The mystery of rig tuning

[jssailem]

tension being all about the mast. Don't look at a guage or a tape measure, look at the mast.

At the basic level I agree.

It is about the mast, but not alone. It is also about the rig. Equally, what it is doing to the boat and the hull. I called it the art of the rigger. It is not tuning the mast or the stays/shrouds. It is about tuning the boat.

Most of the time watching the rigger the initial process involves positioning and aligning the mast. The gauge is used to look at the value of ten being applied to the rig in order to set the mast. Getting to 15% was a general target number. Not an in stone requirement. Perhaps 12% achieves the needed tension to set the mast rake and prebend (when called for by the mast maker and boat designer). When you get to that point you need to be certain that your tension is not deforming the hull.

 

[jviss]

When you get to that point you need to be certain that your tension is not deforming the hull.

With a fiberglass hull, all of this tension is deforming the hull!

My friend says it's like a big bow and arrow getting ready to fire that arrow through the bottom of the boat.

 

[jssailem]

My thoughts:

• do you think there is a limit to the tension you place on the hull?
• Does this tension, if in excess, improve or limit your boat performance?
• What does high tension do to the boat hull’s life?

 

[Will Gilmore]

Getting to 15% was a general target number. Not an in stone requirement.

And that, right there, is the fundamental problem I have with this standard. It is thrown around like it is in stone. The way it is stated, "tension should be 15% of the breaking strength," people, including riggers, misunderstand the fundamental goals of tuning.

It is not tuning the mast or the stays/shrouds. It is about tuning the boat.

-Will

 

[dLj]

I'm so glad you asked that question because it takes me right back to tension being all about the mast. Don't look at a guage or a tape measure, look at the mast. It will tell you when tension is right.

Well I can tell you from direct experience that this is fine for coastal sailing, or spending an amount of time sailing prior to going offshore.

Once offshore, "playing" with your method is not a very agreeable method. You'd better have it right heading out or it can get rather exciting...

dj

 

[Will Gilmore]

Well I can tell you from direct experience that this is fine for coastal sailing, or spending an amount of time sailing prior to going offshore.

Once offshore, "playing" with your method is not a very agreeable method. You'd better have it right heading out or it can get rather exciting...

dj

I can appreciate that. Going to sea is a whole different level.

-Will

 

[dLj]

My thoughts:

• do you think there is a limit to the tension you place on the hull?

Absolutely. But it is very boat specific.

• Does this tension, if in excess, improve or limit your boat performance?

Well, you are kicking in the term "excess". That's a problem word. Simply put, anything in "excess" is not good.

I would say the higher the tension, the better your rig performance in general But again, it is all a trade-off. The higher the tension, the more wear and tear on everything, Rigging needs more maintenance, chain plates need greater scrutiny, everything is under greater stress. But, I would think stiffer rigs allow for better sail shape control. Better sail shape, better performance. Of course you have to upper limit - given the dynamic nature of stresses during sailing, you must set an upper limit to the stress you are putting on your rigging because under the dynamic loading that is occurring, you could reach an overload condition and end up loosing your mast....

• What does high tension do to the boat hull’s life?

I would think that generally the hull life would be very minimally affected for keel stepped masts. For deck stepped masts, you may be putting your structure that holds that mast under greater loads affecting it's longevity. But for hulls, I wouldn't think it much of an issue, if course as long as you aren't with one of these hulls that are very light weight. But high tension will certainly affect all rigging components.

These are all my opinions with no base in real world data.

dj

 

[Screen Saver]

@Screen Saver you replace everything - turnbuckles, connectors, the whole system.

Without going into a long explanation, all 316 is pretty much the same.

dj

Yea I guess insurance doesn't really drive me. They try to make rules to ensure they make money. Im more interested in what is actually required from a safety point of view and its longevity. I have not heard or seen any turnbuckles breaking for example.
I dont know about rigging, but when it comes to stainless anchor chain there is quite a bit of difference between 316 anchor chain made in UK,US etc verse 316 chain made in Asia. Whether that is the case with rigging & fittings Im not sure. When I did the diagonals, I got originals from Selden.

The rig is B&R fractional standard on Hunter 49

 

[dLj]

Yea I guess insurance doesn't really drive me. They try to make rules to ensure they make money. Im more interested in what is actually required from a safety point of view and its longevity. I have not heard or seen any turnbuckles breaking for example.

I've seen numerous turnbuckles break.

I dont know about rigging, but when it comes to stainless anchor chain there is quite a bit of difference between 316 anchor chain made in UK,US etc verse 316 chain made in Asia. Whether that is the case with rigging & fittings Im not sure. When I did the diagonals, I got originals from Selden.

With all due respect, this is mostly myth. I'm not certain how it started but it has pervaded western culture. 316 made anywhere in the world today is of substantially equivalent quality. I would wager that part of the myth may have come from people not knowing what the base material was they were buying, thinking it was 316 where in fact it was not. I have never seen a documented case where certified 316 has been shown to be substantially inferior produced in Asia.

dj