Boshile 10x50 Marine Binoculars Compass & Rangefinder

Compass, Reticle and Big 50 mm Glass

You are running an unfamiliar inlet at last light. The plotter has you roughly where you think you are, but you cannot pick which of the markers ahead is yours, and you cannot tell whether that headland is 500 m off or two kilometres. Guess wrong there and it stops being a navigation problem and starts being a hull problem.

That is what a marine binocular is for, and it is why this one carries two things a normal pair does not. There is a compass card you read through the eyepiece, lit by a push button so it still works on a black night run. And there is a scale etched into the view, with matching distance, object-size and angle rings printed around the objective barrel. Line the scale up on something whose height you already know - a marker, a mast, a lighthouse, a headland you have on the chart - and you can work out how far off it is. Line the compass up on the same thing and you have a bearing to put beside it.

Now the honest part. It is not a laser rangefinder. There is no readout and nothing measures anything for you - you read the scale, you use the height you already know, and you do the sum. It is not night vision either; the only thing that lights up is the compass card, not the view. And Boshile print "Waterproof/Floating" on the body, but they publish no IP code, no ATM figure and no immersion depth, so we are not going to call it waterproof. What you are actually buying is a big, heavy, rubber-armoured porro-prism binocular with 50 mm objectives and a navigation scale built into it.

What It Does

• Picks the right marker: three cans in a line all look the same from the helm. Ten times magnification and 50 mm of glass sorts out which one carries the number you want, before you commit the boat to the gap.
• Gives you a bearing on the spot: the compass card sits in the view, so you take the bearing while you are still looking at the thing. No putting the binoculars down and picking up a hand compass with the boat moving under you.
• Turns a known height into a distance: if you already know how tall the mast, marker or lighthouse is, the etched scale and the printed distance ring let you work out how far off it sits. Useful for judging a run-in, a drift, or whether that boat is closing on you.
• Glasses a ridgeline from the ute: off the blacktop it is the same job with different scenery - reading a distant spur, a track junction or a dam wall before you drive an hour to it.
• Checks a fence line or a water point: on a station run you can stand on the tray and look at the far corner of the paddock instead of driving to it, and the bearing tells you which corner you were actually looking at.

Key Features

• 10x50 porro prism: ten times magnification through 50 mm objectives. The classic marine format - bulky, but it gathers light and it holds its alignment.
• 132 m at 1000 m: the field of view, printed on the body by Boshile. That is how wide the picture is at a kilometre, not how far you can see.
• BAK4 on the hinge cap: the centre cap is marked BAK4. That is the maker's marking, read off the product - no glass certificate was sighted.
• Compass in the eyepiece: the bearing card reads through the eyepiece against the vertical line, and a push button lights it red for night work.
• Mil ranging reticle: etched vertical and horizontal scales in the view, with distance, object-size and angle rings printed around the objective barrel.
• Individual eyepiece focus: each side focuses on its own diopter ring, marked from -5 to +5, so you can dial out the difference between your eyes and then leave it alone.
• Fold-down eyecups: folded down for glasses, folded up without. Rubber, so they take a knock against the wheelhouse.
• Memory IPD scale: the centre hinge is numbered, so once you find your eye spacing you can set it back to the same mark next time.
• Rubber armour and grip panels: moulded non-slip panels on both barrels for wet hands, and a rubber skin over the body.
• Tripod connector fitted: there is a tripod socket behind the centre hinge cap. At ten times magnification you will want it. Thread size is not specified by the supplier.

Limits

This is where we tell you what it will not do, because on a boat the wrong assumption costs more than the binoculars.

• Ten times magnification shakes: hand-held, on a moving deck, 10x is right at the limit of what most people can hold steady. Expect to brace against a rail, a post or the cabin, or put it on the tripod socket. If you want something you can hold one-handed in chop, a lower magnification suits you better.
• It is not a laser rangefinder: nothing measures distance for you and there is no readout. The scale only works if you already know the height of what you are looking at. Guess the height wrong and the distance comes out wrong by the same proportion.
• A field of view is not a range: 132 m at 1000 m describes how wide the picture is at a kilometre. Binoculars do not have a viewing range or a detection range, and anybody quoting one for a pair is quoting the wrong number.
• The printed scale is not a claim: the distance ring is marked out to about 3000. That is the range of the scale, not a promise about what you will be able to identify at that distance.
• It is not night vision: there is no image intensifier and no infrared. The push button lights the compass card, not the view. Big objectives help at dawn and dusk, and that is all they do.
• No water rating is published: Boshile print "Waterproof/Floating" on the body and state the barrels are nitrogen filled and sealed against fogging. There is no IP code, no ATM figure and no immersion depth anywhere on the product or the packaging, and we have sighted no test certificate. Treat it as built for spray, rain and a dunking - not for swimming with, not for snorkelling with, and never for diving.
• Floating is a printed claim, not a tested one: the body and the retail box both say "Floating", and a wide padded neck strap is supplied. The supplier describes that strap only as a comfort strap, not as a flotation strap. We have not put either in the water. Clip it to something before you lean over the rail rather than relying on it bobbing back up.
• It is big and it is heavy: porro prisms buy you light and depth at the cost of bulk. This does not go in a jacket pocket - it lives in the supplied shoulder bag. The supplier does not publish a weight or overall dimensions, so we cannot give you a figure.
• The compass light needs cells: illumination runs off two button cells under a screw-off cover. Flat cells means no lit compass on a night run, and the supplier does not state the cell type or whether cells come in the box.
• It does not replace a plotter: this is a cross-check and a set of eyes, not a navigation system. Keep your GPS, your chart and your paper backup.

Q & A

Do all three colours have the compass and the rangefinder scale?
Yes. The three options are black, green and camouflage, and every one of them is listed as the compass version. The only difference is the finish on the body.

Is the rangefinder a laser?
No. It is an etched reticle plus printed scale rings - the same idea as a mil-dot scale in a rifle scope. You read how many divisions the object covers, you use its known height, and the distance ring gives you the answer. No batteries, no electronics, and nothing happens automatically.

Will they really float if I drop them over the side?
Boshile print "Floating" on the body and on the box, and there is a wide padded neck strap in the box. We have not tested either and there is no buoyancy rating published, so we are not going to promise it. Use the strap.

Can I use them with glasses on?
The eyecups fold down for spectacle wearers, which is the right design for it. The supplier does not publish an eye relief figure, so we cannot tell you whether you will see the full field of view with your glasses on.

How bright are they in low light?
The exit pupil works out at 5 mm - that is simple arithmetic, 50 mm of objective divided by 10x, not a supplier figure. A 5 mm exit pupil is a good match for most eyes at dawn and dusk. The lens coating grade is not specified by the supplier, and coating is the other half of that answer, so we cannot give you the full picture.

Can I mount them on a tripod?
There is a tripod connector behind the centre hinge cap. The thread size is not specified by the supplier, so check it against your adapter before you order one.

What comes in the box?
The binoculars, a nylon shoulder bag with a padded strap, a wide padded neck strap, a rainguard cover for the eyepieces, two tethered objective covers, a lens cloth and an instruction sheet.

How long will they take to get here?
Allow 10 to 14 days from the day you order, and up to three weeks to be safe. Regional and remote addresses take longer again. Delivery is free to Australia and New Zealand.

Specs

Technical Specifications

Watch It Work