Whisker Pole Mast Attachment

[Yojimbo]

A friend is planning to add a whisker pole for the jib on a Catalina 28. What is the best attachment for mounting the mast bracket? Rivets, screws, adhesives a combination of some sort? This is the standard not the tall rig.

TIA

[JBP]

The BEST way is probably a sliding track, but not the cheapest.
For a fixed bracket, aluminum rivets or rivnuts would be my choice. Screws might be OK, but I don't like putting load bearing stuff on screws in the mast. There just isn't enough thread depth to make me comfortable. That said, I've never had screws fail on things other people have installed, so maybe I'm over cautious.

[Bowdrie]

Whisker pole set-ups that don't use a sliding car/track commonly use "eyes" with curved bases, one on each side of the mast.
This minimizes the shear/tension loads on the fasteners, most of the load now being in compression.
Your choice of screws/rivets largely determined by wall thickness of mast.

[Star Fire]

I hate hate hate drilling holes in my mast, especially near the base. That being said, rivets cannot be tightened after being placed. They will have better sheer value that a screw so it’s a toss up. But which ever you choose, the glue will do most of the work. Personally, I’d use 5200 but I don’t know about aluminum to aluminum with 5200. Mast tracks typically use pretty big screw that will give you more inches of thread engagement with the mast even though the depth isn’t there. Whatever you buy should come with manufacturer’s instruction. I’d go with whatever they recommend. But definitely glue and screw/rivet.

What we typically call rivets are actually called pop-rivets and, as a contractor, I only used the to join two pieces of sheet metal for aesthetic purposes and never for structural.

But like we always said in the building industry, RTIS (read the instructions, stupid). Whatever the manufacturer suggests, that’s what I would do.

[psk125]

Originally Posted by Star Fire

What we typically call rivets are actually called pop-rivets and, as a contractor, I only used the to join two pieces of sheet metal for aesthetic purposes and never for structural.

Pop-rivets are routinely used to attach fittings that carry loads to spars. This photo shows them holding the gooseneck fitting to the mast and also holding the inboard boom end fitting to the boom. The boatyard may have a bigger rivet gun than what might be used for installing gutters.

[JBP]

It's worth noting that you want aluminum rivets in a size appropriate to your bracket. You can get them up to 1/4 diameter in various lengths.

It's also worth noting they are handy for fixing a lot of other things.

[Star Fire]

Originally Posted by psk125

Pop-rivets are routinely used to attach fittings that carry loads to spars. This photo shows them holding the gooseneck fitting to the mast and also holding the inboard boom end fitting to the boom. The boatyard may have a bigger rivet gun than what might be used for installing gutters.

Rivets won’t work themselves loose with vibrations. Houses are generally built to the lowest quality standards possible. That’s precisely why I quit. I spent 26 years watching the quality of homes steadily decline. Sailboat construction, however, not so much so. Sure, the boats built in the 60’s and 70’s were better boats that the new ones built today, but even new boats haven’t succumb to the low standards that new homes have.

But, I’m not a boat builder (or a gutter girl) and the manufacturer of the part certainly know more about how to attach it than I do. They’ve seen more of them fail, too. That feedback is important and it influences how they recommend attachments in the future. Go with what they recommend. Boatyards too.

[Yojimbo]

Thanks all for the input, will pass it along and emphasize the use of the manufacturer's recommendations.