Best way to attach a cleat to mast?

[goldenstate]

I've run a topping lift line for a whisker pole. I would like to have a dedicated place to tie off the line on the mast when it is in use.

It doesn't make sense to run it back to the cockpit, as I will be forward messing with whisker pole any time I need to manipulate the line.

I think @Christian Williams had a similar cleat on Thelonious/Makana:



I'm looking for suggestions on the best way to attach such a cleat to the thin wall of my mast.

A few similar threads around on other sites:

Adding a Mast Cleat - Cruisers & Sailing Forums

OK. The furling genny halyard takes up one clutch on the piano, somewhat uselessly. I got a hold of a suitable cleat and am contemplating attaching to the port side of the mast , securing the halyard

www.cruisersforum.com

Attaching a cleat to the mast | Jeanneau Owners Forum

i am looking to replace small cleats on my mast used for lazy jacks with larger ones. My first thought was to drill and tap the mast for machine screws to attach the cleats. When I went

jeanneau.proboards.com

Has anyone used "Rivnuts" ?

Rivnuts in mast - which type?

I intend to mount an extra cleat on my mast, and have decided to use rivnuts. The cleat will be mounted with M6 s/s socket head set screws. The question I have is this. Do I use s/s rivnuts with plenty of chromate paste in the mast or aluminium rivnuts and rely on chromate paste on the...

forums.ybw.com

This guy uses some sort of sleeved connector to attach a clutch to his mast.
He certainly has experience with various penetrations if his earlobes are any guide.

Should I just drill and tap the largest diameter machine screw that will fit through the holes in whatever cleat I buy?

Thank you for any suggestions.

 

[gadangit]

I have attached cam-cleats, horn cleats and a rope clutch to my mast with the drill and tap method. To make myself feel better, I did the math to see how many threads were actually holding and it seemed good enough. And they have all held up just fine, some under some pretty serious load. I gooped up each screw with Tefgel when installing.
Chris

 

[HerbertFriedman]

I have mounted several cleats on my mast and boom, drill and tap, but I use the finest thread I can get. Typically I use 10-32 screws ( to get 4 threads in 1/8 wall thickness) instead of the more normal 1/4-20 and of course tef-gel.

 

[Christian Williams]

Agree. Use the cleat itself as a guide for the tap kit drill. Angling the cleat leaves a little space under the cleat base, given the radius of the mast, and so the drill bit has to enter the metal at a small angle. Put a cleat on each side and make them big enough to suspend their coil of line.

This shows the tapping process:

E32-3 - Halyard Cams on the Mast, Thelonious

Cams on the mast are an easy solution to an issue created by halyards led back: how does one person work the halyard at the mast? As you may have noticed, hauling up the main on the cabin house leaves a pile of halyard at your feet. But the line...

ericsonyachts.org

 

[Martin King]

If you are tapping stainless fasteners into an aluminum mast, be sure to use some anti-seize lube on the threads.

 

[Rocinante33]

I've run a topping lift line for a whisker pole. I would like to have a dedicated place to tie off the line on the mast when it is in use.

It doesn't make sense to run it back to the cockpit, as I will be forward messing with whisker pole any time I need to manipulate the line.

I think @Christian Williams had a similar cleat on Thelonious/Makana:

View attachment 34992

I'm looking for suggestions on the best way to attach such a cleat to the thin wall of my mast.

A few similar threads around on other sites:

Adding a Mast Cleat - Cruisers & Sailing Forums

OK. The furling genny halyard takes up one clutch on the piano, somewhat uselessly. I got a hold of a suitable cleat and am contemplating attaching to the port side of the mast , securing the halyard

www.cruisersforum.com

Attaching a cleat to the mast | Jeanneau Owners Forum

i am looking to replace small cleats on my mast used for lazy jacks with larger ones. My first thought was to drill and tap the mast for machine screws to attach the cleats. When I went

jeanneau.proboards.com

Has anyone used "Rivnuts" ?

Rivnuts in mast - which type?

I intend to mount an extra cleat on my mast, and have decided to use rivnuts. The cleat will be mounted with M6 s/s socket head set screws. The question I have is this. Do I use s/s rivnuts with plenty of chromate paste in the mast or aluminium rivnuts and rely on chromate paste on the...

forums.ybw.com

This guy uses some sort of sleeved connector to attach a clutch to his mast.
He certainly has experience with various penetrations if his earlobes are any guide.

Should I just drill and tap the largest diameter machine screw that will fit through the holes in whatever cleat I buy?

Thank you for any suggestions.

I would agree that the drill and tap technique is the simplest and easiest on the mast. Rivnuts, also called nutserts, Threadserts, are really good when threads have been stripped and the hole must be drilled oversize. But I would only use them if I have to. I see the logic to using fine thread screws, BUT the fine threads are more likely to seize with the dis-similar metals in play. As Martin said, anti-seize compound is essential......locktite blue, ultra TefGel, Lanocote, etc. So perhaps coarse threads are best.

