Ahoy All, Currently in need of clevis pins for the spreaders on my new mast.

I did a search of Brion Toss's rigger's forum, but no joy there.

Is there a perfered metal to use ? Like 316L SS , or 304L SS , and do they need to be drop forged, or cold headed like bolts are ?

Lathe machineing labor costs are quite low here in Singapore, so I am thinking of purchasing 316 SS shouldered bolts to use as round stock to machine the pins, is this a good idea ?

Shipping and import costs almost double the price of each item sent over here.

I did see in the Hayn Marine catalog, that they list 316 SS clevis pins that are CNC machined, but they don't sell to end users .

Douglas, BCC Calliste

Douglas,
On Shaula's Forespar mast, the spreader's cleavis pins are not under any strain, unlike the cleavis pins in the standing rigging. They are there to keep the spreader from falling off in case the rigging falls (or is torn) off? I don't know if your new mast is similar, but it seems likely? ANY quality of pins would work on the Forespar design.
Dan BCC 59

Hi Dan , the new mast is a copy of my existing Forespar mast, with the exception that there is no welding on it or any of it's parts, and there is no taper .

The failure on my existing Forespar mast was at the stb spreader bases.

During the Tsunami my stb spreaders were renched forward, which concaved the mast wall, and ripped the welded on aft part of the spreader base right out of the mast wall.

Nigel Calders book talks about spreader bases welded on the mast wall, and that the welding destroys the mast wall temper, and this damage shure shows that, on both the upper and lower spreader bases.

It seems that you are correct about different applications for clevis pins can result in selecting different metal alloys and fabrication , T Y , for pointing that one out.

My guess is that the drop forged ss pins are for use on toggles chain plates and turnbuckles, where the spreader pins can be just plain 316 ss .

Wonder if there is an easy way to mark them, so that I don't use the wrong pins in the wrong places ?

Douglas

Douglas,
Thanks for explaining your spreader situation. If you aren't using welded bases on the mast, are you going for rivets (or tapped machine screws?) to fasten ss (or Al?) spreader bases on the mast? What are you using for spreaders?

Wouldn't a big fore or aft force on the outboard end of the spreader damage the mast wall adjacent to the base, unless the spreader can pivot? There's a huge amount of leverage, isn't there? I guess if the spreader was tubular rather that the flat, hollow Forespar type, they might just bend back or foreward. What does Calder recommend using instead of welded bases?

In any case, I don't think you need to worry about the clevis pins that hold the spreader to its base. It's under no stress until disaster happens like it did to you, and then something is going to break or bend, but it won't be the clevis pin!
Dan

Hi Dan, Thanks for your replies and questions.

We don't have a spar builder here in S'pore, thus my mast fabrication is all DIY.

Welding to my standards was not cost effective, so had to re-design all the mast bits n pieces, to be bolt together.

I copied designs found on net searches, then looked for examples on boats in the marina, to confirm designs.

The spreader n base design came from Z Spar's thru or root bar, and tapered the spreader same way as their's .

Have been using ss machine screws and bolts to hold everything together, some tapped into the mast wall.

Steve Dashew's book, Offshore Cruising Encyclopidea (P 663) recommends bolt on spreader bases, like the top left photo on the page of a Westsail 32's spreader base ,,,, not sure why the photo of this spreader has a bolt securing it instead of a clevis pin .

You may have a good point about round spreaders, but I like the airfoil spreader look more.

During the Tsunami the sailboat across the pontoon, rolled it's mast into mine, which mine was also rolling into his. The masts and spreaders clashed during which his boat broke away from the pontoon.

Lesson to learn, was to always off set marina berthed sailboats so their masts won't clash together during rolling.


Always learning something new ,,,,, Douglas








Edited 1 times. Last edit at 10/25/10 02:20AM by dwkayaks.

Douglas,
Nice design! Great pictures. Those base plates look tricky to make--are they cast? Your pic shows hex head machine screws holding the spreader to the root bar. Are they tapped in to the root bar? Or pass all the way through with nuts on the bottom? Are you planning to use clevis pins instead of those machine screws? The Z Spar website is interesting. Hopefully, most of us will never have to deal with replacing our masts!?
Dan

The Hex Head bolts are just temporary , to hold things together, to check fits.

Fabricating aluminum from blocks of the stuff is not difficult using woodworking tools and grinders.