Freediving before scubadiving... Dangerous?

[Bombero]

Me and some buddies thought of going on a divingtrip next week, and we have thoughts of both freediving and scubadiving. We are no advanced freedivers, maximum depths around 40 feet.

So to the question... Is it dangerous to Freedive before an Scubadive?

/ M

 

[ZAquaman]

My understanding about freediving and scuba diving in the same day is simply this:

Freediving increases the amount of nitrogen saturation in the blood. There is no way to predict or measure the nitrogen levels durring a freediving session.

With scuba diving this increased saturation can be estimated as a function of depth (pressure), time, and the concentration of nitrogen in the air you are breathing while diving (in the case of nitrox, etc.). That's what the dive tables are all about.

So in short, if you are scuba diving very near or right at the table limits you have a great risk of getting bent if you freedive as your blood nitrogen levels will be elevated.

There are other issues involving micro bubbles, exertion, etc. but it seems that there exists no real saftey data involving freediving and the bends. We do know from experience that freedivers can get the bends from extended periods of extreeme freediving.

 

[Veronika]

Hi,

If you SCUBA-dive, there will be a formation of microbubbles, which are normally filtered by the lung and do not enter the arterial blood circuit.
If you freedive after SCUBA these bubbles are compressed and can cross the lungs without being filtered. The result after surfacing at a high rate potentially is microbubbles where you certainly do not want to have them. So: No freediving after SCUBA.
If you freedive before SCUBA, you will build up microbubbles but these are compressed during the SCUBA-Dive. When you slowly ascend afterwards, they are a minor factor compared to the SCUBA-microbubbles and additionally have the chance to be filtered by the lung properly. This means that freediving _before_ SCUBA is ok.

HTH.

Veronika

 

[Cornholio]

This means that freediving _before_ SCUBA is ok.

I'd adopt a very conservative dive plan, though.