Luther's Tuning Guide

Luther's Advanced Tuning Guide

By Luther Carpenter

[!NOTE] Luther Carpenter is a legendary sailing coach and sailor. This guide offers a deep dive into advanced tuning techniques for the V-15, focusing on the critical relationship between rig tension and rake to maximize boat speed.

The standard tuning guide is a fantastic starting point, but for those looking to squeeze every ounce of speed out of their V-15, we need to go deeper. My approach focuses on the relationship between rake and tension.

When I come back from a day of racing or tuning, I want to know exactly where the rig was set. Since we sail incredibly loose in light air, understanding how rake and tension interact as the wind builds is key. This approach has stepped up the learning curve in our fleet and improved boat speed across the board.

Setting Standards and Baselines

Before we get into the variables, let's establish the constants—the things I try never to change.

Mast Step

I set the mast step with 5 holes showing in front of the one that is actually pinned. This places the mast about halfway back.

[!TIP] The original tuning guide recommends a position much farther forward, but that was written before the spreaders were shortened. I prefer keeping the step back for better downwind performance—at least until someone blows by me upwind in a big breeze with their step forward!

Jib Height

Jib height off the deck is critical. Here is my setup procedure:

  1. Set the rig to its most forward raked position (consult the Spreadsheet below).
  2. Tie the head of the jib so the foot is BARELY touching the deck.
  3. On my luff wire, this measures 2 3/4" from the bearing point of the thimble to the head of the jib.
  4. Important: Ensure you are pulled to racing tension when setting this.

Once the jib is tied at that height, I never adjust the top again. All luff adjustments are done at the bottom of the sail. This keeps the lead position consistent, allowing me to focus solely on rake and jib luff tension while watching the upper twist of the sail.

Jib Luff Tension

[!IMPORTANT] Do not underestimate the importance of adjusting the luff tension for every condition, every day. It is critical.

Use a small enough piece of line at the tack so the adjustment can be made easily on the water through the full range.

Mainsheet Bridle

I set my mainsheet bridle so that the split is 42" from where they are tied to the eye straps.

Jib Tack

I consistently pin the tack of the jib in the middle hole of the bow fitting. This seems to flatten the jib nicely for both light air and big blows.

[!NOTE] I've experimented with the other holes, but the middle has been the most reliable. However, I have started using the aft hole again in puffy, shifty, or choppy conditions as it provides a more forgiving shape that is easier to trim.

The Case for Sta-Masters

Shroud settings in the V-15 are critical—there are no two ways about it. They determine both tension and rake.

I recently sailed in a 15-22 knot big-wave training session and was super fast. When we measured the boats afterwards, I was raked 6" further back and had TONS more tension than the others. One owner had no idea where to put their shrouds for that condition!

This inconsistency often comes from factory shroud cutting. You cannot simply pin your shrouds at the same hole as someone else and assume you have the same setup.

Why use Sta-Masters?

  1. Precision: They allow you to compare settings with confidence (e.g., my "number 5" setting will match yours).
  2. Speed & Safety: You can change your rig in less than 2 minutes, safely, on the water.

[!TIP] I can't tell you how many race days I've been able to make a quick change and gained a serious boat speed advantage. It's simple, safe, calibrated, and affordable.

The Spreadsheet

Once I had a calibrated rig, I started using a tension gauge to track settings. I use a Loos old-style gauge. I also marked a permanent scale on the mast for the jib halyard to reproduce fast settings.

How to Read the Spreadsheet

  • Sta-Master: The setting on your Sta-Master turnbuckles.
  • Rake: Measured from the top of the mast to the transom (standard method).
  • Tension: Shroud / Headstay tension on the Loos gauge.
  • Halyard: Setting on my mast scale.

| Sta-Master | Rake | Tension (Shroud/Headstay) | Halyard | Wind (kts) | Water | Comments | | :--- | :--- | :--- | :--- | :--- | :--- | :--- | | 9 | 21' 10 1/2" | - | 1.5 | 4-13 | All | 2001 Season success - jib was standard shackle height | | 8.5 | 21' 10" | 35 / 23 | 1.5 | - | - | Don't use this setting | | 8.5 | 21' 8 3/4" | 27 / 8 | 2 | - | - | - | | 8.5 | 21' 8" | 18 / -2 | 2.5 | 4-8 | Flat | Won the Midwinters using this setting. | | 8.5 | - | 15 / - | 2.75 | 0-6 | Flat | Headstay sag VERY reactive to mainsheet. | | 7.5 | 21' 8 1/4" | 34 / 19 | 2 | 9-14 | Flat/Chop | Planing in puffs, vanging hard 85% time, great feel. | | 7.5 | 21' 7 3/4" | 33 / 16 | 2.25 | - | - | - | | 7.5 | 21' 7" | 28 / 10 | 2.5 | - | - | - | | 6 | 21' 4 3/4" | 37 / 25 | 2.5 | 9-14 | Rough | Great setting for mod breeze but large waves. Better to be raked in waves. | | 5 | 21' 4" | 36 / 24 | 3.25 | 10-18 | Chop/Flat | Great range - excellent planing in puffs. More puff than lull. | | 4 | 21' ? | 37 | - | 10-16 | Mixed | Great setting for early breeze build - still some holes, but breeze coming on. | | 2.5 | 21' 1/4" | 39 / 26 | 4 1/8 | 17-23 | Big Waves/Flat | Smokin fast. Board up 10", vang mod/hard, both cunninghams wailed. | | 2 | 20' 11 1/4" | 38 | - | 14-19 | Flat/Chop | Elissa tuning - won all breeze races, new main/jib. |

(Note: This tuning was done with a crew weight of 280-290 pounds)

Tips by Condition

0-3 Knots

Who likes sailing in this condition? Not me! So... no comments!

