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Interclub Tuning Guide

Doyle Interclub SailsDoyle Interclub SailsDoyle Interclub Sails

MAST SET-UP

Before stepping the mast, make sure it is straight. Shroud tang location should be at the highest possible location, per the Interclub Class Rules. This is 53” from the center of the mainsail halyard sheave. The forestay should intersect the mast at the lowest possible location, 39” from the center of the main halyard sheave.

BOAT SET-UP

The following measurements are taken from “T1” in the Interclub Class Rules:

  • Aft opening of mast partners: 8’10”.
  • Maximum aft position allowed by the Class Rules to allow for proper rake
  • Forward opening of mast partners: 9’2”
  • Your chain plates should be at/near the maximum forward position, allowed by the Class Rules.

MAST BEND

Mast bend is controlled with the mast blocks at the partners. You should have three thin (1/8”) plastic chocks, and four thick (1/4”) plastic chocks. All tuning measurements shall be taken with a straight mast with all of the chocks in front of the mast. Your mast should be snug (fore-aft) in the partners. If there is space in the partners (fore-aft) you will experience undesired mast bend while sailing upwind.

The mast step should be adjustable so that you may increase your rake for breeze over 16 knots. Measurements taken from “T1”:

  • Aft side of mast at the mast step – 0-16 knots.
    This is the aft step position: 9’2 1/2”
  • Aft side of the mast at the mast step – 16+ knots.
    This is the forward step position: 9’3”

MAST RAKE

Hoist a tape measure and lock into the halyard lock. Ensure your headstay is just slack (but not floppy), and that the mast is resting against the aft edge of the partner with no blocks behind the mast. Shrouds should be firm, at 150lb, but not so tight that shroud tension adds pre-bend to the mast. The mast must be centered in the boat. Measure to the chain plate bearing-point on both sides of the boat to confirm.

  • The mast should be straight, fore-aft and side-side
  • The mast rake measurement to point “T1” should be 18’9” (with a “just slack” headstay)
  • Trim your headstay control line until your rake measurement to “T1” = 18’10”. You should pull about 6” of headstay control line through the cleat (with a 6:1 headstay adjuster)
  • Mark the headstay control line at the point where it exits the cleat
  • This is your base rake setting, for medium sailing conditions.
  • Ensure your mast is straight (fore-aft, not inverted due to headstay tension). Add blocks behind the mast until it is straight.

SHROUD TENSION

This base rake setting, described above, is also your base shroud tension setting. All shroud tension measurements on the tuning matrix are for the 3/32-sized Sta-Master adjusters (small). One full turn on the Sta-Master adjusters is equal to one full pin adjustment on a Ronstan RF2331 shroud adjuster.

All shroud adjustments on the tuning matrix are in “number of turns” from the base shroud tension setting.

Doyle Sailmakers suggests using the Sta-Master shroud adjusters, as it makes on-the water adjustments easier and safer.

BOOM VANG

The vang should not be tight until you are overpowered upwind. Downwind in light air, the vang should be quite loose to allow the leech to open. Some vang tension is needed downwind once the breeze is up to about 5 knots. The vang should be trimmed on for proper roll jibes.

OUTHAUL

The best way to note your outhaul setting is to calibrate the end of your boom. Starting at the forward edge of the black band on the boom, add six marks, spaced 1” apart. The tuning matrix describes which mark your outhaul should be trimmed. In 5-9 knots of breeze, your outhaul should be at “4”. This is 4-inches from the black band.

CUNNINGHAM

The cunningham should be should be used sparingly, until you are overpowered upwind. As the breeze increases, use the Cunningham to reduce the amount of luff wrinkles. Never eliminate all of your luff wrinkles, as this will move the draft of the sail too far forward.

TRAVELER

The traveler should be adjusted based on the sailing conditions. As far as 7” up in light air, and all the way to leeward in heavy breeze. See the tuning matrix.

CENTERBOARD

The centerboard should be maximum area per the Class Rules. The center of the CB pivot hole, measured from “T1” should be at the maximum forward position: 6’7”

The forward rake of the centerboard shall be measured from point “T2” and should be at least 101.5”. This is to the forward-most point of your centerboard.

Doyle Interclub Tuning Matrix

Wind (knots)

Mast Step

CB

Mast Blocks

Rake

Shr'd Tens

Trav'

Head'
stay Control Line

Vang

Cunn

Out'
haul

0-4
Aft
Max Fwd
3 x (1/8") and 1 x (1/4")
18' 11.25"
base - (1/2) turn
7" up
Eased 2" from base. Headstay slack
slack
slack
4
5-8
Aft
Max Fwd
3 x (1/8") 
18' 10"
base
6" up
Base. Headstay just slack
slack
slack
5
9-12
Aft
Btw Max Fwd & Vert
1 x (1/8")
18' 9"
base + 2 turns
3" up
Trimmed 2" from base. Headstay tight
take out slack, tension in puffs
reduce wrikles in luff
5
13-16
Aft
Vert - 2" Raked Aft
None
18' 7.5"
base + 2.5 turns
all the way to leeward
Trimmed 4" from base. Headstay tight
vang sheet, no over-bend wrinkles
reduce wrikles in luff
4
17+
Fwd
3 - 5" Raked Aft
None
18' 5"
base + 2 turns
all the way to leeward
Trimmed 4" from base. Headstay tight
vang sheet just to over-bend wrinkles
max trim in puffs
3

For more information or to order Interclub Class sails: