Rig tuning a 40' cutter

[rcassano]

The boat is a Baba 40:

The last time I had a professional rigger static tune the mast I asked if he was going to remove the Schaefer roller furling drum on both the jib and staysail in order to get the headstay and staysail stay adjusted. His answer was that they were fine and it was not necessary. My question is this:

1. How does he know they are fine when tuning the rig should start with loosening "all" the wires and starting from scratch?

2. Isn't the entire tuning process faulty if the head stay and staysail stay tension are ignored and not included in the "start from scratch" - "loosen everything" basic, Brion Toss rule for starting the rig tuning process? (as stated in the "Tuning Your Rig" video).

3. If the tension on the headstay is not sufficient would this put way too much tension of the forward lowers when the hydraulic back stay is pumped up to flatten the main?

As a boat owner and not a professional rigger I was wondering if maybe I was missing something here? In any case, I'm going to try to adjust and tune the rig myself to see if I can, at least, get things in the ball park. Any advice on the headstay/staysail stay tension would be much appreciated.

[Bob Pingel]

Headstay tension is typically not measured directly because as you mention the furler kinda gets in the way.

Headstay tension is gauged by spar shape and backstay tension, as well as an educated shake of the foils.

Basically you want the headstay reasonably "tight" and still maintain a proper spar shape (again subjective). Spar shape and headstay tension are directly controlled by backstay tension.

And, of course, gauge tension is just the starting point, you need to sail the boat to truly tune it.

Bob

[Brian Duff]

The length of the headstay is adjusted to correct sailing characteristics of the boat. Generally at a rig tune this is not adjusted. A sail tune is required to dertermine if the headstay length is right.

The staysail adjusts the bend of the rig, not the rake, so that matters too, requires sailing to determine correct setting.

does that help?

tension of forestay is set by backstay, IFS by runners

[rcassano]

Very helpful! Thank you. let me give this a try and see how she sails.

[Brian Duff]

if you find a lot of weather helm, try bending the rig more (tighter backstay/ tighter IFS and forward lowers) or raking the mast aft more (longer forestay).

IF the boat doesnt point well try tighter backstay (forestay) but about a foot of forestay sag is acceptable for the usual cruising headsails, less is better there though...depending on sail cut.

[Ian McColgin]

I don't understand Brian Duff's response. Normally moving the center of sail effort aft increases weather helm.

I am not a big advocate of fooling about with mast rake to solve a weather or lee helm problem until one is sure that the boat is floating correctly fore and aft. Many boats with a rep for wicked weather helm are really just a bit down at the head. Since water is ever so much denser than air, it takes less movement of lateral resistance to get near balance than it would moving the sail area. Both are important, but think of hull trimming ballast as the coarse adjustment and sail fore and aft as fine.

[Brian Duff]

Ian is correct. The hull trim of a boat is a significant factor in balance under sail. So is the heel angle. All of these need to be correct before adjusting rake. As IAN SAYS the bend of the rig and rake of the rig come in as very fine tune adjustments meant to effect the ability to keep a balanced helm through a range of conditions, assisting the sailor in keeping the balance and heel of the boat with a constant trim and heel.

A tough task on a larger keel boat sailed short handed. This is probably why many find keeping a small amount of weather helm allows the boat to sail itself well. There is also a theroy that slight weather helm on a keel boat can help create lift to weather, but this is dated and only applies to certain hull types...

On my cruiser (westsail 32) i have to battle constantly with Lee Helm. This is (i think) BECAUSE the boat is really STERN UP due to having no engine and not nearly enough extra ballast to bring the boat to her lines. THis causes the whole rig to be well forward of where its intended, and the hull to be shaped all wrong. In my case I have an extra bronze windlass, a few hundred feet of chain and acouple extra anchors as well as a few batteries back in the engine room, and the boat is still up in the stern by 4" or more. The bow is basically on its lines, about 1" under due to the stern being so high. One would think this would make the boat have a wicked weather helm from hull trim, especially since the W32 is known for slight weather helm (which I have always been able to tune out of the boat to achive complete self sailing upwind) but my boat battles lee helm (maybe from rig trim). I have however added toggles unde the forestay and shortened the backstay chainplates by lowering the boomkin angle. My goal for this winter is to put an engine back in to bring her onto her lines, and help with re-sale value. That said, in the BVI where we keep her an engine is JUST NOT NEEDED. I hope she sails better then...

So, that is a sign that balance of hull is way more important than rig in getting the boat to sail well, (as Ian said) and that the convention of weight foward heads her up and weight aft lets her fall off doesn't allways apply.

Now a second case -Gaff rig cutter from west coast of england, (shirmper really) this boat came with wicked weather helm, i believe intended as she was meant to tow shrimp nets off her leward quarter post and mast, such that the helm would become netural with alot of power still available. To use this boat as a yacht a few things were tried. The hull trim was adjusted as much as possible using human ballast (group of 6 folks adjustnig from one end to the other but that seemed to have no effect) First was a 4' longer bowsprit. That helped alot. next we tried cranking the rig forward, it got worse! Letting the mast fall as far aft as we could helped things better again on the helm, but the boat i think is just meant to have helm unless towing...


So all that leads us to just have to get each boat on the water , balance and trim correct, then judge sail and rig shape to start the guessing game toward correct sailing balance. its fun. it doens't always make sense.

Sailing unballasted dingies can help A LOT to understand balance under sail, sail shape and rig tuning too....

To explain about rake and bend - Theroetically rake aft will increase tendancy to round up, and visa versa. Mast bend increased will typically encourage the boat to be able to point closer to the wind and heel less. Forestay increase in tension typically makes the boat heel less, and point highter. Decrease in forestay tension decreases pointing and adds power (or heel). The reason max depth of sail (minimum mast bend, max forestay bend) is not fastest is that as the boat heels too much or you have to flogg sails to keep on trim, you create drag. Rather than luff sails partially - flatten them.

Any more clairity through all that rambleing? i hope so

[alfredalfred]

If the tension on the headstay is not sufficient would this put way too much tension of the forward lowers when the hydraulic back stay is pumped up to flatten the main???

[Brion Toss]

Hi,
Nice to hear from Bob and Brian! I concur that "loosening everything" rarely includes the jibstay. On the other hand, its starting setting will determine mast rake, as well as mast bend, and both must be achieved simultaneously with good jibstay tune. So if you are at all concerned with mast position, start with the jibstay. And note that way too many riggers hide measuring errors under the furler; don't be surprised if the turnbuckle is two-blocked -- or barely engaged -- in there.
Lovely essay on helm balance anomalies, Brian. I'll add that some boats with very deep keels develop lee helm as they heel, because the CLP actually moves aft with heel. So yes, always exceptions. Overall hull-balance-through-increasing-heel is another big factor; some boats just don't change CLP much as they heel, which is mostly a good thing, unless you want to induce helm.
I'll finish with a favorite rant. Could we please try to avoid the term "professional rigger"? If you are going to a doctor, no one asks you if they are a professional doctor, right? No one says "professional architect" or "professional electrician." This is because we already assume that these trades require levels of skill and commitment not likely to be the provenance of amateurs. The inference with "professional rigger," I believe, is that the art is so simple that extraordinary skill and knowledge is needed before you might even think about having the gall to charge for your services. If someone is a rigger, and deserving of the title, they possess a body of mechanical and abstract skills that are profound, intricate, and elegant.
Fair leads,
Brion Toss