Tune up - Part 1 - Bits of string and what they do
Clynton from Bethwaite
Design asked me to write a few things on 29er tuning. A 29er is
a very simple boat to tune, there are few adjustments. So this
can’t be too hard.
Now it’s possible to get around at the front of the fleet with a
variety of settings compared to the competition. It all depends on
how you sail the boat and what you’re trying to achieve at the
time.
So here’s the first part - a list of the available adjustments -
including major and minor adjustments. It’s difficult to explain
settings in plain english, so I’ve jotted down a few simple points
on what each adjustment does.
It is key (and simple) to understand the impact each has on your
boat, then you can make your own call on when you’d change one or
the other.
So here goes…
1. Main sheet
Simple. More main = more power.
Eased to keep the boat flat, but not before maximum crew weight is
used.
Kept on centreline to provide height.
Used to maintain leech tension without vang.
Kept close to centre downwind to keep the mast up, spinnaker luff
on and steering balanced.
2. Jib sheet
More jib = more power.
Too much jib = stall.
Sheet cracked 1-2 to breathe when required (ie. chop, gusts,
speed).
Eased completely on tight spinnaker legs to get height. Eased lots
downwind keeps the bow up.
3. Spinnaker sheet
Just enough spinnaker sheet to have the luff folding or close to
folding.
Eased significantly on gust onset to allow the boat to breathe and
accelerate.
4. Main halyard
Up. All the way.
1-2 off mast tip brings sail down mast, changing vang and bridle
positions.
5. Jib halyard
Controls jib depth at luff.
Tighter = flat. Loose = power.
6. Spinnaker halyard
Eased flattens luff and curls leech.
Tight fills luff and opens leech.
7. Spinnaker tack line
Same as spinnaker halyard.
Not getting full extension of spinnaker tack from bow.
8. Outhaul
Eased = depth down low. Pull on = flat.
Works in combination with downhaul on main to flatten foot.
9. Downhaul
More downhaul = flatter.
More downhaul bends mast and brings draft forward, opens
leech.
10. Vang
More vang = flatter low down.
More vang = tighter leech.
More vang = more low-down mast bend.
11. Batten tension
More tension forces shape into sail. Less allows the sail to do
whatever it wants.
12. Shroud pin position
Lower = more tension. More tension = less forestay sag.
More tension = more mast bend.
13. Mast heel tune
Correct heel tune = stiffer lower mast.
14. Steering
Simple: uphill up gives height but not speed, down is opposite.
Downhill up gives speed but not depth. Down is opposite.
15. Jib track position
Opens slot between jib and main.
Outer positions allow more sheet tension to be used for similar
slot, therefore tighter leech.
16. Jib clew-board position
Upper hole gives depth down low for same leech tension.
Lower hold gives flat down low for same leech tension, or less
leech tension for same flatness down low.
17. Spinnaker pole length
Longer puts spinnaker further away from rest of rig which helps to
lift bow.
18. Centreboard
Up reduces power.
Down provides more lift/pointing ability.
19. Main bridle
Higher keeps boom on centreline with less sheet tension.
Lower allows more vang/sheet tension to be used.
20. Rudder angle
Tip in makes steering lighter.
21. Forestay length
Longer provides more rake, better for heavier conditions.
Shorter provides less rake, better for lighter conditions.
22. Rig tension
See shroud pin positions.
23. Spreaders (if they were adjustable)
Up gives less poke therefore softer mid-mast.
Forward/down gives stiffer mid-mast.
24. Leech lines
Stops leech vibration.
Rolls last inch of sail to windward.
25. Spinnaker luff line
Similar to leech line.
26. Trapeze height
Down provides more weight for the wire.
27. Boat heel
More heel = more wetted surface.
28. Fore-aft trim
Aft lifts bow and rakes rig.
Forward sinks bow and provides pointing ability, less wetted
surface.
