Reinforcing Deck Cleats

[Blue Crab]

Gotta re-read post #9.

[Matt Johnson]

Why aren't cleats sold with a load rating? If they come-up with rating for everything else, why isn't there one for the cleats sold by any brand? Looking at Defender's website, I can't tell which cleats are strong enough or what.

[Chasing Summer]

Hey, Blue Crab .... I don't claim to be a boat builder although I'm completely rebuilding my Spencer 42, which, yes, is solid fiberglass. NO core. I read all the sailing books I can get my hands on and one of the things that people complain about the most is deck leaks. That's why I've glass over all my backing plates. I've coated the threads generously with marine anti-sieze before glassing in place. You're right, I've never heard of it either. After I launch and take some green water over the deck I'll tell you if I'm happy or not. I got the idea from the chainplates that are glassed over on the under side of the re-inforced deck.
As I was tearing out the interior to start with a fresh hull all the wood near any deck through bolt was rotted. Anyway, that's my story.
Hope to have the boat in the water in a year or so.

[Chasing Summer]

Blue Crab .... Just re-read your reply to my Post #9. I'l bed the bolts with marine anti-sieze and because it doesn't wash out I should never have to worry about it again. If I do remove the based the backing plate stays where it belongs and I just squirt more anti-sieze in the hole before re-installing the bolts.
As far as drilling and tapping ... I thought of that but that would make the backing plate much thicker and WOW what a lot of drilling and tapping. I used 1/8" plate and spot welded flanged nuts. This kept the heat away from the threads. Also .... and important. If you use a bolt to hold the nut in place use a regular bolt and coat it with anti-sieze before welding and DO NOT tighten the assembly. Just finger snug. My first sample I used s/s bolts and tightened and had to cut off the nut and try again.

[Surf City]

Well, I just did this application last week. We are detailing the job on our blog but if you more questions about the process, I will be able to answer more questions about why we did after a day of non boat work.

1. sand existing glass work
2. fill and smooth a level working surface
3. glass above and below hull and deck joint will 34 oz cloth
4. installed large backing plate 1/2 aluminum and 1/2 bolts
5. bedded in devils glue 5200 top and bottom

Wil

s/v Full Monty | Keep up with us as we sail the world and its many remote places.

[GordMay]

Originally Posted by Blue Crab

... The pvc you mentioned: is it really pvc or some sort of H something or other? Where are you getting it? I have 1/4" alum plate I'm using as backing plates. Won't be doing this again in my lifetime.

It's likely High Density Polyethylene (HDPE) like "StarBoard" or Ultra-High-Molecular-Weight Polyethylene (UHMW / UHMWPE), also known as High-Modulus Polyethylene (HMPE)

[barnakiel]

Originally Posted by funjohnson

Why aren't cleats sold with a load rating? If they come-up with rating for everything else, why isn't there one for the cleats sold by any brand? Looking at Defender's website, I can't tell which cleats are strong enough or what.

A 1000 BL lb cleat attached to a 1 mm ply will hold what?

A 100 BL lb one attached to 5 mm fiberglass will hold what?

Any cleat designed for X diameter of line should withstand a load in excess of the BL of the line. I am not sure I am making sense with spectras though (?)

b.

[Blue Crab]

Originally Posted by GordMay

It's likely High Density Polyethylene (HDPE) like "StarBoard" or Ultra-High-Molecular-Weight Polyethylene (UHMW / UHMWPE), also known as High-Modulus Polyethylene (HMPE)

Yep, thanks Gord. I just re-read a thread on that very topic. I'm sticking with the alum. Tried and true.

http://www.cruisersforum.com/forums/...backing+plates

[capn_billl]

That is correct, don't use polyethylene, nothing sticks to it, and it is way too flexible. Starboard is a light weight polyethylene.

I just looked up the plastic I used, it is CPVC. It is heavy, (compaired to other plastics, but the HD designation is misleading), rigid, and has a higher melting point.

The downsides of aluminum, is it is soft, easy to strip, corrodes, and brittle, it may crack when flexed.

Wood gives good strength, has simular flex as fiberglass, but may rot if wet.

Stainless is expensive, may get crevice corrosion if not exposed to oxygen.

