different size of shrouds on same boat - why?

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eranb2

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the baby shroud are 5 m"m.
the long ones are 4 m"m
is it because of the mast should be able to bent? flexibilty ?

some sailors oversize the shrouds by 1 m"m ,

is it a good idea?

the 4 should be 5 and the 5 should be 6 , is that the idea?

Thanks.
 
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some sailors oversize the shrouds by 1 m"m ,

is it a good idea?


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Thicker shrouds will give more weight and windage aloft where you don't want it, also you might have trouble with the clevis pin sizes i.e. the rigging terminals may need a larger diameter pin than the mast tangs can accomodate.
 
There's a lot of rubbish talked about shroud sizes. The fore and aft stays take the greatest loads. The baby shrouds are really only there to allow a degree of mast bend. On my boat, the original shrouds were 5mm and the babies 4mm.

My insurance company replaced the mast and rigging after a demasting (don't ask!) and insisted on it all being 6mm. Overkill IMO.
 
High Topcat47 I would disagree (but may be wrong) that the fore and aft stays take the most load. The forestay is augmented by the halyard tension of the jib and in many boat the correct jib luff tension sees the forestay slack.
The backstay tension is augmented by the load of the mainsail leach when hard on the wind and the main sheet pulled on hard.

In my case with fractional rig the cap shrouds are aft of abeam the mast and so mast is reasonably stable with no backstay tension. (it is adjustable).

No for my money the cap shrouds then the inner shrouds have the greatest load.

yes there is no point in oversized shrouds cos of extra weight and windage. If the fittings are of the swaged type then the fitting must perfectly match the wire size so that may be why odd sizes of wire were used.
Sadly we have no indication from bio about boat size or type to give any suggestions on correct wire size. olewill
 
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.. after a demasting (don't ask!) ...

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Well I would like to ask, if you can bring yourself to remember what must have been a very unpleasant experience! What component actually failed and resulted in the dismasting and what condition was it in [before the failure]? The only reason I ask is so that I can watch out for the problem on my own boat. I've had a boom break and that cost me a couple of weeks holiday whilst a new one was made, but a mast breakage could have far more serious consequences.
 
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the cap shrouds then the inner shrouds have the greatest load.

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You may be right but my understanding is that the inner shrouds have a greater load then the cap shrouds. And often you will find that the thicker wire is used for the inners rather than the caps. I know in my case I had an inner shroud fail last year but the cap shrouds were all fine - however I replaced them all, but left my forestay and backstay. My rigging was only 2 years old but was subject to being battered by waves as well as wind.
 
Re: different size of shrouds on same boat - why?

Lowers take a bigger load because of the angle they make with the mast, caps take less (angle assisted by spreaders). Forestay takes a bigger load than the backstay because the forestay angle is always less than the backstay angle. Some catamarans have their rigs effectively on backwards, however, with the backstay making a sharper angle than the forestay - an exception. Often the forestay is bigger wire because it is usually tensioned more and has the wear and tear of the hanks. Most builders settle on one wire size for commonality of parts which makes good sense.
A rule of thumb for wire size is that the breaking strength should at least equal twice the weight of the ballast.
 
Skipper stupidity......more embarrasing than dangerous....I'd have to be very very drunk to share this with anyone as I still cringe when I think about it.
 
I lost one mast on my fractional rig because the aft swept spreader base failed to the extent that it did not seep aft. ie the base failed to press the tip aft. This allowed the middle of the mast to crumple backwards.
Another friend recently lost a mast through spreader failure. (no details)
I have seen 3 other masts fail in recent years simply from old stays.
I lost another 2 masts from going to close to channel markers. Enbarassing yes even though I wasn't actually helming.
I think I nearly lost a mast last weekend when the boat heeled toward another boat going the other way. (don't know how close but i think a tangle would have been disaster.
These are some things that kill masts. olewill
 
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