Rivets or Machine Screws When Splicing a Mast?

[Chotu]

Originally Posted by MicHughV

Chotu,

Tough to make a comment on this without knowing all the particulars.

There are a variety of topics concerning this issue online with proponents on each side, worthy of some time and effort on your part to read and digest.

I seem to recall you saying in a previous post, that the mast extension will be on the bottom of the mast. If this is correct, I'd favor the machine screws, for a variety of reasons, but in essence, you've already stated that the sleeve and mast are not a perfect fit, and for this reason alone, I'd favor the screws.

But they are really too many other variables here to properly ascertain with any degree of confidence on my part.

At the end of the day, I'd take the mast to a shop or have the shop come to you, as there will be likely a number of fasteners employed and number, spacing, etc, will be important, as well as fastener diameter, thread type, material type and so on.

I've noted this before, the compression and bending loads on a mast is quite enormous, as in tons enormous, so think twice and drill once.

This is not an area where saving a few bucks makes sense, so suck it in and get a pro to do the job for you.

Hey! You almost got yourself rail meat duty on the sailing trip. Ha ha ha.

Why? You missed this:

I’m asking what the PRO should use!

He needs to order these things soon so he can make the deadline to get the mast over to the rigger.

Nothing is a perfect fit in life if you analyze it enough. So I’m imagining there are very small gaps here and there that the inner piece may not fully contact the spliced pieces. It seems something that pulls them together is better than something that doesn’t pull them together. That’s all I was saying. I was trying to come up with something to help with the decision

[boatpoker]

Originally Posted by Chotu

He says, “do you want me to use rivets or screws… I need to know soon so I can order them”

That can be interpreted a a couple of different ways. He either knows what he's doing and believes either method will work or ...

Do you have faith in the guy ?

[Chotu]

Originally Posted by boatpoker

That can be interpreted a a couple of different ways. He either knows what he's doing and believes either method will work or ...

Do you have faith in the guy ?

He’s looking for my preferred way of fastening these things.. And nobody knows what to use. I certainly don’t. There are 2 choices and I have to make one.

This thread has only confused me. Because everybody has their own opinion on which is better and makes perfect sense when they present their case.

So it seems seem very much 50/50. But I need to choose one and have him do it.

Since every mast these days arrives with a splice, what do they use normally? Has anyone seen a new boat recently? I haven’t. I’ve been nose down working and haven’t seen one. But every new boat (of larger size) uses something.

[boatpoker]

Originally Posted by Chotu

He’s looking for my preferred way of fastening these things.. And nobody knows what to use. I certainly don’t. There are 2 choices and I have to make one.

This thread has only confused me. Because everybody has their own opinion on which is better and makes perfect sense when they present their case.

So it seems seem very much 50/50. But I need to choose one and have him do it.

Since every mast these days arrives with a splice, what do they use normally? Has anyone seen a new boat recently? I haven’t. I’ve been nose down working and haven’t seen one. But every new boat (of larger size) uses something.

The 50/50, either or option was my first post on this thread. Hey maybe I was right for once . Whatever you choose I hope it works out for you. It's been a long haul.

[Chotu]

Originally Posted by boatpoker

The 50/50, either or option was my first post on this thread. Hey maybe I was right for once . Whatever you choose I hope it works out for you. It's been a long haul.

For once. Ha ha ha. I don’t know about that. I’m not sure I’ve ever seen you post incorrect information.

Anyway, maybe he should decide. That will make it easier.

[GRIT]

I had to skip a few posts to get here, so if I'm repeating anything, well, you can chastise me later.

I personally assembled a Selden mast (ours) 2 years ago. It had a combination of rivets and screws. I did not use a come-along, but I did pull on the halyards by hand. They may have used a clamp of some sort at the factory, to do the original drilling, but I had great luck building a jig and just pushing the halves together. If the jig is set up true, then you shouldn't need much force to hold them together. I made an external splint to help keep it from moving around while I worked on it. Once you get a few rivets installed, it'll get more rigid. For me, the rivets went in first, then the screws.

This was a one-man job, for me. Though I'd want an extra hand if I were the one doing the original drilling.

Cheers.
Paul.

[CarlF]

I think the more interesting question than “screws or rivets” is whether to also use structural epoxy - and if so, how to get good adhesion to aluminum in this type of assembly.

[Celestialsailor]

Originally Posted by boatpoker

What does the guy thats doing the job have to say ?

https://ballengerspars.com/
Buzz has been building and slicing custom spars for almost 50 years. It doesn't hurt to have another opinion. Certainly more knowledgeable than opinions on a forum.

