The
  Expedition Is More Than Just A Routing Program
 

A Trip Around Expedition

Expedition Navigation software has gained wide acceptance in recent years as being the best navigation and routing software available. Certainly in California the majority of the boats doing any offshore racing use it. However I find that many of them use it for little more than charting a course and downloading weather to run course optimizations. While this a major part of the program there are lots of other performance enhancing features than can be readily accessed and easily used. And the top boats are using these even in short course and buoy racing to up their finish positions.

Expedition has the power to provide all the performance and tactical data you want. Couple that with the Ventus Navigator App and you have the data you want to see wherever you are on the boat. Start out with the basic must have data for sailing the boat efficiently upwind and down; target boat speed and target wind angles. Use polar boat speed for trimming on reaching legs, and have a page set up with your opposite track information along with bearing to the mark, and how much time there is to the layline so you can pick your gybe and tack points with accuracy. Have another page set up with all your next leg information, range and bearing to the next mark, apparent wind angle, and wind speed for the leg, so you know exactly what sail combination you will want to use. The possibilities are endless, Expedition has almost 200 channels of data and the Ventus Navigator can display any you choose to see on your iPhone, iPad, or iPod Touch, right to the individual crewman that needs that information. To quote Simon Fisher of Diverse Yachts “I am a big fan of putting good navigation info into a package that is smaller than a tablet – not only is it easier for the navigator to carry around but also makes specific data accessible to other members of the crew without having to rely on additional deck screens and fixed displays.”                                                                        

                 

Expedition also has the best starting information and data available. Just ping the ends of the start line,  start the timer, and you can get all there is to know about starting; time, distance, and time to burn to either end of the line or the closest point on the line you can sail to along with many other options. It allows you to put in factors for your boat’s rate of turn and acceleration in different winds speeds to provide accuracy second to none. And all of these are available on your Navigator!

Besides being a great program for doing your navigation Expedition also has powerful capabilities for logging performance and giving you access to some of the best instrument calibration available, especially if you have a lower or middle level of instruments without a full race processor integrated into the system. To get data out of your instruments first you have to have them well calibrated and Expedition makes this fairly easy to do. There are only 4 or 5 things that your instrument system actually measure; apparent wind angle, apparent wind speed, boat speed, heading, and possible heel. Your GPS will add a sixth input – course or COG. Everything else is calculated based on those inputs. So if any one of those is not accurate the resulting data you want will be at best unreliable, and at worse will cause you to make bad decisions and sail your boat inefficiently.

The power of Expedition is that it uses full calibration tables that allow you to put in the necessary corrections for all different winds speeds and different wind angles. Calibration should start with boat speed and the most accurate way to calibrate that is by running a measure course length in both directions 3 or 4 times and averaging your results. You do this with the trip log, not by trying to run it at a set speed and recording the time. Each instrument system will have different features for doing this so follow your manual. 

The end goal in calibration is to get accurate results for all the calculated true wind functions. We run a log file and strip charts every time we race. With this data it is easy to see your averages at any point in the race. Going upwind watch your True Wind Angle (Twa) and True Wind Direction (Twd) on both tacks and see if they change from tack to tack. If they do open the Expedition Twa calibration table and enter the correction for that wind speed. If the Twa is bigger on port tack take half of the difference and enter that as a positive number. If the Twa is smaller on Port tack take half the number and enter it as a negative number in the table. Do the same thing gybing back and forth downwind. Below is a sample example of what a True Wind Angle Calibration table looks like. The first column of data is your Target Upwind True wind angle for different wind speeds, the next is at 90 degrees, the third is at your Target Downwind True wind angle, and the last is for dead down wind. If you see places that your instruments have some real anomalies you can add columns at the needed wind angles, Expedition will interpolate between them for any angle and any wind speed. In general it is better to not have more columns than needed.

Calibration: True Wind Angle
0           0           0           55.9      0           90         0           139.9    0           180       0
5           0           0           46.6      1.5        90         0           138.4    -2          180       -3
10         0           0           38.2      1           90         0           150       -1.50     180       -1.5
15         0           0           35.9      2           90         0           140.6    -1.5       180       -2
20         0           0           35.7      2           90         0           140       -1.5       180       -2
25         0           0           36.8      2.5        90         0           150       -2          180       -2.5
30         0           0           37.6      2           90         0           150       -1          180       -1.5

Another place you generally see inaccuracies is the difference between True Wind Speed upwind and downwind. Because of the difference in the airflow around your rig while sailing at different wind angles the wind speed is affected as well as the wind angle. In general without proper corrections instrument systems will read higher wind speeds downwind than they do upwind. Again Expedition makes it very easy to apply the necessary calibration factors. A sample calibration is below.

Calibration True Wind Speed
0           0           0           55.9      0           90         0           139.9    0           180       0
5           0           0           46.6      0           90         -0.15     138.4    -.25       180       -.45
10         0           0           38.2      0           90         -0.2       150       -.45       180       -.70
15         0           0           35.9      0           90         -0.3       140.6    -0.75     180       -1
20         0           0           35.7      0           90         -0.65     140       -1.1       180       -1.25
25         0           0           36.8      0           90         -0.60     150       -1.35     180       -1.60
30         0           0           37.6      0           90         -0.60     150       -1.55     180       -1.80

So with just a little bit of effort running Expedition can really improve your sailing, there is nothing that beats knowing your performance data and what the performance targets should be. The Ventus Navigator takes it to the next step, that of getting the specific data on deck in the hands of the people that need it, when they need it. And it is by far the most economical way to do it. No re-wiring, no expensive displays to buy. On smaller boats even around the buoys we have it running and have an iPhone or iPod for the driver and for the trimmer. Check out our web site for some great options for waterproof cases, some with even a built in extended battery and a solar charger! On longer races we add in an iPad for the navigator and possibly another hand held or two for other crew members. That way they know how far and how much time to the next mark and can start setting up for a rounding when they know they are within the distance they need. With the Next Leg info they will already know what sail changes they should be ready to make. It is a huge benefit to have everyone supplied with data that fits their job; the whole boat runs smoother, quieter, and happier. And a happy boat is a fast boat!

www.ventusnavigation.com
support@ventusnavigation.com

  <Home>