Torque on a cleat

[Tom.B]

We want to add additional cleats to our swim platform so our crossed stern lines are not such a pain to step over to get onboard when we are at floating docks. I have a couple of options where I can mount them. When we were down at the boat last weekend, I saw a boat just like ours that had extra cleats mounted, however, they were mounted on a vertical surface that meant the pull direction was effectively "up" and not laterally. Is there any reason a cleat would be less strong when the load is vertical to the mounting point versus perpendicular?

 

[Ftbinc]

Not sure, but it seems the pressure would be on the horns of the cleat instead of the body. So the force would be, as you noted up, not side to side and the load would be out on the moment arm (the horns) and translate to just the screws/bolts/backing plate instead of the deck. Oversized with big bolts and backing plates?

We want to add additional cleats to our swim platform so our crossed stern lines are not such a pain to step over to get onboard when we are at floating docks. I have a couple of options where I can mount them. When we were down at the boat last weekend, I saw a boat just like ours that had extra cleats mounted, however, they were mounted on a vertical surface that meant the pull direction was effectively "up" and not laterally. Is there any reason a cleat would be less strong when the load is vertical to the mounting point versus perpendicular?

 

[O C Diver]

I would start with, what is my swim platform made of? Is it cored? Where the existing cleats are, is it solid? My swim platform is cored. Short of cutting out the coring and making it solid fiberglass, the cleats would probably tear out.

Ted

 

[Comodave]

If your swim platform is fiberglass then it is almost certainly cored. You can attach cleats to it if it is structurally sound. You will need to remove the core where the bolts go through. Compass Marine has a very good how to for cored decks and through bolting. Then use a substantial backing plate and bed it with thickened epoxy so it is in good contact with the bottom of the platform. But you first need to determine if the swim platform will hold onto the boat if that is where you have it tied to the dock... unless it is an integrated swim platform.

 

[Tom.B]

Thanks for the replies... but I am not needing tips on installing the cleats. Well, not yet anyway. My curiosity is whether the direction of pull is a factor in how it holds. It makes a difference in where I could (or should) mount them. While I think there is little chance of the horns bending and failing... would even a well attached cleat pull out if the direction of torque "up" and not to the side? Is there any difference?


(oh... and yes, I believe the deck is cored, but I am not 100% sure the vertical part is or not. have to check that for sure)

 

[kapnd]

The cleat itself is plenty strong in either direction, the bolts and the backing are more likely to be fail points under high stress.
If you mount the cleats to the swim step, you might want to make them weaker than the swimstep mounts, so that they would fail before the swim step gets torn off the boat.
How about attaching cleats to the hull down low on the outside, or use a hawsepipe with cleats on the inside?

 

[Roamer Blue]

One puts the fasteners and backing under direct load, straight up, the other loads the material the fasteners pass through, sideways.


It depends on install methods through what material?



Lots of poor cleat installs count on the sideways pull/material to do the job, we've all seen poorly installed cleats that would come out by the roots if pulled vertically, yet hang together pulled sideways.

 

[caltexflanc]

Cleats on pilings are vertical.

 

[Tom.B]

(Good point George. Thanks)



Here are the two options. For the sake of argument, let's focus ONLY on these two spots. Everywhere else has challenges.


The arrow on the left is the NORMAL location for secondary cleats on Navigators. The arrow on the right is where the one I saw Saturday is and the one that would pull the cleat straight upward with crossed lines.



TBH, I am leaning toward the left arrow, but it is the hardest to get to the back and the surface has a curve to it, so the install would be more difficult.

 

[Comodave]

The down side of the left arrow location besides what you already stated is that in the case of a fall, someone can get hooked on the cleat much easier than the right side location. We responded to a case with a similar location of a cleat on the boat. The man fell off the swim platform and hooked his wedding ring on the top horn of the cleat. He ended up in the water and his ring and ring finger stayed on the cleat, not pretty.

 

[Jdoc]

A cleat in the left location is more versatile because a line can go to the port or stb aft of the boat, whereas the right side location would chafe the line on the corner of the hull extension when tied to stb.

 

[Tom.B]

The down side of the left arrow location besides what you already stated is that in the case of a fall, someone can get hooked on the cleat much easier than the right side location. We responded to a case with a similar location of a cleat on the boat. The man fell off the swim platform and hooked his wedding ring on the top horn of the cleat. He ended up in the water and his ring and ring finger stayed on the cleat, not pretty.

Well... ummm... okay then. I think the statistical probability of this is so astronomical, it is hard for it to really be a deciding factor. However, thanks for the warning. If I put it there, I will exercise caution.