Any plastic you use will have to be thicker to give the same strength, but will be lighter weight, and will not corrode, or deteriorate unless exposed to the sun. But you will still need fender washers, or some other metal piece to spread the load of the bolts.

CPVC has both high tensile strength, and flexural strength. (of course I may be biased as I have access to a variety of plastics).

[capn_billl]

Originally Posted by barnakiel

A 1000 BL lb cleat attached to a 1 mm ply will hold what?

A 100 BL lb one attached to 5 mm fiberglass will hold what?

Any cleat designed for X diameter of line should withstand a load in excess of the BL of the line. I am not sure I am making sense with spectras though (?)

b.

Good question. A solid steel cleat with chrome plating will probably hold long after the through bolts have completely pulled out or snapped. I've never seen or heard of a cleat breaking. I have heard of them pulling out.

[rognvald]

I also am in the process of replacing some amidship marinium cleats with low profile Schaeffer stainless steel cleats. The original cleats had no backing plate--only washers. The bolt holes were perfect after 21 years and the orginal core was clean and intact in the deck. I have drilled out the holes in the deck, filled with epoxy and will remount the new cleats with a 3/4" marine plywood backing plate saturated in epoxy. My question is: since a cleat has a lateral rather than vertical load apllied during use, is it not the thickness of the deck and the backing plate that provide the lateral resistance/intergrity/strength? The load is spread across a greater area rather than load pointing on a thinner installation with a stainless plate. Any physics junkies out there to make sense of this?

[capn_billl]

Actually the load is a lever applied from the closest point of contact to the furthest point of contact between the cleat and the surface of the deck, and the closest point of contact of the backing plate to the furthest point of contact of the backing plate. Hence the bigger the backing plate, the more load bearing.

This is a simplification, but google some pictures of cleats that have been pulled out, the fiberglass tears from the furthest point toward the direction of pull.

[rognvald]

Originally Posted by capn_billl

Actually the load is a lever applied from the closest point of contact to the furthest point of contact between the cleat and the surface of the deck, and the closest point of contact of the backing plate to the furthest point of contact of the backing plate. Hence the bigger the backing plate, the more load bearing.

This is a simplification, but google some pictures of cleats that have been pulled out, the fiberglass tears from the furthest point toward the direction of pull.

Bill, what then would be the best installation for structural strength? When you say the "bigger the backing plate, the more load bearing" are you referring to the diameter/thickness of the plate or the overall length and width? Best, Ron

[Cheechako]

Originally Posted by rognvald

I also am in the process of replacing some amidship marinium cleats with low profile Schaeffer stainless steel cleats. The original cleats had no backing plate--only washers. The bolt holes were perfect after 21 years and the orginal core was clean and intact in the deck. I have drilled out the holes in the deck, filled with epoxy and will remount the new cleats with a 3/4" marine plywood backing plate saturated in epoxy. My question is: since a cleat has a lateral rather than vertical load apllied during use, is it not the thickness of the deck and the backing plate that provide the lateral resistance/intergrity/strength? The load is spread across a greater area rather than load pointing on a thinner installation with a stainless plate. Any physics junkies out there to make sense of this?

You are probably right about the load being very much in shear when the pull is horizontal, whenever it rises above horizontal the cleat is lifting on one end and bearing down on the other. ... a 3/4 ply backer would help a lot I would think.. the bolts are likely going to shear before you pull out a chunk of deck....

[capn_billl]

The plate has to both be able to resist deforming, so thickness, and hardness, and be big enough to transfer that force to an equivalent area of fiberglass. fender washers insure the nuts won't pull through the backing material. you will have to measure the fiberglass thickness, and the coring thickness at the point the cleats mount to find their strength before determining the amount of desired backing plate.

Usually as the fiberglass of the hull is the last thing you want to break, you make the backing plate oversized so the bolts holding the cleat will fail first. Bolts are easy to replace, reglassing a big hole is not.

I'm a big fan of overkill on things like this. I've had to replace backing on some cleats of a boat I bought because it looked flimsy, and the cleat wiggled when I yanked on it. After; I was being towed one day, and hit a bad wave, the tow line 7/8 Double braid snapped, the cleat didn't move. which is how I like it.

(note to board I'm an electrical engineer not a mechanical engineer, so for an "expert" opinion consider the source)