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Thread: Halyard cleat for circular aluminum mast

  1. #1
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    Default Halyard cleat for circular aluminum mast

    If I didn't want to use a cleat like a flagpole halyard cleat, but rather a full size horn cleat (like wood be used for a wood mast) would riv-nuts and machine screws me an acceptable method for fastening? This is for a small boat with a balanced lug (Welsford Walkabout).

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  2. #2
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    Default Re: Halyard cleat for circular aluminum mast

    Can you drive a closely fitting wooden plug into the mast to the place you want the cleat? Then screw, or through bolt to that.

  3. #3
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    Default Re: Halyard cleat for circular aluminum mast

    I don't know enough to recommend it, but that is what I did. My mast is in 2 sections, with the lower made from fairly thick wall tube (1/8"). It has not seen much use yet.

    This was a test section:


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    David, that's definitely an option, thanks.

    Thanks for the data point, Rick. Did it take much fitting to get the cleat flush with the mast? You know it's funny, now that I'm trying to think my way through the sailing rig, I'm finding that I'm coming to some of the same solutions you used for the same boat. Makes you wonder if it's a great minds think alike thing, or if my subconscious has just hung on to when I went through your build blog a year ago 🤔

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  5. #5
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    Default Re: Halyard cleat for circular aluminum mast

    How do you get the nut into place?
    I assume there's no halyards running through it....?

    The forces are shear, heavy self tapping screws, 14G, have done the job on my mast.
    It's all fun and games until Darth Vader comes.

  6. #6
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    Default Re: Halyard cleat for circular aluminum mast

    I’d lean toward stainless pop rivets. You’ll need a heavy duty rivet gun. Use a four-hole cleat if you can find it.

    Bronze hardware on an aluminum mast will corrode badly in salt water. You might get away with it by using plastic or fiberglass gasket and stainless fasteners, but better to use stainless, aluminum or plastic hardware or interpose stainless bracket of some sort. Always use an anti-seize like Tef-Gel on fasteners in aluminum.

  7. #7
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    Default Re: Halyard cleat for circular aluminum mast

    Pilot holes, the appropriate tap and stainless machine screws are my go-to.

  8. #8
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    Default Re: Halyard cleat for circular aluminum mast

    Those rivet nuts are 5056 aluminum, so are compatible with the mast. I got them from McMaster: https://www.mcmaster.com/94020A343/
    The specs say 1300 lb pull-out and 2000 lb shear strength. If you want to go that way I have plenty of extra nuts you can have, and the install tool which you are welcome to borrow. PM me.

    When I get back on my project, I plan to make one of Joel Bergen's wooden halyard jam cleats. A simple clever solution, there's a description in Small Craft Advisor.


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    I was looking at mcmaster carr as well, should have looked at the datasheet! (Bad engineer, bad) that's more than confidence inspiring enough for me.
    I plan to use 6" aluminum horn cleats with aluminum fastenings, etc. Plan to paint the masts as well.

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    Default Re: Halyard cleat for circular aluminum mast

    Quote Originally Posted by rgthom View Post
    I don't know enough to recommend it, but that is what I did. My mast is in 2 sections, with the lower made from fairly thick wall tube (1/8"). It has not seen much use yet.

    This was a test section:


    That looks like sound mechanical engineering but distinctly shaky for saltwater use.The mixing of copper based alloys with aluminium sets up quite a battery and leads to a lot of corrosion and all the barrier pastes do is delay the inevitable a little.

  11. #11
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    Default Re: Halyard cleat for circular aluminum mast

    Production boats use rivets or stainless screws. Of course the stainless screws break off when you try to remove them 20 years down the road, but they seem to hold up okay otherwise.

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    Default Re: Halyard cleat for circular aluminum mast

    Quote Originally Posted by John Meachen View Post
    That looks like sound mechanical engineering but distinctly shaky for saltwater use.The mixing of copper based alloys with aluminium sets up quite a battery and leads to a lot of corrosion and all the barrier pastes do is delay the inevitable a little.
    This was a test of the aluminum rivets. The other hardware was just stuff lying around, I would not use and do not recommend brass hardware in an aluminum mast. I knew someone would have to comment on that...

  13. #13
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    Default Re: Halyard cleat for circular aluminum mast

    Quote Originally Posted by rgthom View Post
    This was a test of the aluminum rivets. The other hardware was just stuff lying around, I would not use and do not recommend brass hardware in an aluminum mast. I knew someone would have to comment on that...
    Good to know you wouldn't use such a combination and hopefully anybody searching for information on the topic will learn why they shouldn't do it either.

  14. #14
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    Default Re: Halyard cleat for circular aluminum mast

    Al on Al...would it not make sense to just weld it?

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    I'm sure it would, but I don't have the tools or inclination at the moment. I guess I could hire that work out, but what's the fun in that

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  16. #16
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    Default Re: Halyard cleat for circular aluminum mast

    Drill, tap, screw. I have installed numerous fittings in aluminum that way without a problem.

  17. #17
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    Default Re: Halyard cleat for circular aluminum mast

    Drill and tap for machine screw. Then Tef Gel https://www.jamestowndistributors.co...RoCtRkQAvD_BwE
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  18. #18
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    Default Re: Halyard cleat for circular aluminum mast

    There's a lot of smart people saying drill and tap, but you have not said what wall thickness your mast tube is. If only 1/16", a 1/4-20 screw would have just over a single thread.

  19. #19
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    Default Re: Halyard cleat for circular aluminum mast

    You could always make a shaped metal block to fit inside the mast and tap it to suit the hole spacing.Welding an extruded mast may have an adverse effect on the heat treating and wouldn't be the best idea.

  20. #20
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    Default Re: Halyard cleat for circular aluminum mast

    To your point Rick, that's the kicker. These masts are pretty small, the thickness of the extrusion is 0.065" which is 1.3 threads --exactly as you said. I think some of these ideas for backing blocks inside the tube are ultimately pretty similar to fastening a riv-nut (threaded insertion that Rick's pic above demonstrates).
    16'5" Welsford Walkabout

  21. #21
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    Default Re: Halyard cleat for circular aluminum mast

    I would expect a riv-nut to spin at some point if you remove and replace the fastenings.A plate that spans both holes and is tapped will hold the bolts,but if you remove the bolts it may drop out of position and be hard to replace.A dollop of Loctite 638 might alleviate the problem.

  22. #22
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    Default Re: Halyard cleat for circular aluminum mast

    Those knurled rivnuts have a very tight grip, I have used them for other outdoor items such as a luggage rack on my car with no problems. If the threads seized up they could rip out, also the shoulder does protrude a bit. How about John's span plate with one extra threaded hole, for a small flathead screw to permanently hold it in the mast?

  23. #23
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    Default Re: Halyard cleat for circular aluminum mast

    I've done this sort of installation with nothing more than selecting a suitable diameter fine thread SS bolt and properly tapping the mast. Use LocTite or such.

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