Gear Review – ATN Mastclimber

I finally had the opportunity to try out the ATN Mastclimber we purchased earlier this year. While I can’t exactly say I was flying through the air with the greatest of ease, this daring (not so) young man on his flying trapeze (or set of ascenders, actually) had no trouble attaining the highest of heights.


As advertised on the ATN site, you simple clip the ascenders onto a taught halyard, and start climbing. In this case, I clipped the spinnaker halyard to a block at the base of the mast, and then tensioned it with a winch. Once at the desired height, it’s easy to just settle down into your bosun’s seat and get to work.


The video on the ATN website shows someone working without a net (i.e. no safety line), and I suppose that would probably be OK since it’s a redundant system using two ascenders. Unless your running rigging is total crap, it’s very unlikely that your halyard would pick that exact moment to exit the scene. But because I’m Navy trained, I usually take a belt-and-suspenders approach to safety. So I clipped the boom vang to the chair as a safety line, took it to a winch, and had my brother tend it while I went aloft. It was just one less thing to worry about while I was up there.

I’d received a tip from a reader about using gloves to avoid finger pinches, so I donned some sailing gloves before starting to climb. I did learn that next time, I’ll want to put some knee socks on. I felt more stable with the loop stirrups under the arches of my feet rather than the balls, but this caused the nylon loops to chafe and cut into my lower shins, which were pretty raw by the time I descended.


While it might have been a fashion faux pas, I think a pair of tube socks would have helped immensely.

I always felt this device was a bit pricy for what you got, but I discovered that they make it in two flavors, one with and one without a bosun’s seat. Since I already had a really nice seat, I went with the “bring your own seat” version, which was significantly less expensive, and then bought it from Defender on sale. At about $225 total, I figured it would pay for itself after just one or two uses.


It’s a solidly built tool that lets you confidently climb the mast in reasonable comfort, and we highly recommend it as essential maintenance gear on any cruising boat out there. We give it the LOTH™ Seal of Approval.


3 thoughts on “Gear Review – ATN Mastclimber

  1. Stephen Pretti

    Thanks for the review. So you used the shackle on your halyard to connect to a turning block at the base of the mast? I’m not sure I get that, A picture of how you secured the halyard might help me.

  2. John Makar

    I don’t undestand your statement “probably be OK since it’s a redundant system using two ascenders”. I had the opportunity to climb my 50 ft mast after purchasing the ATN Mastclimber from Defender this year. I ascended up the mast to retrieve a lazy jack line at 40 Ft and then started to descend when the pin holding the lower (leg straps) ascender popped out. Luckily I was able to reinsert it and continue my descent. If the upper ascender would have detached from the line due to the pin popping out, the result would have been fatal. The lesson learned is that the ascender is not fool proof and can detach from the line and a climber MUST have a safety line manned by another person.

    1. Robert Post author

      I had to go back and re-read that post, because I wrote it four years ago. What I was trying to say is that I believe that since you’re usually supported by two ascenders, the failure of one probably wouldn’t cause you to fall. It looks like you proved my point, as you had an ascender “fail,” and you didn’t fall. But I did also say in my post that a safety line is always a good idea. I do still believe that climbing a belayed halyard with dual ascenders is probably safer that just clipping the halyard to your bosun’s chair and being hauled up the mast.


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