My cx 25

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APLJaK
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Re: My cx 25

Post by APLJaK »

Wow bellissima barca

That is a beautiful boat you are building! I can't wait to see it in the water.

fallguy1000
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Re: My cx 25

Post by fallguy1000 »

dalnilo wrote: Sat Sep 18, 2021 10:19 am 015A7914-F9BA-474D-82A8-665D08FAA80F.jpegCBC30B5F-7FA8-47F3-91EF-94600EBD0A25.jpegDBC8B35C-E8BF-446A-93BD-F6A4CD0E74BF.jpeg629972CA-6CAE-41FE-A6E4-8952E32D316C.jpegE0665E7C-ED56-40B3-9369-E847E8B5BF0A.jpeg705F3318-583E-45E2-AB0B-228A321A3FE0.jpeg

how does it look to you?
Can you tell me what is behind the cleats? I am worried they can pull off. I like the wood base, but they still need backers I'd say.

sure is pretty
My boat build is here -------->

viewtopic.php?f=12&t=62495

dalnilo
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Re: My cx 25

Post by dalnilo »

fallguy1000 wrote: Sat Sep 18, 2021 6:17 pm
dalnilo wrote: Sat Sep 18, 2021 10:19 am 015A7914-F9BA-474D-82A8-665D08FAA80F.jpegCBC30B5F-7FA8-47F3-91EF-94600EBD0A25.jpegDBC8B35C-E8BF-446A-93BD-F6A4CD0E74BF.jpeg629972CA-6CAE-41FE-A6E4-8952E32D316C.jpegE0665E7C-ED56-40B3-9369-E847E8B5BF0A.jpeg705F3318-583E-45E2-AB0B-228A321A3FE0.jpeg

how does it look to you?


Can you tell me what is behind the cleats? I am worried they can pull off. I like the wood base, but they still need backers I'd say.

sure is pretty
I would like to put a stainless steel plate mm5 with a wooden support, above as you can see in the picture, do you think that is enough. Do you have any advice?

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Re: My cx 25

Post by dalnilo »

APLJaK wrote: Sat Sep 18, 2021 3:46 pm Wow bellissima barca

That is a beautiful boat you are building! I can't wait to see it in the water.
thanks a lot

fallguy1000
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Re: My cx 25

Post by fallguy1000 »

My main concern is how did you apply the wooden base and cleat and what would the psi rating and thus the rating of the cleat be.

For example, let's say you painted the boat and then glued on wood bases and then screwed the cleats down. The bond strength can be no greater than the weakest bond and so the adhesion of the paint and any screw penetration is all you have. Get a bad storm or boat wake and find out the cleats have a rating of say 500 pounds only.

Or, let's say you bolted through a 6mm ply skin. Now, the shear rating of the ply and the backer adhesion is all you have plus the two screws.

What I would want is for there to be a backer on the reverse. It can be aluminum or fiberglass made into say 3/8" thick so it doesn't flex much or even say 1:2-3:4" wood. That backer or the skin then determines the rating for the cleat. You want the cleats here rated to say 2000 pounds. I don't know shear ratings of the ply skin, but if you make 4" x 4" backer, then the load is applied to 16 square inches. And a 2000#/16si is 125psi...pretty high... if you make the backer 10x5", you push the loading to only 40 psi. I don't know the shear rating of the plywood gunwhale skin, but you want the cleat loading to be say 50% of the skin shear or some such.

For my boat, ideally, one cleat would take 50% of the hulls weight rounded up to nearest thousand which is 5000#. A backer for the cleat of say 50 square inches is 100psi. Not sure my skins can survive 100 psi, but that is what I am designing. If you had a much thicker gunwhale of say 3/4"; you'd need no backer I'd say because the shear rating of the thing is sufficient.

Clear as mud?

Try to put as big a backer as practical under the gunwhale is all. No backer and they will probably fail someday. If you bonded the top board with epoxy or 5200, totally different, although 5200 needs a good month to achieve high strength.

I don't know how to calculate the shear rating of the thing you built, but guessing it is equal to the shear rating of the plywood gunwhale and not much more.
My boat build is here -------->

viewtopic.php?f=12&t=62495

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Re: My cx 25

Post by TomW1 »

Fallguy I get your drift. Yes cleats should be through bolted to a backer under the gunwales and glued with a 5200 or similar to them . The backer should be as large as possible to spread the stress that may occur on the cleat in inclement weather or they may pull free from the boat. Here is where I like the 4 hole Herreshoff's cleats, https://shop.hamiltonmarine.com/product ... 29385.html
These also have there own SS backing plate for extra.

