Climbing the mast is a necessary part of operating a sailboat. Whether you are going up to inspect, or going up to repair something, at some point you will need to go up the mast.
The normal method to climb a mast is to have someone winch you up the mast. The problem with this method is that you rely on someone else to hoist you up and even worse you rely on their skill to safely bring you back down to the deck.
Having a gantline setup allows you to pull yourself up and more importantly it allows you to bring yourself back down to the deck. The gantline is simple to setup by attaching a block to a halyard and hoisting it up the mast (with the gantline run through the block, otherwise you just sent your halyard up the mast with no way to retrieve it). The other block is attached to your bosun chain and up you go!
Depending how strong you are and how much you weigh, you can alter the amount of mechanical advantage in the system. Remember, pulleys are a simple machine!
Pulling all of your weight up a mast is very hard work! If you setup a 2:1 purchase system, you only need to pull up 1/2 your weight. If you setup a 3:1 purchase system, you only need to pull up 1/3 of your weight. If you setup a 4:1 purchase system, you only need to pull up 1/4 of your weight.
This sounds great, but there is always a catch! The more you reduce the amount of weight you need to raise, the more you increase the amount of line you need to pull. For a 2:1, you pull 1/2 your weight but you also pull 2x the amount of line! For a 4:1, you pull 1/4 of your weight and 4x the amount of line!
If you are climbing a 50 foot mast, this is the difference between pulling half your weight 100 feet or a quarter of your weight 200 feet! At some point, you will just get tired from the repetition and not from the resistance.
I find that it is best with a 3:1 or 4:1 purchase system. If I’m feeling strong, I will do a 3:1 and get up the mast quickly. If my arms are really tired, I will use a 4:1 even though I will have to pull a lot more line!
It also helps to have an extra person (if they are available) around to pull on the tail and do the work for you so that you can rest on your way up that way you are calm and relaxed up there instead of winded and tired. Best of all, when it is time to come down, you can control your rate of decent.
