Help needed - How to support a mast without the chain plates?

[Privilege]

I'm taking my catamaran out of the water next week for routine maintenance. While she's out, I intend to remove the chain plates as they need to be straightened slightly (But that's another story).

Removing the chain plates is easy, the hard part is how to support the 58' mast while the chain plates are off. I'd rather that it didn't fall over. My provisional plan is to take off one at a time and replace it before removing the next. Having slackened the opposite turnbuckle, I'm thinking of using a come-along from the turnbuckle to the rear side cleat. The lower shroud can go to another cleat or tie it off to somewhere secure. Finally, the topping lift can go backwards to another cleat. Of course, if I had the spare cash, I'd just get a great big crane to hold it for me.

I've never adjusted a turnbuckle or messed with the mast so I'd appreciate any thoughts, tips or input.

[capt-couillon]

From your description, I am assuming you have a single chain plate port and stbd carrying both upper and lower shrouds. Given you will be on the hill, with no loads on the mast other than bare stick, the lower shrouds are really not needed as their primary function is to keep the center of the mast "in column" under sail loads. You would want to secure the upper shrouds to a secure point (somewhere in the area of the chain plate) but they will not require much tension to keep the mast plumb port to stbd. Running the main halyard down to a secure point on the side you are removing the chain plate and taking up a light tension should be adequate.

Be sure that after "straightening" the plate, you inspect (closely) to make sure you have no stress cracking. After the chain plate is back in place, snug up the turnbuckles (loosely) and repeat for the other side.

You probably need to a acquire some local help to do the final "tuning" of the rig as it asks some experience.

[georgelieber]

The mast is surprisingly easy to keep vertical when there is no force from the sails and wind. I usually loosen everything a bit, and then use one of the larger halyards to to pull the mast in the direction of the hardware to be removed and repaired. Just attach the halyard to something secure and crank it tight.

Be wary of pulling upward on cleats. Cleats are strong when pulled sideways... parallel to the deck... but the fasteners are weaker when pulled upward, or away from, the deck. Run a line around a pontoon or something and pull on that if you need to.

[Privilege]

Thanks. I appreciate it.

[chowdan]

You dont need to pull a halyard tight like your rigging. I pulled my chainplates and it was relatively easy.

I dont have a cat, but being the first time messing with that stuff i was nervous. I ran a single halyard to the stanchion base and just pull it tight with a winch. I did loosen the opposite side by a full turn on the turnbuckle. Keep in mind you need to put a wrench on both the turnbuckle and the swag itself otherwise your just twisting the cable and not doing anything.

I would recommend running halyards to both sides of the boat, then pulling the chainplates on both side(leaving fore and aft in place), then once starboard/port is finish repeat the process with the front and back ones.

Doing two at a time shouldn't even be a problem honestly.

[roverhi]

Originally Posted by georgelieber

Be wary of pulling upward on cleats. Cleats are strong when pulled sideways... parallel to the deck... but the fasteners are weaker when pulled upward, or away from, the deck. Run a line around a pontoon or something and pull on that if you need to.

Cleats should be installed with large backing plates on sufficiently strong areas of the deck to practically allow the boat to be hung from them. That's a bit of an exaggeration but they should be hell for stout. The fasteners are plenty strong in tension though they are stronger in shear. If your cleats can't take the minimal forces necessary to keep a bare mast up, you have serious issues with the boat.

Running the halyards out to the edge of the deck and snugging up hand tight will hold the mast in place of the shrouds.

[ozskipper]

Most important!!!!! Before you even touch the turnbuckles, mark them with a permanent marker so you know how tight they need to be when you re-attach them later. That two minutes will save you a lot of future grief trying to re-tune the rig.

[chowdan]

Originally Posted by ozskipper

Most important!!!!! Before you even touch the turnbuckles, mark them with a permanent marker so you know how tight they need to be when you re-attach them later. That two minutes will save you a lot of future grief trying to re-tune the rig.

Definitely do this. Either a permanent marker or a piece of tape(i used electrical tape).

[builder dan]

when you are finished run your eye up your mainsail track to check how straight your mast is, raking back is fine any sideways curve is very bad s bends are even worse