Attaching a cleat to the mast

[capnbrian]

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 to remove the existing small cleats I found that they were attached with sheet metal screws.

Does anyone have an opinion on which would be the better (stronger) way to attach the cleat?  I’m not certain which method would give the best grip.  I also considered a pop rivet but I don’t think I can get one that has a long enough grip to pass through the barrel of the cleat.

thanks for any advice,
Brian

[Tafika II]

I've always drilled & tapped any attachment holes into the mast or used heavy duty pop-rivets. Don't forget to use some sort of anti-seizing coating on the fasteners, whatever you use.

[Don Reaves]

I would go for drilling and tapping for machine screws. I got a lot of practice doing this last spring installing a whisker pole track. It's not at all difficult.

[johannes]

Tapping the mast is usually not recommended since there will be corrosion in the aluminium in the long term. For lazy jacks that might be OK since it is not a critical part. 

If you can't use pop rivets there is a solution with machine screws and nuts that give the same or better strength as rivets and avoids the problem of corrosion. Start with a machine screw that is significantly longer that needed. File down the sides of the end of the screw, to about 5-6 mm from the end, so you get a flat section that can be used to apply torque to the screw with a spanner. Drill a hole through the flat section.

Next, thread a thin steel wire through the hole in the mast, and down to any opening in the mast and try to get it out. Attach the machine screw by the drilled hole, and pull the wire to get the screw though the hole from the inside, so the head of the screw is on the inside. Apply anti-corrosion coating, attach the cleat, and put a nut on the screw (preferably a nyloc-type nut). Fasten the nut with a spanner on the flat part of the screw, and then cut the screw close to the nut.

[Don Reaves]

Brian — For a freshwater boat, corrosion should not be a major issue. Just use a good corrosion inhibitor like Forespar Lanocote and you should be fine. In fact, I have a lot left over from last spring’s project. I’ll be glad to lend it to you next time we meet.

[capnbrian]

Thanks for the advice guys!  I’m going to drill and tap and make sure to use some anti-seizing compound.  I think Don is correct that in fresh water, corrosion shouldn’t be a huge issue.

That was my first thought but had some doubts when I found the originals did not use that method.

[zaphod]

Jan 30, 2020 10:00:36 GMT johannes said:

Tapping the mast is usually not recommended since there will be corrosion in the aluminium in the long term. For lazy jacks that might be OK since it is not a critical part. 

If you can't use pop rivets there is a solution with machine screws and nuts that give the same or better strength as rivets and avoids the problem of corrosion. Start with a machine screw that is significantly longer that needed. File down the sides of the end of the screw, to about 5-6 mm from the end, so you get a flat section that can be used to apply torque to the screw with a spanner. Drill a hole through the flat section.

Next, thread a thin steel wire through the hole in the mast, and down to any opening in the mast and try to get it out. Attach the machine screw by the drilled hole, and pull the wire to get the screw though the hole from the inside, so the head of the screw is on the inside. Apply anti-corrosion coating, attach the cleat, and put a nut on the screw (preferably a nyloc-type nut). Fasten the nut with a spanner on the flat part of the screw, and then cut the screw close to the nut.

That seems like a very awkward and time consuming process. It seems to me that you would have no way to keep the bolt captive to turn the nut. Sure, you can grip the bolt with vice grips to put the nut on initially, but once you cut the excess length close to the nut, you will have nothing to grip when the time comes to remove the cleat in future. The use of a nyloc will make it even worse. You would likely have to try to cut the bolt to get it off. That would be a royal pain in the ass!

There is nothing wrong with drilling and tapping an aluminum mast. Riggers do it all the time, and if done right it can go for decades with no corrosion issues.

Pop rivets are ok for low load applications, but they make removing the hardware more difficult. Rivets are also prone to working loose over time, and when that happens, there is nothing you can do except drill the rivets out, and put new ones in. Drilling the rivets out can be challenging if the rivet is loose because it will just spin.

As far as I'm concerned any hardware that is fastened to the mast should be easily removable.

Machine screws, all the way!

[johannes]

It's an alternative to rivets, which you also have to drill or cut to remove. So no difference there.

Tapping and using machine screws should only be used for non-critical hardware. Riveting is far stronger, and not prone to corrosion in the same way. There is a reason all attachments to the mast done by the manufacturers is done by rivets. I've never seen a professional rigger use anything else.

