How to Create your own Polars
The importance of investing the time to create Polars that are fine-tuned to your own vessel cannot be underestimated. The gains made in understanding your vessel and the rewards reaped from more accurate weather routing are well worth any initial setup effort. The best news is that you probably have all the tools you will need already onboard.
If you want to have an accurate and up-to-date set of Polars for your boat, then there is nothing better than creating your own
In this Polars series we will guide you through the process of collecting and processing your own data to create meaningful polars for your own boat. We show how to set up and calibrate your hardware, what software you need and how to collect the data you will need to create your own polars. Once you have a complete data matrix we will then show you how to go about cleaning up the data and converting it into the correct format to use with PredictWind or other weather routing software.
This is a practical course where you can follow along and set up your own system on your boat ready to record and development polars immediately.
To ensure you are ready to start this course you will need the following equipment:
Hardware
- Wind Instrument
- Boat Log (speedo)
- NMEA output from your instruments via wifi or usb
- Computer or Laptop
Software
- Open CPN
- Excel or LibreOffice Calc
So if you are ready to get started, let’s begin.
What are Polars
Before we get into the details of creating your own, let’s have a look at what we mean by the term Boat Polars.
Boat polars describe your boat speed and wind angle in any given weather situation. There are plenty of websites describing how to read a polar diagram. Essentially it is a graph that shows a boat’s potential speed over a range of wind speeds and relative wind angles. It normally consists of the right side of a line chart with the radius representing the yacht speed and the angle representing the wind direction blowing from top to bottom. Several lines are normally drawn on the chart representing wind speed. To identify how fast a yacht could potentially go you select a particular wind speed curve and particular wind angle. Polar diagrams are normally specific to a particular sailboat design and are created by the yacht designer. If you do not have access to the polars created by the yacht designer (or even if you have) it is worth creating your own set of polars as they will be more accurate for an accurate weather route.
Calibration
Before you start to collect any data you need to make sure that your instruments are calibrated correctly. This means that you must make sure that what your wind instruments are reading is an accurate representation of what the boat is actually feeling.
We have a very basic way to visually check to see if the instruments on Paikea are reading correctly.