Rake

We think of rake in the classical sense.  Backstay and forestay off, and the mast just fixed at the partners (max J) and the butt (max forward).  We then attach both back and forestay, center the stick, and put 1250# [31] on the uppers, 1100# [27] on the lowers, and about 900-950 [17-19] on the intermediates [Loos Model RT-10].  The Sov mast is a classic straight double spreader.  No matter how hard you crank on any of the shrouds, you don’t get pre-bend.  You need swept spreaders for that, or at least chainplates a few inches abaft the mast center.  What the Sov website folks refer to as “rake”, we look at as backstay induced mast bend that is adjustable by the checks.  Once done, the forestay length and backstay tension will determine how much mast bend you have (luff curve) and forestay sag you get.  I have a turnbuckle on the bottom of the forestay that adjusts the forestay between max (about 44’) and min (43’6”) [6'4" - 5'10" with Swing method?].  Max is where the forestay is limp (no backstay) with about 8”-10” of natural sag (wrap the toping lift around it, pull back and measure between the forestay and a taught jib halyard with Mark 1 eyeball or your foredeck person in a chair).

I have the typical Kenyon MORC 4060 section, fixed at the partners with the 10858 collar. The mast base is the standard 10664 and is all the way forward. Somewhere I have measurements from the genoa sheave to our boom black band and to the deck at the partners as well as to the forestay tack pin. I think I also have our mast at the partners to the forestay tack pin. I'll find those and get them out.
genoa sheave to boom black band =
genoa sheave to deck at the partners=
genoa sheave to forestay tack pin=
partners to the forestay tack pin=

Hopefully that should be enough for mast height and rake, at least with respect to the partner position. I can also take the numbers from the bottom of the mast collar ring to the mast base plate to see how long that is.

These values were chosen only because they work in our sail plan, not because they are magic in any sense.  Max is to allow the sail plan to be pulled back (backstay and checks) enough to adjust the center of effort to alleviate lee helm in conditions of 6 kt or less.  Backstay and checks are marked so they won’t be over trimmed, but allow the light #1 to fly with about 4” or so of sag, and the main to be fully powered (fairly straight stick, deep draft, etc ..).  As breeze picks up, we want less “rake” (you certainly do not want to induce weather helm), so we tension the forestay turnbuckle to keep forestay tension in line with our sail change plans.  The L#1, H#1, #2 and #3 blade are all cut with specific draft positions in mind, so we have conformed the rig to these shapes, and have the added benefit of a uniform and consistent headstay sag, no matter what the sail or wind speed.  This also allows checkstay modulation for mainsail draft depth adjustment without worrying about inducing extra sag.

At 6kt or over, we crank in a half inch.  At 12kt we crank in an additional one inch; 15kt another half inch (we’re looking at ¾), and for 18 and over we put in another half inch.  In sum, the rig gets progressively straighter as the wind increases.  In heavy conditions we can develop a lot of forestay tension without “cranking” on the checks.  We use backstay (48:1) a lot for tension control, and use the checks for Main shape.

"Cranking" refers to the forestay turnbuckle. We put on a total of three inches, the "half inch", "one inch" refers to the total that the forestay shortens. The 3/4 inches refers to indecision between sail choice at 15 kts. If we use our #2 more in its top register, I think I would tighten the forestay a bit more (from an additional 1/2 inches total to an additional 3/4 inches total).

Running Backstays and Checkstays

We have the slots for runners at the hounds but don’t hook them up very often.  I crank the checks after a tack to power up the Main and slowly ease them to flatten it out for a speed shape once we are at speed, so runners would hinder the program by having the opposite effect on forestay tension & jib power; tight coming out of the tack and subsequent softening.  I tried runners in Hurricane Gulch (San Pedro) and they worked well, but found that the backstay works just as well at putting headstay tension where the sail design needs it to be.  The jibs are all cut for a uniform 4” of sag which we can reliably obtain.  This leaves the checks available for constant trimming along with the backstay.  One check tail is 1:1 and goes thru the coaming to a cleat & winch for fast trim; the other tail runs along the edge of the cockpit floor to a 12:1 tackle for trimming under way.  The flexibility is just personal preference; I grew up in Finns, Dutchmen & J24s and just like to have tiller in my teeth and all three hands working at the same time.  My tactician & I are side by side and together we control the sheet, traveler, backstay & checks.

