Wednesday, June 8, 2011

Sextant Arc Maintenance

Clean old lubricant and grime from a sextant arc with GoJo hand cream. GoJo makes several types of cleaning solutions so it is important to use the one which is GRIT FREE and contains LANOLIN. Apply liberally then run the worm gear through the arc a few times. Wipe dry with a clean rag and follow up with a light oil applied a few drops at a time onto the worm gear as the micrometer drum is turned through the arc. Try Hoppe's #9 light oil for a gum free final touch.{2DCDC7EB-6048-4686-8021-95D684DA8ACF}&Cpn={BB2D686E-1BA0-408B-9D72-0E2C0CA21A7F}


  1. just a little aside question about sextants.
    Are they any use on their own, i.e. without a table or a something?

  2. Yes Popps... Determining if gaining or losing on a mark or another boat can be done by comparing whether an angle is increasing or decreasing. Measuring an angle relative to the bow when on a steady course is another way to use the sextant by itself. In this method doubling the angle on the bow between two observations has the distance run equal to the distance off. An even more obscure use would be measuring the angle up to the underside of a bridge from a known distance away to be sure the mast will clear when passing beneath. Latitude by Polaris can be made when observed with the big dipper (Ursa Major) in the 2 o'clock or 8 o'clock position. Risk of collision with another vessel can be determined if there is no change in angle relative to the bow over time when on a steady course. Just naming a few examples for you.