Fins and buoyancy..

[Wrayne]

I read somewhere that fins can be positively or negatively buoyant. I was wondering how you tell the difference? When I bought the pair I have now I didn't see any information on this, and the people at the store I went to (the local Sports Chalet) were not much help. The salesperson there just grabbed the biggest, stiffest pair and said that's what I needed for diving, and being totally new at the whole thing I didn't know any different, so I bought them. I ended up having to exchange them for a pair that was a bit smaller and more flexible.

Getting back to the buoyancy issue though, does it really make a lot of difference with the fins?

[ianr33]

Originally Posted by Wrayne

I read somewhere that fins can be positively or negatively buoyant. I was wondering how you tell the difference?

Getting back to the buoyancy issue though, does it really make a lot of difference with the fins?

Put them in water. If they sink they are negative.

The buoyancy of fins is probably not a big deal for a new diver. When you get to the stage of fine tuning your trim though it can make a difference. One of the reasons I switched from Quattros to Jets was to help keep my feet lower. (Jets are pretty negative)

[cummings66]

At one time I was looking for a fin that was positive, I never found one that really floated. Are there some?

[Zenagirl]

My first set of fins floated, which came in handy when they'll pop off during giant stride entries, but since I got those in like 1992 it won't help to say what they were. When they broke, I went with Jetfins and it took me a few dives to get used to the negative buoyancy of them. Had I known about Slipstreams I probably would have gotten them as they are neutrally buoyant.

[gtjason2000]

tusa imprex tri-ex sure do float unfortunately found that out during the divemaster gear exchange.

[meesier42]

the bouyancy of fins can cause trim differences. Many fins are so close to neutral that it doesn't make a big difference though. There are exceptions here though, ie Jets are almost 1lbs negative each. That's a lot of wieght to have that far away from your body.

[quasimoto]

Originally Posted by meesier42

the bouyancy of fins can cause trim differences. Many fins are so close to neutral that it doesn't make a big difference though. There are exceptions here though, ie Jets are almost 1lbs negative each. That's a lot of wieght to have that far away from your body.

That is why you bend your knees when you aren't finning. Trim shouldn't be an issue when you have more weight further up that you can move around.

[dannybot]

what about boots? How much can you tell with a 2-3 mm short boot versus a tall 5mm?

[crpntr133]

Originally Posted by dannybot

what about boots? How much can you tell with a 2-3 mm short boot versus a tall 5mm?

Very little with boots. If you change suits then that can make a bit of a difference. Also a sole difference (thick or thin) can off set the difference in 3mm-5mm, what little there is.