Monday, October 14, 2019

Offshore Navigation

Mid-Ocean Communication and Navigation

Mid-Ocean Communication and Navigation


I had the good fortune to be invited on a friend’s boat to do another east to west transatlantic this past January and this time it took us 18 days to make the passage from the Canaries to Barbados and then another overnight to nearby Saint Lucia.  Rather than do another ‘travel log’ type of article, I thought that many of you might be interested in the gear, programs and techniques that I’ve learned to use over the years as a journeyman navigator on many different ocean cruisers and racers.  Let me start by offering a disclaimer, of sorts.  While the dialog I offer here has worked well for me, this is not to suggest that there are not better systems and techniques and I’d like to get feed back from members on what has worked for them.  And after all, the digital systems for communication and navigation and the technologies that support them is nowadays a fast moving target; what was cutting edge yesterday may be passé tomorrow.

Voice Communications

For years the core of offshore communication was the single side band transceiver and this gear is still to be found on virtually every offshore boat and it’s important to be proficient with the specific set on your boat.  But the Iridium Sat Phone is fast becoming the technology of choice for data collection, email and voice communication on the size boats most of us sail.  I use a 9506A portable Iridium phone that I bought used from Preferred Communications in North Carolina , the company from which I also purchase 500 minutes of airtime each year.  This phone is a generation older than the newest model, but someone told me that the US Army liked this model over the newer one (9555) so I used that as an excuse to buy a used one.  The newer model, by the way, has the advantage of being smaller and will accept a computer USB interface directly rather than having to use an RS232 serial to USB adaptor (get the Keyspan 19HS model) necessary on the older phone.  I have an external patch antenna and extension cable that most often can be fished through a Dorade vent near the chart table.  Duct tape the patch antenna on deck in clear view of the sky where it won’t be kicked or stepped on.  There is a new 3M low residue tape on the market that will leave no glue on deck if you remove it within a month or two (I use this tape everywhere and on this last trip got the nickname ‘Duct Tape Larry’).


Email , Web Browsing and Weather

Now I’m set up for Iridium voice comms anytime and anywhere but to send and receive data (including email) you need a service provider.  I use UUPlus, a son and father team on the west coast .  Jeremy and John have the best customer service on the planet and are perhaps the most affordable.  These guys have written special code for me overnight so I could do a web fetch of a certain NOAA data product and they are otherwise are always there to walk through setups and product use.  I have become an Apple convert; owner now of iPhone, iPad, and MacBook Pro.  I’ll get to the iPhone and iPad later but to stick with communication, I hook up my Sat Phone to the MacBook through the Keyspan 19HS adapter and it talks to my UUPlus software on the Mac.  My Mac has a solid state hard drive which may be a little more robust when the boat you’re riding on drops out of the sky and back into the sea with a bang.  The UUPLus software lets you store up emails you want to send on a given day and then transmit them all a once and during the connection receive any incoming emails queued up for you.  During the (typical) morning connection you can receive NOAA weather maps, Gulf Stream data, and NOAA wind-field model forecasts for many days ahead.  The picture in the sidebar was taken on my iPhone and sent home as an email attachment just before we enjoyed a nice fish dinner on the Mid-Atlantic Ridge


.  Much of this NOAA data is packaged up and available from “SailMail” via email from “SailDocs” (a subset of SailMail) on a multiday subscription basis at no charge.  The two most useful weather products I look at each morning is the multi-day wind-field forecast arranged in GRIB (Gridded Binary) files for storage and display, and the 96 Hour Surface Forecast map.  Another useful piece of companion gear I’ve used on recent trips is a small portable printer.  Printing weather maps, position plots, forecasts, emails and other stuff makes it a lot easier to share information with the whole crew.  There are at least two Government wind field models; GFS and NOGAPS but I like the GFS model.  To display the wind field data and to do basic navigation, I bought GPSNavX navigation software designed for the MacBook.  In spite of its  low price, this is a pretty powerful program and the more I use it, the more I like it.

Plotting and Navigation

I update the forward Noon DR positions for the whole trip on a daily basis and then overlay on the plot a multi day loop of the wind field model (and ocean currents if I’ve downloaded same).  You can download to the GPSNavX Program all the NOAA charts (including the old Newport to Bermuda plotting sheet) for free and a worldwide plotting sheet also comes with the program.


