Recreational Trimix

[LiteHedded]

i just dive it like 32%

 

[Wookie]

That is not what Lamont said. Read his post again. He was very specific about ascent rates and deco.

Actually, you read it again. He wasn't specific about, nor did he mention ascent rates. That's part of the problem I have with his advice. Then, he talks about 3-5 minute stops at 50 feet, and mandatory safety stops, and then whatever stops that 32% require. That isn't exactly a dive plan, nor is it a deco plan.

I have no beef with Lamont, nor do I care how he chooses to conduct his dives. I do take exception when he is giving advice to someone else about how they should conduct their dives, especially when the advice is so non-specific.

I have no beef with litehedded's remark. He isn't giving advice.

 

[LiteHedded]

Actually, you read it again. He wasn't specific about, nor did he mention ascent rates. That's part of the problem I have with his advice. Then, he talks about 3-5 minute stops at 50 feet, and mandatory safety stops, and then whatever stops that 32% require. That isn't exactly a dive plan, nor is it a deco plan.

I have no beef with Lamont, nor do I care how he chooses to conduct his dives. I do take exception when he is giving advice to someone else about how they should conduct their dives, especially when the advice is so non-specific.

I have no beef with litehedded's remark. He isn't giving advice.

yes he does. he mentioned he does minimum deco. that's the same thing I do. on a 100 foot dive it would result in a 10fpm ascent rate from 50' on up.

 

[ScubaFeenD]

As Richard says, different models treat helium differently. Some penalize you for it, some give you credit for it -- but all, I think, require a careful and slow ascent to control bubbling. It really depends on whether the model is worried about rapid diffusion or recognizing that helium's poor solubility means you end up with very little of it to offgas.

So, from what I understand from this, since both vplanner and deco-planner use VPM then if vplanner penalizes deco-planner penalizes too? Is there some adjustment in the algorithm deco-planner uses so that this doesn't happen?

 

[Scott L]

 

[PfcAJ]

So, from what I understand from this, since both vplanner and deco-planner use VPM then if vplanner penalizes deco-planner penalizes too? Is there some adjustment in the algorithm deco-planner uses so that this doesn't happen?

DecoPlanner uses two models, Buhlmann and VPM. You can toggle back and forth between them for easy comparison.

 

[Wookie]

yes he does. he mentioned he does minimum deco. that's the same thing I do. on a 100 foot dive it would result in a 10fpm ascent rate from 50' on up.

Then maybe I need an education, because I have a IANTD trimix card, a TDI trimix card, a PADI trimix card (don't ask), and the only thing "minimum deco" means to me is making sure I clear all of my stops, but don't stay any longer at each stop. Is "minimum deco" something I don't have the secret handshake for?

 

[LiteHedded]

Then maybe I need an education, because I have a IANTD trimix card, a TDI trimix card, a PADI trimix card (don't ask), and the only thing "minimum deco" means to me is making sure I clear all of my stops, but don't stay any longer at each stop. Is "minimum deco" something I don't have the secret handshake for?

yea.

 

[Blackwood]

Is "minimum deco" something I don't have the secret handshake for?

30fpm to 1/2 depth, 10fpm thereon. So 'min deco' from a 100 foot NDL dive, for example, is almost 7 minutes (compared to almost 2 minutes @ 60fpm).

 

[PfcAJ]

Minimum deco is the "minimum" amount of decompression stops you should do on a dive, and generally refers to "No Decompression Limits" dives. An MDL dive roughly equals a no-deco dive in bottom time, but the ascent is different.

There are some variations on this, but its roughly 30fpm till 50% of your avg depth, followed by a 10fpm ascent from there. This replaces the "safety stop" at 15ft for 3-5mins.

For example, an mindeco ascent for a 100ft dive would be roughly 1min, 40 seconds to 50ft, then you creep up 10ft every minute thereafter. Total ascent time would be around 7mins. Contrast this to a regular no deco ascent of 3mins to 15ft, then a 5min hang. Total ascent time is about the same, but the mindeco ascent is a bit smoother from 50ft.

Make sense? When diving 30/30, this slower, more controlled ascent (from 50ft) gives the Helium the time to come out of solution in a controlled manner.