Yacht Chainplate Replacement: When and How It Is Done

Independent guide: Chainplates are primary structure. Replacement often involves hull, bulkhead or knee work; engage an experienced rigger or shipwright.

Quick answer

Chainplates are the fittings that carry each shroud and stay load into the hull. On most boats they pass through the deck and bolt to a bulkhead, knee or hull tie-rod. They fail most often through hidden crevice corrosion where they pass through the deck, which is why the only reliable inspection is to remove them. Replacement means extracting the old plate, inspecting the structure it bolted to, fabricating or sourcing a new plate, and re-bedding it so the deck penetration stays dry.

Why chainplates are a special case

The visible part of a chainplate above deck is usually the least important part. The high-risk zones are:

• the section inside the deck penetration, where water sits without oxygen
• the bolt holes, where load concentrates and water tracks along bolts
• the bulkhead or knee behind it, which can rot (timber) or delaminate (composite)

For the underlying mechanism, see chainplates and how to spot crevice corrosion.

The replacement process

1. Support the mast. Remove load from the relevant shroud, usually with halyards taking over, or do the work with the mast out.
2. Remove interior joinery needed to reach the bolts.
3. Extract the chainplate. Old sealant and corrosion can make this hard; care is needed not to damage the deck or bulkhead.
4. Inspect the plate and structure. Look for cracks, pitting, elongation and the condition of the bulkhead or knee and its bond to the hull.
5. Make or source a replacement. Copies are made in suitable stainless or other alloys; many riggers will improve on original designs where they were marginal.
6. Repair the deck penetration. Wet core around the slot is removed and filled so water cannot reach the core again.
7. Re-bed and refit with suitable sealant and new fasteners, then re-tension the rig.

Material choices

• 316 stainless is common and familiar.
• Duplex or higher-grade stainless is sometimes chosen for better crevice-corrosion resistance.
• Titanium is used on some high-end refits for corrosion resistance, at higher cost.
• Bronze appears on classic boats.

Whatever the material, the geometry must align the chainplate with the stay so it is loaded in line, not bent.

Boats where chainplates deserve extra attention

• Older fibreglass production boats, including many classic Australian designs from the 1970s and 1980s. See classic Australian production yachts.
• Boats with chainplates through a cored deck, where leaks rot or delaminate the core.
• Bluewater yachts preparing for long passages.
• Catamarans, where chainplates may bond into hull sides and bridge-deck structure.
• Classic timber yachts, where bolts through timber frames can be hidden sources of rot.

Cost factors

Access decides most of the cost. A chainplate reached behind a removable panel is a very different job from one glassed into a bulkhead behind built-in joinery. The cost estimator includes a chainplate inspection add-on, but treat any figure as a band until the rigger has looked inside.