How To: Sailboat Mast Climbing Guide

How To: Sailboat Mast Climbing Guide | Life of Sailing

Last Updated by

Beth York

June 15, 2022

Climbing your sailboat mast can be an easy and enjoyable activity. With the right equipment and information you will successfully be able to access all exterior parts of your mast. In this guide, I will teach you how to climb your mast with confidence. As with so many activities on a boat, safety must be your top priority when climbing your mast.

Regardless of your crew situation, the equipment necessary to safely climb your mast is basically the same: two halyards, a bosun's chair, and some form of harness. You can be hoisted by crew or ascend using an ascension device. The particular equipment you choose is up to your preference and budget.

Sailors die every year from improper climbing techniques. By doing your due diligence, you will be ready to safely climb your mast. Ascending your mast is not the time for cursory preparation, so you must double up on all safety equipment. Redundancy is key. Don't put yourself in a position where a single failure of equipment could mean your death.

I have been up my sailboat mast half a dozen times and have never felt unsafe or afraid while aloft. By always following thorough safety precautions and having solid communication with my crew, I actually enjoy going up the mast. It gives me perspective of my vessel and the surrounding area that is normally out of view. I hope this guide helps you enjoy your first time climbing your sailboat mast, as well.

I am not an expert on climbing sailboat masts. I do not know the condition or quality of your equipment. It is your responsibility to ensure your safety and the safety of your crew. This is solely a guide to help you feel better informed on this topic.


Table of contents

The Crewed Climber

The most basic way to climb a mast is to have a crew member crank you up using a winch. This method requires you to have a crew member on board with the brawn and willingness to do that job. If you are lucky enough to have a beefy, willing crew member then this section is for you.

Primary Safety Equipment (w/Crew)

  • Bosun's Chair
  • Main Halyard

Your primary safety equipment will consist of a bosun's chair (or equivalent) connected to a halyard. Ideally the halyard will be one that does not have a free-standing block at the top of the mast. Your main halyard will likely be your best option for your primary line.

Feed your primary line through your bosun's chairs double d-rings and secure using a bowline knot. Tying your halyard to your bosun's chair will eliminate possible failure at the halyard shackle.

Once you have tied your primary line to your bosun's chair using a bowline knot, clip the halyard shackle to the d-rings as a redundant safety measure.

Prior to using your bosun's chair, be sure to read the instruction manual for your particular model so that you are properly secured within the chair.

Secondary Safety Equipment (w/Crew)

  • Harness
  • Secondary line

On my sailboat, my husband and I have climbing harnesses that we use as backup to our bosun's chair. A foul weather harness will work for this application as well.

Put on the harness prior to getting into the bosun's chair. Just as with the primary line, use a bowline knot to secure the second halyard to your harness. On my sailboat, I use the spinnaker halyard as my secondary line. You may have a line better suited for the job such as a removable topping lift.

Which Winch?

Now that you have your primary and secondary gear set up, it's time to deal with the working end of your primary and secondary lines.

Due to the variation in block, winch, and cleat locations from boat to boat, it is difficult to give exact directions for how to set up your lines. On board my vessel we use the main halyard as our primary line. The main halyard runs out of our lower mast, through several blocks and back to our cockpit. We run the primary line back to our starboard jib sheet winch because it is self-tailing and has two speeds. Our secondary line runs back to the port jib sheet winch.

In this method it is necessary for both winches to be self-tailing.

Whichever line you choose to use as your primary line, you will need to find as unobstructed a path as possible for that line to join with your winch. Use blocks as needed to create a chafe-free path for your primary.

Every time I have climbed our mast, my husband has been below at the winch. Even though we use a winch that is self tailing, whenever possible we have a friend tailing the primary line. This additional safety precaution prevents line slippage and a possible accident.

The Hoisting Begins

You now have your harness on with your secondary line attached and you are in the bosun's chair with the primary line attached. It's time to test the system's strength. First, have your winch handler take out any slack in the primary line while you stand with knees bent at the mast base. Have your mate cleat off the primary line. Then, test the strength of it all by bouncing a few times in the bosun's chair.

It might seem silly bouncing around in the bosun's chair just above the deck, but it sure makes me feel better knowing that I have already put more stress on the system than I will at any other point during my climb.

