Using adhesives instead of rivets

[tyson_troy]

I am interested in installing lazy jacks to help tame my mainsail when raising and lowering. My dilemma is that I don’t want to drill and rivet the hardware, which connects to the mast if possible. There is something about drilling holes in a perfectly good mast and possibly affecting the structural integrity of it that I don’t like. I am interested to see if there is an adhesive alternative that I could use instead or if anyone has had any experience with a similar situation. Any suggestions are greatly appreciated.

 

[Ross]

I rather doubt that a 1/4 inch hole will have an adverse effect on a mast.

 

[Don S/V ILLusion]

I rather doubt Ross is wrong

 

[Ed Schenck]

Good thing holes don't bother me. I have added cleats, lazy jacks, and drilled really big holes for exit plates. But an alternative would be band(s) around the mast with the lazyjack hardware attached to the band(s). I have seen stainless hose clamps in the Lowes plumbing section that are big enough.

 

[Joe]

My dilemma is that I don’t want to drill and rivet the hardware, which connects to the mast if possible. There is something about drilling holes in a perfectly good mast and possibly affecting the structural integrity of it that I don’t like.

Not to worry, you would be filling the hole with something else. How else would you attach other accessories.. such as radar, topping lifts, cleats, winches etc. A hose clamp might interfere with the mainsail track, which would defeat your purpose.

 

[dscribner]

The load on a mast is transient, depending on the direction of the wind, but since the shape is normally ovular, with the longest axis bow to stern, I will assume that this is the primary direction of the load. That said, you should be able to drill an enormous hole in the side of the mast without affecting the strength. This would be at the neutral axis. Think of those cheesy sci-fi flicks of the 50's. The space ship invariably had trusses or beams with holes of varying sizes cut in the web that joined the top and bottom flanges. Still, keep the hole as small as possible.

 

[kenn]

Lazy-jacks aren't high loads. I suspect you could simply pop-rivet an eyelet on each side of the mast using 3/16" aluminum pop-rivets, and they would be more than strong enough.

 

[JVB]

The design of the Monerai glider, a kit built airplane, specified using an adhesive to attach the aluminum skin to the aluminum wing structure. The adhesive is Hysol 9430 room temperature setting epoxy. There is a specific time critical preparation sequence which basically assures that the mating surfaces are clean and do not get a chance to oxidize between cleaning and gluing the parts together. If you get silicone on any surface to be glued it becomes a throw-away since there is no way to clean it completely. Glue was also used on the Grumman AA5 series of light airplanes. I don't know if it was the same glue. Some Grumman wings were ruined (weakened or delaminated) years later when paint removal chemicals were allowed to contact the glue joints. So that presents a method for painlessly removing parts glued to the mast.

http://monerai.com/

http://tds.loctite.com/tds5/docs/HYSA9430-EN.pdf

http://www.aircraftspruce.com/catalog/wppages/hysol.php

 

[Bill Roosa]

yes there are adhesaives for metal to metal

You don't use them much as they are really designed for a connection that has a fairly large surface area. You don't have that on a pad eye or cleat.
That is why you universally see metal fasteners used and not glue.
They are also very expensive and require surface prep and most are a 2-part system that needs mixing and rapid installation.

 

[shemandr]

Yikes. You go up in the air with glued on wings?

 

[Rick Sylvester]

I did

Yikes. You go up in the air with glued on wings?

The Grumman Americans built in the 70's had glued aluminum wings (no rivets.)

I drill and tap on my mast. Rivets would be fine too I'm sure. Strength for lazy jacks won't be an issue and it's highly unlikely you'll compromise the mast section. Just be sure you apply a dielectric like Lancote (or whatever) if using stainless fasteners in the aluminum mast.

 

[Prime Time]

Don't Worry

I am interested in installing lazy jacks to help tame my mainsail when raising and lowering. My dilemma is that I don’t want to drill and rivet the hardware, which connects to the mast if possible. There is something about drilling holes in a perfectly good mast and possibly affecting the structural integrity of it that I don’t like. I am interested to see if there is an adhesive alternative that I could use instead or if anyone has had any experience with a similar situation. Any suggestions are greatly appreciated.

Don't worry about the holes. Look at all the other hardware that is installed in that fashion on your mast.

 

[tyson_troy]

Re: yes there are adhesaives for metal to metal

Thanks Bill,
That was one of my concerns while I was locating information on this. There is a pretty serious process to prepare the metal for applying the adhesive. This was the major down side of using this method.

 

[John Nantz]

A couple screws or rivits shouldn't be a problem

A couple screws or rivits on the mast shouldn't be a problem to hold a couple cheek plates. There is a large loading on the typical mast down toward the gooseneck and this is probably the largest "moment area" on the mast and you shouldn't have anything to mount there anyway.

As for fasteners, my personal preference is for machine screws in combination with an anti-sieze compound like "Lanocote" (sp?). Sheet metal screws are "pointy" and internal halyards could potentially snag on them. One could ground the points of so they're rounded, I guess. Rivits are commonly used but I'm not a rivit fan.

As for the comment about Grumman plane using glue, this brings back memories. Way back when I had to travel a long distance every week and started looking into buying a plane. A friend of mine was a FBO (Fixed Base Operator) of an airport and had his plane for sale. A Grumman 4-seat Cheetah. This is a low-wing plane with a cockpit hatch that slid back like on the WWII fighter planes.

Just the mention of Grumman brings up the memory of the test ride on a cold spring day with scattered rain showers. With the throttle firewalled at at 4,000 feet, snow capped mountains all around, we zipped around the valley, in and out of the showers, doing banks, climbs and descents. With it's tight controls and response, it was a real pleasure to fly. One drawback, though, was getting in and out of the cockpit on a rainy day. Slide the canopy back and the seats get all wet!

If I had known the wings might have been "glued on," well, I might not even has considered it. It was really fun to fly though!

 

[RichH]

Small drillings into any spar to attach hardware, especially at the 'ends', will not be any problem at all. Any designer/engineer worth his salt will usually include a 'factor of safety' in the design that accommodates or allows such 'alterations', etc. A spar, etc. designed for 'coastal' service will typically be designed for twice (or more) the functional strength requirments to anticipate 'unknown' loads, an offshore design at 3 times as strong. Just be sure not to drill a *lot* of holes at "mid-span" nor put a LOT of holes in close proximity to one another. In such design only someone who has no design/structural knowledge will design a component without the necessary 'factor of safety' or 'safety factors' that anticipate such 'alterations' or 'unknown loads' - ie.: 'unknowing amateurs'. Just dont make a 'swiss cheese' out of your spar and all will be 'well'.

Drilling and tapping for screws or drilling and using 'rivets' is totally OK .... this allowance should be already included in the original design.

 

[Ed A]

This is kinda funny to me, years ago we lightend a boom by drilling 1-1/2 inch holes all over it. it worked fine to lighted it and was never a real problem, but the wind wislin thru was awful on windy days. (not a bit faster either!) Oh the things you do for speed....