The Offshore Voyaging Reference Site

Tips, Tricks & Thoughts:


  • PredictWind Unlimited With GO! Exec Better Than I Thought

    A few weeks ago I wrote a Tip pointing out that the “unlimited” air time package for Iridium GO! exec was not actually unlimited and therefore I recommended staying with the truly unlimited package available on the original Iridium GO!.

    I have now dug into this in a series of emails with Craig and Matt at PredictWind.

    The result is that, although I was right that the unlimited package does have limits, if we put aside semantics it sounds like a good deal that will enable users to download and analyze the weather, in the way we recommend, for known costs.

    This Tip is focused on PredictWind’s capabilities as they relate to the techniques we recommend in the above-linked Online Book. It’s not a review or a recommendation to go with PredictWind or buy an Iridium GO! Exec. That’s up to you.

    Here’s what an offshore sailor will need, what it will cost, and the capabilities delivered:


    Hardware (one-time cost)
    Iridium GO! Exec with DataHub and external antenna$1,999
    SIM Card$10
    Monthly (ongoing costs)
    PredictWind “Unlimited” Data Package$170
    PredictWind Professional ($499 / Year)$42
    PredictMail ($119.95)$10

    All in US$. Monthly costs rounded up. The standard PW package at $249/year will do, but if we are going to do this right, we might as well go the whole hog.


    1. Up to 4MB of GRIBs a day (plenty).
    2. Unlimited email, including attachments (to download weather maps and forecasts not offered directly by PredictWind).

    Confirming #2 with the folks at PredictWind was the primary reason I wrote this Tip.

    Other Benefits

    • The Iridium GO! Exec is much faster than the original GO!, but not really fast enough for true internet access, which Starlink is.
    • GO! Exec can be used to make a phone call without using a linked cellphone, which makes it far better for emergency use, particularly in a liferaft, than the original GO!.

    Watch Out

    We are only protected from cost overruns with Iridium GO! Exec and the PredictWind “Unlimited Package” as long as we stay within the PredictWind apps listed above.

    If we turn the firewall off to get true internet access, we will need to buy added data packages, which we may blow through in minutes.

    The unlimited package on the original Iridium GO! is truly unlimited, albeit much slower.


    The above is based on an email exchange with PredictWind. I have not tested any of it.

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  • Original Iridium GO! Still a Better Deal Than Exec

    There’s a headline to provoke screams and tearing of hair.

    After all, the new Iridium GO! Exec is 40 times faster than the original GO! and only twice the price, so it’s gotta be the the better deal…right?

    And you can get unlimited data with the original GO! from lots of places for $154.95/month and unlimited for the Exec from PredictWind for $169.95, just a $15/month difference.

    So at this point you must be thinking that the old fart who runs this site has finally and completely slipped his cams when writing that headline.


    As so often in these things, the reason that GO! original is still a better deal than Exec is in the fine print.

    Look at the screenshots at the top of this tip, and see if you can spot it.

    You got it, with the original GO! unlimited plan you get unlimited data minutes for:

    • Email
    • Snapshots of any page on the internet: news, stock prices, whatever.
    • Weather maps unavailable from PredictWind.
    • Really vital weather information unavailable from PredictWind—more in an upcoming article.

    Anything we want, any time we want, as much as we want.

    Sure it’s slow, but so what, we don’t have to stand there and watch it, at least if we use decent software to run it.

    We ran this business, including a ton of email, when out of cell phone range on the original GO! unlimited data plan, and downloaded a bunch of weather data, without ever needing to use more than an hour or so a day.

    But with GO! Exec the “unlimited” is restricted to PredictWind data only!

    Yup, the way I read it, after we buy the “unlimited” package for $169.95/month, we need to then add a data minutes package if we want anything other than stuff from PredictWind.

    And it’s not even clear to me that we would be able to get our email under the “unlimited”.

    So sounds to me like we are going to need to buy say 10MB (not going to go far) for another $40 if we want to venture out of the PredictWind world, and maybe even if we want our email within it.

