♦♦♦ Catamaran Owner Training ♦♦♦
♦♦♦ Catamaran Delivery Services ♦♦♦
♦♦♦ Catamaran Owner Assisted Passages ♦♦♦
♦♦♦ Owner Assisted Catamaran Commissioning ♦♦♦

Celestial Navigation Made Easy 😀

This is a simple step by step guide to fixing your position at sea using the Sun, a Time Piece, a Sextant, Excel Spread Sheet, Arc of Time Table, Graph Paper and a Chart and basic Chart Plotting Instruments.

Buying and Using a Sextant

Step 1 Purchase a Sextant, you can purchase a Davies 15 plastic sextant by clicking on this link.
Step 2 Adjust the Sextant for Errors as shown in the second video Adjusting a Davies 25 & 15 Sextant for Errors.
Step 3 Use the Sextant to take a sun sight as shown in the third video “Taking a Sun Sight with a Davies 15 Sextant”.

Purchasing a Sextant Metal v Plastic

Video exerts courtesy of James Cook from his YouTube video Calibrating and Using a Sextant

Click the Image to Purchase the Sextant Online
Global Shipping Available – Price as at January 2023

Reading Your Sextant Sight

Converting Your Sextant Sight to a Position Line

Download the Sunsight.xls calculator and insert your sun sight details as explained below to obtain your Position Line at the exact Coordinated Universal Time you took your Sun Sextant Sight.

Supplied with compliments of BACKBEARING

Dead Reckoning Reminder

Click image for a free lesson on Dead Reckoning

Converting Local Time to Coordinated Universal Time

Plotting a Position Line

Schematic of Plotting a Position Line

Due to scale, it can be quite difficult to plot your workings on your Ocean Chart. For this we generally use a Mercator Graph Paper plotting sheet, you can’t use standard Graph Paper. Pre printing and using Mercator plotting sheets to the nearest 5 degrees of Latitude is adequate.

Download a free shareware Mercator graph paper printing program at GPaper.exe. 

• Step 1 – Mark up your A4 Mercator graph paper with appropriate Latitude and Longitude scale
• Step 2 – Plot your Assumed Position (AP) on the Graph Paper
• Step 3 – Draw your Azimuth (Zn) line through your AP
• Step 4 –  Measure your Intercept either away from or toward the sun from your AP on your Zn line
• Step 5 – Draw you Position Line 90 degrees to your Zn line through you Intercept
• Step 6 – Plot your Dead Reckoning (DR) Position
• Step 7 – Project your DR position to the closest point on your Position Line (a line 90 degrees to PL from DR)
• Step 8 – That projected DR position now becomes your more accurate Estimated Position based on your Sun Sight

To obtain a Celestial fix we need to take a second sun sight a number of hours later. Then transfer our position as a running fix using our distance run and direction. Where our two position lines cross is our updated 2 celestial line position fix. Traditionally known as a Sun Run Sun fix.

I’m heading to Les Sables France to do an owner assisted commissioning of a brand new Lagoon 46 with some training and an assisted passage to Rubicon Marina Lanzarote Canary Islands over the next few weeks. Upon my return I will update the website with a Sun Run Sun example. In the mean time why not buy a sextant and start practicing your Sun Sights.

Contact Tony via WhatsApp on +44 7448 384 007 to discuss your training needs.