ATN Mastclimber

After several days of research I finally pulled the trigger on the ATN Mastclimber. It’s a solo bosun’s chair that draws upon conventional sailing and mountain climbing toolkits, to solve a common problem with going aloft on a sailboat.

I know, you’re probably thinking the main problem with going aloft is gravity. Unfortunately nothing except hiring a rigger or shipyard travel lift or crane operator to solve your mast-top foibles will diminish the gravity problem. Sorry.

ATN Mastclimber Solo Bosun’s Chair

Let’s take a look at the ATN Mastclimber description.

ATN AscenderThe only bosun’s chair that allows solo, unassisted ascents of the mast, the Mastclimber fits over any taut 3/8″ to 5/8″ rope halyard. Constructed from 1 1/2″ ballistic nylon webbing with a fiberglass-reinforced seat, Mastclimber combines a bosun’s chair and leg straps with a pair of one-way anodized aluminum/stainless jammers, located at the chair seat and the intersection of the leg straps. Climb the mast quickly and safely using only leg muscles. With no need for static lines, the easy-to-use climber is operated by alternatively standing up on the leg straps, which allows you to slide up the one-way jammer of the bosun’s chair. To descend the mast, the procedure is reversed. Recommended by Practical Sailor in June 2010. Maximum waist size 50″.

That golden gadget, the ATN Ascender is the “secret sauce” borrowed from big wall sport climbers. But these ascenders have been manufactured with anodized aluminum and stainless Steel so that they won’t rust or degrade in the damp marine environment. Here’s another detail shot.

ATN Ascender

The system uses two parts, each with its own ascender: One supports the durable fiber-reinforced plastic seat; the other supports a pair of webbed stirrups for the feet. Under load, the ascenders grip the line just like a rope clutch. To go up, you put your weight on one ascender while sliding the other one up a few feet, alternating as you climb. The stand-sit process of climbing is less strenuous than it looks, though it requires a fair degree of fitness, flexibility, and coordination. (Practical Sailor)

Ease or Exercise?

In researching this solo alternative to a traditional bosun’s chair which requires at least one additional person to crank the body-filled gadget up the mast, I repeatedly read grumbles about the difficulty in using the equipment. (I will address a couple of other concerns below.) It’s clear from videos and reviews that a fair amount of exertion is necessary to effectively climb a halyard to the top of the mast, even with a snazzy ATN Mastclimber.

But I spent a couple of years in my twenties rock/wall climbing, and I’m hoping that it’ll be a little bit like riding a bike. And a little exercise seems like a fair swap for being able to service the mast and rigging without an assistant.

Here’s  another video that makes the whole process look pretty painless. It’s worth noting that the fellow in the video is Etienne Giroire who founded ATN. The video description anticipates consumers questions about the difficulty of ascending and descending with the ATN Mastclimbler.

The ATN Mastclimber is for a sailor to ascend the mast safely and with minimal effort…

I’ll address this question difficulty in a follow-up post once I have firsthand experience.

Mast Damage Concerns

In addition to concerns with the physical demands of using the ATN Mastclimbler, I read multiple reviews about damage it the mast caused by the ascenders. Basically sharp metal edges pinned tightly between halyard and mast by body weight result in scrapes and gouges in the paint and/or aluminum. To date I’ve been unable to find anyone who has devised an effective workaround.

The new device can scratch mast paint or anodizing, and—unlike the original—can’t be easily “de-clawed” with a leather chafe guard. (Practical Sailor)

In the video above Etienne Giroire secures the climbing halyard to the starboard gunnel which would likely alleviates the mast scratching concern. Others have secured the line to the base of the mast. Perhaps this is the solution?

Construction Quality Concerns

Although some reviewers have praised the robust design and construction of the ATN Mastclimer, I’ve also read a couple of troubling reviews from users who experienced extremely poor manufacturing. The following photograph and review appeared in the Ericson Yachts forum.

ATN Mastclimber failure by Rob Thomas
ATN Mastclimber failure by Rob Thomas

Purchased ATN’s new version of the “top climber” called the Mastclimber. Worked reasonably well once you get the hang of it. The downside is the clutches scratch the heck out of the mast when you get near the top. There is no way I can see to keep them from rubbing on the mast as you ascend/descend.

Now the scary part. As I started to descend, during some of the gymnastics that are required to operate the system, I heard a pretty disconcerting “pop, pop, pop”!!! In the pic attached you will see my hand, I’m holding the back support section of the bosun’s chair part. The stitching just let go! Now I wasn’t in any danger once I realized what was happening, I was very careful not to lean back the rest of the way down.

The really creepy part is that I can see NO difference in the stitching anywhere else on the rig. This bloody thing could have let go at any of the far more critical sections and I would not be typing this post. So the next step is emailing ATN and returning it. Too bad, its not a bad idea and the seat is very comfy. I just don’t trust it and won’t ever use on again.

Lifes too short to be killed by something dumb like this.

Rob Thomas from Wakefield, Rhode Island (

Sobering. Disturbing. And hopefully an isolated example of sloppy manufacturing and not what I will experience when my ATN Mastclimber arrives next week.

As with the other potential concerns addressed above, I will offer a personal review once I’ve gone aloft. Successfully. I hope…

[Read my “ATN Mastclimber Review“.]

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