Mazu Iridium-Based Communication and Tracking System

By Tom Burden, Last updated: 7/22/2019

Do you need a reliable offshore email and text messaging communication platform that works practically anywhere in the world? Do you need to keep track of the level of your boat's bilge water, the status of your shore power connections or provide yourself some peace of mind with theft-deterrent security? Meet the Mazu app.

Diagram of Mazu system components and how they interact

The three main supplied components of the Mazu system, the ISI-2000 system interface, remote Smart Antenna mounted with a view of the sky, and the four-button keypad. You supply an iPad tablet. The Sentry Monitoring Kit adds vessel monitoring sensors for about $250.

Mazu, an iPad app you can download from the Apple App Store, works with hardware called SkyMate, which in turn connects to the well-established and relatively affordable Iridium Short Burst Data (SBD) satellite constellation. It offers capabilities which are of obvious benefit to long-distance cruising sailors offshore anglers, or boaters who must leave their vessel in a remote location.

Satellite-based, Not Cellular

ISI 2000 system black box

The ISI 2000 System Interface is the heart of the Mazu system. It has several kinds of ports for existing connections—and future ones that do not even exist yet!

illuminated keypad for Mazu system

Illuminated keypad with message-waiting indicator and SOS Emergency Button.

5 inch Mazu  skymate antenna

Compact 5" Mazu/SkyMate antenna with Iridium 9602 SBD modem and 33' digital cable is mounted above deck. It's connected with an Ethernet cable with Power Over Ethernet (POE).

Mazu offers the tradeoff of reliable communication practically anywhere on the globe, in exchange for a very narrow bandwidth from Iridium's constellation of Low Earth Orbit satellites. It's one of several excellent Iridium SBD-based devices, the Garmin inReach Explorer and Iridium GO being two others.

With these satellite-based communications systems, you can send and receive very short email messages, on the order of 100 characters (bytes) per line. Other types of communication are highly compressed as well. NOAA text weather reports, for example, are 1,000 characters per report. NOAA charts use the most characters, approximately 2,000–6,000 per report.

Subscription Data Plans

These are subscription-based communicators, and you pay as you go for data. Mazu is an iPad tablet-based device. Iridium GO is similar, while also connecting to a smartphone and allowing voice sat-phone calls. Mazu/SkyMate does not support voice communication. However, with their voice-relay service, you can have your email read over the phone to any phone service in the US.

What Mazu Does

The Mazu app and its capabilities impressed the editors of Sail Magazine, who awarded it their Pittman Innovation Award for electronics in 2018. It does lots of things. Below are the highlights of what you get with Mazu SkyMate:

Near-global coverage: According to the manufacturer, the SkyMate system will work almost anywhere except the Indian Ocean and the central part of the Pacific Ocean. However, based on my uninterrupted experience with Iridium SBD sat-com devices (inReach and Iridium GO) while racing to Hawaii in 2016, I would expect good coverage in at least that region of the Pacific.

Weather information: Mazu handles weather data including GRIB files up to seven days into the future, seven-day point weather forecasts, live buoy data, NEXRAD radar images, NOAA zone forecasts, weather alerts and tropical storm advisories.

Email and SMS (Short Message Service): Stay in touch with folks back home using email, SMS messaging and position reporting. These are similar to the feature sets offered by inReach and the SPOT Satellite Messenger.

SOS emergency messaging: Lets you notify your shoreside contacts (phone, fax numbers and email addresses) about an emergency, and lets you cancel the message and send pre-configured emergency messages. Mazu uses the GEOS Alliance and their GEOS International Emergency Response Coordination Center (IERCC), the same service utilized by the SPOT Satellite Messenger and other products.

SkyMate’s Weblog Service: Share your adventure with SkyMate's web blog service at Their blog is an online publication page where you can post articles for others to read. Use the personalized weblog as an online journal of your voyage. Send back stories to your family and friends; their comments can be sent back to your vessel in the middle of nowhere.

Sport fishing charts and chat: See satellite-produced sea surface temperature and easily find thermoclines. Overlay chlorophyll charts onscreen. Join and manage group chats with your friends on other fishing boats.

Position reports: Allows your family and friends to see your position. You can specify how often the reports are sent, and who you would like to get them (using their email addresses).

Navigation: Mazu's supports Navionics' excellent and free iPad marine chart app. You can plan and change routes, and see them overlaid on the charts.

Remote vessel monitoring: Purchase the optional Sentry Monitoring Kit that allows you to connect up to four included wired sensors. You get a float switch for monitoring the level of water in the bilge, a door or window open/closed magnetic sensor, a shore power status sensor and a tactile pressure sensor. As a cool bonus, a remote actuator is included to operate an electronic device such as lights, the air conditioner or refrigerator.

Commercial fishing VMS for less: The SkyMate Vessel Monitoring System is designed for commercial fishermen with NOAA tracking requirements. SkyMate offers an affordable VMS system that also includes sea surface temperatures, weather forecasts, fish prices, email and other value-added services that can help anglers run their fishing business.

Mazu Connection Plans

Travel PlanExplore PlanAdventure PlanSport Fishing PlanDrydock Plan
Weather Forecasts 10 Point* 15 Point* 20 Point* 10 Point*None
Messaging20 SMS40 SMS100 SMS100 SMSMaintain access to email
Position Reports304560100None
DataPlus 5,000 BytesPlus 8,000 BytesPlus 25,000 BytesPlus 50,000 BytesNo Iridium Data
Search & RescueGEOS 24/7/365GEOS 24/7/365GEOS 24/7/365GEOS 24/7/365None
Overage Data Rate$2.14 per additional KB$1.88 per additional KB$1.67 per additional KB$1.50 per additional KBNone
Monthly Price$39.99$49.99$79.99$99.99$9.99

*Refers to the number of requests for weather forecasts that can be made per month before allocated data is used.