Rivets or machine screws for mast steps?

[BAD ORCA]

I did a bunch of testing re. strength. Practical Sailor. Rivets in Spars. It may be behind a pay wall.

In a nutshell, less than 1/8" thickness, rivets are stronger, 5/32" machine screws are stronger, and at 1/8" it is a jump ball.

Lots of good advise. I'd go with monel rivets. Easier to work with up in the air (tapping a swaying mast sucks) and no sharp edges inside. I can drill them out.

Actually, I really dislike mast steps, but that is a different topic. I have a Mastmate that I like and have used for 30 years. It gets me nice and high, is fast to climb, and combined with a well-padded harness and tie-offs, is comfortable and versatile.

That was a great article, thank you. It answered my question about using aluminum rivets on an aluminum mast. would never had suspected it would be worse than stainless.

I also have a Mast Mate but my halyard really, really stretches a lot when i use it. It stretches enough that i cant get to the top of the mast to work. Also, i'm having a real hard time adjusting psychologically to the flexiness of the ladder. I dont consider myself afraid of heights, but i'm finding it difficult to get comfortable with and adjust to. I feel fairly comfortable climbing something thats solid and stable without any issues once I've climbed a couple of times.

 

[dLj]

That was a great article, thank you. It answered my question about using aluminum rivets on an aluminum mast. would never had suspected it would be worse than stainless.

I also have a Mast Mate but my halyard really, really stretches a lot when i use it. I bought the ladder and had it made the exact length of the mast to deck level. Big mistake. I'm only 160lbs and the halyard stretches at least three feet when i climb it. It stretches enough that i cant get to the top of the mast to work. Also, i'm having a real hard time adjusting psychologically to the flexiness of the ladder. I dont consider myself afraid of heights, but i'm finding it difficult to get comfortable with and adjust to. I feel fairly comfortable climbing something thats solid and stable without any issues once I've climbed a couple of times.

Mate - I think you need to upgrade your halyard!

Look, everyone has to do what they are most comfortable with - you want mast steps? Get mast steps. the ones you are putting on are probably the best I've ever seen...

I have an ATN ascender. Some people can't stand them. Oh well....

dj

 

[garymalmgren]

If the mast is down, drill and tap.
If the mast is up, pop rivets.

You say that there are 30 steps. ($1860).
That means 60 holes to tap and drill while hanging from a bosun's chair.
Not my idea of fun.

RE: are probably the best I've ever seen...

Take a good look at the pivot point. No support below, (blue arrow)

gary

 

[dLj]

If the mast is down, drill and tap.
If the mast is up, pop rivets.

You say that there are 30 steps. ($1860).
That means 60 holes to tap and drill while hanging from a bosun's chair.
Not my idea of fun.

RE: are probably the best I've ever seen...

Take a good look at the pivot point. No support below, (blue arrow)
View attachment 230881


gary

Gary, If you look at the drawings below this image on that web site, that support is integral to the lower section of the tang in the foot step. Your red arrow is almost pointing to it.

dj

p.s. actually, my biggest concern is the pin used that holds the two parts together.

 

[jssailem]

For Monel rivets. Not corrosion issues.

 

[jssailem]

my halyard really, really stretches a lot when i use it.

It would be less expense to get a new halyard that I low stretch than to put in the steps.

 

[jssailem]

That said, I like the step design.

 

[thinwater]

That was a great article, thank you. It answered my question about using aluminum rivets on an aluminum mast. would never had suspected it would be worse than stainless.

I also have a Mast Mate but my halyard really, really stretches a lot when i use it. It stretches enough that i cant get to the top of the mast to work. Also, i'm having a real hard time adjusting psychologically to the flexiness of the ladder. I dont consider myself afraid of heights, but i'm finding it difficult to get comfortable with and adjust to. I feel fairly comfortable climbing something thats solid and stable without any issues once I've climbed a couple of times.

The solution to halyard stretch is to pretension the halyard with the winch to more than you body weight plus live load. Then there can be zero stretch. Even with polyester halyards, I've done this many times. You should get right to the top. Really. The material of the halyard should play no part if it is pretensioned correctly.

You hands go on the mast, not the ladder. That also helps. Wear shoes that slide into the steps easily (no tread). Roll the ladder the correct way for storage and the rungs will fall open.

(The ladder is at the top of the mast. Keep your weight in and arms around the mast. Most of the steps are nicely open, as you can see, but one got squeezed by the spreader.)

It's all in the tricks.

(Note that the ladder is only about 4 inches down. I could have done better, but this is enough. Polyester halyard.)

 

[Project_Mayhem]

I prefer rivets for this application after I had a screw seize and snap due to corrosion. I guess the factory didn't believe in dissimilar metals causing issues.

 

[Michael Davis]

. I'm worried that its such a thin area of threads though.

Three threads are as strong as the bolt( machine screw) so there is lots of wall thickness for that.

