Updating the Navigator's Toolbox - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > Contributing Authors > Gear and Maintenance Articles
 Not a Member? 


Closed Thread
 
LinkBack Thread Tools
  #1  
Old 07-15-2001
Contributing Authors
 
Join Date: Jan 2000
Posts: 5
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Dan Neri is on a distinguished road
Updating the Navigator's Toolbox


The author aboard his Aerodyne 38, fitted out in cruising mode during a Caribbean sojourn.

Drew Wood won the navigator's award in this year's Bermuda 1-2 Race even though he sold his sextant before the race to pay for the required SOLAS flares. Drew said he figures his award came by default, based mostly on the fact that he forgot to pick up his planning chart from the race committee desk.

Four years ago celestial navigation skills were mandatory for this annual event, which challenges competitors with a 630-mile course from Newport, RI to Bermuda—single-handed on the way down, double-handed on the way back. Today, with $99 backup GPS units, onboard Internet access, and affordable, sophisticated routing software, the navigator's role has shifted from the basics of figuring out where you are to the strategy of positioning the boat for forecasted weather and ocean current conditions.

My Aerodyne 38, Calvin, is equipped with a Single Side Band radio and a Cotex demodulating adaptor and software that allows me to receive weatherfax transmissions on my laptop computer. With this setup I can get a series of weather maps twice a day, as long as I remember to tune the SSB to the correct frequency and boot up the computer at the appropriate time. Airtime on the SSB is free and there is a certain romantic appeal to the party-line aspect of the SSB chat frequencies for passagemakers and ocean racing groups, along with the simple pleasure of listening to the scratchy world news from the BBC in the middle of the ocean. But this is all World War I technology. Now there is a better way to gather and process weather information at sea.


A Globalstar phone coupled with Max Sea's routing software makes for a strong weapon in the navigator's arsenal. 

Before the start of the Bermuda 1-2, I installed a Globalstar satellite phone on board and loaded Max Sea's navigation and routing software in Calvin's laptop computer. With this combination of hardware and software, I was able to access the Internet at my convenience, download detailed wind-forecast files once a day, and check in with the National Weather Service (NWS) every six hours for ship reports and updated forecasts during periods of transitional weather. With the daily wind forecast files (called grib files) I could run a routine that would predict Calvin's performance over the next five days, in two-hour increments, and then suggest an optimum route to get me to Bermuda—and later—back home to Newport. Follow me here and you'll see how this works:

Globalstar Satellite Phone    The Globalstar phone is the most recent entry into the fledgling satellite communications field. My phone came with a "hands-free" kit that included a remote-powered antenna about the size of a bicycle water bottle and a power pack the size of a small lunch pail that I stashed on a bookshelf down below. For voice communication there was no installation requirement. I could turn on the power, dial the phone number and talk with the same clarity as you'd get on landline. On calls from the North Atlantic to anywhere in the US, there was no delay, echo, or breach in the service. (There are other satellite phone systems available, but none that I'm aware of that currently handle both voice and data transmissions.)


En route from Bermuda, the author used the Max Sea software to project his track based on performance data and weather information. The yellow and purple lines show projected positions on two-hour intervals.
The phone came with an installation disk that included a routine to install a dial-up adapter on the ship's computer. Using the Globalstar system, I didn't have to go through a third party Internet Service Provider, so once the dial-up adapter was successfully installed, the connection time was nearly immediate. The data transmission rate on this unit is 9,600 baud. Compared to a mini-M or SSB Sailmail system this is lightning fast. E-mail files without attachments download just as fast through the Globalstar connection as they do through a physical phone line. However, the baud rate becomes an issue when accessing the Internet because today's website designers assume that their users have access to cable connections or even faster avenues of connectivity.

On board Calvin, my typical morning download routine involved grabbing a grib file to use with the Max Sea software, as well as three or four maps from the NWS. The total airtime was typically 10 to 12 minutes. The same routine at home would take me about four minutes. At one point during the return leg, my co-skipper Phil Garland and I tried to access a color-coded thermal map of the Gulf Stream. The file was much too large for the 9,600 baud connection so we were repeatedly timed out just before we could see the part of the stream where we were. Otherwise, the connections were consistently trouble-free, even when Calvin was free falling off the backs of 10-foot waves.