3-8 Knots

This is a condition I really like. The water is super smooth, so once you get up to speed, you can sail super flat and point very high.

  • Jib Trim: My primary focus. I use a middle telltale on the luff which is super sensitive and gives me an "extra" read on pointing. When holding a lane, I focus intently on this telltale.
  • Mainsheet: I generally don't move the mainsheet much. Find the right trim, accelerate, and leave it there unless velocity changes significantly.
  • Headstay Sag: If your rig is set right, you should have a fair amount of sag. Be careful not to trim the main too tight, or you'll pull the sag out.
    • Mantra: "Ease the main for more sag and power, flatten the boat, and point." It feels backwards, but it works.
  • Mainsail Telltale: Surprisingly, the top batten telltale is stalled a fair amount of the time.
  • Crew Position: The two biggest mistakes are not getting the crew far enough forward and sailing too heeled.
    • Crew: Move up to the shroud, whether in the cockpit or hiking.
    • Skipper: I stay right about where the ratchet block is.
  • Technique: Sail extremely flat—sometimes even heeled to windward a slight bit. It is smoking fast and allows you to point very high.
    • Warning: There will be NO FEEL in this condition. The helm will feel dead or even have leeward helm. Ignore the helm feel. Focus on speed through the water, boat flatness, and the pressure of your legs on the rail. Trust the performance.

8-12 Knots

It's tough to beat racing a V-15 in this condition. The boat has enough power to require hard hiking, points great, and is super tactical.

  • Water Conditions:
    • Flat: Sailing raked forward and vanging to depower can be quite good.
    • Wavy: Sailing raked forward gives you sails that are too tight-leeched and flat—not forgiving enough. You want a stable headstay in rough water, so you may find yourself sailing tighter (more tension) in waves. You want the sail plan to carry some depth and twist, maintaining a locked-in, stable trim.
  • Tension: In flat water, don't be in a hurry to take all the headstay sag out. That extra power may be what you need to get off the line or punch through chop.
  • Vang: If it's puffy, I play the vang a lot. I keep the tail of the 8:1 vang extra long so it sits in the crew's lap, always ready.
    • Technique: Throw the vang across the boat before tacking so it's ready on the new side. Get the vang over the windward side when luffing before the start.
    • Skipper Control: I prefer (demand) to adjust the vang myself. The skipper feels the power in the rig and knows exactly how much to ease or trim.
  • Jib Trim: I spend most of my time looking at the leech through the main window and the foot distance to the rail. Fine-tune the jib luff tension! Go for a few wrinkles if underpowered.
  • Hiking: At 10 knots, I start to have the crew move 10" aft of the shroud. If I need to foot, they come back to me; if pointing is the game, they move forward.

12-17 Knots

This condition is awesome! Planing in big puffs, displacement sailing off the line, and that gray area in between.

  • Rig: Rapid drop in rake (see spreadsheet) and consistent tensions around 35-38.
    • 35 Tension: This is about when the leeward shroud stops dangling. Beyond this, we increase headstay tension for a flatter jib with more twist. This allows the jib to stay sheeted in at the deck but still allows for bow-down planing.
  • Jib Luff: Tighten the jib luff tension, removing all wrinkles and starting to "round-out" the front of the sail for acceleration. Don't be lazy—belly up to the bow and make the adjustment!
  • Centerboard: Start raising the board, usually in 2" intervals. By 17 knots, we'll have it up about 6-8". Raise it if the boat feels sluggish to plane in puffs.
  • Cunningham: Pull the main cunningham on aggressively. All wrinkles gone.
  • Vang: Moderately tight, not wailed. It flattens the main nicely, but remember: if the jib is twisty, the main must be too. Too much vang will leave you just shy of the planing threshold.
  • Technique: Bear off with max hike, get planing, shoot up, repeat. It's a rhythm of speed burns and pointing jabs.

17-25 Knots

This is pure tuning heaven. If you have it, you are gone; if not, it's a lot of work with little payoff.

  • Rig Requirements: Massive rake and tight tension.
    • Target: Tension of 39, Rake of 21' or slightly less.
  • Controls:
    • Jib Luff: Wail the adjustment as far down as it will go. You want the jib super draft-forward.
    • Cunningham: Wailed.
    • Vang: Moderately hard, but don't wail it so much that the boat is hard to handle or the main rags in puffs. Use it to flatten, but leave some twist.
    • Centerboard: Can be as high as just under the jib sheet cleat. You want to still be able to play the jib upwind, but have the board as high as possible.
  • Technique: Balance smoothness with rapid transitions from planing to height/depower.
    • If the rig is right, you should not have to ease the jib outside the rail. The boat should plane at will with decent hiking weight, and the helm should be balanced.
    • Tacking: The hardest part is when the boat stops planing. Work extra hard out of tacks to get planing immediately. Tack in smooth spots!

Conclusion

My spreadsheet is an ongoing work, but it provides excellent comparison numbers. Using a tension gauge and tape measure every day might seem overboard, but it undeniably explains why a certain boat was the fastest on the water. In our fleet, we do a quick round of number checks before easing tensions, giving us something concrete to talk about at the bar!

See you on the race course,

Luther Carpenter #1263