[sailbleu]

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I use these for all my mast fixations , and other places . You do need a special tool similar to the pop rivet gun .
By the time galvanic corrosion between the SS (machine screw rivet ) and aluminum (mast) has destroyed the fix you will have finished sailing all together.

Regards

[rxc]

I am going thru a similar issue regarding attachment of equipment to the mast, but my experience has revealed some contradictory wisdom.

During my transatlantic trip in 2008, we stopped in the Azores and I went up the mast to check the rigging. My Raymarine radar is attached to the mast by a separate mount that has four adjustable feet, each of which is attached to the mast with 3 screws (M5 x 12mm size). In the Azores, after a hard passage, 4 of those screws were missing, and several others were loose.

We replaced the missing screws, tightened everything down, and went on to sail all around the EU for 6 years. The boat came back to FLorida in 2013, and in 2014 it went on the hard for a year, with the mast down. Which was time to do a lot of equipment checks.

The radar mount was found to be missing one screw. So, I replaced it, and thought about the matter of corrosion vs screws falling out. I looked everywhere for advice about whether it is more important to have the screws well attached, or removable. Nothing, anywhere. Lots of discussion about the corrosion issue, but no evaluation of the downside of avoiding corrosion (the screws can back out).

I decided to avoid the corrosion, because the thought of drilling out small SS screws, 20 ft up the mast while hanging in a bosn chair, did not appeal at all. So I applied Tefgel to the screws, and tightened everything down, again.

It is now years later, and I went up the mast about 4 weeks ago to find 4 screws missing, and 2 loose, again. No heavy weather sailing, no major abuse, but they still came out. I decided that now the more important issue is to avaoid having the radar fall off the mast, which would be VERY bad, so I took out all the screws and used Loctite Blue thread locker to try to make sure they will not come out again. Two of the holes were stripped, so I have to go buy some appropriate sized aluminum rivets to replace them. Drilling out aluminum rivets is much easier than small SS screws. I had to re-install some hardware on the boom in 2014 with large rivets, and that was very easy, so I am becoming a convert to rivets.

I also recently mounted some padeyes on each side of my boom to attach a preventer line, but they are close enough to the end of the boom that I could use thru bolts with a backing plate and nyloc nuts. Thru bolts are probably the best solution, but not possible for many situations.

I also have to add two new cleats to the mast, and they will be 1/4" (6mm) screws, tapped into the mast. They cannot be riveted, because of the hole locations in the cleats. I just found that a local harware store sells sets of combination drill-taps, in both metric and Imperial sizes, and they work wonderfully. so that will be the solution for the cleats.

In summary, I think that tef-gel might be a good idea for some hardware where it is not critical that it stay attached, but for stuff that you really don't want to fall, rivets are essential. If you must use screws, add some Loctite. After I install these 2 rivets on the radar mount, I will re-consider the situation, and may remove the rest of the screws and replace them with rivets.

[zaphod]

Feb 2, 2020 14:09:17 GMT johannes said:

It's an alternative to rivets, which you also have to drill or cut to remove. So no difference there.

Tapping and using machine screws should only be used for non-critical hardware. Riveting is far stronger, and not prone to corrosion in the same way. There is a reason all attachments to the mast done by the manufacturers is done by rivets. I've never seen a professional rigger use anything else.

Certainly if it is something that is permanently attached to the mast, AND you have access to the appropriate riveting tools, not just a little hand pop riveter.

We are talking about installing a cleat. Perhaps if you are using a simple jam cleat rivets would be fine, but a cam cleat or a rope clutch should be bolted so it is easy to remove for servicing or replacement.

[johannes]

A decent riveting tool costs 100-200 euros. For just occasional use maybe that is a bit expensive, but you can often rent or lend one at a local rigger or marina.

Pop rivets are easy to drill out, so if you need to service the cam cleat or clutch every 3-4 years it's not much extra work. The good thing with rivets is that you can use the same hole an unlimited amount of times. But as I said in my first post, for small cleats such as for lazyjacks, screws will be fine.

[rxc]

Ah, the cost of stuff in the EU - I remember it well. Bread was a good deal, but tools...

Here in the US, you can buy a heavy duty riveter at Harbor Freight for about $25. When I asked my rigger to re-rivet some fittings on to the boom, he suggested that I buy one and do it myself, because it would save all of us time, and me money. The bigger problem is finding the larger rivets, which means an on-line search and waiting for them to arrive. In the EU, it will also likely involve exorbitant shipping costs.

[johannes]

A well stocked chandler here will have Monel rivets in most relevant sizes.