JJ Trim / Field of view

[Der_Derbe]

Hello,

I am not a CCR diver yet and am thinking to get one.

Last weekend I was test diving 3 units, one of which was a JJ.

I liked the JJ most in regards to build quality. However, I wasn´t satisfied during the dive. The main reason was that I couldn´t look horizontal when I was in neutral trim. Instead I head to look to the ground because my neck was restricted and I could not move it far enough to look straight.

Is if this is a general problem of the JJ? Do I either have to look down or leave the neutral trim to look horizontally? Or might that be caused by a configuration problem? I think that the unit was positioned quite high on my back and that in some videos on youtube it seems to be 10 to 20 cm lower.

Many thanks for your input

 

[Der_Derbe]

No JJ user in here who could answer the question?

I also looked at the test results in the download section of jj-ccr.com recently. They state that hydrostatic imbalance is lowest at approx. 30° trim. So maybe it is not even desirable to dive in neutral trim and that I should change trim when doing another try dive?!

 

[nickb]

No JJ user in here who could answer the question?

I also looked at the test results in the download section of jj-ccr.com recently. They state that hydrostatic imbalance is lowest at approx. 30° trim. So maybe it is not even desirable to dive in neutral trim and that I should change trim when doing another try dive?!

I have absolutely no idea what you're talking about here. I can only imagine that the loop may have been shortened.

I am 64 years old and my neck has never been particularly flexible but I've been diving a JJ for 12 years and have zero issues in any position, including horizontal (which is what I assume you mean by 'neutral').

There will always be a position for any rebreather where the hydrostatic imbalance is at its lowest but that doesn't mean that it's particularly bad in any other.

 

[Bobjr]

Hello,

I am not a CCR diver yet and am thinking to get one.

Last weekend I was test diving 3 units, one of which was a JJ.

I liked the JJ most in regards to build quality. However, I wasn´t satisfied during the dive. The main reason was that I couldn´t look horizontal when I was in neutral trim. Instead I head to look to the ground because my neck was restricted and I could not move it far enough to look straight.

Is if this is a general problem of the JJ? Do I either have to look down or leave the neutral trim to look horizontally? Or might that be caused by a configuration problem? I think that the unit was positioned quite high on my back and that in some videos on youtube it seems to be 10 to 20 cm lower.

Many thanks for your input

I think you should get an instructor that understands how to set up a harness so you can get your head back.