Sextant Recomendation Needed

Hello All:

I need to do a few on board assessments for a Cel Nav course. Nobody here has a sextant. What brand/model sextant would you recomend so I can complete these assessments and either:

  1. Toss it in the trash when finished.
  2. Keep it for future nav use.


18 months back other mariners recommended to me the Celestaire Astra IIIB (Whole Horizon). I was able to pick one up 2nd hand at a very good price. It does everything I need.
Someone makes a plastic one that MPT in Ft Lauderdale uses to rent to students.

Bob, I have one you could rent from me…I accept cash and beer…:wink:

Just kidding, I do have one you can use, with the " you break it, you buy it " understanding…It’s the plastic one made by Davis…Let me know how to get it to you…

Davis 25 is the plastic of choice. I’ve had one for years. If you want new metal go with the Astra IIIB. Or… I have a couple of good used Sextants which I bought on Ebay from the ship breakers in India. My best one cost just $200 plus $25 for shipping. If you buy used you are taking a chance on condition/repairability/all parts and accessories.

Bob - The least expense sextant is what some call a “lifeboat” sextant, which is plastic, and does not have a micrometer drum. Rather, you have to determine what the minutes are by where the correct hash mark lines up on the degree scale - a bit of a pain. A plastic sextant with a micrometer is easier to use.

The problem with plastic sextants is that the plastic expands when it comes out into the sun, and is not as accurate. But for training puposes it would be fine.

Here’s a good link to learn more about sextants:

If you have the time to shop around, there are all sorts of sources out there. I ended up purchasing a very good used sextant in like new condition from a pawn shop.

I have used the Davis mk25 for years and it has been just fine. I consistently take shots that are within a 2-3nm accuracy (compared against gps). It is light, travels well, and if you break it or lose it you are only out $200.00. My vessel has a good metal one but given the choice most people onboard use the plastic one. It is lighter and easier to sight when learning how.

I agree: go plastic. On the other hand I have a nice Octant from the 1700’s that belonged to my great great great grandfather, Captain Luke Buddington, like me he was also originally from New London, Connecticut; at any rate the Octant hangs on the wall (used once for sights, still accurate w/in a couple miles of GPS) but its hard to envision my future progeny hanging that plastic sextant on their wall in the 2300’s…

Water, that’s a vernier scale. My first sextant was a Heath with vernier. To speed things up at nautical twilight, we had work sheets (memeographed) with a blank vernier scale heading. After each shot, just mark the work sheet scale and interpolate at your leisure.