My girlfriend has recently got an OSTC Plus (in sport mode) and it seems pretty nice. I'm thinking of changing my old OSTC mk2 over to the newer model so I took it for a couple of dives at Chepstow yesterday to try it out but I was surprised at the differences in deco between the two of them. The OSTC Plus seems to accrue deco faster. Both computers set to OC ZH-L16-GF 30/85. My older OSTC mk2 seems to agree with Subsurface (my dive logging tool) reasonably well but this newer one seems a bit off, quite a bit off in some circumstances.

It also doesn't seem to want stops deeper than 6m (at least in the logged dive I did). The simulator seems to behave correctly when I try it on a made up dive but when I download the logs to look at the new computer is asking for quite a long stop at 6 where as both the old computer and Subsurface switch over to wanting a deeper stop.

Examples of strangeness are that it jumped from wanting 12min at 6m straight to 28min at 6m (I was at about 19m when this happened) and then on the next dive it jumped from wanting 6min at 6m straight to 15min at 6m (I was at 18m at the time) that seems a bit excessive. The older computer at the same point in the dive was asking for 1min at 9m followed by something like 6min at 6m for the first dive and on the second dive it didn't want any deco at all.

Anyone seen similar? Doesn't fill me with confidence for this new computer.

Running 10.53 firmware.