But the oversea charts are expensive, and while the world-wide plotting sheet is perfectly adequate for trans-ocean navigation and weather plotting, it’s not suitable for landfall navigation -  enter the iPad!  Having bought an iPhone when I retired in 2008, I became familiar with Navionics chartware and found it easy to use and very inexpensive.  When Apple announced the iPad, I immediately put one on order primarily to use for navigation and planning.  Be sure to order the 3G  (or 4G) model as those are the ones with the GPS receiver, the non-3G/4G models uses known Wi-Fi hot spots for land navigation, which is obviously useless offshore.  Apple should make this clear, but  they don’t.  When you order the 3G model you don’t have to sign up for the 3G data plan.  The iPad is the best tool for planning and cockpit navigation in coastal regions (in my opinion) and while the charts are a little more expensive than the iPhone versions, there are at least three vendors (see below for the other two) that offer charts a lot cheaper than anything else I’ve seen.  Stored on my iPad I’ve got charts for Greenland to Cape Horn (not that I plan to go there soon), Europe to Africa and all the Atlantic Islands all for less than the cost of one of those old Chartkits for Southern New England waters.  Other useful stuff that comes long with the chartware include tide and current info for time now and out into the future (be careful looking ahead to a different time zone because unless they have fixed it, it won’t compensate; I’ve written that they should at least include a time zone stamp but I haven’t seen it yet) and other astronomical data.  There are two other Navigation apps out there that I know of that also have real merit.  The companion app for the software I have on my MacBook (GPSNavX) for the mobile devices is iNavX.  I haven’t bought this one yet but I may.  Like GPSNavX the US NOAA charts are free but other charts tend to be on the pricy side.  Another nice feature of this app is that you can link it up with a Brookhouse iMux device and send data from your chartplotter to your iPad via an onboard Wi-Fi link.

Another company whose apps I’ve used is Navimatics and they also do excellent programing.  I just purchased US and Canadian chartware from them and an early review suggests it’s pretty powerful and email exchanges with them indicates they plan to aggressively expand their offerings.  Speaking of Navimatics, for those of you who still like to haul out the old sextant once and a while they have a terrific application for the iPhone and iPad to do celestial sight reduction, sight planning and more.  It’s called “Celestial” (by Navimatics).  Sight reduction is so easy that I’ve found that rather than averaging multiple sights of a given body I reduce them all and then compare the intercept values (from the same estimated position) and look for a tight grouping to assure the quality of the LOP, throwing out an outlier.    In looking for sources for new mirrors for my 40 year-old Plath, I’ve found a company in Wichita (yes, Wichita), Kansas called “Celestaire” that has a lot of navigation products at reasonable prices.  Send them an email to get their catalog.  By the way, if you’re thinking of buying a new sextant take a hard look at the Astra IIIB.  For small boat navigation I think I prefer it to the heavier Plath and for the money a great choice in my opinion.  When you order one, pick up a zero magnification sight tube for those rough weather sights.   If you need repair work on your sextant or want to buy locally, Robert White Instruments will provide expert help.

Collision Avoidance

Getting back to modern technology and reflecting of this last trip, We encountered only three ships during the crossing from La Gomera to Barbados, but on the short run from Barbados to Saint Luca we came in close quarters with four large cruise ships.  Our boat was equipped with an AIS (Automatic Identification System) receiver, which enabled us to call each ship by name, and resulted in two of these (friendly) behemoths altering course for us to open up the CPA.  I think the AIS gear is the greatest advance is collision avoidance at sea since the introduction of RADAR and would recommend the transceiver version, which also sends your vessel information out to anyone with an AIS receiver (and all large commercial ships must carry them by international mandate) in VHF range.  The AIS data can also be sent over to the MacBook (or PC) via that same Keyspan adaptor and displayed on the GPSNavX  (or an equivalent program).


Another nice piece of gear we’ve taken along on most trips is iBoat Track manufactured by a local company and BYC member, Jim Feeney.  With this system, friends and family can track your progress across the ocean just by going online.  Rent one from George at Jim’s company and just stick it to the deck and go.

By the way, storing onboard documents such as user manuals, cruising guides, diagrams, etc. on the iPad provides easy access and saves a lot of space.

Offshore sailing is a great pastime and for most of us it’s made even more fun by all this new technology – and there is no end in sight.  Let’s go sailing!


Larry Hall

May, 2012




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