    And note they are charging data by the megabit, not connected time, so the much vaunted speed of Exec is not going to help.

    Begs the question: when is unlimited, limited?

    To make this worse, in their Exec FAQ, PredictWind claims that the unlimited package avoids “bill shock”. But what happens if you don’t buy an added data package, or do and go over it? Don’t know for sure, but I also don’t want to be the one to find out!

    My Recommendations:

    1. Stick with original Iridium GO! and the unlimited plan.
      • I know for sure that package is…unlimited. In several years of use for anything I wanted, including sending super-stupid grinning selfies to my daughter, there was not one single added invoice over and above the unlimited monthly charge.
    2. If you really need a fast solution? Go Starlink as well.
      • Exec, even 40 times faster, is way too slow to actually do anything useful on the internet.
    3. And if you need a solution to take into the liferaft, something Exec does do better than the original GO!, buy a secondhand Iridium handset.
      • There should be plenty around at good prices from people who bought limited unlimited.

    Limited Unlimited?

    One final thought:

    It would be nice if Iridium and PredictWind would be a bit more careful with the word “unlimited”. On this page they specifically write “Unlimited Data”.

    Look it up in the dictionary, guys. The way I read it, “unlimited” means without limits or restrictions. And “data” means all digital data, at least to me, not just that originating at PredictWind.

    I just can’t see how you can be a little bit unlimited, or a little limited when you’re unlimited…OK, I’ll stop.

    More on how we downloaded and analyzed the weather using the original GO!

    This Online Book needs updating. It’s on my list for this winter. That said, the fundamentals are still relevant and can save you a lot of weather-related grief.

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  • Do We Need A $10,000 Plotter?

    I just read a post over at Panbo on Garmin’s new top-of-the-line plotters that start at US$10,000 and go up from there.

    And, of course, to take advantage of all the features we will need to spend a bunch more on supporting gear.

    I’m sure those who are so inclined will be obsessing over all the cool features of these new plotters.

    But to me the bigger question is the opportunity cost of this stuff: What else we could spend ten to twenty, or even more, boat units on?

    A few suggestions for far more important things we could do with that much money on say a 40-foot cruising boat:

    All of the above will contribute far more to cruising safety and enjoyment than the ultimate plotter-based marine electronics system.

    Does that include the keel, rigging and rudder? Yup. If we are at sea with even the slightest nagging suspicion that all is not well in those areas, we will not be having fun!

    Got all that done and still have money in the bank? Sure, go buy a ten-grand plotter.

    I get that we need a good navigation system, but that can be done for way less in a bunch of different ways.

    Never forget to think about the opportunity cost of cool stuff.

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  • Edson Radar Tower

    We are really happy with the way our new radar installation came out, particularly the Edson tower.

    We have long felt that the best place for a radar is on a tower, not on the mast or backstay.

    It even inclines for when we are heeled in fog…yes, we get wind and fog here in Nova Scotia.

    And here’s a fun hack. When I got it installed it was a little wobbly due to the slight play between the tube glassed into the hull and the tower tube, so I preloaded it to the rail with Dyneema lashings—lighter and easier than struts.

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  • Is Your Radio Talking to Your GPS?

    Even though I have been working on our new-to-us J/109 off and on for nearly two years, there are still chores on the to-do list, one being to program our new MMSI number into the VHF—I did our AIS transmitter as soon as we got the boat.

    Luckily for me, although disturbing to find out, there was no MMSI number in the VHF, so the two previous owners were forgoing a big safety feature.

    I say luckily because radios and AIS transmitters sold in the USA can only be programmed once, or at most twice, at least without help from the manufacturer. Who thought that was a good idea? Homeland Security, as I understand it. Don’t get me started.

    Anyway, I had assumed that the radio was at least getting GPS positioning sentences, since there were two wires leading from the correct terminals on the radio to…the wrong terminals on the source.

    I hadn’t changed that, so clearly it had been that way for years since the “professional” hooked it up and never bothered to check it worked! Saints preserve us from “professionally maintained boats”.