Lee also be prepared to spend an amazing on dock lines. Nylon has gone through the roof.

Tom
Last edited by TomW1 on Sun Sep 19, 2021 4:06 pm, edited 1 time in total.
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

dalnilo
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Re: My cx 25

Post by dalnilo »

fallguy1000 wrote: Sun Sep 19, 2021 1:29 pm My main concern is how did you apply the wooden base and cleat and what would the psi rating and thus the rating of the cleat be.

For example, let's say you painted the boat and then glued on wood bases and then screwed the cleats down. The bond strength can be no greater than the weakest bond and so the adhesion of the paint and any screw penetration is all you have. Get a bad storm or boat wake and find out the cleats have a rating of say 500 pounds only.

Or, let's say you bolted through a 6mm ply skin. Now, the shear rating of the ply and the backer adhesion is all you have plus the two screws.

What I would want is for there to be a backer on the reverse. It can be aluminum or fiberglass made into say 3/8" thick so it doesn't flex much or even say 1:2-3:4" wood. That backer or the skin then determines the rating for the cleat. You want the cleats here rated to say 2000 pounds. I don't know shear ratings of the ply skin, but if you make 4" x 4" backer, then the load is applied to 16 square inches. And a 2000#/16si is 125psi...pretty high... if you make the backer 10x5", you push the loading to only 40 psi. I don't know the shear rating of the plywood gunwhale skin, but you want the cleat loading to be say 50% of the skin shear or some such.

For my boat, ideally, one cleat would take 50% of the hulls weight rounded up to nearest thousand which is 5000#. A backer for the cleat of say 50 square inches is 100psi. Not sure my skins can survive 100 psi, but that is what I am designing. If you had a much thicker gunwhale of say 3/4"; you'd need no backer I'd say because the shear rating of the thing is sufficient.

Clear as mud?

Try to put as big a backer as practical under the gunwhale is all. No backer and they will probably fail someday. If you bonded the top board with epoxy or 5200, totally different, although 5200 needs a good month to achieve high strength.

I don't know how to calculate the shear rating of the thing you built, but guessing it is equal to the shear rating of the plywood gunwhale and not much more.
I thank you for all the info, in reality I still have not pasted anything, I want to do it in the best way,
the wood that goes above will actually be almost exclusively aesthetic, for the teneta I will see you follow your advice with wood underneath with aluminum or stainless steel.
before fixing I will send the photos to make sure I do a good job

fallguy1000
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Re: My cx 25

Post by fallguy1000 »

TomW1 wrote: Sun Sep 19, 2021 3:16 pm Fallguy I get your drift. Yes cleats should be through bolted to a backer under the gunwales and glued with a 5200 or similar to them . The backer should be as large as possible to spread the stress that may occur on the cleat in inclement weather or they may pull free from the boat. Here is where I like the 4 hole Herreshoff's cleats, https://shop.hamiltonmarine.com/product ... 29385.html
These also have there own SS backing plate for extra.

Lee also be prepared to spend an amazing on dock lines. Nylon has gone through the roof.

Tom
Hmmm. I don't have lines purchased. Maybe I wil wait then.
My boat build is here -------->

viewtopic.php?f=12&t=62495

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Jaysen
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Re: My cx 25

Post by Jaysen »

Quick word on dock lines… get the cheaper 3 strand twist and make your own. Braiding a loop is easy and you will need to replace lines frequently no matter how careful you are. Keep a 300’ spool and made the exactly lines you need. Especially if you have a fixed dock site.

A set of exact length, double ended (loops each end) lines takes all the guess work out of final tie off. Also makes hurricane prep forken simple.
My already completed 'Lil Bit'. A Martens Goosen V12 set up to sail me to the fishing holes.
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TomW1
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Re: My cx 25

Post by TomW1 »

Jaysen have to disagree with you 3 strand twist is to weak for his 6000lb boat in a major storm he needs at least 8 strand braid nylon 1' rated at 23000lbs breaking strength. That is triple the weight of his boat and will not stretch enough with doubled lines to put it on the dock if he has it tied down from both sides.

I also disagree on the loops, they do not let you adjust the lines length for tides or other expected conditions. No need for them on them on both ends, just one. It depends on the tide fluctuation sometimes they never have to be moved sometimes they need to be adjusted hourly. Looks like CC only has one tide cycle that varies from .5 - 1.75 feet a day in the cycle I could check.

Tom
Last edited by TomW1 on Sun Sep 19, 2021 9:53 pm, edited 1 time in total.
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