Updated July 3, 2022: The system is no longer available. For a while it was on the Port of Friday Harbor office building, with the antenna at the peak of the roof (after 3 years aboard my boat). This was a 50-watt station with high-gain collinear antenna about 60 feet above mean sea level in the Port of Friday Harbor (48.536 N 123.016 W). Unfortunately, the service has been discontinued, but I am leaving this story in the archive for historical reasons.

This post is mostly for my fellow mariners in the Pacific Northwest, and is about the necessary evil known as the radio check… and a new service that helps solve the problem.

In busy areas during high season, it can drive you crazy… folks putting out a call on a busy channel to see if their marine VHF is working. It’s a good thing to know, of course, but the information you derive from this method is iffy at best. When someone says, “sounding good, Skipper,” it doesn’t have much meaning unless you also know the distance between you, the nature of both rig/antenna systems, and what the stranger means by “good.”

If you try this on Channel 16 (the calling and distress frequency where you are most likely to be heard), then you’re breaking the law… so in various places channels 9 and 22A have become the defaults (22A around here). But it’s kind of intimidating to bother the Coast Guard for a radio check… and they often find it annoying on busy days.

To address this, Seatow started setting up a string of automated stations on the East Coast in 2010, occupying the now-dormant marine radiotelephone channels (24, 26, 27, and 28). These Maritel rigs consist of a Motorola Radius marine VHF and a controller, along with a high-gain TG-5 antenna from GAM Electronics. They do one thing, and they do it very well: whenever the station hears a transmission, it temporarily records it… then pauses a couple of seconds and transmits a voice announcement along with a replay of the captured audio, followed by a second safety-related announcement.

The beauty of this is that you can hear your own signal and you know where the station is located. This provides much more useful information about how well your rig is working, and you don’t have to bother anybody to get it!

One of our previous sites in Friday Harbor.

In 2012, after installing the Icom M504 in Nomadness, I was sitting at the dock wondering if it worked. Like most folks, I kinda hate bugging the Coast Guard for trivial radio checks, and a quick exchange with the Port office only told me that my signal was making it a few hundred yards. I did a web search to confirm that it was still OK to use channel 22A for a test, and stumbled across the Seatow link above… but was immediately frustrated to discover that there were no stations in the Pacific Northwest! I sent them a note and things went from there… and I am delighted to report that I now host an automated radio check machine on VHF channel 28.

Line-of-sight from current antenna location (though actual coverage is much better due to refraction and reflection, though sometimes with accompanying multipath). But please note that there are areas around this hilly archipelago where coverage from an antenna in Friday Harbor is highly unlikely (Roche, the Straits, etc). Image generated by HeyWhatsThat.

Please help us map coverage!

For this to become a useful utility around here, there needs to be some idea of the station’s range and dead spots. The terrain of the San Juan Islands is highly varied, with open water, mountains, and a maze of twisty passages that makes it an exciting place to explore by boat. That does not translate into simple inverse-square-law propagation predictions, however.

If you are out and about on your boat, please give this a try. Simply call for a radio check on VHF 28 (you don’t need to identify your vessel, although you can if you like), and listen for the automated reply. If it works, or even if it does not, please send me a quick note to tell me about it… along with this information:

  • Where were you?
  • How clearly did you hear the station?
  • How clear was YOUR signal as re-transmitted?
  • Is your radio fixed or hand-held, and is the antenna low or atop a mast?
Radio check antenna base on Datawake
Radio check antenna base on Datawake

I have created a Google map for signal reports, and it appears below. I have some test data, including a video report from a sailboat in Bellingham, about 25 miles away (with a likely reflection off Mount Constitution on Orcas to get around the 1665-foot peak of Lummi Island). It has also been heard at Shilshole Marina in Seattle (though the path was one-way), and we have received good signal reports from Oak Harbor, Sequim, Anacortes, and Sidney as well as the surrounding waters of the San Juans. Now that the site has moved, more data would be good. Thanks to all who help with testing!