 

[firstbase]

People jumping off the boat or swim platform and catching bathing suit or shirt on it is certainly more probable. Although...given the name of your boat that might not be an issue.....

 

[markpierce]

If not an integral part of the hull, I'd be leery of any cleats on a swim platform.

 

[sbu22]

The forces on the cleat will have both a vertical (up) and a horizontal component, particularly with crossed lines. Not sure that will be a lot different than, say, a typical cleat tied off to a fixed location with tidal and wave action.

Practical Sailor did a cleat test of a bunch of cleat material types some years ago. Think they varied the load vectors considerably. The only cleats that failed were nylon and some other "plastic" units. The other failures occurred in the fastening bolts. As usual, the performance will probably be dictated by the quality of the base mounting materials and the backing plates.

 

[Tom.B]

People jumping off the boat or swim platform and catching bathing suit or shirt on it is certainly more probable. Although...given the name of your boat that might not be an issue.....

:lol:

 

[Tom.B]

The forces on the cleat will have both a vertical (up) and a horizontal component, particularly with crossed lines. Not sure that will be a lot different than, say, a typical cleat tied off to a fixed location with tidal and wave action.

Practical Sailor did a cleat test of a bunch of cleat material types some years ago. Think they varied the load vectors considerably. The only cleats that failed were nylon and some other "plastic" units. The other failures occurred in the fastening bolts. As usual, the performance will probably be dictated by the quality of the base mounting materials and the backing plates.

Good stuff. Thanks.


I wonder if there is a way to discover the fiberglass thickness of a hull section WITHOUT drilling thru it? Any ideas?

 

[Bacchus]

Good stuff. Thanks.
I wonder if there is a way to discover the fiberglass thickness of a hull section WITHOUT drilling thru it? Any ideas?

Tom
If you pull the cover on your elec inlet you will get an indication on thkness but not exact.
No matter where you put them I'd recommend the Pop Up cleats - very neat and they eliminate the hang-up issue mentioned... funny the odds must not be as high as we think - we had a guy reach and fall catching his belt on a cleat at the stern. Ended up hanging upside down at stern w/ engines running - his wife froze.

Do you have access to the transom area? I had a similar situation and looked for a way to get stern cleats down low. I ended up only able to get one on the stbd side but that was the area of concern for boarding from floating docks. I'll attach a pic.

Pop-up Cleats The Attwoods are very nice and you can get a SS backing plate to match the holes - recommend the backer Pl.

Mounting low to the swim deck like the pic works very well if you can get access behind the stern to place a backer & tighten the nuts. Mine was solid FG near waterline - cored above so it worked well - if not you can do the oversize fill & redrill approach. Lines not a tripper easy to step on or over them

 

[sbu22]

Tom- I expect that your local ultrasonic tester (usually an industrial service) could do it with a recalibration of their tools. $ might be the issue. A couple of years ago I posted my decidedly unscientific study of the use of helicoils in FG for stanchion bases on my boat. Bolts anchored with helicoils with 1/4 20 fasteners could only be removed with a crowbar and took several surrounding square inches of FG with it. That was 3/8 FG.

 

[Rain Dog]

BoatUS tested cleat strength at different pull angles:

https://www.boatus.org/findings/16/

 

[BruceK]

... man fell off the swim platform and hooked his wedding ring on the top horn of the cleat. He ended up in the water and his ring and ring finger stayed on the cleat, not pretty.

Few things are perfect,a downside of marriage.

 

[North Baltic sea]

BoatUS tested cleat strength at different pull angles:

https://www.boatus.org/findings/16/

Hi, thanks for sharing the test, the fact is better on this matter than just the opinion, interesting different materials work logically when the pull angle change.

NBS

 

[vanderzeeh]

I woud not go for the classic cleat on a swimplatform on the positions as marked by Tom. People wil get hurt sooner or later. A better solution is using cleats with can be moved into save positions, See 2 exampels below.

 

[wkearney99]

My first thought, before reading any replies, was ouch, don't mount fender horns upward along a surface that has any chance of someone sliding down across it.

Well... ummm... okay then. I think the statistical probability of this is so astronomical, it is hard for it to really be a deciding factor. However, thanks for the warning. If I put it there, I will exercise caution.

Losing fingers is more common than you'd think. A friend had a guest onboard trying to handle lines during a raft-up. The ring worn on the thumb when with it and the situation suddenly went wrong and there was too much tension on the line.

 

[wkearney99]

People jumping off the boat or swim platform and catching bathing suit or shirt on it is certainly more probable. Although...given the name of your boat that might not be an issue.....

https://www.msn.com/en-gb/video/new...ween-fence-panels-by-its-testicles/vi-BBORNsr