Going from 3mm to 5mm wetsuit....

[hammet]

how much weight to add?

 

[tbone1004]

which suit is the 3mm? Which suit is the 5mm? how deep do you plan to dive? What size is the suit?

There is no substitute for proper weight checks. A good place to start is to add 2lbs of lead per mm of wetsuit thickness, but it is all but guarantee that that won't be right

 

[Lorenzoid]

tbone is spot on with the question of suit size. Keep in mind that the buoyancy of a suit depends not only on how thick the neoprene is but also on how many square inches of neoprene the suit is made of. A 5mm XXL suit is a lot more buoyant than a 5 mm Medium suit. Even different brands can have different buoyancies. Also, because neoprene loses a bit of buoyancy as it is repeatedly compressed over many dives, a brand new suit will be more buoyant than a suit of the same brand, size, and thickness that has seen a lot of use. If your goal is precision weighting, you just have to experiment.

 

[hammet]

just looking for a general theoretical rule of thumb. Guess 4 lbs is a good initial approx.

 

[coldwaterlloyd]

I add 4 lbs when I switch from full 3mm - full 5mm , definately a good start

 

[sh1513]

I removed 2 kgs when going from 5mm to a 3mm full suits.

 

[Saniflush]

My XL 3mm is worth 3lbs of buoyancy. If I were going to go to 5mm I would probably start off by doubling to 6 lbs and then go from there.