[Chotu]

Originally Posted by Celestialsailor

https://ballengerspars.com/
Buzz has been building and slicing custom spars for almost 50 years. It doesn't hurt to have another opinion. Certainly more knowledgeable than opinions on a forum.

I don’t feel comfortable just calling someone and using them like that. That guy is in business.

[Chotu]

Originally Posted by GRIT

I had to skip a few posts to get here, so if I'm repeating anything, well, you can chastise me later.

I personally assembled a Selden mast (ours) 2 years ago. It had a combination of rivets and screws. I did not use a come-along, but I did pull on the halyards by hand. They may have used a clamp of some sort at the factory, to do the original drilling, but I had great luck building a jig and just pushing the halves together. If the jig is set up true, then you shouldn't need much force to hold them together. I made an external splint to help keep it from moving around while I worked on it. Once you get a few rivets installed, it'll get more rigid. For me, the rivets went in first, then the screws.

This was a one-man job, for me. Though I'd want an extra hand if I were the one doing the original drilling.

Cheers.
Paul.

Interesting, Paul. So it looks like there is one line of rivets in yours probably on each side. And the rest screws. I wonder why they specified it like that.

The internal piece is a bit shorter in yours than I thought it would be.

Maybe shows again that this is a case of overthinking everything.

Looks like you have countersunk machine screws, diameter unknown. Stainless steel. And you said you drilled and tapped out the holes for the threads?

[neilpride]

50 ft custom multihull, go with machine screws , Pro here , this is a sparcraft in mast furling stick from a 50 ft beneteau , the guy lose the mast in Hurricane Irma, you can see in the first Pic the close tolerance in the sleeve, sometimes we use soap and straps to close the both sections, the threads are in the sleeve, 1 or 2 in line screws in the front section, 3 rows in zig zag in both sides, 2 rows each side in line back side close to the mainsail track, counter sink the holes, get the best SS screws you can found there , 100º, allen head its the best, put a small drip of hig strenght red loctite in each screw before screwing, dont tighten screw by screw , its more like tighten a engine head.

With the screws tight, shake the mast side ways, back and forth , re tight the screws , dont apply excesive force and your ready to go.

Your metal guy should be able to mark the rows and screw holes with the sleeve in place and with top and bottom mast sections in place , mast straight in the stands, check that both faces match in the joint perfectly.

Dont forget to run your new VHF wire antena and all the DC gizmos , same for halyhards etc...

As i say before , we spliced lots of mast with rivets to, but never on large masts, Hope this help.

[Chotu]

Neil pride:

You are my hero here.

Thank you!

Every time I see your user name it reminds me of a set of sails I first had when I started sailing.
No I have a really good understanding of how this works. Thank you so much for that post. Now I can give the guy good information.

I really like that pattern. That makes a lot of sense to me.

Machine screws it definitely is. I will consider this thread solved.

[Chotu]

That post has to earn an invite to the inaugural cruise.

[Dave_S]

If the sleeve isn't a neat fit in the mast sections and the sleeve is thicker at 1/4" rather than 3/16" that I thought it was I will change my vote to screw fixings.

Again though, I would not use countersunk screws, I'd use pan head, torx drive 1/4". I like the sleeve length ratio in alanpride's images above rather than the shorter one shown previously. I would change the first row of fixings though to be staggered either side of the join line.

The mismatch you mentioned between inner and outer sections will require that the sleeve be progressively pulled into contact, matching the form of the outer sections of the mast. This will require you to spend some time re- tensioning the fixings in a cyclic pattern untill the mast and sleeve faces contact, then all fixing should tension the same. However as the surfaces are still moving and pulling together each screw tightened will relieve some of the load from adjoining fixings and these will need to be tightened again.....repeat untill no change is found.

I still worry about the standard of workmanship, but that seems to be just me.

P.S.
If you are going to use Loctite, first fit and tension all the screws, then remove them one at a time and Loctite.

[GRIT]

Originally Posted by Chotu

Interesting, Paul. So it looks like there is one line of rivets in yours probably on each side. And the rest screws. I wonder why they specified it like that.

The internal piece is a bit shorter in yours than I thought it would be.

Maybe shows again that this is a case of overthinking everything.

Looks like you have countersunk machine screws, diameter unknown. Stainless steel. And you said you drilled and tapped out the holes for the threads?

There are 4 rows of rivets, one front, one back, one on each side. The screw holes are countersunk, and I'm not the one who drilled and tapped them, Selden did that. But yes, they are tapped, on the sleeve. The mast itself is drilled to a close tolerance to the screws, and countersunk.

Good luck.
Paul.