 

[garymalmgren]

I have to disagree DJ.
The heel should look like this.
There also should be something to at least to resist the foot slipping sideways.

I know that there are reasons for foldaway mast steps but for safety, nothing beats the stirrup type.
Your foot cannot slip out sideways.

Back to the OP.
If you are going the (monel) pop rivet route try to beg, borrow or steal a power riveter.
As I mentioned 60 holes and rivets suspended is no fun.
A power riveter won't make it more enjoyable , but will cut the time aloft dramatically.
$50 on Ama###
Gary

 

[sailme88]

Rivets need to stand proud inside the mast. That makes for an excellent place for halyards and wires to foul..

I would drill and tap and use machine screws that will be flush to the interior wall....

 

[JBP-PA]

My mast is about 5/32" wall thickness. My mast steps came with stainless machine screws, but am wondering if stainless rivets might be better/stronger at securing the steps to the mast? Anyone have an opinion one way or the other? I like the rivets if they are safe enough because there is nothing protruding on the inside of the mast. I have internal halyards.

Rivnuts are another option. The strength of rivets and the removability of screws.

 

[Benny17441]

Rivets would be fine if you can use some high in quality and strength, not the cheap ones commonly found in box stores.

 

[dLj]

I have to disagree DJ.
The heel should look like this.
There also should be something to at least to resist the foot slipping sideways.

View attachment 230888
I know that there are reasons for foldaway mast steps but for safety, nothing beats the stirrup type.
Your foot cannot slip out sideways.

Foldaway and stirrup are two different things. Other than both being mast steps, not a lot more you can do to compare them. As in everything boating, there are compromises.

Although I would like to hear more on why you feel you need that added red section? Maybe I'm missing something. To me, that region is all about the strength to keep the step in it's unfolded position. Is there something more that you feel it needs to do?

The purple addition you have drawn - yeah maybe, but you are heading more to the stirrup type step which I feel is another system. You can't have both.

As foldaway steps, these present the least windage, cordage fouling, side profile I've seen. The construction appears to be very well done. If I were going to a foldaway step, I've never seen a better looking and well made one on the market. Hence my comment these are the best I've seen.

dj

 

[thinwater]

Rivets would be fine if you can use some high in quality and strength, not the cheap ones commonly found in box stores.

McMaster Carr. All kinds, some VERY strong.

 

[smokey73]

These are good looking steps but I see a few misconceptions/problems.

1. The attachments (screws) are not just in shear. In fact, the top screw is clearly in tension as the pivot point acts as a fulcrum and tends to "pull out" the top screw. Even the bottom screw is probably in some tension depending on the geometry and when where the foot is on the step but it looks like it would be in some tension. Do an experiment. Screw the step into some wood (not very deep or big to you don't have to strain too hard) and then pull down on the step. I'll bet dollars to donuts that the top screw will pull out easily followed by the bottom screw. I'm not saying it is a bad design, but the top screw is clearly in tension.

2. I have folding steps (three). I frequently go up on these to secure the sail when it is down. I find that sometimes if my foot "catches" on one of the steps as I step up and it folds up. When it does that I can get down okay, but if it were to happen up high on the mast I'd be hard pressed to get to the next step down without some gymnastics. Of course, I assume you'd be going up higher on the mast with some sort of secondary way to lower you. If not, you might be up the creek without a paddle.

 

[smokey73]

From an installation standpoint. The screws require drilling the hole in the mast while suspended and then using a tap to thread the holes. Any, even small, misalignment will make it difficult to install the threaded fastener. While suspended in the air, the "opportunity" to drill the hole even a little off or the tap at a little bit of an angle is at least non-zero. With high strength rivets you cut out one of the steps and there is a little more clearance in how the rivet typically fits into the hole. If you can get the strength you are comfortable with I'd go with the rivets. (JMHO)

 

[Hayden Watson]

On my C30, I attached a 1" T-track to the front of my mast for a mast mounted whisker pole which used 1/4" screws. I drilled and tapped them into the mast, and all were able to torque down to 15-ft-lb. I measured the total length needed to fully engage the threaded cut into the mast and got screws that were just a bit longer. I then used my bench grinder to round the ends of the treads to a smooth round surface that would not snag on my four internal halyards. It has worked perfectly for the past 12-years. I set each screw into TEF-45, and the paint has not shown any signs of blistering, and the screws are each to remove.

I installed most of the screw from my bosun's with drill and tap. I used a self-centering push spring punch to make the dimple for the drill and all fit perfectly. I would drill, tap and install each screw before moving to the next. I ended up with 20 screws with none that did not fit.

 

[LloydB]

Just offhand I suspect that you would be able to support yourself by standing on the outside end of the step if the top screw ONLY was screwed into the mast. It wouldn't matter how many threads were attached to the air inside the mast as long as the screw was torqued down properly. However I suspect their insurance company would not accept that as proof of concept but would instead expect engineering diagrams.