    The fix took minutes and was confirmed when “GPS” came up on the panel.

    With these two problems put together, the nice red distress button on the radio was for decoration only.

    So I have made a mental note to always check the display for that indicator when I turn the radio on, since it would be easy for the wires to get disconnected or a parameter to get changed in the source GPS (say BAUD rate), rendering this important feature useless.

    By the way, while this crappy little radio is adequate for our needs, if I we were still going offshore and cruising countries where DSC is used more than it is here, we would be replacing it. More here.

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  • Bluetooth Autopilot Remote Rocks

    Given that, this remote control for our new B&G autopilot is invaluable and just generally adds to the fun. A couple of button presses will even make the boat tack automatically while I handle the sheets—beats heck out of steering with a foot while tacking.

    Highly recommended and way better than wired remotes or running back and forth to a fixed autopilot control panel, although we need that too in case Bluetooth goes screwy—not to be relied upon for mission-critical stuff.

    B&G sell the gadget with a neck strap, which, if you think about it, is a very bad idea, particularly for a singlehander constantly hanging over and grinding winches—do these people actually ever go sailing?

    Anyway, it will also fit on a velcro watchband. I bought one from Amazon and then kluged it to work with a needle and palm. Supposedly B&G sell a band, for extra (of course), but I couldn’t find one.

    Note to B&G: Stop being jerks and just ship the thing with a band before someone strangles themselves!

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  • B&G Navigation App Not Ready For Use

    We ended up with a B&G system on our J/109, mainly because most of it was already there when we got the boat.

    Given that, I thought it would be a good idea to use the B&G App on our iPad, which we use to supplement the plotter.

    What a mistake that was:

    • No manual
    • Constant hangups
    • Clunky synchronization of routes with the plotter
    • Terrible and counterintuitive interface
    • Dangerous autorouting function

    I just canceled my subscription, thankfully before the two-week trial ran out.

    Back to TZ iBoat, which is, in my view, the gold standard for tablet navigation software.

    Hopefully B&G will get their app sorted out, since I would love to have a tablet app that synchronized routes with the plotter, but B&G have a long, long, long way to go to catch up with TZ iBoat or to even be a safe and functional app, in my view.

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  • Beware Auto-Tune on Modern Radars

    Engineer and experienced mariner Eric Klem has just updated his review of his Furuno DRS2D-NXT doppler radar with a sobering account of how the auto-tune feature failed during a night approach to a crowded harbour.

    Eric is an experienced radar user, and so was able to quickly diagnose the problem and fix it by taking over manual control of the gain and clutter settings, but those of us who are used to relying on fully automated radars may not have been able to do the same, or even figure out what the problem was.

    To me the takeaway from Eric’s experience is that it’s vital to take the time to understand what these automated electronics are doing and how to take over when the automations get it wrong.

    Further Reading

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  • Instrument Loads

    Seems like a lot of cruisers are leaving their instrumentation on, even when at anchor, these days.

    Do what you want, but this practice could push you into a major electrical system makeover that might not be necessary if we just turned that stuff off.

    The above photo shows the load (battery monitor to the right) from the instrument package and NMEA 2000 network on our J/109, added to a 9″ plotter.

    Nearly two amps at 12 volts. Leave that on for 24 hours and that’s nearly 50 amp hours out of the battery!

    And our system is comparatively small and miserly. Add in a big plotter, AIS, and worst off all, a laptop computer running navigation software, and we can easily burn through 100 amp hours or more.

    To put that in perspective that’s over a third of the power Phyllis and I used in the run of a day for everything on our 56 foot live-aboard boat!

    When left on all the time, small loads add up to big usage.

    Here’s how to estimate usage and choose the right battery bank size, the easy way—no long boring spreadsheet to fill out…we provide a short, and not boring, spreadsheet.

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  • NMEA 2000 Trouble Shooting Kit

    I’m in the throws of installing a new autopilot and radar on our new-to-us J/109.

