Oversized rigging

[brak]

Last year when replacing rigging, I went a size (half size, really) up from original on a premise that it'd be "stronger". Since then I've got a few new hairline cracks around mast base (well, not really new, more like old repair failed - but it was ok for a long time).

So, I thought about it and it does seem like bigger rigging increases downward force on the mast base - since rigging is taught to about 10% of design strength, with the larger size my shrouds are now pulling over 1000lbs each, as opposed to about 700lbs with original size - for a total of 6000lbs, most of it pushing down (vs. 4200lbs previously).

Was it dumb to go up in rigging size? Should I untune my rigging a bit to keep it less tight?

[sailingdog]

Just cause you went up a size on the rigging, doesn't necessarily mean you have to tension it more than it was previously tensioned. I would reduce the tension in the rigging to what the original rigging was set to.

Did you also upsize the chainplates as well, when you increased the size of the rigging?? How about the mast tangs?

[negrini]

brak, if previous rigg match original plan, designed by a respectable naval architect or serious builder, you should not try to re-design it using your guessing experience. You're just addind a lot of weight aloft, unmatching your keel size/weight. Just where actual trend is exactly to reduce weight ...

[sailingfool]

I don't think the oversize rigging will have done anything other than make your boat a bit more tender, due to weight aloft. Tension pressure is the same in a thin or larger wire, the first may stretch more and break sooner the second. You COULD tension large wire more, but if you have tuned your rig correctly the force holding your mast in column is the same as before...

[merc2dogs]

I'd detune it, bring it down to the oem level or near it, that's the loads the deck, step, chainplates, and supporting structures are designed for. I've seen a few that were marginal at design loads

See no problem going up in rigging size, Both my boats have the same rigging size, and the Triton is about 3ft longer, and just under 3000lbs heavier than the Ariel. (yeah, I like the old Alberg Pearsons)

Ken.

[Delirious]

The rigging diameter has no bearing on it. It is how much you tighten it. Loose 5/16" rigging has less applied force than taut 1/4" rigging. So, if you have tightened it to a % of the breaking strength using stronger (larger) rigging then yes, you have likely exceeded what the cabin top and deck/chainplates were designed for.

Did you beef up the mast collar tie-rod assembly to compensate for the added strength of the rig?

Or is this a deck-stepped mast?

[brak]

Originally Posted by sailingdog

Just cause you went up a size on the rigging, doesn't necessarily mean you have to tension it more than it was previously tensioned. I would reduce the tension in the rigging to what the original rigging was set to.

Did you also upsize the chainplates as well, when you increased the size of the rigging?? How about the mast tangs?

I kept originals - but those (at least chainplates) are much larger than what would be found on a modern boat with comparable rigging (say, on production Catalina - which is what I used for comparison when deciding on rigging size).

I let riggers tune my rigging - and they pretty much set lowers to just under 10% of their spec., uppers - a bit higher. At lower tension (comparable to what smaller size would be tensioned to) they feel a bit slack, but I guess it is the right thing to do anyway.

[sailingdog]

Yeah, going up a half-wire size will make the boat marginally more tender...but if you're planning on going bluewater, it is a pretty common safety measure to take.

[brak]

Originally Posted by Delirious

Or is this a deck-stepped mast?

It's a deck stepped mast.

[brak]

Originally Posted by negrini

brak, if previous rigg match original plan, designed by a respectable naval architect or serious builder, you should not try to re-design it using your guessing experience. You're just addind a lot of weight aloft, unmatching your keel size/weight. Just where actual trend is exactly to reduce weight ...

Well, too late for that It's already there and considering the expense and the trouble I've got to live with it. It ain't much weight fortunately and I have a pretty short mast and a fairly heavy boat.

Part of the issue is - presumably original rigging used stainless 304, and most of the rigging now is 316 so half a size up seemed like a way to compensate for the material difference.