Unstepping mast yourself (SO37)
Oct 13, 2020 14:20:00 GMT
Post by johannes on Oct 13, 2020 14:20:00 GMT
I dropped the mast today in preparation for winter, with the help from three friends. This is a write-up on how we do it. There are many variations on this, but this works well for us with our Sun Odyssey 37 and the circumstances in our marina.
It is best to be at least three people: one to operate the winch, one to hold the mast, and one to hold the forestay/furler. It helps to have a fourth person to assist wherever needed. You always forget some little detail.
First, strip the rig of sails, canvas, and tie up all halyards and running rigging securely to the mast. Un-thread the control line for the furler and tie it to the furler drum. Remove boom: if you have a solid vang, attach the topping lift or a halyard to take the load off it. Disconnect all electrical cables and secure them to the foot of the mast. I use blue masking tape. These preparations can be done well in advance of the actual unstepping.
Picture 1: sails, boom removed, halyards tied up. Backstay tensioner disconnected.
Picture 2: Cables disconnected.
With a single spreader mast, setting up the sling is easy. With a double spreader mast, it is more tricky since you want the lifting point above the lower spreaders. On some boats you can use the spinnaker pole lift, but only if it is above the mid-point of the mast. Om the SO37 it is not, so it is not usable. I use long piece of webbing to set up the sling. I throw the webbing over the lower spreader on one side from stern going forward, and then back going aft on the other side. Use something heavy but soft to attach to the end of the line to help throwing. I make a big noose with the webbing so that I can attach the winch hook from the crane later.
On the front side of the mast, attach a line to the webbing with a loose bowline. This serves two purposes: it allows you to control the webbing sling as you raise the winch hook, so it does not snag on anything such as the engine light. It also serves as a means to pull down the winch hook in case something goes wrong and you have to start over.
Picture 3: Webbing sling ready. In queue for the mast crane. The boat being unstepped has single spreaders, much easier!
Disconnect the backstay and loosen the shrouds. Disconnect the lower and mid shrouds. This can be done while waiting the for mast crane to be free: the mast will be supported by the cap shrouds and the forestay (assuming you have a rig with swept spreaders. If not, keep the lower aft shrouds attached).
Protect the threaded terminals on the shrouds once they are disconnected. This can be done with fancy little cloth bags that you tie on to the terminals, or just use plastic bags and duct tape. When you later handle mast on land, you don't want the terminals to drag on the ground unprotected.
Position the boat under the crane with the lifting point about 10 cm aft of the mast. Attach the winch hook to the webbing sling so that the noose will close as you tighten it. Raise the hook so the noose closes, to a position above the mid-point. On our boat about one metre below the upper spreaders is good. It is not super critical: the higher you go, the more stable the mast will be when lifting, but you will have to handle more weight when rotating the mast to horisontal.
Picture 4: Webbing sling attached to hook at the right position (the black "can" is the hook).
You adjust the position of the hook and sling along the mast with the free end of the webbing. When in the correct position, tie the webbing to a cleat on the mast. This will now support the weight of the mast, so attach it carefully.
Picture 5: Free end of the webbing sling attached to a cleat on the mast. Note the shroud terminals, protected by plastic bags attached with tape.
Raise the hook until the sling and winch line are taut. You can now disconnect the forestay and the cap shrouds. Have one of your assistants hold on to the mast so that it does not pop out of the mast base before you are ready to lift. From this point on, the assistant must not let go of the mast until it is horisontal and on the ground. Have the other assistant hold the furler drum. Then raise the mast out of its base with the winch, rotate it towards the jetty, making sure it clears the lifelines. Now lower the winch and keep rotating the mast to horisontal as you go. The second assistant follows with the furler. Put the mast on temporary supports on the jetty, or directly on a mast trolley if there is one available.
I have not weighed the mast on our SO37, but I estimate the weight to be around 120-130 kg. Three people can lift it with some effort, although with four it's easier.
Picture 6: Boat naked!
It is best to be at least three people: one to operate the winch, one to hold the mast, and one to hold the forestay/furler. It helps to have a fourth person to assist wherever needed. You always forget some little detail.
First, strip the rig of sails, canvas, and tie up all halyards and running rigging securely to the mast. Un-thread the control line for the furler and tie it to the furler drum. Remove boom: if you have a solid vang, attach the topping lift or a halyard to take the load off it. Disconnect all electrical cables and secure them to the foot of the mast. I use blue masking tape. These preparations can be done well in advance of the actual unstepping.
Picture 1: sails, boom removed, halyards tied up. Backstay tensioner disconnected.
Picture 2: Cables disconnected.
With a single spreader mast, setting up the sling is easy. With a double spreader mast, it is more tricky since you want the lifting point above the lower spreaders. On some boats you can use the spinnaker pole lift, but only if it is above the mid-point of the mast. Om the SO37 it is not, so it is not usable. I use long piece of webbing to set up the sling. I throw the webbing over the lower spreader on one side from stern going forward, and then back going aft on the other side. Use something heavy but soft to attach to the end of the line to help throwing. I make a big noose with the webbing so that I can attach the winch hook from the crane later.
On the front side of the mast, attach a line to the webbing with a loose bowline. This serves two purposes: it allows you to control the webbing sling as you raise the winch hook, so it does not snag on anything such as the engine light. It also serves as a means to pull down the winch hook in case something goes wrong and you have to start over.
Picture 3: Webbing sling ready. In queue for the mast crane. The boat being unstepped has single spreaders, much easier!
Disconnect the backstay and loosen the shrouds. Disconnect the lower and mid shrouds. This can be done while waiting the for mast crane to be free: the mast will be supported by the cap shrouds and the forestay (assuming you have a rig with swept spreaders. If not, keep the lower aft shrouds attached).
Protect the threaded terminals on the shrouds once they are disconnected. This can be done with fancy little cloth bags that you tie on to the terminals, or just use plastic bags and duct tape. When you later handle mast on land, you don't want the terminals to drag on the ground unprotected.
Position the boat under the crane with the lifting point about 10 cm aft of the mast. Attach the winch hook to the webbing sling so that the noose will close as you tighten it. Raise the hook so the noose closes, to a position above the mid-point. On our boat about one metre below the upper spreaders is good. It is not super critical: the higher you go, the more stable the mast will be when lifting, but you will have to handle more weight when rotating the mast to horisontal.
Picture 4: Webbing sling attached to hook at the right position (the black "can" is the hook).
You adjust the position of the hook and sling along the mast with the free end of the webbing. When in the correct position, tie the webbing to a cleat on the mast. This will now support the weight of the mast, so attach it carefully.
Picture 5: Free end of the webbing sling attached to a cleat on the mast. Note the shroud terminals, protected by plastic bags attached with tape.
Raise the hook until the sling and winch line are taut. You can now disconnect the forestay and the cap shrouds. Have one of your assistants hold on to the mast so that it does not pop out of the mast base before you are ready to lift. From this point on, the assistant must not let go of the mast until it is horisontal and on the ground. Have the other assistant hold the furler drum. Then raise the mast out of its base with the winch, rotate it towards the jetty, making sure it clears the lifelines. Now lower the winch and keep rotating the mast to horisontal as you go. The second assistant follows with the furler. Put the mast on temporary supports on the jetty, or directly on a mast trolley if there is one available.
I have not weighed the mast on our SO37, but I estimate the weight to be around 120-130 kg. Three people can lift it with some effort, although with four it's easier.
Picture 6: Boat naked!
