Moire Light and Highest Astronomical Tide
What is a Moire Light and how to work out Highest Astronomical Tide (HAT) for secondary ports
Please do not teach how to work out HAT for secondary ports. This information is for use by the instructor only, if you get asked.
All of the calculations have been done for you for the RYA training charts and are published in the Training Almanac on page 12. HAT is given for primary ports in update information for Reeds Almanac available on the Reeds website.
Some instructors are unsure of what a Moire light looks like. The animated slides in the link below should help. Click on the slides for animation. There is also reference to the light in 5011 under directional lights.
Download the slides