The essentials in 30 seconds
- Screen size is chosen based on viewing distance, not budget: measure the distance from the helm to the intended location before comparing models.
- 9 inches: the coastal format — readable up close, two to three comfortable windows (chartplotter + depth sounder or chartplotter + instruments).
- 12 inches: the offshore format — readable from the helm, true multi-window use (chartplotter + radar + AIS simultaneously) in rough seas.
- Brand choice follows the onboard ecosystem: Raymarine (Axiom) if the autopilot and radar are Raymarine; B&G (Zeus/Vulcan) for sailing functions and H5000 integration; Garmin for mixed fishing/navigation.
- Beyond 45–50 feet, the real question becomes one large screen or two screens — and our workshop’s answer is usually: two (redundancy).
Table of contents
The GPS-depth sounder combo has become the navigation brain of the modern sailboat. Charts, radar, AIS, depth sounder, instruments: everything converges on this screen. Choosing the size commits you to ten years of cockpit use — and it hinges on readability and window layout, not the spec sheet. For the chart data powering the chartplotter, see our marine chartplotter comparison.
Why screen size matters
- Viewing distance. A screen is chosen from the helm where it will be read: a 9-inch perfectly readable at the chart table becomes cramped when read from the helm, over a meter away, in rough seas. The onboard measurement takes precedence over any general rule.
- Simultaneous windows. The larger the surface, the more views you can display in parallel without making them unreadable. In busy coastal waters, being able to keep chartplotter + radar + AIS together is a real safety gain.
- Interface. Current recreational combos are touchscreen; some models add physical buttons, handy in rough seas and with gloves. For offshore, a remote keypad complements a touchscreen well.
9 inches: coastal use
The modern entry-level format, suited to most 25–35 ft sailboats on coastal programs: close-up viewing, two to three windows, reasonable footprint on a cockpit console. The families we install: Raymarine Axiom 9, B&G Vulcan 9 (sailing orientation), Garmin GPSMAP 9-inch (mixed fishing/navigation orientation). Today’s specs and prices are on the GPS-depth sounder combo collection.
12 inches: offshore use
The 12-inch format becomes necessary as soon as the screen is read from the helm and the program goes beyond coastal cruising: offshore cruising, racing, transatlantic. What it delivers in practice: readable distance in rough seas, and true multi-window use — large-scale chartplotter plus radar, AIS, and depth sounder simultaneously. The references we install most: B&G Zeus 3S 12 (sailing integration and H5000), Raymarine Axiom Pro 12 (touchscreen + buttons), Garmin GPSMAP 12-inch.
Multi-screen and glass helm
Beyond 50 feet or on demanding programs, you move to multi-screens or glass helm: either two 12-inch screens side by side, or a large format like Zeus S 3015 UltraWide 15" or the Zeus³S Glass Helm 16" pack with ZC2 keypad. At this level, the choice is conceived as a system (screens, keypad, repeaters, network) — it’s a pre-study topic, not a product page.
Workshop verdict by program
25–30 ft sailboat, summer coastal cruising: a well-placed 9-inch does the job. Put the budget difference into the depth sounder and installation rather than inches you won’t read from farther away.
35–45 ft sailboat, offshore cruising: the 12-inch is our workshop standard — it’s readability from the helm that justifies it, not prestige.
Mixed cruising/racing program: main 12-inch screen + second screen or repeater at the navigation station, within the central system ecosystem (H5000 → B&G).
Large vessel or charter: glass helm or dual 12-inch screens, designed in a pre-study with redundancy and ergonomics in mind. Tell us about the boat before deciding from the catalog.
One large screen or two?
On sailboats over 40 feet, the question “one 16-inch or two 12-inch screens” comes up often. Our workshop position: two screens win in most cases — a failure doesn’t leave you blind, functions are split (chartplotter/radar on one side, depth sounder/instruments on the other), and two screens sit at eye level where a very large format forces its console. A single large format retains the advantage when there’s only one helm station and a strong aesthetic integration requirement.
Installation errors to avoid
Seen in the workshop:
- Screen size chosen without measuring the viewing distance. A 9-inch at 1.5 m from the helm is hard to read in rough seas. Measure before buying.
- Internal GPS blocked. A flush-mounted combo under a dodger or in the cabin may receive poorly — plan an external GPS antenna in that case.
- Network cable routed alongside power cables. Interference and frozen screens: separate signal and power, cross at 90° if needed.
- No backup plan offshore. A failure of the main screen must not stop navigation: second screen, repeater, or independent backup solution.
- Commissioning without calibrating upstream sensors. The combo aggregates data: if compass, knotmeter, and depth sounder aren’t calibrated, its calculations (VMG, laylines, ETA) are wrong. Calibration is part of installation, not an option.
FAQ
Does the touchscreen resist spray and gloves?
Current recreational screens are built for marine use and work with fine gloves and spray. With thick offshore gloves or in very bad weather, physical buttons or a remote keypad remain safer — a key model selection criterion.
Can you mix Raymarine and B&G on the same boat?
Yes for standard data via NMEA 2000 (position, AIS, wind, depth). However, advanced integrations — autopilot control from the screen, sailing functions from the central system — remain proprietary to each ecosystem. Consistency within one ecosystem on the main chain remains our recommendation.
How long do you keep a combo?
About a decade in the workshop: the electronics last, it’s software and chart updates that eventually drive replacement. A recent-generation model remains perfectly usable for years.
Touchscreen or buttons offshore?
For quick manipulations in rough seas, physical buttons have the edge. Mixed models (touchscreen + buttons), or adding a remote keypad, are preferred setups in racing and long-range cruising.
Do you need a separate depth sounder module?
The integrated depth sounder in current combos is enough for cruising. A dedicated depth sounder module (external black box) is justified for demanding fishing or fine bathymetry — check module/screen compatibility before purchase, or ask us.
Also read
- Marine chartplotter software: Navionics+ vs C-MAP vs Garmin
- Through-hull vs transom-mount transducers — 2026 choices
- NMEA 2000 on a sailboat: backbone, drops, terminators
- GPS-depth sounder combo catalog · Chartplotters
About the author
Pol Conin, Digital Manager at Skysat. Software engineer and tech entrepreneur, Pol joined the adventure to bring Skysat into the digital age. See his author page for a full list of articles.
Transparency: Skysat distributes Raymarine, B&G, and Garmin and sells the products mentioned; links point to our catalog. This does not change the criteria proposed or the cases where we advise against the higher tier.
