Two numbers define a marine CCTV system, and neither one is the camera count. The first is how many views have to record at the same time, which sets the channel count. The second is how long that video has to stay playable, which sets the storage. Fix those two and the recorder, the drive bays and the power budget follow almost automatically. Work from a camera schedule instead, and you’ll buy a system that shows a live picture beautifully and can’t answer a question asked three weeks later.
That’s an expensive way to find out. The cost is rarely the recorder. It’s reopening a finished refit to add a switch and a second box, or finding during a cargo claim that the footage rolled over before anyone asked for it. Both keep happening because CCTV arrives on a drawing as a camera list, not a recording requirement.
What Separates a Recording CCTV System From Bridge Cameras?
A bridge camera exists for the officer on watch right now. A CCTV system exists for whoever asks a question later. That difference changes the hardware behind the lens. Live viewing needs a camera, a path and a screen. Recording needs a recorder, disks, and a decision about how long to keep what lands on them.
The distinction is easiest to see in a system built purely for watchkeeping. The no-latency DigiCoax arrangement on our own site is specified as a seven-inch monitor working with a switcher and four cameras, powered only from a 24 volt DC input. It is a complete low-latency viewing chain with no recorder in it, so if a question arrives the next morning it has nothing to offer.
None of this argues against live cameras. It argues against assuming one buys the other. If you’re still deciding which sensors belong where, we’ve covered what a bridge camera plan is actually for separately. This article picks up where somebody says the video has to be kept.
How Many Channels Does the Vessel Actually Have to Record?
Count recorded views, not cameras. A channel is one feed the recorder writes to disk continuously, so a camera that only ever appears on a monitor is not a channel and a single camera routed to two displays is still one. Start from the views someone would need to review after the fact, then check which of them are required rather than merely useful.
For US-flag commercial vessels, part of that count is not a preference at all. Title 46 of the United States Code sets surveillance requirements for oceangoing non-passenger commercial vessels, and on placement it says that video and audio surveillance equipment shall be placed in passageways on to which doors from staterooms open, in a manner ensuring the visibility of every door in each such passageway. Read that as a coverage test, not a camera count. A long alleyway with a dogleg in it won’t satisfy every door from one position, and that is a second channel nobody budgeted for.
Whether the section reaches your vessel is its own check. It covers documented vessels with overnight accommodation for at least ten people on voyages of at least 600 miles seaward of the Boundary Line, vessels at least 24 metres long carrying a load line, and documented vessels of at least 500 gross tons on an international voyage. Other flags set their own rules.
The rest of the count is operational, and it is where the real growth happens:
- Accommodation passageways, sized so every stateroom door is genuinely in frame rather than nearly in frame.
- Machinery spaces, for unattended monitoring and review of an alarm nobody witnessed.
- Cargo areas, deck working areas and lifting operations, where damage disputes originate.
- Gangway and mooring stations, covering access control and everything crossing it.
- Any space a charterer, insurer or terminal has asked about in writing.
Added up honestly, the number is usually larger than the four channels a compact installation starts from, and four is a real boundary in hardware rather than a marketing tier. On the four-channel PoE recording system specification, four network ports carry PoE and two further gigabit ports do not. Cameras one through four plug straight into the recorder. Camera five needs a separate powered switch, a mounting place, its own supply and its own failure mode. The larger embedded chassis in the same family publishes two gigabit ports and no PoE ports at all, so there every camera is fed from a switch.
How Long Does the Footage Have to Stay Playable?
Retention is set by your flag, your class society, your insurer and your charterer, and only then by what the disks hold. It is the number people guess at, and the one that quietly decides how much storage the system needs. Ask what the longest binding obligation is before anyone quotes a drive.
For vessels inside the scope above, that obligation is written down. The same section requires the owner to retain all records of audio and video surveillance for not less than 1 year after the footage is obtained, and adds that footage associated with an alleged incident should be preserved for not less than five years from the date of that incident. A year is a very different specification from a fortnight, and it isn’t a number you reach by adding a drive later on.
There’s a second reason retention deserves more respect than it gets. Federal rules on marine casualty investigations list the material gathered during an investigation and include, alongside photographs and physical evidence, interview statements, wreckage documentation, voyage data recorder information, and surveillance video. Your CCTV recording sits in the same sentence as the voyage data recorder. The difference is that the VDR’s retention behaviour comes from its own performance standard, while your CCTV retention is whatever you specified on the day of purchase.
