Binoculars have a wide range of uses, such as admiring wildlife on the land, spotting birds in the air or watching whales in the water. They can be used during the day for hunting and during the night for astronomy. Regardless of how you use them, binoculars can be an essential accessory for anyone who enjoys the outdoors - even if you’re on a boat. But what should you look for when choosing marine binoculars? And which are the best marine binoculars in 2023?

Marine vs Regular Binoculars - What’s the Difference?

If you’re thinking about buying binoculars for your yacht or boat, you may be thinking that regular binoculars will be just fine - and while that’s not untrue, marine binoculars are designed to be used at sea and, consequently, they tend to have a few features that regular binoculars don’t.

These features make the binoculars a better choice for both navigation and general marine use.

For example:

• Individual focusing
• Compass
• Rangefinder
• Armoring

Individual Focusing

With regular binoculars, you use the center focus ring to adjust the view for your left eye, and then use the diopter on the right eyepiece to make adjustments for your right eye. However, many marine binoculars will have individual focusing for each eyepiece.

This can be handy, as you won’t need to adjust the focus of the binoculars every time you use them. This, in turn, can save you a lot of time and bother if you’re using the binoculars for navigation. 

Compass

Many marine binoculars will have a built-in compass that can help you get your bearings while at sea. Depending on the binoculars, your heading could be projected onto the view or it might be visible on a digital display.

Rangefinder

Another useful feature that’s commonly found on marine binoculars is the rangefinder. This is often a reticle that can be used to calculate distances, but some binoculars will feature a laser that can calculate the distance automatically.

Unfortunately, whether you choose binoculars with a reticle or a laser rangefinder, you might find the result to be inaccurate.

More specifically, with a reticle rangefinder, you’ll need to know the height of your target and then make the necessary calculations to find the distance yourself. This, of course, can lead to errors.

Laser rangefinders might be more convenient, but can be inaccurate over water. They also tend to cost more and, of course, they require batteries. 

Armoring

While many binoculars - both regular and marine - feature armoring, it’s particularly important on marine binoculars. After all, you’re at sea and the conditions can be rough. The last thing you want is for your binoculars to be damaged because you dropped them onto the deck, or they were knocked against the structure of the boat.

With that in mind, many manufacturers will produce marine binoculars that are specifically designed to survive a higher than average number of knocks, drops and bumps.

How to Choose the Best Marine Binoculars

When it comes to choosing the best marine binoculars, there are a number of factors you should keep in mind:

• Magnification & Aperture
• Exit Pupil
• The Environment

Magnification & Aperture

As most people know, there are always two numbers associated with binoculars. The first indicates the magnification, while the second indicates the aperture of the objective lenses. The objective lenses are the large lenses you point toward your target, and the aperture is always measured in millimeters.

For example, 10x50 binoculars have a magnification of 10x and an aperture of 50mm. The magnification is fairly self-explanatory, as it indicates how much larger an object will appear through the binoculars. 

While having a larger magnification might seem like a good idea, it’s worth remembering that your binoculars will also magnify any shaking that might occur, either from arm fatigue or the movement of the boat. The larger the magnification, the greater the shaking. 

In terms of the aperture, the larger the aperture, the more light the binoculars can gather. This is important during the night, twilight or general low-light conditions, as it will allow you to see greater detail under those circumstances. However, there’s a tradeoff: the larger the aperture, the heavier the binoculars.

With this in mind, 7x50 binoculars can provide a good combination of magnification and aperture. Magnifications of 6x and 8x are also an option, but 10x could prove to be problematic as the movement of the boat could cause the view through the binoculars to shake too much. Similarly, a slightly lower aperture of 40mm could still be useful in low light conditions, but anything more than 50mm could be a little heavy and cause arm fatigue. 

Exit Pupil

This is a term you might not be familiar with. The exit pupil is essentially the diameter of the image formed by the binoculars as it exits the eyepieces, and like the aperture, it’s measured in millimeters. The larger the exit pupil, the more of the image you’ll see and the brighter it will appear. Again, like aperture, this can be important under low light conditions.

The exit pupil is calculated by dividing the aperture of the binoculars (again, in millimeters) by the magnification. This is another reason why 7x50 binoculars are a good choice, as they have a large magnification to aperture ratio and, consequently, a large exit pupil. 

For example:

7x50 Binoculars: 50mm (aperture) / 7 (magnification) = 7.1mm exit pupil

8x42 Binoculars: 42mm (aperture) / 8 (magnification) = 5.3mm exit pupil

10x50 Binoculars: 50mm (aperture) / 10 (magnification) = 5mm exit pupil

Incidentally, there are some 6x50 binoculars on the market, which would give you an exit pupil of 8.3mm, but they’re not very common and therefore not widely available.

The Environment

When it comes to marine binoculars, having waterproof and fog-proof binoculars is a must. You could even argue that binoculars lacking these two features don’t belong on a boat! More than this, it’s often a good idea to also look for floating neckstraps, as this will make it easier to retrieve your binoculars if they should drop into the water.

As mentioned previously, be sure to also consider models that feature a compass and rangefinder, as this can make navigation easier, and shockproof armoring to protect your investment against knocks and drops.

Lastly, it goes without saying that a boat is rarely steady and stable and that your view through the binoculars can be shaky as a result. With that in mind, it can be worth also considering image stabilized binoculars. The downside, as you might expect, is that they cost more, and the name brands tend to be very expensive.

Frequently Asked Questions