Master's MateSafety Initiative Network
The Master's Mate Safety Initiative Network (MMSIn) — like AAA for the ocean, but free & community-driven. Cruisers keeping each other safe: anchor-drag & distress alerts, a verified captains directory, and a watch network that has your back.
Passenger (Inspected)
THE SLOOP JOHN B
MMSI 366743260 · Call sign WTG8920
Not yet on Master's MateType
Passenger (Inspected)
Flag
USALength
11.1 m
Beam
4.1 m
Draft
1.9 m
Call sign
WTG8920
Official No.
557322
AIS reports
1
On the American registry, THE SLOOP JOHN B is an 11.1-metre passenger vessel. THE SLOOP JOHN B has 4.1 metres in the beam and a 1.9 m draft. She's listed under MMSI 366743260, call sign WTG8920. The Master's Mate Safety Initiative Network welcomes THE SLOOP JOHN B — free to join, cruiser-run, and always on watch.
Free forever · No credit card · for passenger & charter operators
Keep every soul aboard THE SLOOP JOHN B safe.
Distress alerting, live AIS, onboard monitoring and weather routing — the safety stack for boats that carry people.
Switch on the safety stack — free →Takes 60 seconds · Your data stays yours · Built by cruisers, for cruisers
Wherever THE SLOOP JOHN B roams, you're never out there alone.
Thousands of cruisers on the Master's Mate Network — ready to help the moment something goes wrong.
Free with your claim · for passenger & charter operators
The most powerful cruising platform ever built — yours, free.
Joining the Safety Initiative Network doesn't just put THE SLOOP JOHN B on the map. It hands you the full bridge:
Distress Mesh
Mayday & Pan-Pan that ripple out to nearby cruisers — a watch network that has your back.
Live AIS & Traffic
See every vessel around you in real time. Closest-approach warnings before they matter.
Systems Monitoring
Batteries, bilge, tanks, Victron & NMEA 2000 telemetry — your whole boat on one dashboard.
Weather & Routing
GRIB wind, swell & current on the chart. Plan passages with ETA-calibrated forecasts per leg.
Anchor Watch
GPS-precise drag alarms that actually wake you — and your whole crew. Sleep through the night.
Worldwide Charts
Navionics-grade vector charts, satellite & raster overlays, online or off. Your whole cruising ground.
Onboard Cameras
Watch your boat from anywhere — live feeds and 24h recording, straight from your gateway.
Hail Any Captain
A verified captains directory + direct hailing. Reach the boat next to you, or across the bay.
Claim THE SLOOP JOHN B and switch it all on
Free to join · nothing to install to start · cancel anytime
About THE SLOOP JOHN B
What kind of vessel is THE SLOOP JOHN B?
THE SLOOP JOHN B is a Passenger (Inspected) flagged to United States of America.
What is THE SLOOP JOHN B's MMSI?
THE SLOOP JOHN B's MMSI is 366743260. Call sign WTG8920.
How big is THE SLOOP JOHN B?
THE SLOOP JOHN B is about 11.1 m long, 4.1 m on the beam, drawing 1.9 m.
Is THE SLOOP JOHN B on the Master's Mate Safety Initiative Network?
Not yet. If THE SLOOP JOHN B is your boat, you can claim it free and join the Master's Mate Safety Initiative Network (MMSIn).
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