It really depends on exacally what needs to be done, and that really can't be determined until you get the mast
down the chainplates out of the boat and can do a dye penetration test on them.
Basically what you are looking at is to destep the mast
, which depends on the yard. For me I would expect about $10/foot at our yard. But different yards can have very different costs for destep ping.
Once the mast is out, you have to unbolt the chainplates. This can take anywhere from about an hour per chainplate to 4-5 hours per depending on how easy they are to get to, and how stuck they are. I have seen some where each bolt had to be cut off becaus they were seized to the nuts, this obviously takes more time than if they just unbolt easily.
Once the chainplates are out of the mast you might be able to immediately determine that they have to be thrown away. If there is any visible pitting, discoloration or cracks, they really need to be replaced. If they look ok after being cleaned up then you need to do a penetrating dye test (the dye test stuff costs about $20) to determine if there is ay crevice corrosion
. Particularly in the hidden area (the area covered by the deck) crevice corrosion
is notorious in stainless steel, and probably accounts for the majority of demastings I have dealt with.
Assuming everything is clean, and you find no evidence of corrosion, then just bolt them back together, seal the holes with 3m 5200, and put the rig back together. If you do find corrosion then you have to replace the chainplates.
If you have to replace the chainplates, then you have two options. The first is to replace them with stainless steel. 300 series steel is quite good at resisting corrosion, but does have a habit of failing due to device corrosion in the hidden areas due to the low oxygen environment
The other option is to switch to titanium chainplates (I sell these so I can't give unbiased help here). Depending on the geometry of the chainplates the price
for titanium can be anywhere from 30% to roughly double the cost of stainless, but will be roughly 2.5 times as strong, and will never corrode. Practical Sailor just did a nice write up on our Chainplate replacements
in their last magazine.
My recommendation would be to have the rig destepped by the yard, then pull the old chainplates out yourself, you will likely be able to tell then if there is any chance to save the old parts
. If you can't reuse them then have them professionally machined (local in 316 or send me a PM for titanium).
If they look ok, then I would get someone familure with dye testing to do that. The dye is cheap
, but it takes some expertise to really do it well, and making a mistake here could cost you your rig. Personally if I found one that was bad I would replace them all, but if a few pass the dye test they should be ok.
The reinstall isn't that difficult. Just thread them through, bolt them in place the way they were, and caulk with 3M 5200. Restep the mast and go sailing.
The total price
really depends on what you find when you pull the old chainplates out of the boat. But this is a labor intinsive job more than a materials one, other than the cost of the new chainplates.