New mast partner pin fabricated

[Jim Walsh]

Since I have a keel stepped mast I have a mast partner which is the collar bolted to the cabin top which the mast passes through before terminating at the mast step on the keel. After the mast has been dropped into position there is a 3/8 pin which passes horizontally through the partner and the mast. Having witnessed the difficulty the rigging crew had in lining up the holes in the partner and the mast last spring I resolved to improve (hopefully) the process. The original pin is a stainless steel rod with blunt ends. I may prove to be wrong, but I could see no practical reason why a pin made of aluminum would not suffice since the partner itself is an aluminum casting. The photo below shows the raw aluminum rod on the bottom, the original stainless steel pin on the top, and the aluminum replacement pin I fabricated in the middle. My replacement pin is 3/4 of an inch longer than the original. The original pin had the 1/8 inch holes for the Clevis pins drilled at the extreme ends of the pin and left a paper thin wall on both ends. On the pin I fabricated I have drilled the 1/8 inch holes 1/4 inch from one end and 3/4 inch from the opposite end. The reason for the expanded overall length is that I have incorporated a tapered section which I hope will assist the riggers in lining up the holes in the mast with the holes in the partners. I've seen steel workers line up holes with a steel drift pin but I'd prefer that my mast be "coaxed" and not forced into final alignment.

[Steve Laume]

The design seems very good but I question the material. Different metals and harnesses of those materials can have very different sheering qualities. I really don't know if using aluminum in a high shear situation could case problems but maybe someone else could help out. How critical is the pin? If it does shear off, do bad things happen to the rig? Once again, I don't know the answer to this question. You could consider the one you have to be a mock up and make one out of stainless if you are going to be thinking about it while you are a few hundred miles off shore. I do like the fact that Raven is deck stepped when considering such things, Steve.

[Jim Walsh]

The vast majority of boats with keel stepped masts do not have pins at the partners. They just use wedges to get the mast squared in the opening and tune the rig. Since the mast is not a round section it can't move once it's lowered onto the mast step. Seems to me than the pin helps to center the mast in the opening allowing the wedges to be placed in position without the mast leaning fore or aft prior to tuning the rig. To center the mast athwartships a line affixed to the mast can be led to a winch to help if needed but it's never been necessary for me. That's the type of thing common in the racing fraternity with boats such as J24's, they have to step their masts and tune them at every event as they trailer across country.
In effect the pin serves a purpose but is not load bearing.

[John Stone]

I think the pin serves two primary purposes
1. It keeps the mast heel in place should the mast get brokers off due to a capsize or catastrophic rig failure. Holding the heel in place keeps it from punching a hole in the hull. On my new mast we pinned the mast at the heel. Same principal, different technique.

2. Because the pin is run through the aluminum deck collar, which in turn is bolted to the deck, it stiffens the deck up to further resist upward tension placed on it from the mainsheet turning block.

There may be others reasons as well.

[Jim_B]

Suppose you use your newly fabricated pin to align the holes and then slide the original stainless pin in behind, it pushing the aluminum pin out? Seems like that would br a win/win.

[Jim Walsh]

Suppose you use your newly fabricated pin to align the holes and then slide the original stainless pin in behind, it pushing the aluminum pin out? Seems like that would br a win/win.

That's probably a good idea. I really would need to fabricate a new stainless pin anyway. Notice the hole for the cotter pin. The left no wall at all and the pin is essentially blunt at both ends. If I'm going to go through the trouble I might as well use the aluminum pin as a full scale model for the new stainless pin.
Someone on the site used to mention he could fabricate things for a very reasonable rate. If I can find out who he was I'd probably let him give it a go since a lathe would be ideal.

[eb1smith]

I just bought a long S/S bolt and ran it through.