Exploring SPINNACER 1.1

SPINNACER (SOL Polar Inspector, Nautical Navigator And Calculator to Enhance Racing) is a java program that should help its users understand the polars (as used by sailonline.org) better, and performing (more accurate) calculations, e.g. for setting DCs. The “NN” part in SPINNACER is still in development, polar inspector and calculator are available :)

Changes since first version

Changes since v1.1-beta

  • Version number

Changes since v1.1-rc

  • Notifications-section to inform users about new updates or other news
  • Zooming (in basic and pro view) can (in addition to scolling) be done with right click+drag
  • Pro Polar View had a slider to change True Wind Speed. This can still be done with the usual shift+scroll and alt+scroll too.
  • In Pro Polar View, users can left click (short) to fix the cursor at the current possition.
  • When Super Pro Polar View has finished calculating, Pro Polar View will show unfavourable angles (polar hop).
  • The polar bear image is included in the download, so that the application does not need to download the image every time it is started.

Changes since v1.0-beta

Not listed

Getting SPINNACER to work

If you are running java 6 or java 7 (which you probably are), download the latest version of SPINNACER. It’s available in .zip format and .tar.gz format, if you’re not sure which to choose, go for the .zip

Then go to the directory where you saved the download, right click on the file and choose “extract” or “unzip” (or something similar). You should now have a folder called “spinnacer”, in which is are two folders “polars” and “spinnacer” and a file “SPINNACER.jar”. You may move the file and folders to another place on your computer, but keep the three together.

Now you should try to run the .jar file. On some operating system this can be done by simply clicking the file, or double clickig. But what will always work is using the terminal/command prompt. For example, if your file is at this location: “D:\name\sol\SPINNACER.jar”, use the command “java -jar D:\name\sol\SPINNACER.jar”. Now it should run. If not, check your java version with the command “java -version”, if it’s not version 1.6 or higher, consider updating java. I made a java 1.5 compatible version of SPINNACER, but it freezes temporarily while larger calculations are performed. These downloads are also available in .zip format and .tar.gz format.


SPINNACER’s main purposes are accurate polar calculations, and finding&recognising “polar hop” locations in the polar. The calculator can help you set DCs.

Opening Files

When the program first starts it looks like this:

There is a guide-tab for a quick reminder of some of the controls, and the “open file”-tab consists of the sections. The right section contains messages about new versions of spinnacer, or other news. The left section explains what files can be opened. These are the files that brainaid supplies on his site as “detailed data as csv”. Some polars are included in the download, these are in the folder called polars. When you click the “Open polar file” button below the text, an “open file”-dialog should pop up, showing the contents of the “polars”-folder. You are free to store your polars somewhere else though.

Select a polar, and click “open”. Now you should see something like this (within a couple of seconds):

There are 5 tabs:

  • Basic Polar View
  • Pro Polar View
  • Super Pro Polar View
  • Polar Calculator
  • Polar Bear

Each of which is explained below. At the very top, there are two tabs “open file” and one with the name of the file you just opened. If you go back to the “open file”-tab you can check the guide again, and open a second polar file (which will show in a third, top level tab)

Basic Polar View

This view displays the polar. Lines are drawn at 1 kts intervals of TWS. You can scroll to zoom, getting a closer look at the polar, and you can left click and drag to move the polar around a bit. A gray line and circel should intersect at the location of your mouse, In the lower right corner of your screen you can read TWA and boatspeed (SOG) at mouse location. If you cannot scroll, you can use left click+drag to zoom.

Pro Polar View

This is the same as basic view, but only one line is drawn: only for the current TWS. You can <shift>+scroll to change the TWS with 1 kts, and <alt>+scroll to change the TWS with 0.1 kts. You can read the current TWS in the lower left corner. You can also use the slider on the bottom of the screen to change TWS. When the slider is selected (click on it once), you can use the arrow keys to change TWS with 0.01 kts. The orange lines represent best VMC speed and angle to mouse location. Right click to toggle the visibility of the VMC lines. Left click (short) to fix the cursor and VMC lines at the current location. Click again to let them follow the mouse.

When Super Pro Polar View has finished calculating, Pro Polar View will show light red areas on slow angles. It’s almost always faster the sail a while left of the light red area, and then a while right of it, than sailing a straight line. (See 76trombones’ blog about VMG sailing and polar hops)

NOTE: These red locations are not very precise, use the VMC line to find the exact edges.

Super Pro Polar View

When you open this tab for the first time, it only show you grey text. Left click somewhere near the text, and the program start calculating. This should not take much more than a minute. When the calculation is done, a black image with gray-ish chrome colours is shown. The lower left corner of the image displays information for TWS=0 and TWA=0. going to the right TWA increases up to 180 degrees on the far right. Going up, TWS increases up to about 75 kts. The black spots area slow angles (which are displayed red in Pro Polar View). This visualises where the polar hop locations are, and how the best VMG angles change when TWS increases (or decreases). On places where the colour is bright, the polar a “pointy”, on the darkes (almost black) places, the polar is “flat”.

Polar Calculator

Abbreviations used:
TWD – True Wind Direction (compass direction)
BRG – Bearing (course to next waypoint, used for VMC calculation)
COG – Course Over Ground
TWA – True Wind Angle (compared to the boat heading)
TWS – True Wind Speed (wind speed)
SOG – Speed Over Ground (boat speed)
VMC – Velocity Made to Course
VMG – Velocity Made Good
DST – Distance
DMC – Distance Made to Course (not official)
DMG – Distance Made Good
Time – Current time
Delay – Time span
ETA – Expected Time of Arrival
You can fill the white text field with the input of your calculation. The textfields that have a itallic font are the resulst of a calculation, but if it has a white back ground, you can overwrite the value, and the calculator will change another value to keep all numbers coherent. One can check the checkboxes to auto fill some of the values.

Let’s say you have TWA and TWS and want to know your SOG:
Fill in TWA and TWS (uncheck the best VMC/VMG checkboxes), and your SOG will appear in the SOG box.
Let’s say you want to now the best VMG downwind with a given TWS:
Fill in TWS and check “Best VMG downwind”, now you TWA, SOG and VMG will be filled in automatically. When you want to know how far you have sailed in 30m, fill in “30m” in the big Delay box (or 0.5 in the small one), and the calculator calculates your ETA, DST, DMG and DMC.
I hope you now understand how the calculater works, once you do, you’ll find out that there’s a little too much possible calculations to describe all of them.

Polar Bear

This is a bear, without a bear you can’t bear away. Click the button below to bear away. Once the bear is away, you will be given the ability to “head up” (same button). This will show the head of the bear again. This bear is very important in steering a boat.

Room For Improvement

I would like to hear your opinion. What do you and don’t you like about SPINNACER? What improvements would you suggest? Did you find any bugs? Do/did you use spreadsheets for this kind of calculations, then are there any things you can do in your spreadsheet that you can’t do in SPINNACER?

Comment below, or contact me via forum, chat or mail: 

One thought on “Exploring SPINNACER 1.1”

  1. Hi Kroppyer

    Great Work! The first really usable Polar-Inspector i’ve come across, which were not many, though.

    I would very much appreciate to know the Cursor Position in Terms of TWS and TWA, especially in the SuperPro Polar View, maybe in the upper right corner.

    And i’ve found a severe Bug: I’m missing the Polar Bear under Linux although the images are there. :)

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