Getting in tune

[Windward]

When I was on the coast, I was not pleased with Windward's performance to, um, windward. While there I eased the forestay turnbuckle a couple of turns and noticed a significant difference. I still wasn't pointing the way I wanted to, though. In addition, the new 130 has a slightly flat cut, so it needed some more headstay sag to provide good power in mild conditions, and when slugging into chop.

When I raised the mast last weekend I decided to increase mast rake by easing the headstay tension, effectively lengthening it. Dangling a wrench from the main halyard, I think I ended up with about 5" of rake, measured to where the gooseneck is mounted on the mast. This was probably 1/2" longer on the forestay than I'd been using, and I think equates to a little less than 1 degree of rake.

I then centered the mast laterally using the cap shrouds and left the lowers loose but roughly even. Using a Loos "B" gauge, I adjusted the caps to about 27 on the gauge, roughly 15% of the 3/16" shroud's breaking strength. I had to adjust the spreader angle once to get them to bisect the shroud's angle.

I tensioned the forward lowers to get about an inch of forward prebend at the spreaders, and tweaked enough to remove a slight bow to starboard. I tensioned the aft lowers until they provided some slight resistance, then brought the forward lowers to about 22 on the Loos gauge. Still had about an inch of prebend.

I adjusted the backstay until it read about 0 on the Loos, quite a bit looser than I'd had it in the past. I then cranked down the backstay adjuster. There's no scale for 5/32 wire on the B gauge, but max tension was around 25 on the gauge. At that point I eased, recranked, then adjusted the aft lowers to limit the mast bend to between 2 and 2.5". I eased the backstay adjuster again, then had to retension the caps from 25 to 27. Also retensioned the forward lowers a bit.

Got her rigged, then went sailing. The day's great 15-20 kt breeze had of course dropped to 0 - 10, sometimes a bit higher, gusting maybe 15, and shifty. Notice I said SHIFTY, not with two Ts.

She was like a different boat, the one I remembered somewhere in the past before a couple of rounds of mast and rigging repair. Despite funky breeze, I immediately noticed that she was pointing better, with more authority, and tacking through around 90 degrees. The helm was much improved, too -- I could tie it off and she tracked like a slot car. By playing the backstay adjuster I found I could really tune both the power of the jib and the fullness of the main. I was comfortably making 4.8 - 5.7 kt upwind, and the apparent wind was certainly no higher than 10 - 15 (need to get that anemometer hooked up).

My big concern was that I'd be rounding up frequently with the additional rake. There wasn't enough breeze to be a decent test, but I had no such problem in the 14-18 kt (true) gusts. When things were on the blustery side I yanked the adjuster down, tensioned the vang, cunningham and outhaul some and dropped the traveler slightly. Also eased the jib tweaker, effectively moving the lead aft. She felt wonderful!

I'm looking forward to bigger breezes and lengthier testing (for science, of course -- someone has to do these things), but my conclusion is that even if you think you have your boat dialed in, it's well worth the time to play with the tuning a bit. Once you have settings that work, absolutely be sure the write them down, along with any notes you make during sea trials. I'd be pleased with the results so far even if they cost money. The fact that they were free is gravy.

[EmergencyExit]

Excellent post and great advice, I bookmarked this thread ! - thanks Jeff

[hp18carr]

Reading Jeff's post I feel like I'm back at collage sitting under a professor... something about quantum mathematics. (LOL)... well back to the books. Speaking about back stay adjusters, it sounds like another item I need to add to my wish list... where could I find a good one?

Terrence
Wilmington N.C.
Chrysler 26' 1980
Pandora (for now)

[Windward]

Terrence, I'll try to take some pics. There are numerous solutions possible, but for a 5:1 purchase I used:

=> An adjuster sheave and becket slider car thing: http://www.defender.com/product.jsp?pat ... 4&id=76471 (the original was a stainless ring with a pair of Harken hi-load cable blocks, but this is smoother and easier on the backstay bridle)
=> A single block to starboard (Harken 29 or 40, dinghy, Ronstan 30 or 40 or similar)
=> A Harken double block with becket, shackled to the becket on the slider
=> A fiddle with becket and cam to port (I used a Ronstan 40, but a 30 would work and Harken's always cool)
=> 1/4" StaSet line... don't recall how long... I'm betting between 25 and 30 feet
=> A couple of 3/16" D shackles

I might consider going to a triple on top and a single with becket to starboard, plus another 5-6' of line, to get 6:1, but really 5:1 purchase seems adequate in this application

[Mario G]

Again does any wounder why I discribe what Windward was doing as danceing around us?
Now that we are on the live aboard/cruising end of sailing I hope to get to his level.

[LeatherneckPA]

I'm not really sure what a great deal of thism eans, BUT I bookmarked it for reference in the spring when I get Believer in the water.

[Paul]

Ok, my question is how you know the hull is level in order to know that the plumbs you do are accurate. Is thre a location (the mast step for instance) you use to get it flat for and aft as well as side to side?

Paul

[Windward]

There probably is, but since there's some testing and iteration (sounds better than trial and error, or SWAG) you really just need a consistent reference trim for your boat. I get her balanced on her lines, essentially in sailing trim, and go from there based on what happens when she sails.

If I can't point, I want more rake. If she's rounding up like crazy, or at least has too much weather helm, I probably need less rake. If I can't power up the jib, I try less headstay tension. If any of the leeward shrouds are visibly slack while sailing in the highest winds I encounter, I usually need more tension on them (both leeward and windward, since they work in pairs). Then I try it again and see if it's better or worse.

I use a couple of 6" crescent wrenches to adjust the turnbuckles, one to hold the flat on the swage (keeps the shroud from twisting as you tighten or loosen), one rotate the turnbuckle. Once I'm close, adjustments are made a half-turn at a time. I had been using anti-seize on the threads, but saltwater seemed to make it really gummy, almost like locktight; I cleaned it up and have been using 3-in-1 oil with good success.

[EmergencyExit]

Ok, my question is how you know the hull is level in order to know that the plumbs you do are accurate. Is thre a location (the mast step for instance) you use to get it flat for and aft as well as side to side?

Paul

You can use a halyard to get towards an initial plumb. After the mast stepping pull a halyard over to a point on the toe rail and mark it. Then pull the same halyard to to same point on the opposite toe rail and the distance should be the same. Fore and aft is a different matter, you might could measure an equal point fore and aft away from the mast base, but the cabin top isn't really flat. For fore and aft plumb I get the boat in the water, and hang a heavy wrench from the halyard - if it hangs just a bit aft of the sail track that's a good starting point.


Then I wait and read what Jeff has done, and do that

[CaptainScott]

Excellent thread! Thanks for sharing Jeff!
Scott

[Windward]

You can use a halyard to get towards an initial plumb. After the mast stepping pull a halyard over to a point on the toe rail and mark it. Then pull the same halyard to to same point on the opposite toe rail and the distance should be the same.

Yup, that's how I get it centered side to side. Fore and aft (rake) is via the dangling wrench technique.

[sailbob2]

I noticed that CRYSTA has a bit of rake in her rig and it works well for me also. I just look at the water line to make sure I'm level from bow to stern.