T-10 Tuning Guide

Congratulations on your purchase of your new Doyle T-10 sails. Although T-10's are one design, you should check your boat to make sure that you have it set up correctly.


Your new Doyle sails are a development of T-10 sails that have won more major titles then any other brand of sails in the T-10. This guide is intended to give you a general guide to trimming your new sails.


Jib Tracks

It is legal to drill extra holes in your jib tracks. Since the jib trims in a very small area of the tracks you only need to put intermediate holes in a 6 inch area, from about 14' to 14'6" aft of the forestay. While you are doing this make sure you tracks were installed evenly on the boat. Many T-10's have tracks which one of the sides is further forward than the other. This is not a problem as long as you know where a constant measuring point is.


If you are sailing class make sure your forestay is MAX. This is very important, if you only sail PHRF make it 4" longer. The attachment at the mast varies in some boats. Measure from the but of the mast to the attachment point. Use the following chart to determine for stay length.

Distance Butt to Forestay Attachment

Forestay Length Allowable


34' 3"
36' 3"
34' 4"
36' 3 7/8"
34' 5"
36' 4 5/8"
34' 6"
36' 5 1/16"
34' 7"
36' 5 1/2"

Upper Stays

For starters set them at 37 on a large Loos gage. This is only a starting point.

Lower Stays

For starters set at 35, making sure the mast looks straight at the dock (Sight up the groove of the mast,) then loosen the lower stays two full turns. The will be loose, probably will wiggle 3 to 4" without much pressure. This setting will allow the middle of the mast to sag into the slot and makes the main fuller. We will refer to this setting as the "base" setting.


Usually you will want this shortened as much as possible, since you will have the forestay as long as possible. Some boats have had to shorten the stay by cutting and re-swaging it. You want the adjuster to start bending the mast up high in the "V", this will give you better purchase. Your backstay adjuster line should be lead forward, to in front of the traveler so it is easy to adjust underway by the skipper or main trimmer.

Jib Cunningham

Rig one. Four to one is sufficient purchase. A deflector for the halyard is a good alternative to the cunningham but raising and lowering the halyard actually changes your jib lead and is not as good as a cunningham.

Jib Tack

Doyle T-10 Tuning Guide Jib Tack

We assume you are still using the jib horns which come with the boat. These leave the tack about 3" off the deck. Make sure you have a shock cord loop which keeps the jib from falling off the horn when it is lowered. Some boats are using shackles at the tack. This often raises the tack which changes the clew lead position. A higher tack makes the lead further aft.

Line ties to horn to keep jib on the horn.

Doyle T-10 Tuning Guide, Horn to Micro Block

Lead comes up from the horn to a micro block on the sail (not supplied), down to a block (Harken 301 wire block), which is bolted to the other side of the horn.

Using 16MM Harken Air blocks, one double and a single, (as shown in the picture to the left) we have just tied the purchase to the pole downhaul eye.

Doyle T-10 Tuning Guide, jib line led aft The line is led to the rail then aft to a cleat next to the jib lead. You may want to lead the adjuster nearer to the jib trimmer. The cleat can be a Harken 279 cam-matic.

0 to 5 Knots True Wind

  • Uppers

    Loosen uppers 1 1/2 turns and lowers 1 to 2 turn. In the light end of the range, the mast will look straight because there is no air. What you are trying to do is let the forestay sag and make the jib fuller. This also drops the jib into the slot between the main and jib. At 5 knots the mast should sag to leeward in the middle (when you sight up the groove) making the main fuller and closing the slot between the two sails.

  • Backstay


  • Main Traveler

    High enough to make the boom 3" to 5" above centerline.

  • Mainsheet

    Trimmed to make top batten parallel with boom. You can try sheeting a bit more but be careful tight can slow the boat down stop you. In the lightest air error in the loose side of main trim.

  • Main Luff Tension

    There should be wrinkles. Your new main has a long luff. Hoist the sail to the band and there should still be some wrinkles in the luff.

  • Outhaul

    There should be about 3 to 4" between the boom and the top of the shelf. We have also had luck with the outhaul very tight in this condition.

  • Jib

    Jib car should be at 14' 2" maybe try 14' 1".

  • Luff

    Just get the wrinkles out of the luff no tighter.

  • Sheet Trim

    Top batten pocket should point to 3" inside the tip of the spreader. Take the top batten out. It is very important to get the top batten out of the sail in light air, to get the fullness you will need for power.

  • Crew Position

    Position is very important. If you can't "feel" the helm, heel the boat more. Generally move the crew forward. In the lightest end of this range put one crew in front of the side stays. If your crew won't mutiny some can go below and sit on the keel.

5 to 10 Knots True Wind

  • Uppers

    Uppers at normal position.

  • Lowers

    Lowers normal position (35 less 2 turns)

  • Jib Car

    Jib car should be at 14' 2"

  • Doyle T-10 Tuning Guide, Jib Car Placement
  • Main Traveler

    Start with it high enough to make the boom 3 to 5" above centerline like in the 0 to 5 range. As the wind builds you will sheet on to keep the top batten parallel with the boom. when the boat heels past 8 degrees and you feel a bit to much helm drop the traveler so the boom is on center line. If the boat heels more hike harder.

