Servicing The Chain Plates

Serviced chainplatesThe chainplate is typically a metal plate used to fasten a stay to the boat. One end of the chainplate has a hole for the pin of the turnbuckle, the remainder of the chainplate is used to attach the plate to the boat  via a bulkhead, knee, tie rod or the hull itself. Chainplates get their name from the old wooden ships that used to use three strand tarred manila or hemp rope (instead of wire) in conjunction with dead eyes and lanyards to tension the rigging. The dead eye would be attached to a chain or a link which would be connected to a plate that was fastened to the hull. This plate was called the chain plate.

Traditional Chainplates

externally mounted chainplate

Modern day chain plates are typically made of stainless steel and sometimes aluminum. When replacing a boat’s standing rigging one should also be sure to, remove, inspect, clean up and refasten the chainplate. Apart from design and material flaws there are three primary factors in the life expectancy of any chainplate: fatigue, age, and corrosion. One of the common misperceptions of stainless steel is that it does not rust. Depending on its grade, stainless steel is very resistant to rusting, but will rust and may do so prematurely without the presence of the oxygen molecule. This in-itself presents a problem when sealing a chainplate to the deck or the hull in effort to keep water out. Chainplates that are mounted through the deck are the most suspect because they are prone to suffering from crevice corrosion mostly due to the seal created at the deck. Again, this is due Serviced  chinaplateto the lack of oxygen which is typically supplied by water or air. This can create an area of concern mainly due to the fact that it is right in-between the two pulling forces of the plate, i.e. the top bolt hole and the hole that accepts the pin for the stay’s turnbuckle. Through-deck chainplates are susceptible to failure because of this if not inspected regularly.

This brings me to the cover plate that mounts horizontally onto the deck. The chainplate cover plate is there to merely promote a seal. It is not structural, does not need to be through-bolted, and should be lifted, cleaned, and resealed every two to three years (give or take) depending on geographical location and use. This is both to preserve the decks core materials as well as keeping water out from below decks (Read our blog here on sealants and their uses).

Deck mounted chainplate

Deck mounted chainplates will typically have few issues with failure within the actual plate (again, this is aside from fatigue, design and/or manufacturing flaws of course). The fasteners in this case are taking the ‘ brunt of it’ and care should be taken to ensure that the fasteners and/ or any associated tie-rods are in optimal condition. When removing the stainless steel fasteners you will see evidence of rust where they go through the deck. These types of chainplates should be resealed and have the fasteners replaced regularly (about every five to seven years, depending on use and geographical location).

U-bolt chaijnplate

U-bolt style chainplates, should also be pulled, inspected and re-sealed regularly. These types of chainplates should be replaced more frequently than the other styles. This is due to the fact that they depend solely on the threads used to fasten them through the deck.

cracked and rusted chainplateSo when do you need to replace your chainplates altogether? Replacing chainplates should be done if there is damage or evidence of cracking. Unless there is clear evidence of impact, one should replace ALL of the boat’s chainplates if there are signs of wear or damage on any one of them. Extreme age (30 + years, again depending on geographical region and use) can also be a factor for replacement. In terms of fatigue; if a boat has been sailed hard for many, many miles, i.e. a circumnavigation, one should consider having new chainplates made before setting off again. The quality of the stainless used is an important consideration as well. Many Taiwanese and some Floridian 304 grade Stainless steel chainplatemanufacturers, amongst others, are notorious for using sub-marine-grade stainless steel for their chainplates. The life expectancy for these low grade metals cannot be estimated in a marine environment and should therefore be replaced as soon as possible!

Sealed chainplate

In conclusion, chainplates are an often overlooked portion of ones rigging. I have even witnessed rigging shops that neglect to inform customers of the importance of chainplate inspection. If in doubt of your chainplate’s state, it is, at the very least it is a good idea to have them removed, cleaned up and inspected by a professional. If you are a do it yourself-er, there is no shame in seeking advice, not just for removal but most importantly for inspecting them as well as tips on installing them properly. So if you are having your boat re-rigged, be sure to ask about those chainplates.

REMEMBER: Don’t forget to replace the fasteners!

Have a question, leave us a comment or shoot us an email and we will be glad to reply!

About The Rigging Company, LLP

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16 Responses to Servicing The Chain Plates

  1. John Doyle says:

    Mine is a Cape Dory 30K 1978. The chain/backing plates look like Baklava. .I just got the boat and plan to haul out next week to start the process. They used iron backing plates with welded rebar glassed to the hull would you recommend something better? I don’t want to put exterior chainplates I would like to keep things the same but maybe different material.Thanks

    • The Rigging Company, LLP says:

      Hey John,
      I love Baklava, but not made of Iron. Do you have any pictures you can email us? The CP’s on deck are pad eyes made of bronze, right? It may be ideal for the backing plate to be made of 316 grade stainless…even G10 composite may be a nice upgrade. Oh and definitely replace the screws. Please email Jimmie@TheRiggingCo.com for the pics and further advice.

      ~T.R.C.

  2. Paul Dunford says:

    Do you have any information please on repairing chainplates on a Colvic UFO 34. One has gone rusty inside the firbreglass. Thy are below deck inside the saloon and are encased in fibreglass.
    Do you make these chainplates? Paul

    • The Rigging Company, LLP says:

      Thanks for commenting. We don’t have specific experience with this boat, but we have dealt with galssed-in chainplates in the past. You will likely do best by consulting a fiberglass specialist for tips and adivce on getting them out. Depending on the age of the boat, it especially sounds like you should try and get them removed and inspected at the very least, perhaps replaced, and then re-install them…all of them. Typically we have found a bolt on solution on most of these projects for the install. This will entail new chainplates to be made.

