Will my mast stay up if I undo all those wires?

[LadyStardust]

I need to remove all the chainplates, check and rebed them and the deck plates on my 30ft Cutter rigged baba 30 yacht. I am fairly new to all of this and I would really like to do this without taking the mast down. I'm currently afloat in a marina and hate the thought of putting the boat in the yard right now. The Forestay and backstay fittings are fine.
I think in theory that I should be able to do them one by one, using the genoa halyard as a substitute. Presumably i should slacken the opposite shroud when i do this? I have 4 shrouds each side, cap, forward lower, aft lower and cutter aft stay.
Does this sound like a sensible plan? It could make an awfull mess of my neighbours boats if I got this wrong?

Thanks in advance

 

[Swagman]

Yes you should be OK

IMHO should not be a problem if you do as you say and address each one in turn. It does no harm to back up using your spare halyard as you say.
Beg / borrow a tension guage when you come to retune the rig - with rebedding of chaiplates in mind it is likely the settings will change the second time around.

 

[Strathglass]

sounds like a sensible plan, If you take one or two precautions. Here are one or two precautions you may or may not consider taking. I have certainly done this sort of thing often to Virgo Voyagers, Leisure 22/27 and others on the water.

I see that she now has an alloy mast instead of the original wooden one, that helps.

You haven't said but I presume the mast is deck stepped. If it is keel stepped you can take more liberties.

If it is deck stepped how well does the mast step hold the foot of the mast?

Do not fully slacken the rigging.

Remove the stays in matched pairs.

Do not rely on one rope to suport the mast for a long period of time ropes break, (ask Mike Golding). This is especially true when using hayliards at 90 degrees to their normal exiting angle.
I would tend to tie a pair of ropes to the end of the Genny hailyard then hoist it fully and set a rope to each side. This way you will be less liable to have chaff and to damage the wheel on the hailyard exit on the mast.

When leaving the boat look up the mast and check that the temporary rope rigging is not puting too much bend on the mast.

Just a few thoughts, hope they are of use to you.

Iain

 

[scarlett]

I have done it without an accident. I would watch the long term weather forecast and stop the job if high winds are expected. You could get amazing forces on the mast under unfavouable circumstances.

 

[LadyStardust]

Thanks for the reassurance. The mast is deck stepped in a casting that would need to mast to jump an inch or two to escape, I hadn’t considered the chaffing issues, will give some thought to this, however I don’t intend to leave the mast supported on the halyard for any length of time.
Thanks,

 

[oldharry]

You can quite safely detach any one side shroud at a time, provided the boat is not being rocked about, and the wind is not much above around 20 knots or so. Also, as long as you have the cap shrouds (top ones) secure, then you can entirely safely remove both lowers. They are not supporting the mast as such, but prevent the mast bending in the middle under the load of the spreaders and the mainsail under way. When it comes to doing the cap shroud (the upper ones') chain plates, the mast would stay up with only one lower attached, but for safety have both attached.

But NEVER EVER remove the fore or aft stay without providing an alternative means of support.
(purists: yes I know the lowers will continue to support the mast if the fore or back stay are removed, but a 3/4 rig does not have forward lowers and the mast will come down
if the forestay is detached. Also if the shrouds are incorrectly positioned it can be very dangerous. I can not assume things are correctly set up)

The rigging is designed to take large amounts of stress when under sail in rough water. Not just the force of the wind on the sails, but the shock loads on everything when the boat is crashing its way to windward, which can be in the order of tons in a really bad sea. So there really is no danger of the mast, weighing in at a few dozen Kg, damaging anything, or falling down, providing there is always at least one wire in each direction to stop it moving.

We do this quite regularly when setting up or removing deck mounted masts (of which I help do 20 or 30 a year)

Halyards can be used as temporary stays, and are essential if you do have to take off the fore or aft stays. Not much use for the shrouds at the side because a: they are being pulled out of line which can damage the sheave or block at the top, and b: they do not run over the spreaders, so the mechanical advantage is far lower, so that if the mast moves (e.g. under wind pressure or movement of the boat) the load on the halyard is far greater than on the wire. However, it is better than nothing!

The heel fitting described will not support the mast if it starts to fall sideways, and will just break. It is designed mainly to take the mast compression load, and only relatively low sideways thrust, and it will certainly tolerate very little twisting movement before it or its fastenings fail catastrophically.

 

[Hardley]

You have received lots of good advice, you could also use the shroud that you disconnect, by tieing a line round the shroud, using a rolling hitch and securing the other end to a suitable point.

 

[ShipsWoofy]

Off topic, your website has made me feel a little homesick. I love the shot of the marine lake, the first place I ever sailed in our old GP14 (202).

I think you will know quite a few of my family too.

Welcome to the forum....

 

[LadyStardust]

Thanks everyone, I removed my first chainplate today and found rusty crevices on its hidden side. I'm off to get new ones made now. but replacing the chainplate should be a 30 minute job for each plate.
Cheers,

 

[jonjo]

Re: Prebend warning

Maybe my advice is not relevant to your yacht's design but if someone with a more performance oriented mast is considering doing the same, then be careful of mast pre-bend.

A lot of tension can be loaded into the rigging via the cap shrouds and lowers when creating mast pre-bend. I know someone who fell down with his mast while at the top in a bosons chair. The job at the top of the mast required a sort term disconnection of the forestay, this was achieved by loading a lot of tension into a halyard.

The boat in question was a fractional rigged Sigma 33 with a lot of pre-bend. The halyard gave way.

Later when the mess was sorted out the owner was told by a pro rigger that he should have backed off the shrouds until the mast was straight before thinking about disconnecting the forestay.

 

[LadyStardust]

Re: Prebend warning

Thanks for that, in fact my mast actually has some negative pre-bend, i.e. inversion. It has been recomended that I move the forward lower aft shrouds forward of the mast foot. At the moment they are on the same chainplate as the cap shrouds. Being a cutter rig it has not been possible to put any tension into the aft lowers or aft cutter backstays without exagerating this inversion.
I plan to change the lower afts first, then move the lower forwards to their new chainplates about 3 ft forward of the mast base. I hope between them I will have enough to hold the mast happily to do the cutter backstays and then finally the cap shrouds, with the aid of a halyard and rolling hitch solution.