Coldwater/Weight question

cbdiver88 · Dec 2, 2013

I normally dive in warm water (80F) but this week going to do a dive 65-70F water in about 60-80 FSW. The last dive I did was a shore dive in about 15 FSW and wore a 5mm full suit. I wore 16lbs and my weight was pretty close to perfect. For this dive I am going to use a 5mm hooded vest along with my 5mm full suit. So that will be 10 mm at the chest and 5mm on legs and arms. I was considering adding 2-4 lbs more to compensate for that added suit. I weigh 160 lbs. Would this be a good increase in weight or would you add more or less?

I am also considering wearing a 0.5mm suit underneath would I have to add any weight wearing that?

Thanks!

---------- Post added December 2nd, 2013 at 03:55 PM ----------

Sorry also forgot diving a AL80 tank.

Vegan Shark · Dec 2, 2013

I add 2 lbs when adding a 5mm hooded vest (or semi-john) and it's worked for me.

Phil_C · Dec 2, 2013

There will be a lot of 'compression' difference between a total of 10mm of neoprene going down to 80 fsw. and 5 mm only going to 15 fsw. so you will need to be aware of this. Any recommendation to add a certain amount of weight can only be a "guestimate" at best, and as the dive profiles will be different you may find your spot on weight more difficult to achieve. For example buoyancy variation with small depth changes at 15 fsw. are far greater than buoyancy changes with similar depth changes at 80 fsw. and controlling those changes may not be so intuitive.

I really would suggest a proper weight check and then add weight for the gas used during the dive. What you don't want is to come up from the 80 foot dive and find you can't hold your safety stop, a SS isn't as important on a 15 fsw. dive, but from 80 foot you really want to be able to control your speed of ascent and then hold at your SS comfortably.

I have never had anyone raise a problem when I have said I need to do a proper weight check, and the few minutes it takes are well worth the effort and peace of mind.

Enjoy the dive - Phil

Diving Dubai · Dec 3, 2013

Phil_C:
There will be a lot of 'compression' difference between a total of 10mm of neoprene going down to 80 fsw. and 5 mm only going to 15 fsw. so you will need to be aware of this. Any recommendation to add a certain amount of weight can only be a "guestimate" at best, and as the dive profiles will be different you may find your spot on weight more difficult to achieve. For example buoyancy variation with small depth changes at 15 fsw. are far greater than buoyancy changes with similar depth changes at 80 fsw. and controlling those changes may not be so intuitive.

I really would suggest a proper weight check and then add weight for the gas used during the dive. What you don't want is to come up from the 80 foot dive and find you can't hold your safety stop, a SS isn't as important on a 15 fsw. dive, but from 80 foot you really want to be able to control your speed of ascent and then hold at your SS comfortably.

I have never had anyone raise a problem when I have said I need to do a proper weight check, and the few minutes it takes are well worth the effort and peace of mind.

Enjoy the dive - Phil

+1 For this Weight checks as really important and taught on every scuba course. Yes we all guess what we need and go diving to get in the water but you know it's wrong.

Some time ago I changed my rig, took a guess and jumped in - with a full tank I was fine - but at the end of the dive (100FSW) I couldn't hold a safety stop - thankfully I had a reef hook and something to hang on too. I can assure you when I surfaced I did a proper weight check and learnt from my mistake. Had I been in blue water with no chance of hooking on there would have been a problem for me and potentially for my buddy.

azshohan · Dec 3, 2013

I am also aware of weight. By this reply, I just came to know the right thing.

Thanks Phil for a good and useful reply.

Coldwater/Weight question

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