BTW, my mast thickness (tapered mast) is listed as, 0.140 to 0.300”, so there is pretty good thickness there to tap threads into. YMMV

 

[garryh]

it is somewhat counter-intuitive, but coarse threads should be used on an aluminum mast. The amount of (soft metal) material left between fine threads may not be sufficient 'grab' to resisit the significant forces that can occur. But a backing plate with a nut of any kind if far superior

 

[Second Star]

I have used "nut-certs" to attach to my boom and it would be a good solution for a mast too. They are essentially a "pop rivet" but once installed you have a nut permanently installed rather than a rivet. You then use an appropriately sized bolt to attach your item.

 

[tenders]

My current favorite method is to drill and tap a strip of 1/2” G10 to slide inside the mast to use in lieu of a backing plate and nut (with butyl tape around the fastener from the outside). Very strong, will not corrode the mast or the fastener threads, and just drops at the mast step if I decide to remove the fitting. If necessary, you can make the strip extra-long to use as a handle to position it in the mast, or tape it temporarily to a stick.

G10 used like this is also useful for backing plates for hardware mounted on deck, when the headliner might be in the way for a normal nut. I have this issue for the turning blocks coming off the mast.

 

[goldenstate]

My current favorite method is to drill and tap a strip of 1/2” G10 to slide inside the mast to use in lieu of a backing plate and nut (with butyl tape around the fastener from the outside). Very strong, will not corrode the mast or the fastener threads, and just drops at the mast step if I decide to remove the fitting. If necessary, you can make the strip extra-long to use as a handle to position it in the mast, or tape it temporarily to a stick.

G10 used like this is also useful for backing plates for hardware mounted on deck, when the headliner might be in the way for a normal nut. I have this issue for the turning blocks coming off the mast.

Do you mean that you thread into the G10 alone? Or G10 with a nut behind it?

 

[tenders]

Just the G10, no nut. G10 takes and holds a surprisingly wicked thread, and is easy to tap.

 

[goldenstate]

Interesting. I wouldn't have guessed it would hold threads, but I have little knowledge of G10.

With my keel-stepped mast and my desired cleat placement, I would have to find a way to reach that small piece of G10 backer about 8-9 feet up inside the currently un-stepped mast. I'm not sure I have the patience for such a process

 

[tenders]

Ah. Yes, an 8-9 foot run might be a little tricky. (My mast is deck-stepped.)

But,,,I bet there’s a way. What if you pulled the backer to the location with thread through one hole, got the other hole started, removed the thread, and used the partially-threaded bolt to align the previously-threaded hole?

 

[Kenneth K]

Not sure why anyone would use a backing plate for fasteners in threaded structural aluminum. If it's a high-load application, the answer is to use more (and/or larger) fasteners (look at your boom-gooseneck and boom-vang attachment plates, for example). It's particularly confusing when the backing plate material is weaker than the material which holds the threads.

 

[Christian Williams]

I had similar thoughts.

 

[tenders]

For my suggestion: because over time the stainless/aluminum threaded connection corrodes, and everybody loses. The G10 backer is in lieu of a nut, not really a backing plate as you’d use on a stanchion base.

I’ll refund the money you paid me for this advice if you don’t like the result!

 

[Christian Williams]

It's a useful discussion. A few applications do seem to require backing plates. I've seen that recommended for powerful vangs.

But there are scores--hundreds--of fittings normally attached to spars by stainless screws, tapped and not tapped. Sometimes rivets are used, aluminum or stainless. They need a coating of Tef-gel or similar against corrosion. It works.

 

[Kenneth K]

I was a bit nervous last year when I drilled and tapped my first holes into the mast for this halyard cleat:



This year, I drilled and tapped 22 more holes in the mast--2 for a halyard clamcleat, and 20 for a spinnaker pole track. All of them came out with a great fit. The biggest challenge is aligning holes properly across the curvature of the mast--having a proper fitting mounting base helps for that. For the clamcleat, I made a curve-fit base with thickened epoxy "poured" against blue painters tape stuck to the mast (then painted with black enamel).



The pole track required twenty 5/16-18 holes in a straight line:



(as if by magic, the front and base of the mast got painted along the way.)

My recommendations for tapping spars:

- I always start with a new or fairly new tap (I used 2 taps for the 20 holes to ensure they were sharp--cost me an extra $8....).
- Buy self-aligning taps (they have a longer "nose" which fits further into the pilot hole to help alignment before you start cutting threads)
- Buy the exact size pilot bit for the tap: (Irwin sells self-aligning bits that come with the proper pilot bit included)
- Use a cutting oil formulated specifically for aluminum (a machine-shop guy told me this matters)
- Always use Tef-Gel or Duralac, etc on the fasteners (to tenders' comments about corrosion)

 

[G Kiba]

Are you guys forgetting that in most cleat applications the force is in shear on the fasteners? Pulling out threads is less of a concern. Fine pitch threads work well in thin aluminum. In fact you want a minimum of three threads! So for 1/4-20 thread in .125 thick material, 20 x .125= 2.5 threads. For 1/4-28 thread, 28 x .125 = 3.5.

 

[gadangit]

Are you guys forgetting that in most cleat applications the force is in shear on the fasteners? Pulling out threads is less of a concern. Fine pitch threads work well in thin aluminum. In fact you want a minimum of three threads! So for 1/4-20 thread in .125 thick material, 20 x .125= 2.5 threads. For 1/4-28 thread, 28 x .125 = 3.5.

Broken cam cleat. Threads are just fine and continue to hole the replacement 3 years later.