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.
Freight Barge
SER 421 B
U.S. Official No. 557672
Not yet on Master's MateType
Freight Barge
Flag
USALength
61 m
Beam
10.7 m
Draft
3.6 m
First reported
Jun 2026
AIS reports
1
Registered in the United States, SER 421 B is a 61-metre cargo barge. Below, she has a beam of 10.7 m and a draft of 3.6 m. Her papers read U.S. official number 557672. SER 421 B is welcome on the Master's Mate Safety Initiative Network — free situational awareness and a watch network shared by vessels of every size.
Free forever · No credit card · for commercial operators
Eyes on SER 421 B, around the clock.
Real-time AIS, full systems telemetry, distress alerting and worldwide charts — your hull on one dashboard, from anywhere.
Put her on the dashboard — free →Takes 60 seconds · Your data stays yours · Built by cruisers, for cruisers
Wherever SER 421 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 commercial operators
The most powerful cruising platform ever built — yours, free.
Joining the Safety Initiative Network doesn't just put SER 421 B on the map. It hands you the full bridge:
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.
Distress Mesh
Mayday & Pan-Pan that ripple out to nearby cruisers — a watch network that has your back.
Worldwide Charts
Navionics-grade vector charts, satellite & raster overlays, online or off. Your whole cruising ground.
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.
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 SER 421 B and switch it all on
Free to join · nothing to install to start · cancel anytime
About SER 421 B
What kind of vessel is SER 421 B?
SER 421 B is a Freight Barge flagged to United States of America.
What is SER 421 B's U.S. Official No.?
SER 421 B's U.S. Official No. is 557672.
How big is SER 421 B?
SER 421 B is about 61 m long, 10.7 m on the beam, drawing 3.6 m.
Is SER 421 B on the Master's Mate Safety Initiative Network?
Not yet. If SER 421 B is your boat, you can claim it free and join the Master's Mate Safety Initiative Network (MMSIn).
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