Backstay/Checkstay Tune

To runner or just check is an open question and depends solely on whether a rig can establish the headstaytension a sailmaker requires for a particular sail design. Some might require runners for their program, others do not. If a rig has too much sag or it's just too hard to pull it out, runners are the option. If sag is easily pulled out to where the sailmaker wants it, you don't need them . basically it's just that simple. The sail design is what's important. For Example Dennis Conner sailed Menace XX with only checks about 80% of the time and runners perhaps 20%; that's according to Dennis, when I raced with and against him, I never saw him use runners. North made him a different main for whenever he used the runners, because his regular cut wouldn't "cut it" :)

In our case, we can pull on 2711# easily with our 48:1 backstay; our adjustment marks go much higher than that. We like the flexibility of independently adjustable checks (independently adjustable forestay tension and mast bend). We adapted an analytical program that makes adjustments to headstay tension for sag and mast bend for main shape repeatable, and allows the checks and backstay to be "adjusted together" as the experts like to say in the articles. What we do is:

At the dock, unzip about 10 to 15 feet of the Tuffluff. Attach the LOOS gauge to the exposed headstay as high as you can (step ladder's good). Crank on backstay (NO check) and mark the line when the gauge reads 750, 1000, 1250, 1500, 2000, 2500, 3000. We call these marks B1, B2, . . . Bn. Lining up colored tape on the purchase part works very well and allows for lots of variability between marks.

Go back to the B1 mark, and now add check till mast bend is where the sail cut requires it and mark the check line (this will be C1). Record the mast bend number (this will be FB1) and the new headstay tension (FT1) number (it will have increased). With the check still at C1, crank backstay to B2 and record this mast bend (IB2). Add check till the bend is right and mark C2, record this mast bend (FB2) and new final tension (FT2). Continue thru the matrix. You should now have a nice matrix of tensions and mast bend numbers, both in a hard checked and soft checked condition, based on just a few marks on the backstay, and the same on the check line.

With no checks, mark B1 thru B whatever each desired IT.

Reset to B1, verify IB1. Then set C1, read and record FB1 and FT1.

Keep C1 on, set B2, read/record IB2. Set C2, read/record FB2 and FT2.

Keep C2 on, set B3, read/record IB3. Set C3, read/record FB3 and FT3.

Keep C3 on, set B4, read/record IB4. Set C4, read/record FB4 and FT4.

etc.

Go sailing & put up the right sails for the wind conditions. Load up the sails and move through the combos (B1/C1, B2/C2, B3/C3, . etc) till you get the correct sag for the sail/wind. At Bx/Cx record the sail, TWS or AWS, and headstay sag. Also try Bx-1/Cx-1 and Bx+1/Cx+1 and record the sail, AWS/TWS, and sag. Half and quarter positions are easy to judge and use as well. Keep the matrix with you and do it again for the other sails in the inventory. Now you know exactly how much bend (FB), tension (FT), and sag you have for every setting at any wind speed for all the sails.

Unfortunately, we don't have any tricks for measuring forestay sag, I just use the Mark #1 eyeball and try to put it where the sailmaker likes it. The initial sag number we got by Harry and I sitting on the bow and looking at the sag and the draft as the boat powered and feathered and with backstay and check adjustments. Everything we do is to keep the sag consistent with changing sails. It's about three to four inches, and we try to keep it so, as a base value, whether we have the light #1 up or the #3. That way, Harry can cut for a consistent sag that we are able to dial in repeatably.