    As part of that I cleaned up the dogs breakfast of a NMEA 2000 network the boat came with to make it both easier to trouble shoot and hopefully more reliable, particularly since this new kit required adding quite a few network devices.

    When all was said and done I ended up with a couple of old network cables that I had replaced because they looked a bit manky (another deeply technical word).

    I was about to throw the old cables away when it struck me that by cutting them both in half and stripping the ends I would end up with a zero cost NMEA 2000 trouble shooting kit for use with a voltmeter.

    I also added a male to female connector I had left over to the kit. Useful to substitute for a T connector to get a suspected device or drop out of the mix, but still keep the backbone connected.

    The kit proved invaluable while hunting down a brand new power-T with an open circuit on one of the network lines.

    And here’s a good primer on trouble shooting NMEA 2000.

    By the way, I don’t think most of us need an expensive N2K meter, particular since a lot of devices, such as plotters, have trouble shooting screens which will let us check for excess error packets and the like—dig deep in the menus and check regularly to catch potential intermittent problems early.

    More thoughts on NMEA 2000:

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  • Garmin Cut Vesper Users Loose


    Although we had a lot of trouble with our first Vesper AIS, I have long been a fan of their products, with the exception of the Cortex, which tried to do too many things in one unit and had a lot of issues as a result.

    When Garmin bought Vesper I had a sense of impending doom—these acquisitions of small companies by big ones almost always go badly for us users.

    And I was right, Garmin has just announced that they will no longer sell any of the Vesper products except the Cortex, which, as I understand it, is still buggy.

    That’s bad news since these were still good products at a fair price.

    The Big Suck

    But far worse news is that Garmin will not maintain the WatchMate app, which means that at some point, probably sooner rather than later, those of us with Vesper products—particularly those with no screen, like the XB-8000—are truly screwed, since unmaintained apps tend to stop working when the device operating system is updated.

    In my view, this is totally unacceptable behaviour on the part of Garmin, particularly since the units that they are, in effect, trashing, were available for sale up until a few weeks ago, and some are still in the supply chainour XB-8000 on our new-to-us J/109 is just 30 months old.

    To be clear, this likely means that someone who bought a XB-8000 a week ago will have a near-useless lump of plastic and components on their hands a couple of years from now, and maybe sooner.

    And even if it keeps working with some reduced functionality, a working app was what said buyer was sold, so they should get that for a reasonable period of time.

    Decent companies like, for example, Furuno make sure that their products are fully supported with parts and software for at least ten years after the last one is sold.

    I suggest we all write to Garmin pointing out their bad behaviour and informing them that we will not buy their products in the future because they clearly don’t give a damn about us—this is my letter to them.

    At the very least, Gamin should be maintaining the app on iTunes and Google Play for 10 years. That’s just basic, guys, and not that hard.

    I’m also disappointed in Panbo for not making more of a fuss about this. I get that they are advertising funded, and Garmin are probably a big part of that, but, even so, sometimes you have to stand up and be counted. Just telling us that we can buy a new fancy and expensive, and probably still buggy Cortex from Gamin is not good enough, guys.

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  • TZ iBoat Updated

    I have used a bunch of iPad navigation software over the years, but TZ iBoat, by the same folks who have been doing navigation software on computers for some 30 years, is by far the best.

    Lots of reasons, but the most important is that it’s the only app that I can enter and edit a route on without being driven to distraction. No, not as easy as a computer with a mouse, but way better than a plotter.

    Anyway, TZ iBoat has just been upgraded with three new features, two useful, and one that should be avoided like the plague:

    • Autopilot Output: TZ iBoat is now able to send information to your Autopilot (NMEA0183 sentences via TCP) when a route is activated. Make sure to check out their user guide for more information under the “Help” section.
    • Bluetooth Mouse support: Many of our power users on iPad wanted a way to control TZ iBoat with a mouse. This is now possible.
      • This is a wonderful upgrade. A finger is just too blunt an instrument for entering waypoints and routes, and a mouse (or track ball) is best.
    • Instruments Damping and Offset: TZ iBoat offers new settings to offset and damp instruments (course, speed, wind…). Speed damping can be especially useful in some cases to stabilize the Estimated Time of Arrival (ETA).
      • Probably useful, depending on setup.

