Strong cleats...

Discussion in 'Wooden Boat Building and Restoration' started by missinginaction, May 22, 2012.

  1. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    Last summer hurricane Irene caused a lot of flooding here and many boats were damaged and some lost. Seeing first hand the power of the current I decided then and there to really make some strong docking cleats for my Silverton.

    The original cleats were just screwed through the plywood deck with little, thin backing washers and flimsy plywood backing plates. As many will know the plywood crushed and as the previous owner tightened the cleats the problem only got worse.

    The photos show the process I used to make my new cleats as strong as I could. The new cleats will be mounted on a small hard maple pad proud of the deck by about 3/4". The pads are drilled out oversize and then bored 17/64" to accept 1/4" 20 stainless machine screws. A larger backing pad is bored identically to the top pad. I found some heavy 1/8" thick fender washers to complete the job. Before installation the maple will be painted, and the pads bonded to the deck (deck drilled and counter bored just like the pads) with Sika 291.

    Over engineered, maybe, but I'll sleep well if we get another flood.

    Regards,

    MIA
     

    Attached Files:

  2. DCockey
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    DCockey Senior Member

    Maple is generally not considered a durable wood in exterior use or when exposed to moisture. Keep an eye on it and be prepared to replace it in a few years.
     
  3. variverrunner
    Joined: Dec 2009
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    variverrunner Junior Member

    Maple?

    The wood in the photos appears to be ring porous to me.

    Is there any chance that is actually oak and not maple?

    It would be great news if it is.


    Allan
     
  4. Petros
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    Petros Senior Member

    What you want to accomplish is to spread the load out over a larger area, and your installation certainly does that. It might have been accomplished with a bit less bulk, but it should work. As noted, watch the condition of the wood over time. White oak might have been a better choice.

    You should also verify the condition of not just the decking, but also where the deck is attached to the rest of the hull. A chain is only as strong as weakest link, you have to follow the load path all the way to primary structure, and verify that everything can handle the new loads. You may not rip out a cleat, but you could rip the deck off the hull if the whole load path is not strong enough to take the load.
     
  5. Stumble
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    Stumble Senior Member

    I probably would have used g-10 board instead of wood for this. And certainly not maple. But the parts look great.
     
  6. missinginaction
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    missinginaction Senior Member

    Thanks for the input guys. That wood is called birds eye maple. I had some left over after we installed it on the floors in our house about 10 years ago. I understand that it's not rot resistant but it's hard as rock. It was a challenge for my planer. Much harder than oak. Hopefully with three coats of epoxy and primer and paint it will hold up for awhile. If not.....well I can just knock the pads off and make some new ones.

    Petros, you're right about the support structure. I addressed that a couple of years ago, as I went through this old boat. The pictures below were taken back in 2009 when I was replacing the original decks. I stayed true to the original design and made some modest changes where I found the original design to have failed over time. For instance the butt joints were much more heavily reinforced than in the original design. The support for the deck at the hull/deck joint (called a clamp I believe) seemed sufficient as originally designed. The fore and aft beam that supports the deck at the cabin wall had failed as it was made of Southern Yellow Pine and was too light. It allowed the deck to flex aft of the cabin where people stepped into and out of the boat. I replaced the original beam with a larger one made of some pretty dense Philippine Mahogany. Much stronger.



    Regards,

    MIA
     

    Attached Files:

  7. Stumble
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    Stumble Senior Member

    Your wood, your boat. But birds eye has zero rot resistance, and even when varnished hold up poorly in the sun. Even going to Southern pine will increase the durability of the wood. Ideally though teak would be used if you want wood.
     
  8. garyohv
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    garyohv Junior Member

    What is the reason for the top plate? It does not add strength (being on top). The backing plate is oversized on thickness and dependent on the deck for strength. In failure, it could rip the deck out. I would calculate the strengths of the cleat, bolts, and deck/pad. I would leave off the useless top plate and add a thinner larger backing plate. Type of wood doesn't matter much as it will be sealed.
     
  9. missinginaction
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    missinginaction Senior Member

    The top plate has been added because in the original design, side loads on the cleats caused the top plywood decking material to crush somewhat over time. As the cleats loosened and the previous owner tried to tighten them up leakage occurred and water penetrated the deck at the cleats.

    I want to spread the load on the top of the deck as well as underneath.

    The foredeck is 1 1/8" thick Douglas Fir, the side decks and aft decks are 5/8".

    You're right BTW, I want the entire deck to tear out before a cleat goes. This assembly will hopefully insure it never comes to that.

    Thanks for the input,

    MIA
     
  10. DCockey
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    DCockey Senior Member

    So you want to insure there is a large hole rather than a small one if "design" load is exceeded?

    Okay.
     
  11. PAR
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    PAR Yacht Designer/Builder

    I've never been a fan of solid wood backing plates. They tend to split, check, move around from moisture content, etc. G-10 or metal are my usual choices. Next down the list would be plywood, because of it's dimensional stability.
     

  12. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    Well, I'm going to have to keep a close eye on these cleats over the next few years. Since the wooden pads and backers are epoxied and the mounting holes were drilled oversize and epoxied I hope that they will stay well sealed and won't check or crack. If any problems develop I'll just use the old assembly as a template and make up new parts and based on the posts here I'll certainly use different materials. As for my 'hole in the deck" comment, of course I don't want to see any damage. My goal is to make certain the boat never gets loose.

    Thanks for all the comments,

    MIA
     
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