"The connections were consistently trouble-free, even when free-falling off the backs of 10-foot waves."
Max Sea Software   
The Max Sea navigation and routing software looks similar to most other navigating software packages at first glance, and it makes use of most popular chartpacks including Mapmedia, C-Map, Softcharts and Maptech. The magic of the Max Sea software is found in its weather forecasting and routing algorithms.

Each day a self-extracting grib file is posted on the Internet at the navcenter.com website. These files are free, in the public domain, and therefore acceptable for use during a race. They are available for all regions of the planet. I used the Great Lakes file for wind forecasts along the New England coast, and then shifted to the North Atlantic file for the ocean region between the continental shelf and Bermuda. The grib file dumps detailed wind barb forecasts onto the digital chart for a five-day period. The forecast can be viewed for any time during the five-day period in two-hour increments. And if you really have nothing else to do, it is possible to zoom out for a view of the entire North Atlantic and watch a "movie" of the changing forecast over the same five-day period. I had a few other things to attend to on my way to Bermuda.


Two Class A boats vie for position at the start of the double-handed return leg from Bermuda. Using their novel approach to navigation, the author and his co-skipper finished second boat-for-boat, slightly behind the Nelson/Marek 40 C-Spray shown above with the dark hull.

The grib file supplies the software with the wind-forecast information it needs to determine the amount of fuel that will be available for your sail plan. For this to work, you need to provide the software with a second file that predicts your boat's performance or its polars over a range of conditions. For this, I got Calvin's designer, Rodger Martin, to send me an Excel spreadsheet for the boat and I imported that directly to Max Sea. From those base numbers I extrapolated some more conservative polars based on the fact that I was sailing single-handed, with no crew weight on the rail. After some experimentation I ended up using 92 percent efficiency when sailing to windward and 95 percent off the wind.

With the right polar files and the most recent wind forecast grib files loaded, the route plans calculated by Max Sea were remarkably accurate. In a 24 to 36-hour window, the forecasted wind shifts were typically accurate to within three to four hours and 15 to 20 degrees. This is better accuracy than most human strategists can claim. And more to the point, there is no hedging with the software. It calculates your route and then draws a big red line on the screen telling you where to go. It did not take long for me to realize the benefit of a concrete decision, even if it was coming from a machine. After slamming through the Gulf Stream for 20 hours and working on 10-minute catnaps, the addled brain of a single-handed novice is no match for the pure computing power of a well-written algorithm.

The next step for the Max Sea team and their competitors in the routing software field is to successfully merge the ocean current grib files with the wind forecast grib files. For most parts of the world, this function is fully operable, but it was not quite ready for the Gulf Stream currents, which are much more difficult to forecast in the North Atlantic.

Dan Neri was presented with the Rhode Island Governor's trophy and the Goat Island Yacht Club's Commodore's Cup for his performance in the Bermuda 1-2. He and Phil Garland finished second overall in the 2001 Bermuda 1-2 with a combined time of 217 hours and five minutes.

Going It Alone

Single-handed double-handed racing isn't for everyone, but it can serve to heighten your boat-handling as well as your navigation skills. The Bermuda 1-2, which has been held biennially since 1977, is just one of many such contests around the country. Sailors who live in the San Francisco Bay area can get additional information on short-handed sailing through the Singlehanded Sailing Society (www.sfbaysss.org). In Southern California, contact the Pacific Singlehanded Sailing Association (www.pssala.org). If you don't live on the West Coast, contact yacht clubs and harbor masters nearby to investigate if any organizations or events exist that specifically cater to solo sailors in your area.

To find out more about Globalstar Satellite Phones, have a look at this page in the SailNet Store: Globalstar Satellite Phones. For additional information about Max Sea software, log on to www.informatique-mer.fr/maxsea.


Suggested Reading:

A Few GPS Basics by Jim Sexton

Singlehanded Sailing by John Kretschmer

Newport to Bermuda, the Navigator's Race by Bill Biewenga


Buying Guide: High Frequency Radios

Quick reply to this message
Closed Thread

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



All times are GMT -4. The time now is 09:41 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.