    Further Reading

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  • Q & A: Iridium Go! or Go Exec


    The new Predict Wind Iridium Go Exec device does indeed have a subscription plan that limits data according to how much one pays, i.e: $159.95/month buys you only 50MB of data. That includes all data transfer including tracking data.

    Do you happen to have a clue how much data you found that you used, on the average, per month with the original Iridium Go device?

    I am just trying to figure out what size plan would be needed in order to not have to worry about constantly hitting the ceiling towards the end of the month. I believe you & I would have similar usage (that is forecasts & basic emails).


    The exact amount of data we used varied a lot, so I don’t think that’s the way to make the decision.

    Rather, what I can say is that we never had a problem getting all the weather information I needed, and I download a lot more than most people, as well as being able to handle all of our email, which, again, is a heavier load than most people, because of running AAC.

    Sure, sometimes the GO! took as much as an hour to deal with all that, but so what? With good software you don’t need to sit around and watch it, and if there’s a drop-out it reconnects automatically and continues on until done.

    So if it were me, I would stick with GO! to get the unlimited plan, given that I just don’t want the stress and aggravation of worrying about a hard data limit and the huge charges if that gets inadvertently breached.

    I also would not want to have to figure out how to buy more data if I ran out while at sea.

    So given that GO Exec is not fast enough to surf the internet, and does not have an unlimited data plan, I just don’t see the point of it against the original GO! with an unlimited plan.

    That said, as I have said before, being able to make calls without the kluge of a connected smart phone is a nice upgrade, but not enough to push me into Exec. Rather I would recommend buying a secondhand Iridium handset for the emergency call function.

    More on exactly how to use G0! For both strategic and tactical weather forecasting.

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  • Updated: Our Tips On Using Tablets For Navigation


    We just updated our 11 tips to make navigating with a tablet easier and safer chapter based on our experience of doing just that on our new-to-us J/109.

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  • The Rolls Royce of iPad Waterproof Covers

    While I’m not a fan of relying on tablets exclusively for navigation, on smaller boats like our new-to-us J/109 they can be a good option, at least in conjunction with a plotter.

    However, the big problem can be how to charge a tablet and still keep it waterproof. The product pictured above solves that problem.

    I’m planning to order one for next season.

    On the same subject, here are:

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  • Navigation Where It Belongs

    I don’t care how much butchery it takes, we are having a plotter/radar at the forward end of the cockpit where it belongs, to supplement and backup the iPad we use for navigation.

    The plotter below-decks is useless when shorthanded and we don’t like plotters on the binnacle, either.

    The new on-deck plotter will act as an autopilot control head as well as show strategic information like laylines, should I have a rush of blood to the head and go racing.

    The new plotter is much smaller than I would like, but compromises are required on any boat, and the smaller the boat gets, the bigger the compromises.

    More on making the most of these small-boat navigation compromises.

    Mock-up of the fascia that I just made to assist the composite technician who is going to fix my butchery and make it look nice.

    Yes, I could do the glasswork, but it would take me three times as long and look half as nice—know your limitations.

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  • New Iridium Go! exec

    Predict Wind have a preliminary announcement video for a new faster version of the Iridium GO!.

    Not a lot of details yet, but it’s supposedly a lot faster, although not fast enough to use for actual internet surfing.

    The big drawback will be if the unlimited data package available with the original GO! is not offered with this new unit or is a lot more expensive.

    I’m guessing it might not be the great deal that the unlimited plan on the original unit is since the new GO! uses the Certus modem like Iridium Pro.

    If no unlimited plan is offered, or a much more expensive one, I’m thinking that for many users who are just looking to download email and weather information at sea the original GO! may still be the best option since I have never had any problems getting all the weather data and email I need over the older unit.