You can zoom and pan around the map… it should get interesting once I hear from more people who try the service (I even took a ferry trip to Anacortes with a handheld on the deck and did my own quick survey…)

In the map below, droplet style rounded icons are fixed-mount radios installed in boats, with the dotted ones sail and the plain ones power. The push-pins are hand-held VHF rigs (low power and inefficient rubber-duckie antenna). In all cases, I use this color code:

Green – solid copy with little or no noise
Blue – fully usable, but with some noise & dropouts
Yellow – marginal signal… in there, but hard to understand
Red – no copy at all

View Friday Harbor Automatic Radio Check Coverage in a larger map

2022 Note: this coverage map is no longer relevant, and is just here for historical context.

Cheers from Datawake!


  1. Thomas Plummer on December 1, 2012 at 11:59 am

    I am out of the area for a while but will give it a try as soon as I get back. I moor my boat at Skyline Marina. Would like to put a notice up on our bulletin board. if that is ok with you please send me the verbiage you would like to use.

  2. Steve on December 1, 2012 at 12:59 pm

    Thanks, Thomas! It will be interesting to see if the signal makes it past Lopez and Fidalgo Head… it will take some reflections. I look forward to the test.

    And sure, a notice is a great idea! Maybe I should make up a little sign I can post as a PDF, getting the essential elements in: Radio checks are illegal on Channel 16 and random elsewhere unless you bug the Coast Guard on 22A. Hear your own signal played back on Channel 28, from an automated station at 150′ elevation in Friday Harbor.

    I’ll try to do something a little smoother than that and add it to this page as a download for clubs and marinas.


  3. Ralph Hammersborg on February 6, 2013 at 1:07 pm

    Fantastic use of technology. Thanks for doing that! Especially needed in the central Puget Sound area. Thanks again! I will attempt to advertise in the Seattle area.

  4. Harvey Hochstetter on March 24, 2013 at 2:45 pm

    I saw the notice about your service on the C-Brat site. Posted by your friend, Larry. Thank you for providing a much needed Service. I boat out of Sequim Bay so will try from there and occasionally as I cross to Cattle Pass.

    Thanks again,

    22 C-Dory Cruiser

  5. Harvey on March 31, 2013 at 9:36 pm

    You can put a blue-green pin down at the northeast corner of Sequim Bay, out by the buoy #2. Good copy today, no dropout but some background static. My antennas are mounted about 5-6 feet above the waterline.

    Thanks for the service.


  6. Steve on April 1, 2013 at 11:31 am

    Thank you for the first signal report from the peninsula, Harvey!

  7. Alison on April 8, 2013 at 1:53 pm

    I agree, this service is very much needed in the Puget Sound area. Glad someone out there knows what they are doing with technology! Thanks for the info.

  8. Thomas Plummer on July 10, 2013 at 11:45 am

    Location: Skyline Marina, Fadalgo Island
    Station response: Loud and clear
    Repeat Back: Faint but understandable
    Radio: Fixed with a masthead antenna

    Great service thanks for providing it.

  9. Tom k on May 31, 2014 at 10:14 am

    No response from Bellingham’s Squalicum Harbor. 18″ whip on 60′ mast.

  10. Steve on June 1, 2014 at 6:59 pm

    Thanks for the data point, Tom (first attempt from there with antenna in new location, which is about 50′ lower elevation compared to the previous site at the FH Airport).

  11. Bruce Evertz on July 22, 2014 at 4:29 pm

    The automatic response didn’t work well. Last year I tried it several times with good results from Skyline in Anacortes.
    This year in early June the automatic response with the thanks for using it reply loud and clear but the recording of my call was weak and garbled, unreadable. I later checked with the Canadian CG on 83A with a good report. I had no trouble at all with my VHF. Returning in mid July I tried it again and still could not make out my transmission. FYI

  12. Steve on July 23, 2014 at 4:08 pm

    Mmm, thanks for the data point. The new location is lower elevation (in town, instead of the airport). Same antenna, mast, and radio. I’ll see if there is a way to get more height when the company hosting the installation re-does the roof soon….

  13. […] clear view towards Friday Harbor, Steve Roberts of microship.com, and specifically to test out his automated marine radio check system on VHF channel 28.¬†Unfortunately I was not successful. Whenever I am messing around with radio stuff, I head over to […]

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