Feeling confident that all systems are go, your crew member will begin cranking on the winch from the cockpit. Being raised up the mast can take a while. Be sure to wear shoes and gloves so that if you decide to assist in your ascension, you don't end up with paint slivers in your hands and feet.

Your crew member will crank you up a few feet at a time or perhaps a few inches at a time, depending on their vigor. Every time they pause on the primary winch, they will pull in slack on the secondary. They must secure the primary line prior to attending to the secondary. This will ensure that if your primary fails you will only drop a short distance onto your secondary line.

Once you have reached your working point on your mast, your crew member below will cleat off both lines. Your winch handler will surely feel like it's nap time but their job isn't over yet. While you're working, be sure your crew member stays attentive in case you realize you don't have the necessary tools for the job or you are ready to descend.

I have been at the top of my mast only to realize that I need a flat head instead of a Phillips, or electrical tape, or a multimeter. It's beyond frustrating to be at the top of the mast and realize that you forgot something or don't have what you need.

To save the arms of your cranking crewmember, bring a long piece of string in the pocket of your bosons chair. If you realize you need an additional tool, you can lower the string to your crew member and they will tie on the forgotten item for you to pull up. If you happen to be particularly forgetful, it would be clever to employ a canvas bag to receive the tools.

I have found that it's difficult to see the top of my mast while sitting in the bosun's chair even when it's fully raised. I remedy this by bringing a looped piece of webbing (a sling) which I connect with a carabiner to the top of my mast. I then step into the piece of webbing which raises me high enough to see the top of the mast .

The Fun Part

One of the most enjoyable parts of climbing the mast is coming back down. The work is done and now you get to enjoy a smooth, steady descent to deck level.

It's essential that your crew member below wear gloves for this part of the job. I recommend gloves for the entire job but certainly for this bit.

From the cockpit, your crew member will uncleat the secondary line and remove that line from it's winch. Your crew member will then take the line out of the self-tailing mechanism on the primary winch while maintaining a firm grip on the line. They will slowly let out the primary line while keeping three wraps on the winch. Continue slowly releasing line until all crew are deck side.

To aid in exiting the bosun's chair I recommend descending until you are sitting on deck. The extra slack will help you remove yourself from the bosun's chair as gracefully as possible.

The Crewless Climber

Knowing how to climb your mast independently is invaluable, even if you never sail solo. Lifting an adult using a winch can be difficult, time consuming, and tiring. By having the right equipment you can climb your mast with very little to no assistance.

Primary Safety Equipment (Solo)

There are many types of products on the market to help you climb the mast. There are ladders which utilize your mainsail mast track, webbing loops raised to the mast top using the main halyard, and permanently installed mast steps. Alternatively, there are devices which attach directly to the main halyard which allows you to climb the halyard. I'm going to refer to any device that is used to climb the halyard as an "ascension device".

Regardless of the ascension device you choose, these items are essential:

  • Bosun's Chair
  • Main Halyard
  • Ascension Device
  • 3 Climbing Carabiners
  • 2 Foot Slings
  • 1 Sling

Secondary Safety Equipment (Solo)

  • Harness
  • Secondary Line
  • Ascension Device
  • 1 Climbing Carabiner
  • 1 Sling

Sailboats are not all rigged the same. You may find that your spinnaker halyard is your only option for the secondary line. On some vessels, the topping lift will be the best option. You will need to determine which line works best for you.

Using The Ascension Device

The ladder style ascension devices are fairly self-explanatory. If you know how to climb a ladder, you're all set. So, I will not go into their use here. In this section, I will explain how to use a rock climbing ascension device to climb your mast.

This is an example of a rock climbing ascension device:

In order to climb your main halyard using this device, the halyard needs to be as tight as possible. First, attach the shackle of your halyard to the base of your mast. Then, pull the line taut with the other end of the halyard and cleat it off.

If you have a winch on your mast, I recommend you use it to tighten down your main halyard. Any slack in your primary line can cause you to swing away from the mast as you're climbing. Attach your secondary line snugly to the base of the mast.

Be sure to read the directions of your particular ascension device as these directions pertain only to the Petzl Ascension.

