Announcing the SubGravity H3 - Powered by SeaBear

[rjradical]

Thanks for catching that. I was looking for salinity not water(H2O) density. The unit's default setting is for EN13319. Being an engineer I will add this, Thank you Shearwater.

A cubic meter of pure water has a mass of 1000kg

Some guidelines:

• Fresh Water = 1000kg/m³
• EN13319 = 1020 kg/m³
• Salt Water = 1025 to 1035 kg/m³

The EN13319 value corresponds to a 10m increase in depth for pressure increase of 1 bar.

 

[stuartv]

Still no answer on whether the H3 will ever support VPM?

 

[tbone1004]

you're not going to get confirmation from them. There is a reason most computers don't have VPM on there and it's highly unlikely this one will get it. Market just isn't there to justify the tremendous cost to implement this algorithm if their primary market doesn't use it. That's why it is a paid upgrade on the Shearwaters, it isn't worth the cost to put on all of them because few use it, and realistically it shouldn't be the driving factor at this stage in the game for you. VPM is very easy to dive with tables and you can set GF's up to mimic it pretty closely by lowering the first GF to start putting deep stops in earlier.

My take is that pure Buhlman is too aggressive, so they introduced GF's to allow the diver to choose his profile. Gives a bit more control the diver making the dives based on the conditions and actual dive profile. From what I understand it is also much easier to implement from a software perspective and a hardware requirement perspective.

Nothing wrong with VPM, it may very well be the way of the future, but I like being able to control my risk with the theoretical numbers and be able to tailor the plans a bit more. I think 20/85 is similar to VPM+2.

Lots of unproven data on both sides, it's personal preference, but between the two, I wouldn't make a choice against a computer because it ran GF's instead of VPM.

 

[MixAddict]

No current plans for VPM.

 

[RonR]

.... From what I understand it is also much easier to implement from a software perspective and a hardware requirement perspective...

That’s very true. Fully iterative bubble models, VPM or RGBM, are extremely computationally intensive. Implementing them so they can run efficiently on low powered processors is a non-trivial undertaking. That’s why almost all computers marketed as RGBM are running a “folded” algorithm- essentially applying factors to a Haldane/ Buhlmann algorithm to approximate the results the fully iterative RGBM algorithm would give. To my knowledge, the Atomic Cobalt is still the only computer that ships with a fully iterative real time bubble model installed, and that only kicks in on dives deeper than 150’. Several technically oriented computers, of course, have VPM or RGBM available as an extra.

FWIW, I completely agree that lack of VPM would not be a reason to dismiss a computer that you liked in other respects- differences between established algorithms are mostly academic and much less important than other factors. And, as you say, it is possible to adjust settings on GF to suit.

-Ron

 

[stuartv]

Thanks, tbone, MixAddict, and RonR.

My primary concern was in the event my Tech instructor had a strong preference for VPM. I have asked him and now learned that he uses Buhlmann for planning and on his Petrel. So, it's pretty much a non-issue for me now, other than I like to be an informed consumer before I make a purchase.

My instructor also approved of my proposal to hold off on buying a computer for right now and do my training using MultiDeco on the computer (his preference) and my current dive computer in gauge mode for the actual training dives.

So, I will wait and see what develops with Shearwater, SeaBear/SubGravity, and others for at least a couple of months, if not 6 or more months. If the H3 WAI comes out and they have some kind of sweet package deal, I might jump on it then.

 

[tbone1004]

you'll find that package at DEMA, obviously no idea on pricing, but it'll be out then.

You're doing ocean dives, nothing wrong with tables and gauge mode, but like I said, you can find "close enoughs" with GF's and VPM settings to get you pretty close on just about anything. You won't see anything from Shearwater, you guys keep hoping, but they have said there isn't anything groundbreaking coming out, and DEMA is only 3 months away, so that'll be your best bet

Oh, and if you aren't aware, Ron developed the Cobalt, so if anyone knows what that thing does, it's him

 

[stuartv]

Yes, I have read other posts from RonR and have a pretty good idea of who he is and why I should listen to what he has to say. If you read my posts in the "What computer should I buy" thread, I have linked to several of his posts so that other newbies (like me) can more easily find his nuggets of wisdom.

 

[Dr. Lecter]

The SubGravity H3 powered by SEABEAR

Is the bear on some kind of tiny, generator-connected hamster wheel? I always figured it was powered by batteries, but since you're selling them I guess you know best.

 

[THRASH]

This computer definitely intrigues me. Somebody buy one, change their mind and then sell it to me for a discounted price.....PLEASE!

Seriously...I can't wait for the transmitter to come out (maybe DEMA) and then maybe there will be some killer package deals!?!?