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Over the Horizon AIS
Over the Horizon AIS - FAQ
Over the Horizon AIS - FAQ

Frequently Asked Questions about Over the Horizon on the DataHub

Matt Crockett avatar
Written by Matt Crockett
Updated this week

Over the Horizon AIS compatibility

Over the Horizon AIS data is streamed from the DataHub in industry standard NMEA2000 and NMEA0183 sentences. Any device or App that can display this should be able to receive and show AIS targets sent by the DataHub if connected and configured correctly.

How many targets your chartplotter or App will collect, display, and track is specific to your device. The device or App you are using will likely permit fewer AIS targets than the number or range of targets that Over the Horizon AIS can provide. Please test and calibrate your Over the Horizon AIS settings to match those suitable for your devices.

Over the Horizon AIS was developed and tested on RayMarine Axiom chartplotters and with AquaMaps on a laptop; however, we have already received reports that it works well on many RayMarine, B&G, Simrad, Furuno and Vesper devices. If you enable Over the Horizon AIS and find an unlisted brand that works for you, please let us know so we can update this article.

Garmin devices and the Navionics App have been reported as not displaying targets up to 75 miles only, and we have received reports of Furuno devices which can display up to 100 AIS targets from all sources.

Important Notes: Some RayMarine devices will require a DataHub Firmware update to display target names correctly. Please see more details here.

Some Garmin-brand Chartplotters are incompatible with Over the Horizon AIS. They require NMEA2000 data in a proprietary Garmin format unavailable to PredictWind. If your Garmin does work, please let us know. Your Garmin GPS will work fine for GPS tracking; this may only affect the AIS display.

Is Over the Horizon AIS a replacement for VHF AIS?

No, OHA is not a replacement for VHF AIS. Still, it will serve as a reliable backup in case of standard AIS receiver failure, ensuring you're never without critical collision avoidance, security, and navigational safety.

Over the Horizon AIS complements and greatly extends your existing VHF AIS range by up to 300 nautical miles.

Over the Horizon AIS Setup

I cannot see Over the Horizon AIS to enable it on the DataHub

If you cannot see the option to enable Over the Horizon AIS in the DataHub, please check your Firmware is version 4.05 or later and your PredictWind Account details have been validated in the DataHub.

To validate your PredictWind Forecast Account in the DataHub:

  • Click the Settings->Settings menu, then click the top menu Account.

  • Type in your PredictWind Professional subscription email address and password.

  • Click Save & Apply.

  • If successful, you will see Status: PROFESSIONAL appear.

My PredictWind Account settings fail to validate. Status: INVALID

If your email address or password needs to be corrected from above, it will show Status: INVALID. Please check that they are both correct, using the * to reveal the password.

Why can't I use Over the Horizon AIS on the DataHub?

To see and use Over the Horizon AIS on the DataHub, you need the following:

  • A PredictWind Forecast Professional subscription. You can upgrade to Pro here.

  • DataHub Firmware version 4.0 or later, 4.05 or later is recommended.

  • Your PredictWind Forecast Account is validated in the DataHub.

  • Over the Horizon AIS is enabled in the DataHub.

  • An Internet connection is available for the DataHub.

To view Over the Horizon AIS requires a Chartplotter connected via NMEA2000 or Wi-Fi, which can display AIS supplied in a standard NMEA0183 or NMEA2000 format. You can also view AIS data in navigation software Apps on a device connected to the DataHub via Wi-Fi if configured to receive the DataHub AIS feed, e.g. AquaMaps, OpenCPN or Navionics on a laptop or iPad. We expect Expedition to work; please let us know.

Over the Horizon AIS Usage

How often does Over the Horizon update?

Sampling intervals are up to 1 minute for direct, always on high-speed Internet, e.g. Starlink, Wi-Fi hotspot, 4G/5G router or cellular USB tethering. Update frequency is reduced where many targets are acquired to prevent overwhelming the N2K network.

Where the Iridium GO option is enabled, the DataHub will update AIS through your Iridium GO!/GO exec each time it polls, e.g. 60 minutes or as frequently as 15 minutes.

Updating via the Iridium GO! may take a long time, depending on your settings and connection stability. Please set the Range conservatively and increase it slowly to test.

Is Over the Horizon AIS data included in my GO exec Unlimited PredictWind Data Plan?

Yes! This data is included in your GO exec Unlimited PredictWind Data plan.

Over the Horizon AIS data is also excluded from your daily weather forecast download limit, up to 1.5MB per weather download and 4 MB per day. Please note: if you activate AnyApp data, all data transferred during that session will be deducted from your AnyApp data balance.

Is Over the Horizon AIS data included in my GO exec MB monthly airtime plan?

This data is treated like any other data the GO exec transfers for other monthly plans. This is another excellent reason to switch to the Unlimited Plan if you've not already.

For other GO exec MB plan customers, after activating Over the Horizon AIS, please monitor your data usage via the GO exec data counter and your Satellite account to ensure you do not incur unexpected overages.

How much data does Over the Horizon AIS use?

The amount of data used depends on the range and target age you set and how frequently it is updated. As a general guide, up to 1000 vessels, updated hourly, would transfer approximately 307kb daily.

5000 vessels would transfer ~64kb of data. Via a GO exec, on a 15-minute polling interval, this equals 6.14 MB per day.

Can I limit Over the Horizon AIS data usage to a fixed amount?

A specific data limit cannot be set directly for Over the Horizon AIS; however, an update to do this is coming soon. To reduce the amount of data transferred, please reduce the Range and Target Age, and if via Iridium GO!/GO exec, adjust the Polling Interval in the Tracking menu.

Can I stop Over the Horizon AIS using my Iridium GO!/GO exec?

Yes! Please remove the tick from the Iridium GO box and click Save & Apply.

How can I tell DataHub AIS vs VHF AIS targets?

The DataHub automatically tags AIS targets sent via NMEA2000 as being acquired from the DataHub. If you tap to view more AIS target information, this should be displayed on your Chartplotter or Navigation App.

For NMEA0183 Apps that do not support NMEA0183 tags, please enable the Mark AIS setting, and the Callsign field in NMEA183 AIS sentences will be set to "DATAHUB", allowing users to differentiate between VHF and Internet-acquired targets when viewing in nav apps that do not support NMEA0183 tags.

Class A ETA and destination are also modified to display the time of the last position update.

Can I see a demo of Over the Horizon AIS?

Sure! This video by Luis Soltero, the DataHub designer and developer, demonstrates Over the Horizon AIS and explains how it works.

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