  • Mainsheet

    Trimmed to make top batten parallel with boom. This is always done while sighting from the center of the boom. The top tell tale should fly about 50% of the time.

  • Main Luff Tension

    There should be wrinkles you can pull some out if you just don't like the look of wrinkles but they are supposed to be there.

  • Outhaul

    There should be about 2 to 4" between the boom and the top of the shelf.

  • Jib

    Jib car should be at 14' 2"

  • Luff

    Just get the wrinkles out of the luff no tighter. To point better have more wrinkles, but the sail will get harder to steer to. For speed take the wrinkle out. The rounder entry will widen the groove of the boat.

  • Sheet

    Top batten pocket should point to 3" inside the tip of the spreader. Top batten should still be out of the sail.

  • General

    In 5-10 pointing is a function of speed. If you can't point with someone, make sure you are going fast first. The speed will make the keel work more efficiently and the boat will lift to weather. Crew weight and position is critical in this condition. Keep the boat heeled six to eight degrees.

10-15 Knots True Wind

  • Crew Position

    At this point you need to be hiking. Crew weight makes a big difference, especially if there are waves and you need power. If your fleet doesn't have a crew limit, eight people is a good number.

  • Upper Stays

    Upper stays should be tightened two to four from the base setting of 37 upper and 35 lower.

  • Lower Stays

    Tightened one for every three turns on the uppers. Over tightening the lowers restricts the bend and will make the main to full low.

  • Jib Car

    Jib car can stay in the 14' 2' location or moved aft up to 1 1/2". It is better to lead a second sheet to the rail and sail with four sheets on the jib. You tack using the normal lead, then bump the clew out depending the wind. In twelve MPH true (which is where white caps begin) you might bump the clew out only 3/4" while at 15 you will have the clew out 3" (almost to the shrouds). The leech is still trimmed so the top batten pocket is pointing 3" inside the spreader tip. The top batten should be in the sail in this range.

  • Backstay

    The backstay is the adjustment which should be used to power up and de-power the boat. The main trimmer should keep the backstay in his hand and play the puffs. The traveler is a more gross tune. Position the traveler so the boat is stable then work the backstay. In very puffy conditions you may have to play the traveler to keep the boat stable.

  • Mainsheet

    Don't play the main sheet to de-power. Easing the main will sag the fore stay and make the jib fuller.

  • Outhaul

    All the way on.

16 to 25 Knots and up True Wind

  • Crew Position

    In this condition the more crew weight you sail with the faster you will go. Invite all of your friends if you sail in an area with no crew restrictions.

  • Upper Stays

    At the top of this range you will be seven full turns tighter than the base tightness. We have never had enough nerve to go tighter. At this setting you can cause a dimple in the side of the hull of the boat at the chain plates. If you sail this tight or tighter, loosen the stays after the race.

  • Lower Stays

    Tighten two to three turns maybe four turns, the mast should be straight side to side up to the forestay. The tip will fall off to leeward. Tightening the lower stays too much will restrict the bend low and force the bend higher. Just try to get the mast in column (straight) from base to forestay attachment. When checking the mast in this condition make sure you have the main trimmed and the backstay on. The sight up the luff grove of the mast.

  • Mainsheet

    Trim hard, the sheet is supporting the forestay. The top batten should be parallel to the boom or as much as six degrees to leeward.

  • Main Luff

    Just take the wrinkles out of the luff. As the main ages you will have to apply more cunningham to move the draft into proper position.

  • Outhaul

    Max out

  • Reefing

    The lighter your crew the sooner you will have to reef. Somewhere between 18 and 25 MPH true you will reef. Quite often the second reef is better than the first.

  • Jib Luff

    Just get the wrinkles out.

  • Battens

    Make sure the batten is in the jib. You might want to try stiffer battens if you sail with a light crew.

  • Jib Car

    Set the car at 14' 3" and you will have to sail with 4 sheets on the jib, two regular sheets and 2 barber haulers. Barber-haul leads are positioned on the rail parallel to the jib leads and led in front of the stays. Leading the sheets in back of the stays also works.

  • Doyle T-10 Tuning Guide Jib Car Placement
  • Trim Jib

    Top batten should point between 2 inches inside the spreader tip to four inches outside the spreader tip. Sea conditions as much as wind speed dictated position. In smooth water you will barber-haul out a bit but keep the upper leech fairly tight. In waves you need to twist the head open to give the boat a wider groove.


0-5 Knots

  • Angles

    In light conditions you need to sail angles downwind. The spinnaker is the biggest tell tale in the world. Watch the leeward clew, if it starts to drop head up. get the boat going before you start heading back down.

  • Crew Position

    Move the crew forward and to leeward. If you want they can go below and play cards. You need to keep a heel on the boat to help the sail stay full.

  • General

    Light sheets are important in this condition. You should not need an extra set of sheets. The new Spectra or T900 sheets with their covers stripped off are very light and strong.

5-10 Knots

  • Angles

    You will still have to sail angle in this condition but really work on getting downwind. Aggressively square the pole.

  • Crew Position

    Sail the boat flat.

10 -18 Knots

  • Angles

    You can sail very low in 10 to 15.

  • Crew Position

    You can heel the boat to weather a bit in these conditions. Square the pole way back. Never let the clew of the spinnaker go beyond the forestay.

For more information or to order T-10 Class sails: