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ksporry

Member Since 07 Jul 2013
Offline Last Active May 10 2014 06:57 AM
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Posts I've Made

In Topic: trim issues caused by buoyant fins

02 May 2014 - 12:53 AM

 

You mention "standing on one knee", do you mean kneeling? Generally, I would discourage you from contact with the bottom at all, as there is always the risk of environmental damage.

 

 

 

 

 

 

There are some places in the world where kneeing is "allowed" and that is on sandy patches where you may watch shark feeding in the carribbean for example.
Sandy bottom sems to be dead, but this is completely wrong and damage to marine life (or you kneeing on a Weever orsimilar) can still happen!

 

 

Actually, I don't just kneel or stand anywhere. This is always during instruction sessions and always on sand or dead rock/rubble. Never anywhere where it could potentially do harm to aquatic life. I'm very conscious about aquatic life when I'm diving, which is why I flag this up as an issue that I'm hoping to address with new lightweight but slightly negatively buoyant fins. (if I can't fin backward, that introduces more risk).

I also did get my PPB, but I got that before I got my own gear. The 2 PPB dives do not teach a diver sufficient trimming or buoyancy effects of gear and its use.

 

 

 

Carrying weight requires the addition of more air to achieve neutral buoyancy. This further adds to potential buoyancy shifts as the air moves around the buoyancy system. It is interesting that you record that with steel doubles, the situation is exacerbated-this is perhaps due to the fact that they are very negatively buoyant and hence you are adding significantly more air to offset this? The reason that ankle weights failed to prevent the issue may well have been due to the fact that you added more weight, requiring more air and hence more instability...

 

 

This is an interesting point that I may try out. I don't use a dry or wet suit. I only dive with a rash guard and shorts as it's usually 28 degC in the water.

However, I did get the feeling that I could do with less weight (e.g. at the end of the dive I still have some air in my BCD to keep me neutral, and that's with a 15l tank). Currently I'm on 4kg. I'll try to reduce that to 3 and see if my trim gets better as a result.

 

As a note, a camera can definitely affect buoyancy and trim. If the camera is 1kg negatively buoyant then thats extra weight. I actually used that to trim my position with my previous BCD. If i wanted to be more head down I pushed out my camera, and if I wanted to be more feet down I pulled it in. With my current camera rig, BCD and fins I'm nicely horizontal, except my feet want to go up.

 

 

So I'll try out that theory about less weight and less air before changing more gear...


In Topic: trim issues caused by buoyant fins

26 April 2014 - 09:33 PM

I'm sure my camera weight/buoyancy affects my trim, but the point is to have a good trim with camera. My camera is a bit negatively buoyant (I have an EPL5 with nauticam housing, 2 Z240's, with either a 6" dome port or a macro port. I used INON 24cm floats with 24cm sticks, I now changed that to h2o floats, both 28, one 3 cm diameter, another 4,5 cm diameter. I tried 24 + 28cm INON floats but that was too buoyant. The new setup should be somewhere in between).

 

However, i don't think I should consider the camera buoyancy to be the problem. Because, when I stand on one knee on the bottom, that's a position thats difficult because my feet constantly want to float (i.e I need to push them down).

During photography It makes my positioning very uncomfortable as it tends to result in me arching my back more than is comfortable for a long period of time, which ends up sore at the end of the day.

I think with neutral or slightly negatively buoyant fins I might be in a more comfortable position.


In Topic: Trimming the buoyancy of your rig using float or float arms

26 April 2014 - 08:43 PM

So, I think what we see here is a whole mix of different buoyancy control mechanisms. Buoyancy of your camera is a personal thing I believe. Different people have different preferences. At ADEX I was talking to a german guy from h2o tools. I got a few float arms of them. They guy expressed that he wants his camera perfectly neutrally buoyant, and he said that was the way to go. I told him I disagreed. I personally want my rig to be slightly negatively buoyant and in a decent trim. Having it negatively buoyant gives me a more stable feeling when handling the rig. The guy actually insisted neutrally buoyant was the way to go, and I just told him again I preferred slightly negative, and said its a personal thing (I'm actually wondering if he was trying a sales pitch, which I absolutely hate. Especially when someone already expressed their preferences, which should indicate they experimented and found what they prefer).

 

Anyway, my point is, because it's a personal thing, you can play with any and all mechanisms to do a mix and match for your personal optimum.


In Topic: Stability Issues with setup

13 August 2013 - 02:52 PM

Thanks guys, useful stuff!


In Topic: Stability Issues with setup

13 August 2013 - 06:18 AM

I realised this afternoon that the 3-way clamps could do what I want. I'll explore that possibility. It may not seem necessary in water, but forces are still forces, and I feel more comfortable with some stiffness. eliminates vibrations too...