inaccurate maximum depth

[fetzy...@gmail.com]

Goodmorning everyone! I am a very happy subsurface user with a problem: when I upload the dives to the logbook the maximum depth indicated is not precise, but rounded. This doesn't always happen, only in certain dives. I thought it was a rounding when the depth reached approaches the whole number (example: 26.9 becomes 27 meters) but sometimes it saves it correctly, others it doesn't.

Is this the same for you?

Thanks!

[Robert C. Helling]

Assuming you are using the metric system, depth up to 20m are displayed with one place behind the decimal point while greater depths are rounded to the next meter. The rationale is to declutter the display and reflect the typical accuracy of the depth sensor (a 10cm error at 10m depth would be 1% while at 40m it would be only 0.25%, probably much less than the typical error of a depth sensor/pressure gauge). Diving with more than one computer, ideally from different manufacturers shows you that differences at that order are quite common.

Please note that this only done at the last display stage. Internally (for example for the decompression calculations) all depths in Subsurface are in mm. So rounding errors do not add up.

Besides that, the maximum depth is not necessarily the depth of the deepest point in your dive profile (as displayed). Some dive computers report a separate maximum depth from the sample values. This makes sense as often enough the depth is reported only at discrete time intervals (typical can be 20s or 30s for dive computers with small internal memory) and the maximum depth can occur between recorded samples (while the sampling during the dive is done more often).

Hope that helps

Robert