You will need two ascension devices to climb the halyard. One will hold your weight while the other is being slid up the line. The devices will take turns holding weight and moving up the line. I recommend purchasing one right handed and one left handed device.

Attach the device to your halyard like this:

Attach a climbing carabiner to the bottom of the ascension device. Clip a foot sling and a loop sling into the carabiner. Repeat for the second primary ascension device. You can make a foot sling yourself using webbing and a good sewing machine, but there are also plenty of quality slings on the market such as this Petzl Adjustable FootSling.

To your secondary line attach a third ascension device. This can be the climbing ascension device or a friction knot. Attach the third sling to the ascension device/knot.

If you have crew available to attend to your secondary line, then by all means utilize them. It will give you one less job to do as you climb the mast. Simply attach the secondary line to your harness instead of the mast base and have a crew member winch in your slack as you climb. No ascension device needed on the secondary line.

How To Tie A Friction Knot

An alternative to the climbing ascension device is the Klemheist Knot.

The Klemheist knot is a friction knot that can be used in place of the mechanical ascension device. It slides up the line easily without weight on it and locks onto the line once weight is applied. For the purposes of this article, the Klemheist Knot will be considered an accession device.

With your halyards, ascension devices and slings set up, it's time to first put on your harness, and then your bosun's chair. It's up to you whether you use a climbing harness or a foul weather harness. They are a redundancy and will hopefully never take your weight for long.

The two slings mentioned earlier are used to attach your bosun's chair to one of your primary belay devices and your harness to the secondary line device/knot. Simply clip one end of the sling into the climbing carabiner on the device and the other end of the sling to the climbing carabiners on your bosun's chair and harness.

Up You Go!

So, you are wearing your harness and you've put on your bosun's chair. You're wondering 'Do I really want to do this? Do I really need an anchor/steaming/deck light?' I can't answer that for you, but I do know that you can do this.

You will first slide both ascension devices up the line to about chest height. Then, step into the foot sling of the lower device. Once your weight is on the lower device, slide the upper device up the line and place your foot into its sling.

With your weight on the upper device, slide the lower device up the line to just under the upper device. Put your weight back onto the lower device and slide the upper device up the line. Continue transferring weight and sliding devices as you work your way up the mast.

The tricky part is managing your secondary safety line. Hopefully your Klemheist knot will simply slide along the line as you climb. You may find that you need to guide it along occasionally.

Once you've reached your destination, it's a good idea to secure yourself to the mast while you're working. Most mast heads have some form of anchor that you can clip into. If you're at the spreaders you can wrap a sling around the mast and clip both ends into your bosun's chair or harness.

Descending With Devices

After you've completed your work and gotten a good look at the view, it's time to come down. Every ascension device works a little differently so be sure to read the directions of your specific device.

Descending is a lot like ascending. You will transfer your weight from one device to the other as you maneuver down the line.

Start with the lower device. Release the toothed cam and slide the device down the line a foot or two. Re-engage the cam and transfer your weight to the lower foot sling. Repeat this with the upper device, sliding it down the line until it is just above the lower device.

Continue transferring your weight and sliding the devices down the line until you are at deck level.

You may need to slide your Klemheist knot down your secondary line as you descend.

Clear the deck

It's very important to be sure that no crew stands directly below the person working up the mast. Anything that may fall becomes a lethal hazard to those below. It's also absolutely necessary to make sure that there is always a crew member watching the person on the mast. Just be sure to keep your distance from the base of the mast.

You Got This

I definitely recommend that no matter which method you use to climb your mast (crewed, solo, winched, or climbing), practice just above deck level prior to heading up. You want to feel comfortable and confident as you climb the mast. So, work out any kinks before they become disastrous.

There are countless videos portraying the use of ascension devices as well as mast climbing. Use whatever resources necessary to ensure that you have a productive, successful, and safe mast climb.

How To: Sailboat Mast Climbing Guide
Beth York

Beth York

Beth lives on board her 1983 30ft S2 sailboat with her husband, 6 year-old son, and her two fur babies. She has been sailing and boating for most of her life. Beth has been blessed to experience cruising in the Great Lakes, the Bahamas, and in Alaska. She loves to travel and adores living on her tiny boat with her family.

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