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.
Tug
TB SEMAR 21
MMSI 525020121 · Call sign YDA3183
Not yet on Master's MateType
Tug
Flag
IDNLength
26 m
Beam
8 m
Call sign
YDA3183
IMO
9666144
First reported
Jun 2026
Last reported
Jun 2026
AIS reports
79
On the Indonesian registry, TB SEMAR 21 is a 26-metre tug. Her hull carries a 8 m beam. Find her under MMSI 525020121, call sign YDA3183, IMO 9666144. The Master's Mate Safety Initiative Network welcomes TB SEMAR 21 — free to join, cruiser-run, and always on watch.
Free forever · No credit card · for working boats
Built for boats that work — like TB SEMAR 21.
Engine & systems telemetry, live AIS, weather and distress alerting for the vessels that earn their keep.
Rig her out — free →Takes 60 seconds · Your data stays yours · Built by cruisers, for cruisers
Live AIS position · Jun 9, 2026 11:59 UTC
Position
2.1468° S, 104.9363° E
Status
Under way (engine)
Speed
0.1 kn
Course
0°
Wherever TB SEMAR 21 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 working boats
The most powerful cruising platform ever built — yours, free.
Joining the Safety Initiative Network doesn't just put TB SEMAR 21 on the map. It hands you the full bridge:
Systems Monitoring
Batteries, bilge, tanks, Victron & NMEA 2000 telemetry — your whole boat on one dashboard.
Live AIS & Traffic
See every vessel around you in real time. Closest-approach warnings before they matter.
Weather & Routing
GRIB wind, swell & current on the chart. Plan passages with ETA-calibrated forecasts per leg.
Distress Mesh
Mayday & Pan-Pan that ripple out to nearby cruisers — a watch network that has your back.
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 TB SEMAR 21 and switch it all on
Free to join · nothing to install to start · cancel anytime
About TB SEMAR 21
What kind of vessel is TB SEMAR 21?
TB SEMAR 21 is a Tug flagged to Indonesia.
Where was TB SEMAR 21 last seen?
TB SEMAR 21 was last reported in around 2°S 105°E in Jun 2026 on public AIS.
What is TB SEMAR 21's MMSI?
TB SEMAR 21's MMSI is 525020121. Call sign YDA3183. IMO 9666144.
How big is TB SEMAR 21?
TB SEMAR 21 is about 26 m long, 8 m on the beam.
Is TB SEMAR 21 on the Master's Mate Safety Initiative Network?
Not yet. If TB SEMAR 21 is your boat, you can claim it free and join the Master's Mate Safety Initiative Network (MMSIn).
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