--- title: "Day of diving" weight: 45 description: "Planning several dives in a day with MV-Plan: a series chained on residual nitrogen, surface intervals, cumulative CNS and OTU, exports and saved days." source_hash: a0954c2856d0 --- # Day of diving A second dive is not computed like a first one: you get back in the water with nitrogen still dissolved, and the decompression takes that into account. The **Day of diving** screen chains the dives of your day, each one computed on the tissue state the previous one left behind, separated by the surface interval you set. It is also the screen for going back and forth: lengthen the interval, shorten the first dive, compute the rest again, until the bottom time of the second dive is acceptable. ## Where to find it - **On a computer**: the calendar icon in the left sidebar. - **On a phone**: the **Day** tab in the bottom bar. ## Building the series The day is filled from the [Plan](/mvplan/planification) screen, which remains the only place where a dive is built. 1. Build the dive on the Plan screen, as usual. 2. Go to the Day screen and click **Add the current dive**. 3. From the second dive on, MV-Plan asks for the **surface interval** before it, in minutes. The first dive of the day has no interval: it follows nothing. The following ones require one, and an emptied field is never read as zero - getting straight back in the water is not the same dive as getting back in two hours later. Each dive in the list carries a number, a free name (optional), and a reminder of what it is: maximum depth, total time, OC or CCR mode. ## Setting the surface intervals The interval shown between two dives can be **edited in place**: type the new value, the series is invalidated and only waits to be computed again. The duration is recalled in hours and minutes next to the field. No ceiling is imposed. For a dive whose tissues are not yet clear from **the day before**, put yesterday's dive at the head of the series and give it a long interval (900 min for fifteen hours): off-gassing is computed over the real duration, at the altitude of the site. ## Computing the day **Calculate the day** replays the whole series in order, handing the tissue state of each dive to the next one. Dives already computed and still valid are not computed again. A dive refused by the engine **stops the chain**: the dives after it are flagged and not planned. Computing them as first dives of the day would show less decompression than the series owes. ## What each dive shows Once computed, a dive shows its stops, its TTS and its runtime. Three situations are deliberately told apart, rather than leaving an empty line in all three cases: - **Not calculated yet**: it is in the series, it has never been planned. - **Calculated before an edit**: its plan exists but no longer describes the series, because you touched that dive, a dive before it, an interval or a shared setting. - **Dive refused**: the engine could not plan it. The message points back to the previous dives, since that is often where the cause is. ## What invalidates the series MV-Plan throws away results that have become wrong rather than keep showing them: - editing a dive invalidates **that dive and every dive after it**, not the ones before, which remain true; - editing a surface interval does the same; - changing a **shared setting** - calculation settings, environment, gases, diluents - invalidates the **whole** day; - removing a dive invalidates the rest of the series. The dive on the Plan screen is independent: editing it does not touch the day until you save it back into the series. ## Editing a dive of the series The **Edit** button of a dive opens it on the Plan screen, the only dive editor in the application. A banner there recalls that you are editing dive N of the day, with two ways out: - **Save into the day**: puts the dive back into the series and invalidates what follows. - **Detach**: leaves it on the Plan screen as an ordinary dive, the day is not touched. While that banner is showing, the Plan screen computes the dive **in its series context**, that is on the tissues left by the previous dive, and not as a first dive of the day. ## Day totals Below the series, a block gives the number of dives, the **CNS** and the **OTU** accumulated over the day, and the no-fly delay in force for the series. CNS decays during the surface intervals, with a 90 min half-life. OTU is carried over as it is: practice is a daily total against a limit of 300, with no recovery model. When only part of the series is computed, the totals say so and state how many dives they cover. On the Plan screen, the CNS and OTU shown become those of the series as soon as the dive belongs to one, under a label that says so: the exposure that matters is the one of the day, not the one of the single dive. ## Exporting Exports cover the whole series: - **PDF**: one page per computed dive - the usual condensed sheet - followed by a totals page. - **HTML**: one section per dive, then the totals. A dive that has not been computed is not exported, but the numbering is kept: dive 3 stays dive 3. ## Saved days **Save the day** keeps the whole series: the dives and their segments, the intervals, and the context it was planned with (gases, diluents, settings, environment). Without that context, reloading the day under other settings would compute a different series. Days live on the [Saved plans](/mvplan/plans-favoris) screen, next to the plans, with the same actions: load, rename, duplicate, export, delete, import. They are two separate lists, and the import refuses a file that is not a day. As with a plan, **results are never saved**: a reloaded day is computed again. And if one dive of the saved day is unreadable, the whole day is refused on loading - handing you back a truncated series would turn a repetitive dive into a first dive. ## Rebreather A rebreather dive is chained on its **CCR plan**, never on its bailout. The bailout is the branch where the loop failed, a dive that did not happen: chaining on it would charge you twice for an incident that never occurred. ## See also - [Planning](/mvplan/planification): building a dive. - [Settings](/mvplan/reglages): what the day shares across all its dives. - [Saved plans](/mvplan/plans-favoris): the stored lists.