Howdy, people have asked us many questions about how we obtain our weather info while we're at sea. The best method invented, yet, is to look out a porthole. Next best would be to keep the US Navy meteorological team on retainer. Unfortunately this was not an option for us so I've been using a little system that involves a SW radio and a laptop.
Everything is detailed in this little article I penned for a sailing rag last year.
“Weather Forecasting Without a Fortune”
You may not know it, but if you sail only in U.S. waters, you’re very spoiled by having some of the best weather information anywhere in the world literally at your fingertips – your trusty VHF radio and NOAA weather forecasts. But what is the poor sailor to do when visiting strange and far off lands?
Let’s first take a look at the typical SSB/HAM setup found on many boats these days, the same unit that many cruisers depend on for weather forecasts. The basic function of HAM radio for long distance, two-way communications has been replaced largely by the desire to perform other higher order tasks such as decoding weather faxes, sending and receiving e-mail, and accessing the Internet. Once you get into some of those more high tech options, costs really start to add up. (All prices, except the modem, are quoted from West Marine.)
Base radio unit (ICOM IC-M802): $2000
Automatic antennae tuner: $500
Backstay insulator: $70
Grounding plate: $310
Pactor III modem: $700
Total price: $3650
Looking at these average prices, the cost of a full setup can quickly reach more than $3,000. Wow, that’s a lot to spend when you’re on a tight budget! Not included in the list is a laptop or a professional installation (even if you install the gear yourself, many manufacturers still suggest having a pro come out to test the setup).
But don’t worry! There’s still hope for the rest of us.
Before setting out on the grand adventure, I had heard a rumor about shortwave radio/receivers that also have single sideband capabilities. I wanted to tap into Mexican cruising nets (frequencies where cruisers congregate to stay in touch and get weather information), listen to U.S. Coast Guard high seas high frequency voice broadcasts (basically a computer that reads you a weather fax), and maybe even pull down those elusive weather fax charts onto my laptop.
But, at the same time, I was very skeptical of the quality of the high frequency radio reception. If they were any good, then why would so many people automatically install a full SSB rig? Until then, I hadn’t met anyone who had ever tried to use this simple system. Ultimately, I decided to pick one up for its side benefit of worldband radio reception (BBC, Voice of Japan, etc.). Great for those lonely nights on watch.
Comparing different radios online, I decided on the Grundig Yachtboy 400PE, which cost around $150. I’ve found since then that it is the most common receiver used by fellow cruisers. For those elusive weather faxes, I also picked up some weather fax software and a cable to interface the radio to the laptop. I spent $30 on the software; some versions you can download for free. The cable you can pick up for peanuts at any audio supply store.
I made these investments in the vain hope that someday I would make them all work together and have weather forecasts from multiple sources at my fingertips. But, when we finally left San Diego for our first stop in Baja, I was still no closer to getting weather information via this equipment. I went for months without delving into the details. Why should I when weather forecasts were so easily shared by fellow cruisers?
However, as our months in Mexico passed, and our plans to puddle jump began to take shape, I became more determined to finally work out the kinks in my system.
First, I had to know all the necessary frequencies for HF high seas voice, weather fax (from the three stations nearest me), and the cruiser nets. Here’s where you can find those frequencies that apply to you:
Second, I spliced a connector onto the end of the shortwave cable antennae and attached it to my backstay. What a difference! The combination of the right frequencies and the juiced-up antennae made all the pieces start falling into place. Now I could explore all the ways that nets, HF high seas voice, and weather fax could help me in my attempt to forecast weather. As is true for full SSB setups if you’re testing the system in a marina you can expect more signal noise due to all the mast interference.
Cruiser Nets in Mexico
You could just stop here in Mexico if all you’re interested in is really great weather forecasting. You can’t do much better than Don Anderson’s Summer Passage updates. At last count he was providing forecasting daily on at least four nets. They all pertain to the west coast of Mexico and to those leaving to other world destinations via that coast.
But what if you don’t have a Don and need to do a little forecasting on your own?
HF High Seas Voice
The U.S. Coast Guard provides an automated, scheduled set of broadcasts for the Pacific and Atlantic oceans. Basically, it’s a computer that reads the data from weather faxes. There are six stations broadcasting weather information on SSB. For example, if you tune your radio to 6501 or 8764 at 0545 UTC, you can hear the latest Pacific forecast from the Honolulu station (where there are four daily broadcasts).
