Adjusting Your Rig

[Valiente]

I was rather pleased to find out that my motorsailer's 6 x 9 inch "tree stump" mast was in fact a Selden, so I purchased a Selden pole lift ring to fit in the handy grooves. Now, of course, I have to tap in holes for cheek blocks (or cut rectangular holes for sheeve boxes) to move the thing up and down.

I have a further question out of these Selden pages, though, Alex: See here?



Everyone I know tightens the turnbuckle with a screwdriver. Why a wrench/spanner?

[Giulietta]

Originally Posted by Valiente

Everyone I know tightens the turnbuckle with a screwdriver. Why a wrench/spanner?

I'll keep it simple...

That type of turnbuckles are designed to support tension forces only, and has very little torsion strenght, mainly because there are very little lateral efforts they need to support.....it's made that way when the turnbuckle is made, when the metalurgists make sure the grain of metal is more oblong, making it tension resistant, harder, but less resistant to lateral forces.

In using a screw driver, you are stressing the legs of the turnbuckle with lateral forces, (for which the piece was not designed for), and even twisting the turnbuckle legs, wich then get stressed, and the integrety of the intergranular structure gets compromised, possible causing it to fail at a later stage.

For this reason, the turnbuckle manufacturers make 2 flat surfaces, like a nut, to use a wrench, that will in turn provide rotational forces without stressing the legs of the turnbuckle.

Hope it was simple.

Alex

[Valiente]

Yes, that explains it perfectly, and I will change my habits accordingly.

Although I am lucky enough to have old Merriman turnbuckles in chromed bronze and they seem a little more robust than the current types.

This is Merriman "style":

They aren't made anymore, as far as I know.

[KeelHaulin]

Originally Posted by Giulietta

Keel, I am not going to argue this anymore.

Was not trying to argue anything Giu; I was simply trying to add some information to your excellent post of how to adjust your rig tension.

Since there was confusion on what your post was saying I tried to determine why it would be 1mm extension for 1 meter or 2 meters; but it is off by ~50%. The calculation is correct; so it must be a problem with the published breaking strengths. So I was doing some more research on 316 stainless and it turns out that the published breaking strengths must not be actual ultimate breaking loads; they seem to have a safety factor of 2 built in. The 15% breaking strength calculations I did earlier were based on the published breaking loads; while the Selden formula is based on the true Utimate Tensile Strength of stainless wire (actual failure strength).

[obarut]

I have an in-mast furling for main sail. Therefore when I bend the mast during sailing the furling system operation is adversly effected. Is it a good idea to bend such masts or to keep them straight is better?

[tommays]

Bending of the mast is usally done to adjust sail shape ,with a roller furling main you are generaly giving that up as a tradeoff to the convience of furling

[windship]

All good info but really...it's not that difficult to do.
Lay on your back, feet facing the bow, looking up the mast to see the straightness of it port to stbd. Adjust until straight with moderate tension on the shrouds or stays. Next lay on your back with your feet off the beam while looking up the side of the mast to check for bend for and aft. Adjust acordingly until straight with moderate tension on shrouds and stays...done. I've been doing it for 15 years this way.

[captainmidnight]

[maybe robust, but they're also likely older than I am and due for replacement, cheap and easy compared to replacing entire rig, nothing lasts forever

[HenryTully]

Anyone,

I have NavTec rod rigging on my 40' boat. Should the lower shrouds have the same level of tension at rest as wire shrouds or should there be more tension? I noticed this summer that the lee shrouds were flopping around when we were sailing.

Hank Tully

[knothead]

Originally Posted by HenryTully

Anyone,

I have NavTec rod rigging on my 40' boat. Should the lower shrouds have the same level of tension at rest as wire shrouds or should there be more tension? I noticed this summer that the lee shrouds were flopping around when we were sailing.

Hank Tully

Usually, the uppers are tightest, next the intermediates and then the lowers. This can vary with the type of rig. A good rule of thumb is that the larger the diameter, the more tension.
Your lee shrouds, in my opinion, should not be flopping around.