Mast Steps

[JamHass]

This has been a great thread. Let me start by noting a couple of disclosures:
1. I am one of Matt's satisfied customers
2. I am a former rock climber
3. (Contrary to Matt's statement) I'm over 60 (thanks Matt!)

All that said, let me amplify Brion's (and other's) cautions that some form of fall protection is necessary, and that applies to any mast steps. In my opinion, ALL one can ask of any mast steps is to make the task of getting up there less strenuous, and that alone makes it safer. I climbed my mast many times before installing Matt's steps, and I've tried probably all methods, from hand-over-hand to prussiks & Jumars, and several rigs and proprietary methods. None are as easy as steps, and Matt's work very well.

I noticed a comment that the two screws/rivets might not be sufficient. I am an engineer, and I'm not concerned. The load will always be static, limited to the climbers weight, and on the order of 10% of the shear strength of 2 1/4-inch screws. I have cleats and other fittings held with 2 1/4 inch bolts threaded into the mast that take far greater loads.

The small size can be seen as an advantage: they certainly do NOT give you a false sense of security, so there is a very good chance the average sailor will actually use a proper belay.

All in all, I am very pleased with the results, and recommend them. With luck, the time I spent installing them will reduce the chance I'll need them "in anger" (fat chance.)

Jim

[Bluenose]

Originally Posted by JamHass

.....I noticed a comment that the two screws/rivets might not be sufficient. I am an engineer, and I'm not concerned. The load will always be static, limited to the climbers weight, and on the order of 10% of the shear strength of 2 1/4-inch screws. I have cleats and other fittings held with 2 1/4 inch bolts threaded into the mast that take far greater loads......Jim

Jim,

Obviously you have more installation experience with these than we do, but from the website pictures it really looks like a pair of aluminum pop rivets supporting the mast step.



I did some structural engineering in a past life as well and it wouldn't be the shear loads that would concern me. It would be the tension loads on the fasteners required to react the heel and toe moment cause by the climbers weight. I never really liked having pop rivets in shear, but I would never used them in tension.

And baring detailed dynamic loads, we always assumed a minimum dynamic amplification factor of 2. And I can think of a few scenarios where a factor greater than 1 would occur.

I don't know any actual dimensions but it appears that the width of the mast step is similar to the distance between the rivets and the bottom of the bracket (the heel and toe).



Therefor the loads on the fastener will be similar to the load of someone standing on the edge of the mast step. Add in a dynamic factor, say you slip off the step above and a 200 pound person could applied a tension load of a couple hundred pounds per rivet. And that is a real load for a 1/4 inch aluminum rivet. Nothing like the shear loads they experience holding a cleat to the boom (although I still prefer tapped screws here as well). Blind rivets just weren't designed to take tension.



I don't have a dog in this fight since my sailing priorities would negate mast steps as an option but I think Brion makes some pretty valid points and I would really look hard at any potential failure mechanisms since your life may depend on it.

Bill

[Auspicious]

With all due respect to the creativity of the designers, those things scare the bejeepers out of me. If one were to slip off and swing on the safety line the pain and injury from hitting one or more steps edge on when swinging back would be really awful.

Of course I don't think free-climbing a rock face is any fun either.

In my opinion the very best advance in getting to the masthead is an electric winch. The ride is steady and smooth and darn near peaceful. Further, for those of us that don't have gorillas to grind us up, you don't have to sit there and wait fruitlessly while your grinder rests.

sail fast, dave

[Ian McColgin]

Anyone who cruises extensivly will need a way all the way up sometime, likely in poor conditions with lots of breakage around. I'm a former rock climber myself and worked as a steeple jack, arborist and rigger so I have a lot of confidence about what I can climb. But when I was doing an artificial climb, I never relied on a cliff hanger if I could put in a nut. 'Nuff said to any climber.

[JamHass]

Bill:

You are absolutely right, I wouldn't trust aluminum pop rivets either. The ones in the photos are actually stainless steel. When I installed mine, I used SS screws, but more for ease of maintenance in case of future removal for painting, etc.

Structurally, I suspect that its really a push using stainless screws vs stainless pop rivets. Its the threads in the aluminum that are the weak spot for screws, and the pop rivet likely has a similar overall resistance to tension. Since its pretty easy to mess up the threads -- bad drilling, bad threading or overtorquing the screw -- there is some advantage to the rivets.

I also agree that Brion raised some very valid points. In particular, they are indeed easy to slip off of, and it is neither particularly comfortable nor highly secure to stand on them for very long. Because of that I used a pair of folding mast steps at the masthead to provide more secure footing.

And yes, I always use protection when climbing the mast. I never was a free-free climber, and I don't plan to become one now.