      Feel free to send us some pictures and ask more questions if you need to.

      Thanks,
      ~T.R.C.

  3. kelly foote says:

    I have a Rawson 30 and cant find any information about removing or replacing the chainplates, do you have any resources or any experience with these boats? the originals seem to just be glassed in as i cant find any bolts but that doesn’t really make sense..

    • The Rigging Company, LLP says:

      Hi Kelly, thanks for the comment. It would be hard to say as most boats have so many variations for the chain plate install. However, your comment couldn’t have better timing, because I am going to look at a Rawson 30 within the next two weeks for a furler replacement. While I am there I will also take a look a the chain plates and make some recommendations for you based on this.

      Talk to you soon….
      Jim

    • The Rigging Company, LLP says:

      Hi Kelly,

      I went out to the Rawson30 that we are putting a new furler on today. I noticed the chainplates and they are fiber glassed into the hull! I may contact a fiberglass and paint specialist to help you remove them for inspection. I may also be inclined to bolt them to the outside of the hull for easy future inspections. 
      

      ….I hope this helps and thanks again for commenting.

      T.R.C.

      • Anonymous says:

        That’s exactly what I did. Thanks for the reply.

        • Anonymous says:

          i have a rawson 30 and i am dealing with the same issue now.. anychance you could send me a pic of what you did? thanks scott scottjep@gmail.com

          • The Rigging Company, LLP says:

            I don’t have any immediately available but still have access to them. Check in on this comment section once and a while and I may end up uploading some.

            What we did was, have them cut out from the inside (some interior removal and modification necessary). We then installed them mechanically, again on the inside of the hull, but through bolted form the outside using polished carriage bolts. Then we made new ones as well as a custom “T” plate that was married in via the top bolt hole. This helped spread the load to the underside of the deck at the toe rail… a very strong corner. This was done primarily because the hull material seemed a bit thin. I guess an alternative might be to reinforce the hill in patches from the inside via fiberglass laminates. This is just the route we chose this time around. Hope that’s not all too confusing
            .
            In the end we added chainplate cover plates, screwed into the toe rail, to create a proper seal.

            Hope that helps…
            ~T.R.C.

  4. roy says:

    I have had a local boat yard re-fasten chainplates on a wooden hull ( first removed and then re-fastened in same position) and bungs from screws into the ribs have popped out in various places next to the chainplates. Is this because the chainplates have been screwed down too tight? My feeling is yes, and they should have been just “snugged up”. To make matters worse, the boat has been out of the water for two years so she will experience significant swelling. The hull is strip built pine, edge nailed and then screwed to frame (where the bungs have popped). Please advise.

    • The Rigging Company, LLP says:

      It is hard to say for sure. It does seem that the chainplate job has something to do with it, as the affected area is around the chainplates. However, it also a wooden boat and there is a lot of movement in wooden boats (especially when going from completely swollen to completely dry). This movement may have just caused the bungs to pop around the newly fastened chainplates because the chainplates being fastened to the hull now offer a now stiffer reinforced area to the hull, so instead of the wood moving evenly throughout it runs into a hard spot where these plates were fastened. Then again it could be a number of other reasons, so it is hard to say.

      I may just put the boat in the water and let her settle in for a while then go around the hull with a raft and refasten and re-bung as needed. Because if the boat has been dry for a while it will certainly change shape a good bit once swelled. I am sure other things will happen like maybe some of the seems may need to be re-caulked. You just won’t know until she is wet again and settled in. For this reason alone I think it is always prudent to wait until the boat is wet to caulk, bung, refasten, even paint the hull above the water line. A good raft can be a useful investment.

      Thanks for the comment and let us know if we can help any further!

      ~T.R.C.

  5. chris says:

    I have a Hudson Force 50 one of the chain plates has a hair crack do you make these style plates

    • The Rigging Company, LLP says:

      We do! We would recommend that all of the plates and fasteners get replaced simultaneously. We would need the plates that are to be replaced for duplicatuon. If you can send a picture of the chainplate style I can provide you a quote for replacement. Thanks for the comment!
      ~T.R.C.

  6. E.Linox says:

    I’ve noticed heavy rust stains around the port chain plate of the mast rig on a 2005 Bavaria 38 C. lying in Denia/Spain. What could be the reason and what is the best and most economical procedure to follow? Can I do this on my own? Thank you for your attention.

    • The Rigging Company, LLP says:

      This seems like a fairly new boat and the first thing I might do is contact Bavaria to see if this is something they have encountered before. Reasons for excessive rusting could be:
      1. Poor quality stainless
      2. The stainless has somehow been contaminated with steel or iron
      3. It could also be that the metal is covered by grease, sealant, dirt or some other substance that can cause oxygen to not be able to get to the metal.
      Stainless steel can rust, especially when it can’t breathe. If Bavaria is of no help, then you can remove the chain plate, clean the rust off with a stainless steel wire brush, polish it, remove any excess Polish with acetone and inspect the plate for cracks and other issues. Reinstall using new sealant and monitor the plate for the next few years. If the rust returns, I would have a new chain plate made.
      To remove the chain plate with the mast up make sure you properly secure this side of the mast with multiple halyards and detune the the opposite shrouds. Removal is easiest when the mast is out of the boat.
      Hope this helps and thanks for the comment!

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