Front Cross Beam Cleats?

[pstadt]

Currently in the yard for a bottom job and having estimates worked up for installing a couple of cleats on the forward cross beam - boat is a 2011 FP Orana.

Yard has recommended drilling and tapping the top, isolating each stainless cleat with a 1/32" pad of G-10 and coating the bolts before attachment and that's what we are currently favoring. Service manager has also recommended removing every couple of years for inspection of connections once installed.

We've considered the other two options that I know of (completely through-bolting, with same isolations or welding the cleats to the cross beam).

Any other logical options that we are overlooking?

Any objections to the yard recommendation of drilling and tapping?

Recommended cleat size? Currently looking at same size as mooring cleats that came on the boat from FP.

Thanks!

Pat and Michelle

[DotDun]

IMO, you need to be careful with crossbeam cleats. The beam was not designed for the twisting loads that mooring cleats can place on it. I took this picture at a boat show on a Leopard catamaran which comes from the factory with crossbeam cleats. It may be worth asking FP their opinion.

[neilpride]

The warning label say all, be aware what you rig to the cleats and forget welding unless you want to weak the crossbeam.....

[paxfish]

My front cross beam is made from an aluminum mast section. The builder through bolted the cleat in the center, with an aluminum backing plate inside. How he positioned the plate and held the nuts while tightening I have yet to figure out, since it was about 9 FEET down the tube.

Anybody know what sort of trick might have been used?



If I add cleats - there will be one near each end of the beam and mooring lines will cross.

[neilpride]

They usually fit a aluminium cover big enough to handle the inside in most production cats.. Now i dont know if yours have the cover plate.....

[Privilege]

A better option if you are able...

[Cotemar]

pstadt,

My vote would be to add Bow cleats instead of seagull striker cleats.
Bow cleats will be dual purpose. Mooring / Down wind sail (Parasailor).
With Bow cleats you can use a soft shackle and a block for your down wind sail.

Make a 3/8 inch thick backer plate out of AL6016 aluminum for the Bow Cleats.

If you prefer the seagull striker cleats, then I would through bolt them and just use nylon washers on both sides.
Did that on our last cat and had no corrosion for the 7 years that we owned her.

You have Goiot Deck Cleats, but not sure what size.

[Cotemar]

Correction from my post above.
Make a 3/8 inch thick backer plate out of AL6061 Aluminum for the Bow Cleats.

[Tingum]

You do not just through bolt them to the cross beam. You must use a compression tube on each bolt inside the extrusion to keep from compressing it. If it is compressed out of shape you have created a weak spot. As others have suggested it is easier and just as strong to put them on the hulls with a good Aluminium backing plate with lots of goop to keep moisture from getting between the plate and the hull.

[Rapanui]

If I understand the OP right, the intention is to tap the mast section. Is the mast section sufficiently thick to have a sensible number of threads for strength?. I have my doubts. How thick is the section and what thread are they tapping?

[Stumble]

I absolutely would not do this, and certainly not without calling the builder and getting their approval for it. Any defect in the crossbeam can cause point loading and catastrophic failure at far lower loads than designed for.

Find somewhere else to add a cleat.

[thinwater]

The OP has not told us what they are for or given any hint as to the load. We don't know the cross beam design. Nothing to talk about.

But yeah, the whole idea is very disconcerting. The fact that they are the same size as mooring cleats is scary.

---

I have 2 small pad eyes on my beam, near each end in a low stress area. They are for chute bridles, and the load is probably never over ~ 500 pounds, and not at the same time as the genoa. No problem. On the other hand, if they were for a bowsprit or mooring, it could be bad. Just don't know.

[Palarran]

First, I have no idea why you would need cleats on the cross beam, but in any case, no way would I do it. The strength of the cross beam is outward and up, not forward.

[out42]

I really wouldn't do this. Having just had the martingale stay on mine torn off by a wave, you suddenly become very aware of how vital the front beam is!
A better plan would be to put some fairleads on the beam where you might have put the cleats and then use the cleats on the hulls. That gives you all the cross-threading you could want for your ropes but doesn't weaken the beam as the fairleads can be screwed into tapped holes in the beam and backed with epoxy. No compression or bending stresses.

[UNCIVILIZED]

Originally Posted by Stumble

I absolutely would not do this, and certainly not without calling the builder and getting their approval for it. Any defect in the crossbeam can cause point loading and catastrophic failure at far lower loads than designed for.

Find somewhere else to add a cleat.

The above gets my vote... mostly. And I say mostly, as I'd be hesitant to do it even with the nod from the builder. As the price for having the cleats weaken the beam at all is simply too high. And assigning a "load rating" to cleats there distinctly creates a severe problem waiting to happen. Ditto on a warning sticker on the crossbeam being useless for the same reasons.

Originally Posted by thinwater

The OP has not told us what they are for or given any hint as to the load. We don't know the cross beam design. Nothing to talk about.

But yeah, the whole idea is very disconcerting. The fact that they are the same size as mooring cleats is scary.

---

I have 2 small pad eyes on my beam, near each end in a low stress area. They are for chute bridles, and the load is probably never over ~ 500 pounds, and not at the same time as the genoa. No problem. On the other hand, if they were for a bowsprit or mooring, it could be bad. Just don't know.

I can partially understand the thinking above. But what happens when the halyard shackle lets go, & you wind up with the kite going into the water while doing 8kts. That creates tremenddous loads on everything that it's attached to. And having a spinnaker go for a swim tends to be a "when" (will it occur) type question, not an "if" type one.

The other thing is that regardless of how well the skipper knows the "load rating" of a particular pair of cleats, not all of the crew will. And strangers definitely won't. So then what happens when they attach a dock line to them when you're not there. Which again is a question of when will it happen, not one based on "if" it happens.


Edit: For those who asked, or are wondering, most mast extrusions have wall thicknesses in the 3.5 - 4.5mm range. Which isn't thick enough to tap for the fasteners used in the cleats discussed. Plus, aluminum dislikes shock leads on fasteners that are tapped into it, & cleats certainly see loads that meet that description.