The reason we mark the Bs with no check and then mark the Cs later is so we can get the IBx and FBx values for a Bx/Cx set. The FBx value suggest the bend for the "power shape" mainsail, the IBx values suggest the "speed shape" mainsail. Adjusting a combo "together" can be done either uniformly (i.e., going from B4/C4 to B4.5/C4.5) or by tilting up (going from B4/C4 to B4.5/C3.5) or tilting down (B4/C4 to B3.5/C4.5). Tilting up is flattening out or shifting to high gear (tighter headstay, flatter main), tilting down is powering up or down-shifting (more sag, straighter stick and fuller main). If the boat has a close hauled wind instrument, sail the nominal combo for conditions and record the heading to the wind (point angle) and average boat speed; lots of readings over a couple of minutes and take average. Try a bit of up-combo, a bit of down-combo, tilt up, & tilt down. This will give a good indication of how the settings effect point and speed for those conditions. A real benefit comes if your instruments can reliably derive VMG.

For example, in a tack (assuming a B4/C4 setting), tilt down (down shift for acceleration). Ease backstay to B3.5 (or B3.75 or whatever) to power up the main and genoa. Aggressively trim the new check hard to C4.25 or whatever (again power up the main). Go back up through the gears (second gear might be a flat B4/C4, third gear might be tilted up slightly to B4.25/C3.75). Lumps might mean the nominal combo is more tilted down than normal (i.e., B3.5/C4), while flat water might mean the nominal combo is more tilted up (B4/C3.5) . you get the picture. The the checks and backstay can be "adjusted together" for any kind of conditions, and have a good basis for experimental departure.

When we tack, I do ease the backstay to the next lower mark. We check to around the FB mark and straighten the mast, then when getting to speed, pull on backstay as the check is eased to around the IB mark. Basically the typical backstay program, but we add some check adjustment. We're usually racing in a fleet of Schock 35s (rate 72), where Dave Ullman does the same thing, so we have to do everything we can to save our time.

I made the matrix as more of a point of departure; sort of a dock tune. The actual marks got adjusted when the wind came up and we were able to change sails and see what happened. At that point, we again looked at the sag and drafts and made some adjustments to the marks and turnbuckle tension. Realistically, adjusting the forestay turnbuckle had quite an effect on the sag, to the point that a turnbuckle adjustment equaled a backstay adjustment; we can sail at B3 to B4 most of the time, avoiding the "hard on B5" setting. B5 is available, in case we can't adjust the forestay (in Long Beach we often start the first race in 6 to 8 and finish in 12 to 14; start the second in 14 and finish in 18 to 20). Then we use the normal matrix settings. I guess what I'm saying is that B4, C4, IB4, FB4 (plus a forestay adjustment) give about the same tensions (desired shape) as B5, C5, IB5 and FB5 without.

IB and FB are mast bend. Our luff curve is about 3 to 4 inches for a 40% draft. We try to maintain the bend basis at about 3 to 4 inches at midgirth. Check "on" usually puts the draft at about 35-38%, check eased puts it at about 45-48%.

Sails vs. Rig Tune

We don't have separate numbers for different sails, serendipity happened and we found the numbers were valid over the inventory. The H#1 uses the same number set (generally B2 going to B3) as the L#1 (plus a forestay adjust). The #2 adds a forestay adjust and uses the same number set (B3 going to B4); same for the #3 (add a forestay adjust and use B3 going to B4).

Haven't tracked setting changes over time. I don't think they will change much. It didn't take long to get dialed in on tension and mast bend control. After a while, we got very used to trimming and tuning up by the shape and didn't look much at the marks; a glance now and again to make sure we're not choked but just as a guide.

