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Fireball
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TUNING
YOUR INTERNATIONAL FIREBALL
The first step to success is to make sure you have a competitive hull and whilst it need not be new, it must be stiff enough to withstand high rig tensions and be down to weight. |
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Layout
systems
Aft mainsheet - transom bridle sewn into mainsheet along boom to centre jamber. Kicker - 16:1, cascade block and tackle system led back to mainsheet jamber and to helm. Cunningham - 2:1, led back to centreboard case and helmsman. Pole uphaul - 2:1, led back to centreboard case and helmsman. Outhaul - 4:1, led back to centreboard case and helmsman or cleat on boom. Pole downhaul - 1:1 Spectra to stopper knot and elasticated. Spinnaker Halyard - 2:1 pump action with 4:1 elasticated take-up. Jib Halyard - 12:1, led to aft end of centreboard case. Jib Fairleads - a bullet block attached to a rod that goes through a car on a track for athwartship adjustment and a 2:1 on the rod which adjusts leech tension, which is led back to helmsman on centreboard case. Jib Cleat - Mounted on inside of side tank just aft of shrouds, so that crew tacks facing forward. Mast Strut - 12:1 ball bearing traveller car mounted on foredeck, control led back to helmsman. Prebend - 6:1, led back to helmsman. Rig - The prebend rig is the most popular and used by most of teams around the World with the Proctor Stratos being the favourite. These prebent rigs have a full luff curve mainsail which are more "user friendly" than a straight rig, they are more flexible and have a better gust response. The mast foot should be mounted close to the front bulkhead to get the best balance between jib and main. Mast rake needs to be altered for different wind conditions, but maintaining rig tension. The Fireball goes faster with more rake in stronger winds - and vice versa. Set-up 1. Apply rig tension to the rig to insure the mast is set up straight side ways. Your shrouds may have to be adjusted slightly to achieve this, the mast should be a snug fit at deck level. 2. Pull your tape measure to the top of the mast and measure to the top of your black band at gooseneck. The measurement should be 18'9" (5715 mm), once you have achieved this measurement, take the tape measure to the top of the transom, then you can measure your rake. 3. Set the mast to the lightest air setting with the correct rig tension. Calibrate your shrouds and jib halyard, then gradually work trough the different wind speed settings and calibrate as necessary. Be sure you can achieve maximum rake! 4. Strut: With your rig upright calibrate your strut to its neutral position. As you can see from the chart, the strut is hardly moved through out the wind range. 5. Jib sheeting angles need to be changed to suit wind and sea state. (See our tuning guide below). All these measurements are only a guide and should be adjusted to account for different crew weights and sail shapes. One last tip for heavy air sailing - raise the centreboard up to 25% upwind, which improves balance and makes the fireball faster and easier to sail. |
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FIREBALL
TUNING GUIDE
Stratos / M7 |
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CREW
WEIGHT
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SPREADER
LENGTH
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PREBEND
(22' - 8" RAKE)
400lbs RIG (Jib Wire) |
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10.5
- 11 stone
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410mm
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25
- 30mm
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11
- 12 stone
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415mm
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25
- 30mm
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12+
stone
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420mm
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25mm
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For
new all Glass Winder boats increase spreader length by 5mm.
Spreader angles should be to suit prebend. |
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FIREBALL
RIG TUNING GUIDE
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WIND
SPEED (KNOTS)
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1-4
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1-4
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5-9
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5-9
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10-15
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10-15
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16-20
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21-UP
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SEA
STATE
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FLAT
WATER
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CHOPPY
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FLAT
WATER
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CHOPPY
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FLAT
WATER
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CHOPPY
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MAST
RAKE - imperial
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22'6"
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22'8"
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22'8"
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22'8"
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22'6"
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22'6"
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22'4"
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22'3"
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RIG
TENSION Jib Luff Lbs
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400
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400
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400
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400
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400
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400
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400
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350-400
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KICKER
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NONE
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NONE
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A
BIT
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A
BIT
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LOADS
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LOADS
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-
reason
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TOP
TELL TALE SHOULD BE STALLING 30% OF THE TIME
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TO
CONTROL TWIST & BLADE OUT MAINSAIL
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CUNNINGHAM
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NONE
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NONE
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NONE
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NONE
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NONE
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NONE
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YES
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YES
- LOTS
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JIB
FAIRLEADS
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LOWER
LINE
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MIDDLE
LINE
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LOWER
LINE
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TOP
LINE
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MIDDLE
LINE
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TOP
LINE
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TOP
LINE
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TOP
LINE
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from
c/line (mm)
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250
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250
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250
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250
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250
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250-270
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275-300
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275-300
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JIB
SHEET TENSION
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NORMAL
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EASE_"
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NORMAL
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NORMAL
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NORMAL
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NORMAL
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EASE_"-_"
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EASE_"-3/4
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STRUT
(from neutral)
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0
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0
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0
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0~+1/4"
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0
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0~+1/2"
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0~+3/4"
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-_"
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JIBB
LUFF TENSION
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WRINKLES
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WRINKLES
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WRINKLES
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WRINKLES
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NO
WRINKLES
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NO
WRINKLES
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TIGHT
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TIGHT
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CENTREBOARD
POSITION
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FORWARD
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FORWARD
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FORWARD
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FORWARD
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UPRIGHT~+1"
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+1~2"
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2~4"
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4~5"
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| OUTHAUL | TIGHT | 1_" | _" | 1" | _" | _" | V TIGHT | V TIGHT |
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N.B.
Mast Rake is critical, so lighter crews may have to Rake earlier (14-15
knots)
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WORLD'S
NO.1 PERFORMANCE DINGHY MAST MANUFACTURE
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