Inspiration Vision deco model - multi-day

Kevin Swindin

forgive me if this is a question covered before - please point me in the right direction if this is the case.

I have ordered my unit and am due to do my mod 1 first week of sept. I am busy reading the downloaded manual as suggested by my instructor. One of the things that occurs to me when reading the the sections on dive planning is that there is no mention of multi-day diving.

I am assuming that, unlike my Suunto OC computer, the vision model does not cater for multi-day diving i.e. does not become more conservative over a series of dives. What do people do if they are diving for a week or more? Do you progressively increase the conservatism via the gradient factors/conservatism settings? are you using another computer that does track loadings over multiple days or using some other form of management strategy?

thanks

Kevin

OH - I suppose I should say that I am not yet trimix qualified so am treat me gently!

Timbo

In short, the Vision electronics cope with multi dives per day, and cope with multiple days diving.

It allows for build up of gas tissues ect,

I am off on Saturday for a weeks trimixing in Ireland on my Vision. If weather permits!!!! I will do 7 days back to back trimix dives, 1 per day depths in the 65-75M range. Have done this before and never an issue.

I do NOT change gradient factors between dives.

Tim B

PS always carry back up tables/computer. Such as VR3 ect.

__________________
OOER ITS DARK DOWN HERE

PCDiver

The Vision does work for multi-day diving. It maintains your tissue saturation over multiple dives. No reason to increase the conservatism (unless you want to).

Kevin Swindin

OK - thanks for these. Is there a link to an explanation of the deco model anywhere other than that in the manual?

Kevin

Kevin Swindin

I don't wish to be a smart alec, but the manual that I am reading (Inspiration 10/05) says on p96 that the decompression calculator "makes no adjustments for these (yo yo, multidive day, multi day diving) profiles." So by implication not even taking account of current nitrogen loading on a subsequent dive!

so it looks to me as if we should be wary of following the computers plan without increasing the conservativeism of the gradient factors. Am I missing something here?

Tino de Rijk

Valid question, but wrong interpretation. What is meant here in the manual (and admittedly could be worded a bit better) is that the deco-model used does not make EXTRA adaptations for non-standard, extra-risk-containing dive behaviour like e.g. yo-yo diving. It follows the standard Buhlmann ZHL-16 algoritm, which DOES cater for a.o. repetitive diving. However, no deco-model on this earth can do a really reliable prediction for multi-day diving, or multi-dive-days, i.e. more than one repetive dive. It will give you results, and will incorporate tissue-loading from previous dives, but it is a sort of "guarantee only untill the door" - a "best guess". This applies to ANY diving computer and ANY model, despite what vendors will claim otherwise. APD is just being honest here, telling you that multi-day diving, and especially multi-dive-days during multi-day diving (e.g. 5 days live-aboard, 4 dives a day) is not reliably predictable by the model - or in fact ANY model. RGBM claims to sort of compensate for it, but how reliable that is remains to be seen.
For this sort of profiles it would be wise to "up" the GF conservatism a bit, to build a slightly higher safety barrier.
this on top of other wise moves: no alcohol, lots of water drinking, feeling well, build in a rest-day after 3 days diving, etc.; the usual stuff to reduce your risk (but not eliminate) ending up in a tank.

bottom line: the Vision does cater for repetitive diving, as well as any other computer. APD is just being honest about the reliability of it. It you don't like that, blame Buhlmann instead of APD. That will be a hard call, as he is dead... :-).

ciao,

Tino.

Kevin Swindin

Tino,

a really helpful response. You are right that the manual is not well worded and in my opinion misleading. My mind is now somewhat more at ease but as you rightly point out it is diver beware - its only a model.

thanks

Kevin