Chain Plates

A common problem with many chain plate designs is that the chain plate will leak over time and cause structural damage. Many of these designs have the chain plates penetrating through foam or balsa cored decks. Eventually, the outer layer of glass starts to leak, allowing water into the core material which starts a rotting process that is not noticeable until the rot is extensive enough to allow water past the inner layer and into the boat.

Many boats use a simple bolted on chain plate for forestays or backstays. This design also works very well for shrouds and we feel this is the best choice for reliable, easy to maintain chain plates without leaks.

This design will move the shrouds all the way to the outside of the boat, which has the following advantages:

  • Wider decks to walk on,
  • Less stress on the rigging, therefore reduced mast section size and thus lighter weight in the rigging. This results in less required keel weight, reducing the weight of the boat by almost 300 kg (660 lbs),
  • Lower Cost to build,
  • No obstructions in the interior,
  • Easier to inspect,
  • Easier to maintain,
  • Easier and lower cost to replace if ever required,
  • Remains water tight for much longer.

Every great plan has disadvantages as well, but in this case, we can overcome them.

  • No overlapping jibs upwind,
  • There is a potential that a stay gets snagged behind something when mooring does not go as planned.

These were two concerns that we had in mind when designing “Bagheera”. She has been in use for 8 years and has never snagged anything with the mainstays. The only real disadvantage is that overlapping jibs become much less effective when sailing upwind. On the other hand, when sailing shorthanded one generally prefers to have smaller jibs that are easier to handle. Additionally, as soon as the apparent wind comes in at 50 degrees, a code0 can be set and that will make up for the lack of a large jib. With the rig size we have chosen for the Offshore 42, upwind performance is not going to be an issue.

chainplates

The chain plate design for the Offshore 42

 

5 thoughts on “Chain Plates

  1. Stein Varjord says:

    In my opinion, this is the right choice. It’s the most tested type of chain plates and the very reason for its name. It also makes the load distribution in the boat easier and better. The bulkheads will only see compression. No fear of failed bulkhead bonding at the hull, which is a problem with other solutions.

    Snagging the shrouds when docking can’t be an actual problem. We’re not supposed to approach piers at speed, like a drive by shooting. 🙂 I’ve sailed lots of boats through 40 years of racing with the shrouds at the widest point of the boat. Never even heard of anybody having that problem. Theoretically it might happen, but i reality i think not.

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    • offshoresailboats says:

      Stein,

      Thanks for the comment! We agree that snagging the shrouds should be a non-issue, but one should also be careful when maneuvering through tight corners or around docks with tall overhangs. We think the better load distribution is far more important though, as docking is only a small fraction of the time spent on a sailing trip!

      Liked by 1 person

  2. Bill Attwood says:

    Hi.
    I agrèe that the conventional through- deck chainplate is less than ideal. Why not use “my” method? The deck in way of the chainplate is not cored, but filled with a substantial plug of solid epoxy + microfibres. The chainplate itself is NiAl Bronze thus removing any concerns about corrosion. The chainplates below deck are all easily checked. Leaks (eventually) are inevitable but can be seen, and the bedding renewed. A furthe advantage is that the shroud tension is directly in line with the chainplate – no bends.
    I don’t claim this as my invention, merely how I have modified my chainplates for peace of kind.
    Comments?
    Best regards
    Bill

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  3. Bill Attwood says:

    Hi,
    Thought I had already commented on this, but it hasn’t appeared. Question: why not use a material more resistant to corrosion such as NiAlBronze? If the deck is solid grp iwo the chainplates, then problems are solved. Leaks can be dealt with by rebedding. If the chainplates are fixed throught the hull, then presumably the hull iwo the chainplates will be solid grp
    Regards
    Bill Attwood

    Like

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