Which Sextant Is Best For A Beginner?

If you have recently started learning celestial navigation, you are probably now considering buying your first sextant.

An online search will quickly tell you that they range in price from under $50 through to $1000+. To decide which sextant to buy, there are a lot of choices to make: new vs old; plastic vs metal; or a half or full mirrored horizon mirror.

If you just want my recommendation though, the best sextant for a beginner is the Davis Mk15. It is an affordable plastic sextant, yet it can still produce highly accurate readings. Unlike cheaper options, the Mk15 retains similar features to its expensive counterparts, giving you an ideal foundation in using a proper sextant.

In coming up with my recommendation, I considered all the different features that were important to me when I started out learning celestial navigation.

Pro Tip: The Mk15 is not a perfect sextant, so you should read my full review if you are considering buying one yourself: Davis Mk15 Sextant Review

What to look for when selecting a sextant as a beginner

If you ask a professional navigator which sextant is the best, I am sure they will tell you that you need a $1,500 top of the range model to be able to get accurate sights.

What they won’t tell you, however, is that as a beginner, an expensive model will not actually help you to learn any quicker. In fact, my own experience has shown me that a top range model can actually slow down your progress.

Instead, you should assess each of the characteristics of a sextant and decide for yourself which one would be best.

Note: I am only focusing on the best sextant for a beginner in this article. For a more general guide to buying a sextant, check out: Choosing The Perfect Sextant: Which One Is Best?

Should you buy a used or a new sextant as a beginner?

When it comes to cost, comparisons are always made between a new plastic sextant and a used top of the range metal sextant.

You can pick up some great deals on eBay, often getting a used metal sextant from a shipbreakers yard for a similar price to the Davis Mk15 plastic sextant that I recommend.

The reason I do not recommend a used sextant for a beginner is that you will have no way of knowing about the quality of the sextant you buy. It could have missing parts or screws, or have received damage during its lifetime.

In time, as you become more familiar with sextants, you will be able to consider a used model because you will be able to spot issues, and potentially fix any problems with it yourself.

As your first sextant, I always recommend a beginner purchase from a reputable source, which usually ends up being a new model from a well-known brand.

Is a plastic or metal sextant better for a beginner?

There are advantages and disadvantages to both plastic and metal sextants.

Metal sextants have a reputation for accuracy and reliability, while plastic sextants have a reputation for affordability.

In terms of accuracy and reliability, as a beginner, both metal and plastic sextants will be enough to suit your needs.

Your priority should be getting an instrument that lets you practise corrections and sight taking.

When I learned to use a sextant, I used a metal one that belonged to the merchant ship I was sailing on. It was a very accurate model that held its corrections incredibly well. As such, I got lazy and didn’t perform full corrections every time because there was never any error to remove.

Had I trained with a plastic sextant, errors would have crept in more frequently, forcing me to practise corrections more often.

A properly corrected plastic sextant will be able to achieve similar accuracy to a metal sextant. The main disadvantage of a plastic sextant is that the corrections need to be applied more frequently. As a beginner, however, you may see that as an advantage.

What type of horizon mirror is best for a sextant?

The horizon mirror of a sextant can either be a full semi-silvered mirror, or a split mirror.

Comparison between a semisilvered mirror and a split mirror on a sextant
The left circle illustrates a full semi-silvered mirror, and the right circle illustrates a split mirror.

A full semi-silvered mirror is easier to use for bright objects because they will be reflected across the entire mirror surface. It makes it easier to bring them down to line up with the horizon.

A split mirror is easier to use for dim objects because the mirror is more reflective, allowing more light to reach your eyes. It makes it easier to see faint stars and bring them down to the horizon.

As a beginner, you will learn the optimal time to take your sights. Read more in this article: What Is The Best Time To Use A Sextant? 

You will learn that in order to take star sights you still need a horizon to be visible, so you still need a little light in the sky. The more light you have, the dimmer the stars will appear.

Consequently, the best type of mirror to use as a beginner is the split mirror because it gives you the widest possible window for taking your sights and practising.

Fortunately, split mirrors are cheaper to manufacture than full semi-silvered mirrors, so the Davis Mk15 is already ideally set up for a beginner.

How much should you spend on a sextant as a beginner?

With your first sextant, you should spend whatever you are comfortable spending. You should not feel any pressure to push for a more expensive model in the hope that it will make you better at taking sights.

In fact, I always recommend a beginner to spend as little as possible on their first sextant, as long as you still get the features you need.

The reason for this is that you will be adjusting it frequently, and probably over-adjusting it. You may even be intentionally applying errors so that you can practise removing them.

Your first sextant should be the most affordable instrument you can find because it will give you more freedom to practise and make mistakes.

Once you become more skilled in using your sextant, you can consider upgrading only if you feel you would benefit from a more expensive instrument. This might be the case if you are planning on sailing in extreme temperature environments.

Otherwise, don’t feel pressure to overstretch your budget. You can get excellent results with an inexpensive sextant like the Davis Mk15.

What scopes do you need on a sextant?

On a sextant, the scope is the part you look through when taking sights. It could be a simple viewfinder, or it could be a high magnification telescope.

When considering the best sextant for a beginner, I recommend you don’t worry too much about the scope. A viewfinder will work perfectly fine if that is all you have.

Telescopes are great on a sextant if you are trying to take sights of feint stars that need magnification. Generally the stars you take as a beginner will be brighter ones, or even the sun or planets. You should not have any issues finding them in the sky.

A telescope may make things a little easier, but I don’t recommend it being a factor in the sextant you choose to buy.

Telescope and viewfinder on the Davis Mk15 Sextant
The Davis Mk15 comes with an interchangeable viewfinder and 3X optical zoom telescope.

Other beginner sextants

There are a few different sextants on the market that are also ideal for beginners.

Astra IIIB Deluxe Sextant

For around $800, you can get a beginner-friendly aluminium sextant. This is the lowest cost metal sextant that I have found and is around half the price of other models. If you are determined that you want to learn with a metal sextant, the Astra IIIB could suit you perfectly.

Davis Mk25 Sextant

A more expensive version of the Mk15, the Mk25 is meant to be more sturdy, comes with a full semi-silvered mirror and an LED. As a beginner, you might consider the Mk25 if you want a full semi-silvered mirror.

Davis Mk3 Sextant

As a true budget option, the Mk3 will cost you around the same price as a meal in a restaurant. It could be an ideal option for someone wanting to learn the principles of celestial navigation, without the need for any accuracy in a position fix. Anyone serious about learning celestial navigation should avoid the Mk3 in order to learn how a real sextant works instead.