Four on four off, and the dog watches that save it

Four on, four off is the pattern most people mean by “watches”. It is simple, it runs with four crew, and without dog watches it is also the system that parks the same people on the same nights forever. The dogs are not a nicety. They are the fairness mechanism.

The pattern

Two watches, four hours on and four hours off, around the clock. Traditionally first watch 20:00–00:00, middle 00:00–04:00, morning 04:00–08:00, forenoon 08:00–12:00, afternoon 12:00–16:00, then the first dog 16:00–18:00 and last dog 18:00–20:00. That is seven watches in the day, not six.

It works down to four crew in two watches, which is why deliveries live on it. The theoretical eight hours off becomes six and a half once you have handed over, eaten and turned in. Fine for a week. Grim for three. See the five systems compared.

What dog watches are

Dog watches are the two short watches that split 16:00–20:00. They exist so the day contains an odd number of watches. An odd number is what shifts the pattern one slot each day, so the same person does not always stand the middle watch.

If you run straight four on four off with no dogs, you have six watches and a 24-hour repeat. Red owns 00:00–04:00 for the entire Atlantic. That is the failure mode the dogs were invented to prevent. A watch rota that does not move the nights is not finished.

Why it fails six-hour rest

Maritime Labour Convention rest rules want 10 hours of rest in 24, in no more than two periods, one of them at least six hours. Four on four off usually produces enough total rest and still fails, because the rest arrives in three or four separate blocks with none reaching six hours. That is the consolidation requirement, not the total.

For a private pleasure vessel this is often not a legal problem. For a commercially coded yacht, a paid delivery or a sail-training boat it is. Do not pretend a four-on-four-off grid is an hours-of-rest record. See hours of rest and the hours of rest app.

When it is still right

Four crew, a short or medium passage, a delivery where people already know the pattern, or a boat that wants two people on deck without inventing staggered pairs. It is also the right teaching pattern: everybody already understands four hours.

It is the wrong pattern for six people who could run Swedish or staggered pairs and get real night sleep. Using four on four off with six crew is leaving rest on the table.

What to use instead

Six crew, long passage: Swedish or staggered pairs. Mixed experience: staggered pairs, because a handover never clears the whole deck. Two-handed: stop using the word system and protect one dark sleep block — two-handed watch system.

DeckVakt will still build four on four off with dogs if that is what you want. It will also show you the sleep-debt gap against Swedish for the same names, which is usually the conversation that changes the rota in the marina rather than on night four.

Questions skippers ask