When the report begins, it’s up to you to get the information down. Develop a system for recording it quickly and easily. I record the voice broadcast on my laptop, so I can review it again after it’s completed. If you take dictation well, maybe you can make notes throughout the course of the broadcast and plot them on a weather chart. In any case, practice a few times to see what works best before setting out to sea. The appendix in the back of Capt. John Rain’s Mex WX is a great resource on the format of the information provided in the USCG broadcasts.
Here’s a little about how weather fax works in general. It’s a pretty simple technology: there is a pulse for each data block and a beep/signal to fill in the grey scale color parts of the grid (it’s not just black and white; just wait till you see your first satellite photo). The broadcast station publishes a schedule of each specific chart so you don’t have to grab every single one. I’ve found I’m only interested in the big picture analysis for now: 24, 48, and 96-hour forecasts, satellite photos, and wind/wave charts.
What’s the drawback to this on-the-cheapo system? The major downside I’ve encountered is grounding. To date I’ve not found a good method of grounding the radio to copper foil or a ground plate (if you do, please contact me). This means that you get a much lower quality signal while running the engine, using an inverter, or even when someone zips by in their dinghy with their 2.5 hp outboard.
The other drawback is that you’re dealing with communications on a receive-only basis. You won’t be able to email your mom to tell her you made it alive to the Galapagos or call up your friend anchored in Huahine on the Pacific Net. But hey, if you needed that much contact with everyone you should have stayed at home. Or dropped over $3000 on a full-blown SSB system.
Have fun. Your mileage may vary and stay in touch (though not till you’ve reached land again).
“How to Receive Weather Faxes on the Cheap”
You, the average poor sailor without an high frequency radio rig, can get weather faxes on your laptop just like the big boys. What you’ll need:
Before making the connection from the receiver to the computer, spend some time listening to the signal. Listening will get you in the ballpark of the correct frequency. Use headphones or you’ll cause a mutiny in short time onboard – it’s just a series of high-pitched tones and beeps. At first, you’ll wonder if you’re even listening to the right frequency. But with practice, you’ll learn to use the fine tuning to get the pitch just right and to get the RPMs ticking along as they should (120 RPMs per line). It gets easier once you know what to listen for.
One gotcha you’ll need to be aware of is that when you’re grabbing a weather fax you need to set your radio to 1.9 KHz below the frequency stated by the schedule. For example, if the schedule says to tune to 17150.9 KHz, look for a good signal with your radio set to 17149 KHz. Use the fine tuning dial on the radio to make adjustments.
When you think you’re close to the right signal, try to see what you’re getting. Plug the receiver into the computer (headphone jack of the receiver attached to the microphone jack of the computer). In theory, a PCMCIA card could reduce some of the noise in the system, but at the price of added complexity. If you have a PCMCIA card, bypass the microphone jack.
Turn the receiver on and launch your weather fax decoding software. The charts begin when the station broadcasts a “start” signal. If the receiver is tuned correctly, the download to your computer should kickoff automatically. If it’s not tuned correctly, you may have to manually start the download. A weather chart will slowly start to draw itself on the screen, line by line, from the top down. At the end of the chart broadcast a similar “stop” signal is sent. This lets the software create individual files for all the charts you’ve received. As with the start signal, if your radio isn’t tuned perfectly, you’ll need to manually stop the download.
At times, you’ll need to use manual mode for critical maps and to baby sit the download to be sure you’re getting what you need. There is probably a learning curve for every software system out there. I found that if I jump in after a fax chart broadcast has started, I need to make adjustments to the image. Those adjustments are called the skew of the image. Once I mastered the skew feature, I was able to line up everything and see the image well.
After you start receiving a fax it’s very useful to enlarge the image being downloaded to 100% so you can continue to fine tune reception to get the best image possible. If you’re seeing all black try moving the dial up to a slightly higher frequency with the fine tuning. Once dialed in you should be getting mostly white, except for satellite photos.
And that’s it! You can now see the hurricane right before it hits you at 100 knots.
|Copyright © 2004 Warren Johnson and Stephanie Parry - Design by Destruk|