    Definitely the key thing to look into and clearly understand before purchasing one of these new units is the availability and cost of an unlimited plan.

    One upgrade I did like is that the new unit has a speaker and microphone and so can be used for telephone calls without connecting a smartphone. This is a big safety benefit since there have been incidents with the old GO! where users were not able to get voice communications working quickly in an emergency.

    Here’s the intro video, not that it’s much use:

    And here’s a Q&A that might be more useful.

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  • A Crash Jibe Looking For A Place

    I’m in the throes of replacing the autopilot computer on our J/109 (more on that in a full article).

    First off, when I opened this box to connect up the drive and clutch I was distressed to see this terminal type.

    These things have no place on a boat, at least if they rely on the screws alone rather than contact plates that the screw compresses onto the wire, but, even then, for critical systems I far prefer ring terminal blocks.

    That’s bad enough, but my distress turned to horror when I disconnected the clutch wires and found that whoever had set this up—given the history of the boat almost certainly a boatyard “professional”—had jammed the wires so far in that the screws were on the insulation, not the wire—look closely at the photo.

    This could have caused a nasty, and likely intermittent, failure at any time over the last 18 years since the autopilot was installed.

    Bottom line: you gotta check everything and “boatyard maintained” is often more of a warning than a reassurance.

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  • Is It Time To Consider a Robot For Watchkeeping?

    OK, that was a clickbait title, if ever there was one.

    Anyway, I have been vaguely interested in the AI lookout and collision avoidance technology that has been used in the singlehanded racing game for some years, called OSCAR.

    Now I see that the company has rebranded as SEA.AI and their entry level product is down to a still eye-watering €9,999.

    But, then again, if this entry level unit really works, I can see that kind of investment (no more than a good integrated plotter and radar system) being worth it for singlehanders, or even double-handed crews.

    And if we were still heading for the high latitudes regularly, Phyllis and I would be all over this technology, assuming it works for detecting small growlers.

    Worth thinking about, although I’m guessing that waiting a bit longer before spending on this technology probably makes sense for most of us.

    The other thing that could be a problem is how much power this thing uses. I note that it needs 24 volts—to avoid voltage drops on the mast cable since this model has all its brains at the top of the mast, I’m guessing—which is a bit of a smoking gun on what a hog it is.

    Do any of you members have any first-hand experience with these things?

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  • Long Live Free-Standing Radars

    Based on 30 years of radar use in some of the foggier and icier waters in the world, I have long advocated for free-standing radars, at least for those who venture into these waters, rather than integrating radar into a plotter.

    So it’s way-cool to see that Furuno have just brought out two brand new free-standing radar displays that are compatible with their latest scanners, either magnetron, or digital.

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  • Review of Furuno DRS2DNXT Radar

    Eric Klem, a deeply experienced commercial and recreational mariner, and professional engineer with huge radar experience, just reviewed the latest Solid-State Radar from Furuno.

    Don’t miss this comment (membership required to read), you will learn a huge amount, just like I did.

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  • Starlink Maritime

    Starlink are going to provide a solution for moving vessels, but before we get too excited check out the price! Think US$10,000 for the unit and US$7000/month for service!

    Looks like I will be right that Iridium will the solution for most of us for some time to come. In 2019 I predicted 10 years more of standard old Iridium for most of us.

    Might still be right, but then again five years from now might be closer for always-on internet at sea at a reasonable price—only 30 years after the billionaires started promising it for “next year”.

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  • No Position

    We were out sailing our new-to-us J/109 when I realized that neither of the default screens on the plotter or TZiBoat showed position. Pretty standard these days…and oh so wrong. Imagine a crew overboard and we need to radio for help, but first have to dig through a bunch of screens to find our position. Two minutes to fix (above photo), but worth thinking about.

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  • iPad Clamp

    Well, this is better than duct taping it to the companionway, but it still feels like a kluge. Probably OK for round the bay, but I need to make it more waterproof and improve power feed. Even then I’m glad there’s a plotter below for backup and offshore use. Nice clamp from Scanstrut.

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