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.
Tank Barge
HMC 504
U.S. Official No. 558337
Not yet on Master's MateType
Tank Barge
Flag
USALength
45 m
Beam
16.5 m
Draft
3 m
First reported
Jun 2026
AIS reports
1
HMC 504 is an American tanker, 45 metres long. Her hull carries a beam of 16.5 m and a draft of 3 m. Her papers read U.S. official number 558337. HMC 504 is welcome on the Master's Mate Safety Initiative Network — a free, community-run watch where boats look out for one another.
Free forever · No credit card · for commercial operators
Eyes on HMC 504, 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 HMC 504 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 HMC 504 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 HMC 504 and switch it all on
Free to join · nothing to install to start · cancel anytime
About HMC 504
What kind of vessel is HMC 504?
HMC 504 is a Tank Barge flagged to United States of America.
What is HMC 504's U.S. Official No.?
HMC 504's U.S. Official No. is 558337.
How big is HMC 504?
HMC 504 is about 45 m long, 16.5 m on the beam, drawing 3 m.
Is HMC 504 on the Master's Mate Safety Initiative Network?
Not yet. If HMC 504 is your boat, you can claim it free and join the Master's Mate Safety Initiative Network (MMSIn).
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