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)

Semisub One

MMSI 367488690 · Call sign WDF7840

Not yet on Master's Mate

Type

Passenger (Inspected)

Flag

USA

Length

21.9 m

Beam

7.6 m

Draft

3 m

Call sign

WDF7840

Official No.

1230570

AIS reports

Out of the United States, Semisub One is a 21.9-metre passenger ship. Below, she has a beam of 7.6 m and a draft measuring 3 metres. Find her under MMSI 367488690, call sign WDF7840. Sign Semisub One up free to the Master's Mate Safety Initiative Network and join a fleet that looks after its own.

Free forever · No credit card · for passenger & charter operators

Keep every soul aboard Semisub One 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 Semisub One 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 Semisub One 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 Semisub One and switch it all on

Free to join · nothing to install to start · cancel anytime

Claim free → unlock everything

About Semisub One

What kind of vessel is Semisub One?

Semisub One is a Passenger (Inspected) flagged to United States of America.

What is Semisub One's MMSI?

Semisub One's MMSI is 367488690. Call sign WDF7840.

How big is Semisub One?

Semisub One is about 21.9 m long, 7.6 m on the beam, drawing 3 m.

Is Semisub One on the Master's Mate Safety Initiative Network?

Not yet. If Semisub One is your boat, you can claim it free and join the Master's Mate Safety Initiative Network (MMSIn).