Long retention is also where an embedded recorder stops being the right answer. Four small bays and a one-year obligation across a dozen channels don’t reconcile, and the honest conclusion is a different architecture, not a bigger box. We’ve worked through the point where the storage pool belongs in a rack separately, and if your two numbers collide, that is the piece to read next.
Where the Recorder, the Bays and the Power Budget Get Decided
Once the two numbers exist, hardware selection becomes arithmetic. The check we run before recommending a recorder is arithmetic, not taste: channel count against published PoE port count, retention against published bay count and RAID mode, and the vessel’s DC bus against the published input range. Every figure in that sentence is printed on the product page, which is the point.
| The number you fix | What it decides | The published figure to check it against |
|---|---|---|
| Recorded channels | How many cameras the recorder takes directly | The count of network ports that carry PoE, not the total port count |
| Retention window | How much storage has to live inside the box | The number of drive bays and the form factor those bays accept |
| Redundancy level | How much of that storage you actually get to use | The RAID modes the chassis supports |
| Vessel supply | Whether the recorder rides out the bus it is fed from | The published input voltage range and power mode support |
| Equipment space | Whether the box can live where you want to put it | The published operating temperature range |
The redundancy row surprises buyers. Both recording chassis in the marine CCTV range we build these systems from publish four SATA bays in the two-and-a-half-inch form factor with RAID levels zero, one, five and ten. Those are very different usable capacities from the same four drives. Mirroring halves what you keep, parity costs one drive’s worth, and striping gives you everything with no protection, which on a vessel that can’t be serviced at sea is a poor trade. Choose the level before you calculate retention.
Power and environment are the rows people skip and then regret. Both chassis publish a wide input range of 9 to 48 volts DC and operation from minus 25 to 70 degrees Celsius at the lower CPU rating. Those numbers exist because a recorder sits on a bus that sags during starts, in air nobody conditions for it.
Two things are worth flagging honestly, because they aren’t on the pages. The PoE ports are published as ports with PoE function, without a stated power class or total budget, so if your cameras are heated or motorised, confirm the power per port and across the chassis in writing. Neither page publishes a maximum drive capacity for those bays. Short PoE headroom is a far worse discovery at commissioning than at quotation.
Frequently Asked Questions
Can one box do live viewing and recording at the same time?
Usually yes, and the display outputs are the thing to check rather than the processor. A recorder publishing three independent display outputs can drive a watch monitor and a review position without a second machine. What it can’t do is replace a purpose-built low-latency chain when an operator is manoeuvring on that picture.
Does RAID on the recorder replace an off-vessel copy?
No. RAID protects against a drive failing, not against fire, flooding, theft of the box or somebody deleting the wrong period. A multi-year preservation obligation is better served by getting that material off the vessel, with the on-board array carrying the rolling window rather than the legal record.
What limits how much video an embedded recorder can hold?
Three things, in this order: the number of bays, the largest drive that fits the bay form factor, and the RAID level chosen. A compact chassis using two-and-a-half-inch bays is more constrained than a rack machine using larger drives, and that constraint is physical rather than something a firmware setting rescues.
Do all channels have to record at the same resolution and frame rate?
No, and treating them identically is the most common way to waste storage. A passageway camera that has to show who opened a door needs detail but very little motion fidelity. A deck camera watching a lift needs the opposite. Match each channel to its evidence purpose and the same disks cover a longer window.
Where does the recorder physically belong on a vessel?
Somewhere with a stable supply, tolerable temperature and access that doesn’t require shutting down a watch station. Fanless chassis exist so the box can sit in salt-laden air with no filtered airflow. Cable runs usually decide the final location, so settle the mounting position before the cable schedule is drawn.
Send the Two Numbers Before You Ask for a Quote
A camera list produces a price. A channel count and a retention window produce a system. If you can say how many views must record continuously, how long the video has to stay playable, and what the DC supply looks like at the equipment space, the rest of the specification is largely determined, and any gap shows up immediately.
Bring those numbers and the applicable flag or class rule, and tell the display team what has to be recorded and for how long. If an embedded recorder turns out to be the wrong shape for your obligation, that’s worth knowing before the drawings are issued rather than after the drives are full.