how do you dive a 7.5 mm full suit

[Jayfarmlaw]

Ok...I thought I was a pretty good diver. All but 2 of my 150+ dives have been in a skin or 3/2 full suit. (Or naked...not...maybe....). Several year ago I bought a 7.5 used, but almost new, full suit in anticipation of Bonne Terre and Blue Hole/Santa Rosa NM. I broke it out today for my Birthday dive (because everybody should dive on their birthday) and put 16 pounds in trimweights and waist pockets. 2/2/6/6. Couldn't sink...stuffed a 3 pound weight in my wetsuit and was able to dive. The last time I dove it it took 25 in a jacket type bcd and I was very new.

Once I got to 20 feet, I guess the neoprene compressed and I was dropping like the titanic. I finished a 40 minute dive but always felt heavy. Buoyancy was fine, but there was more air in my wing than I wanted. 43 minute dive down to 90 feet, 49 degrees. I need thicker gloves and maybe thicker boots or a thick dive sock (I was wearing regular socks too)

So...the question is: should you swim down until the neoprene compresses or just plan on diving heavier than you prefer?

Thanks,
Jay

 

[tomfcrist]

Thick suits need lots of weight...at the surface...and a big ass wing at depth.

I for that reason only have 2 suits...3mm full suit for warm water, and a drysuit if it’s below 70.

 

[northernone]

Ok...I though I was a pretty good diver. All but 2 of my 150+ dives have been in a skin or 3/2 full suit. (Or naked...not...maybe....). Several year ago I bought a 7.5 used, but almost new, full suit in anticipation of Bonne Terre and Blue Hole/Santa Rosa NM. I broke it out today for my Birthday dive (because everybody should dive on their birthday) and put 16 pounds in trimweights and waist pockets. 2/2/6/6. Couldn't sink...stuffed a 3 pound weight in my wetsuit and was able to dive. The last time I dove it it took 25 in a jacket type bcd and I was very new.

Once I got to 20 feet, I guess the neoprene compressed and I was dropping like the titanic. I finished a 40 minute dive but always felt heavy. Buoyancy was fine, but there was more air in my wing than I wanted. 43 minute dive down to 90 feet, 49 degrees. I need thicker gloves and maybe thicker boots or a thick dive sock (I was wearing regular socks too)

So...the question is: should you swim down until the neoprene compresses or just plan on diving heavier than you prefer?

Thanks,
Jay

Hi, welcome to colder water diving!

You need to be able to be weighted to be neutral at the end of the dive for the safety stop without struggling to swim down. It does seem like a lot of lead but it is necessary.

It's possible there's air trapped in the suit and it takes a few moments to soak. You want to be weighted soaked, not dry. Normally that lets you drop a few lbs.

The sinking at depth is normal with so much neoprene compressing..

Cameron

 

[BRT]

You are going to get lighter during the dive as you use air. IMO you should weight yourself so you are neutral on safety stop with a nearly empty tank. I have ended up too light on safety stop when I really wanted to breath my tank down. Not in decompression by my very liberal computer but too close. Not much fun swimming down to hold a stop when you really want to maximize how long the last few hundred pounds last.

 

[DerekR]

If you have to swim down and you are wearing an AL80, you will spit to the top like a cork at the end of your dive! You need to be able to hold 15' at the end of the dive.
In my full 7mm (not a 7/5), it takes 32 pounds to get my head wet.I only need 26 pounds for the same configuration in my drysuit.

 

[KevinNM]

When I had a 7mm farmer john I had quite a bit of lead and often swam down to maybe 10 feet. But I was also fatter then.

But always have enough lead that you can hold a 10ft safety stop. Next time you dive at the end of the dive empty your BCD and blow the tank to 500 PSI with the purge and see if you can hold a 10 feet stop just sitting there motionless, so without swimming down. If you keep floating up then next dive you need more lead. If you can stop there or sink very slowly then it's probably good. If you sink rapidly then you probably should remove some lead.

 

[TMHeimer]

Yeah, all what they said. I need 42 pounds for my 7 mil farmer john. Then I await replies saying I use too much.

 

[boulderjohn]

The best thing to do is to have a weighter employed to help you out. You take all the weight you need to sink, then once at depth you call out "Oh, weighter!" and hand over the extra weight you no longer need at depth. When you are ready to ascend, you make the same call and get the weights back that you need for the ascent.

Not practical in your case?

Then join the many frustrated people who are learning to dive with thick wetsuits. You have already received good tips from others--nothing I disagree with above. It takes a lot of practice. In time, you might start a new thread asking for advice on the best dry suit to purchase. A dry suit has constant buoyancy throughout the dive, so the weight you need to descend is the weight you need to dive.

 

[Jayfarmlaw]

all the weight you need to sink, then once at depth you call out "Oh, weighter!" and hand over the extra weight you no longer need at depth. When you are ready to ascend, you make the same call and get the weights back that you need for the ascent.

I was diving solo, but I use a mesh bag with extra weight in it to hold my dive flag. With a 3 mil, I use 4 pounds in salt water and the same set up, less hood and gloves.

Glad to here it just takes a crap load of weight to sink this suit. I was in a hurry to get on with this dive because of my text to my wife saying 45 minute dive, 20 minute to gear up and in the water, 10 minutes to get out. I didn't my want her to worry or call out the Calvary.

Sounds like everything was close to normal. My bag o weights worked fine and will co tinge to do it that way if I dive this suit local again. I was diving an al100 with a 3300 fill. Still had 40 minutes of air left on my computer so didn't get floaty in the least.

Thanks again for all the responses. Belize in 10 days, then maybe Bonne Terre in June.

Jay

 

[Stoo]

When I started diving 200 years ago, I wore a 2 piece 1/4" suit. I have always been sinky, but this was before BCDs.... we wore little "Mae Wests" for emergency flotation at the surface.

On deeper dives (100' +), I would typically take my weight-belt off once I got to the bottom, do the dive, then put the belt back on before I surfaced.

I also new guys that would wear a lighter belt, but begin the dive (from a boat) holding a half of a concrete block, which was abandoned at the bottom. For many years, the area around the Arabia in Tobermory was littered with half blocks, and I presume they're still there, under the silt.

You don't often hear me referring to the "Good Old Days" when it comes to diving.