Mast Climbing

Unassisted Mast Climbing with GriGri

Updated 4/5/2024 by Allen Edwards



In THIS article, I compare a number of methods of climbing a sailboat mast unassisted. One method was the GriGri method named after the main device used in the method. I did not recommend the method for a variety of reasons. I still do not recommend it but I use it. The reason I do not recommend it is that it is complicated and the occasional sailor who needs to climb a mast once a year is better served by the recommended system. Given that, why do I use it? First, there were a number of serious issues with the initial system and these have been solved so they no longer disqualify it outright. Second, I am very familiar with the system and the GriGri system takes much less effort to climb and virtually no effort to get down. While I consider myself fit and strong, I am not as young as I used to be and I appreciate the ease of going up and down with this system.

The reason I am writing this article is that there may be others who are intent on using a GriGri system and even though I do not personally recommend it and I want to share the significant improvements I have made for people who want to take the time to learn it.


Climbing a mast is dangerous and I am not responsible for your safety, you are. Whatever system you use, practice at low heights until you are comfortable with it. I use a 100% redundant system so no single failure will kill me. Some object to that but I definitely recommend it. Stuff can break and the backup might save your life. Finally, this article is for entertainment only, don't use it, blah, blah, blah...


This system is based on a RAD system. Petzl promotes them based on either an ID or RIG which are similar to a GriGri but much more expensive and much larger. I prefer the GriGri because of the expense and the fact it is less likely to bang into the mast because it is smaller. The RAD system does not allow the climber to get high enough to get above the masthead so that was the first problem to be solved. The ID does have a lock, which is necessary to safely get above the top of the mast so if using a GriGri, you need to have a way to lock it. The other issue with the GriGri is that descents are frightening requiring finesse in working the release lever. That produces a very jerky ride which tends to be frightening and might lead to panic and a fall. Some devices have a panic mode that also causes it to lock. Better to eliminate the source of the panic. These are all problems that are addressed in the "Tricks" explanations below. They were also problems that made me initially reject the GriGri system until I figured out the solutions.

Why I used this method and why I no longer do

It is very easy to go up.

It is effortless going down.

And you can get above the masthead.

I no longer use it because it is just too complicated and still too scary. I use the Ultimate Unassisted Mast Climbing instead.

The Gear

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gearThe system is shown on the left. Here are the components. The main component is the GriGri. It is a belay device and not strictly speaking an ascending or descending device. It will work in those modes but much better with the modifications described below. The main problem with the GriGri as a descender is well documented on the web and that is a jerky descend. I solved that by threading the tail of the rope through the carabiner. It is explained below. A GriGri is also very fussy about what kind of rope you use. The sizes that work are limited and climbing line is a must. I use 10.5mm static rope. It is rated for 8.9 to 11 mm rope.

The ascender holds the pulley and the foot loops. It is also a place to pull up. In this system you lift with both feet and both hands making it very east to get up. The pulley redirects the line so you can pull down on the line coming up our of the GriGri. I actually use a small Camp. There are several just be sure you get a small one. Some are quite large.

I really like the Petzl Attache carabiner old style. It has a round cross section and I use them for jib twings. They are not available. The new version should work fine. Finally, you need to make some foot straps using climbing tubular webbing. Be sure it is climbing webbing, UIAA certified.

You also need a small loop of climbing line for the safety knot.

Bosun Chair and Harness

I use a chair I had left over from my Top Climber with some added reinforcements because I didn't trust it. I use a Petzl Tour Harness as the backup but any would do. I like the tour becasue it is light and fits under my bosun's chair webbing. The Harken Bosun chair looks nice but looks pretty bulky. Harken Ballistic Nylon Deluxe Bosun Chair, $156 at Defender. Some people just use a climbing harness and maybe there are climbing harnesses that would work without a chair. I tried going up with just my climbing harness and got about 6 inches and thought my legs were going to cramp up and came back down. No comparison in comfort. A quality bosun chair like the Harken one might be sufficient so that you would not need the harness, just attach both halyards to the chair. That is a decision for you to make. Personally I am sticking with 100% redundancy so if you decide to just use one, don't come complaining to me if you die. I ended up buying the Crewlift Crewlift 40 Bosuns but have not used it. I should as it looks much nicer than my modified Top Climber chair but it is larger and would take up more room on the boat.