Nomenclature

Running backstays attach at the hounds, in the vicinity of the forestay; check stays attach partially up the mast and are designed to bear at the point of maximum deflection under load.  I’ll try to describe our setup.

click image to expand

When we used to have our runners connected, we ran both the runner and check ends through a titanium ring (both ¼” spectra with luggage tag splices at the back).  A Harken Airblock is strap headed to the Ti ring.  Our control line goes thru the top Airblock and down to another Airblock on the transom (mounted as far down and inboard as possible), goes up thru the back surface of the coaming, runs along the inside, and exits through a through-deck to a cleat.  These are oriented so the line can lead fair to a winch if we ever need to use one.  The other end of the control line leads through a cheek block on the cockpit side (again as far down and aft as possible) and runs forward along the edge of the cockpit floor, terminating in a block.  We use the block as a doubler for a 6:1 tackle, giving a 12:1 purchase, with the tail going to a cleat just by the traveler.  This also leads fair to a winch if necessary.

When we had the runners on, we used to adjust checkstay tension with twing lines, in order to keep the back end of the boat cleaner, free of flogging gear and allow for continuous adjustment under sail.  The twings turned at the base of the mast and had tails long enough to spin around a cabin-top winch if necessary.  The twings and control lines were ¼” spectra with poly covers where they might have to go on winches or thru cleats.

To keep our marks consistent, and have a repeatable termination point, we put a sheet stopper on the coarse side of the control line where it enters the coaming (mark A on the drawing).  We can release lots for a bear away, but only pull it in to the stopper.  When the coarse is in to the stopper, it pre-positions the fine trim side so the trim marks are consistent.  We also calibrate the distance between the moving block of the 6:1 and the doubler block (mark B on the drawing).  When the tail is released, the moving block can only ease the calibrated distance to the doubler.  This gives enough slack to the leeward (off) runner/check lines so they won’t interfere with the main.  When we tack, we keep the coarse sides fixed and just ease the old fine, while trimming the new fine.  On a set of course, we pop both coarse and fine.

In our present configuration, we eliminated the running backstays (just undid the luggage tags) and took the twings off the checkstays, but the control line setup is identical.

More on Runners

No friction problems on casting off the fine trim; we have a bungy that pulls the 6:1 back.  The backstay is indeed a 48:1.  We have two cascade doublers over the backstay termination block (a third doubler) giving an 8:1 effective doubler to a 6:1 backstay purchase.  I can give you a drawing if you want.

I can get you dimensions or photos of the backstay if you need them.  We have enough play in the backstay purchase so we can fraculate till the mast is a bit forward of vertical.

We have no trouble with headstay tension.  Just for grins, check out the Schock 35 website at www.vossassociates.com/schock/ .  The Schock 35 is a Soverel 33 on steroids, with “check stays” only on a masthead rig.  They have a good tuning guide developed by Dave Ullman that talks about headstay tension and sag.  In fact, we ripped off our check stay fine and gross trim line setup from a combination of Ray Godwin’s Schock, “Whiplash” and Dave Ullman’s Schock, “Buttercup”.

Ian Fraser also did a tuning guide for a Tripp 36, which is basically a Schock 35 with a 7/8 fractional rig; running backs and adjustable checkstays like in our drawing.  Since the Tripp is 14/16, and the Schock is 16/16, the 15/16 Soverel fits right in between.  The Schocks (16/16) are set up with max, max backstay (bottomed out in big air) at 3200#.  This works out to 75# pull on a 48:1 backstay line.  The Tripp (14/16) wants 2800# on the runner for max, max headstay tension; a little over 55# pull on a 48:1 backstay.  The Schock has a much larger genoa than the Sov with consequently greater loads.  The Tripp is about 14% larger with consequently greater loads.  The backstay on the Sov is more than sufficient to give you any amount of headstay tension that might be required.  By the way, in their tuning guides, both of these “Pros” refer to the check stays as “runners”, even Ian talks about the “runner loads” when he is referring to the loads on both the running backstays and the check stays on the Tripp.  It seems that even the rock stars mix their metaphors.