spending energy pushing a large surface area forward. A diver who is properly weighted and trimmed, should be horizontal and spear through the water with minimal effort. He's probably also anxious because he's not comfortable, which also takes up energy. No wonder he's sucking down air.

Insta-Gator's recommendation to be a basic buoyancy check is a good one. If he's having trouble sinking AND is overweighted, you should also see what is keeping him up at the surface. To sink properly, a diver should hold their fins still, dump air from their BC and exhale completely. Once you get down to 15 feet or so, the pressure will compress your wetsuit (and reduce your buoyancy) enough that you no longer have to pay so much attention to making yourself sink.

Let's go through each of these - finning, breath and dumping: (1) A lot of new divers unconsciously fin upwards when they sink. They then pop to the surface and report that they can't sink and need more weight. When they get more weight, they start sinking faster and unconsciously fin faster. You end up with a nasty cycle. Watch your dad's fins when he starts to sink. They should be still. If someone wants to check themselves, cross your legs at the ankles - you'll feel your legs kick each other even if you aren't conscious of finning.

(2) An adult male can swing their buoyancy 10 pounds just using their lungs. An excited or stressed diver will tend to fill their lungs to prepare their body for action. You need to relax and exhale exhale exhale to get down. You don't know how much air is in your lungs until you really try to get rid of it all.

(3) Make sure the inflater/dump hose is fully extended above the head of the diver when dumping air. A mistake I've seen among some new divers is operating the inflator assembly at shoulder level, where the hose dips down to chest level, where it is impossible to dump the air at the top of the BC.

There are a few other less likely possibilities, like air bubbles in too-tight exposure suit, but I would think rechecking buoyancy while keeping an eye on proper technique will solve your dad's problem. I really recommend you make this a separate session in a pool or confined water, so you can take your time and have somewhere to put all the weight you'll be losing. And don't worry if it takes a while to zero in on the proper weight and weight distribution. I'm still trying to get the perfect trim.

 

[halocline]

While proper weighting and proper weight distribuiton will help, that is not your main problem. What you are dealing with is someone who does not understand what it is to be neutral.His swimming angle is caused buy him being considerably negative while he swims and he is using a lot of air because he is working hard to both swim and not sink. The 45 deg angle and moving straight is a dead give a way. He is both swimming UP to keep from sinking forward to move ahead at the same time, hence the 45 deg angle. If he were neutral, at a 45 deg angle he would rocket to the surface as soon as he started to fin.

Yep, this is it exactly. Once he's weighted correctly, you can start with adjusting the weight distribution to get him nice and horizontal. This might sound funny, but you actually might start with having him do some skin diving to get used to the idea of really swimming horizontally; it's amazing how many new divers are simply not used to the idea of moving forward while horizontal.

 

[mselenaous]

+1 on what they said.

I've got 2 comments to add.

1- While starting to descend and figure out if he can sink or not, he is vertical. In this position, have him cross his feet keeping his fins still. Many folks inadvertently wiggle their fins (thus this slight finning is pushing them upward while trying to descend).

2- It is simple physics. Picture this. When over-weighted, air has to be added. Now you have a teeter-totter balancing the air-bubble in the bcd vs the weight (usually around the waist/hips). When trying to be horizontal with too much lead and too much bubble, picture the extra lead pushing the lower half the body down. Thus the air bubble in the BCD will only travel up, into the shoulder/upper back area pulling the head upward.

Getting a good grasp on this will help. It may take alot of practice and fine-tuning. He will work less hard during each dive thereby improving his gas consumption.

 

[TSandM]

First off, does your dad see this as a problem HE wants to solve? If so:

Begin with a weight check, as described. If he has problems descending when he is properly weighted, it's a technique problem, and he needs to solve it without adding more weight. Many less experienced divers have trouble descending, because they are sitting at the surface and kicking. Kicking keeps them up! Another problem is that they hold up the inflator hose and depress the vent button, and exhale. By the time their head goes underwater, they have to inhale again, and they go back up. Learning to float in the water without kicking is a good start. Then, when the descent is begun, see if he can cross his ankles with his knees slightly bent. This will both prevent kicking, and prevent going over on his back. Finally, have him hold up the inflator hose and take a deep breath and hold it. As his head gets to the waterline, he should exhale sharply and hold that for a couple of seconds. That will continue his descent, and even a few feet underwater helps to compress neoprene and any residual BC air, and make further descent easier.

Second, regarding trim and buoyancy -- they are intimately related, as has already been mentioned. If the diver is not confident enough to get really neutral, he will tend to stay negative and kick himself up to avoid sinking. This requires that 45 degree angle you're talking about. On the other hand, if his weighting and POSTURE tend to rotate him feet-down, he has to remain negative, or his kick will push him shallower in the water column. Good trim begins with good posture -- being flat from the shoulders to the knees. Flexing the hips and allowing the knees to drop below the rest of the body will tend to rotate the diver into a feet-down position. Your dad may want to practice good body position on a bench or floor, and then in very shallow water, lying on the sea floor (if you have that option) to get a feet for horizontal and flat. Then he can slowly add some gas to his BC, and as he floats, see which way he rotates. That will tell you where you need to add weight. But the posture has to come first.

Finally, if adding weight up on his shoulders or tank valve makes the problem WORSE, he might actually be trying to cope with a rig that puts him head-down. This can happen with very short tanks on tall people, and often happens to people starting out with double tanks. They find themselves angling up, and keep adding weight high on the body, and the problem just keeps getting worse. If you add weight low and balance the diver, the head-up position automatically goes away.

Hope these tips are helpful. HERE (go down to the trim articles) and HERE are some articles you and he can read that go into things in much more detail.