The Tricks that make it work

Getting above the Masthead

top To get above the masthead, you need to get the GriGri and your chair close to the masthead. You don't want the ascender above it. The trick is to leave a long tail in the knot that you use to attache the climbing rope to your shackle. By the way, do not tie your climbing line in the shackle itself. Tie it in the ring where your halyard goes. If you can't do that, use a bend to tie the climbing line to the halyard itself. I leave about 6 feet so just to be clear, after you have your knot, you have one piece longer than your mast and another piece 6 feet long. Put a stopper knot in the 6 foot piece so you don't accidentally let the ascender leave you. Your foot loops also need to be shortened to get over the masthead. Sew a loop or make a knot down a couple of feet from your main attachment. I recommend you use knots to make your foot straps. If you have a Sailrite zigzag, you can make 5 bar tacks by going back and forth on the webbing.

Make for a smooth descent


descentWhen I first bought the GriGir and used it in my attic, it scared the hell out of me. To go down, you pull on the release handle. Pull too hard and you drop like a stone. Don't pull enough and nothing happens. The difference between those two states is small which made the descent difficult to control. What I did was thread the line through the carabiner. That greatly adds to the friction both over the rounded edge of the GriGri as well as through the carabiner. The net result is that you can completely release the GriGri handle and just let the line pass slowly through your hand. The really sweet thing is that you can hold the knot on the backup line with the same hand (shown on right) so you just go down in one continuous controlled motion all the way to the deck.

Locking the GriGri at the top

The other surprise if you don't use this trick is that when you do go above the top of the mast you are unloading the GriGri. The deal is that the GriGri only locks when it is loaded so when you sit back down, you fall for a bit before your load locks it. That is very surprising and unsettling to say the least. The solution to that was simple enough and found courtesy of another YouTube video. It wasn't exactly what was needed, but it gave the inspiration to come up with something that worked. The knot is formed around the GriGri with a simple loop. Look at this short video to see how to tie it. The second half of this video is just the knot. Stop it if you want to study how it is made.

Description of how to use it

Start with tying the climbing rope to the halyard but not to the working part of the shackle. Pull through about six extra feet of line and then tie a knot. I use a bowline. Then put a stopper at the end of the extra section and take it to the top of the mast and cleat it off. The second safety line can be a regular halyard. Take you small loop and tie a prusik knot or klemheist around the second halyard. the small line can be made into a loop using a fisherman's knot.

I use both a bosun chair and a climbing harness. The reason is that the bosun chair is comfortable but I don't trust it. I trust the climbing harness but it is uncomfortable. As I sometimes spent several hours aloft at a time painting my old wood mast, I wanted the comfort of the chair. I may switch to just the harness now that I have an aluminum mast. In any event, clip the GriGri to the chair and the safety line to the harness. If just using one, clip both to it.

The ascender goes above the GriGri and has the foot strap attached to the bottom hole. Note the position of the carabiners. It is important that they be exactly the way they are shown so that the re rigging at the top goes smoothly. Put the small pulley on the line and put the carabiner throuh it and attach it to the top hole in the ascender. Using the bottom hole and one carabiner has several disadvantages. It limits the amount you can go up per stroke because you run into the pulley. It also fails to lock the ascender to the line. Finally, it makes it more difficult to do the re rigging when you need to shorten the foot loops.

Now you can put your feet in the foot loops and go up. It is helpful to have a little extra weighg on the end of the safety line so I tend to coil up the extra length and let it hang. The going up action is to stand, then take the slack out of the line, then sit and push the ascender up. Pull the safety knot up and repeat.

At the top, you need to remove the ascender and place it on the 6 foot section. Shorter the foot loops by lowering the ascender, opening the carabiner, and putting the secondary loop through the carabiner. Now you can stand and use an upward pull to move the GriGri up as high ss possible. Remove and secure the pulley on your harness. You do not need to remove the line from the pulley. Then follow the instrudtions to tie off the GriGri so it will not slip when you go above the masthead.

To get down, you remove the ascender and clip it to your climbing belt loops. Undo the loop knot and hold the backup knot and the tail of the climbing line in your left hand and open the GriGri with your left hand. You can control your descent with how tight you hold the line.

video of entire up and down trip.

NOTE: If you tire of watching me climb, you can skip to the top by clicking HERE. Then use the browser back arrow to return to the article.

Closing Comments

I hope you found this entertaining. If you should decide to try this and have any questions, please post on the forum and I will respond. If I have made any errors in this article, please let me know.

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