Explaining the Melges
20 rig
The Melges 20 rig is sophisticated and it not easy to set it
up and tune it correctly. Let’s take a quick look at the basics: The rig
features two sets of spreaders with diamonds-, primaries (V1) and lower
shrouds. The setup can get away with the absence of a back-stay, due to the
very strong carbon mast section, combined with the support of the double
spreader/diamonds set-up. This also allows for a nice and efficient square-top
main!
Each pair of shrouds serves a different purpose.
Diamonds: The tension on this set of shrouds, in combination
with the spreader angles, directly control the pre-bend of the rig. More
tension and/or more swept back spreaders result in more pre-bend (which in
return flattens out the main sail)
Primaries (also called uppers): This set of shrouds mostly
influences head stay tension, but also to a certain extent mast bend (between
the hounds and the bottom)
Lowers: Lowers have a huge effect on tuning and therefor
must be tuned correctly. They control the mast bend in the lower part of the
rig and significantly influence head stay tension!
Initial Set-up of the
Melges 20 rig
Melges Boat Works does a great job at initially setting up
your spreaders and putting all the fittings in the right spot. Nevertheless it’s
worth spending some time ensuring that your spreaders are parallel and perpendicular
to the mast foot. Also check if the triangulation of the shroud cars and mast
step position are correct by using a tape measurer.
Put the rig in the boat, attach your forestay, get your base
settings more or less sorted. Measure your mast rake and also side-to-side position
to ensure that your rig is straight in the boat. This might take some iteration
initially as all the tensions interact with each other. If it’s a brand new
rig, don’t worry too much about getting the numbers exactly right or if the rig
seems to have a sideways or “S” bend in it. Once you have sailed with it in the
breeze and everything is stretched in you can get more precise about it.
Base setting
Use the most updated tuning chart you can find (not easy!).
The sail makers are constantly refining their sails and therefore also their
tuning charts change. Ask the teams at the front end of the fleet to share
their numbers with you. On the next page
you can find what has been working for us on the Bacio Team.
Our base setting is 120-130 kg on the diamonds and the
lowers (lowers with two holes showing on the track) and about 250-260 kg on the
primaries at 9350 mm (30ft 8”) mast rake. We set our spreader deflections at
1400 mm (center to center of shrouds) for the lower spreaders and 655 mm for
the upper spreaders. These tensions are measured with the Harken Digital tuning
gizmo.
Bacio Tuning Chart (Base Setting in RED), December 2012
Step
|
Wind Speed (kts)
|
Uppers Track
|
Uppers Turnbuckle
|
Lowers Track
|
Lowers Turnbuckle
|
Diamonds Turnbuckle
|
-3
|
3 - 5
|
0
|
- 8
|
0
|
0
|
- 4
|
-2
|
5 - 8
|
0 - 3
|
- 8
|
0 - 2
|
0
|
- 8
|
-1
|
8 - 11
|
0 - 4
|
- 4
|
1 - 4
|
0
|
- 4
|
0 (Base)
|
11 -14
|
1 - 4
|
0
|
2 - 4
|
0
|
0
|
1
|
15 - 18
|
2 - 4
|
+ 4
|
3 - 5
|
0
|
+ 4
|
2
|
19 - 22
|
3 - 5
|
+ 8
|
4 - 5
|
+ 1
|
+ 6
|
3
|
23+
|
4 - 6
|
+ 10
|
4 - 5
|
+ 1.5
|
+ 10
|
Step -3 (super light)
Drifting conditions, with at least one person to leeward.
Please notice that we have a good amount of tension on the diamonds in order to
flatten out the main and open up the main sail leech to help flow.
Step -2 (light, looking for power)
Here it’s all about generating power in the boat and getting
people on the rail. As long as you aren’t constantly easing the main sheet (due
to too much power) you can make this setting work great. You might also be
pulling on a little bit of vang at times. With these settings your main sheet
tension is critical in regards to head stay tension (and jib luff sag), so be
“smooth” on your main sheet. You will notice the leeward shrouds flopping
around quite a bit, but no worries there!
Step -1 (always fully powered up, pulling vang on, hiking
hard)
Now you are starting to hit good upwind target speeds and
playing the main sheet more. As you start pulling more vang on, also pull
lowers on in order to keep the bottom of the main sail from going too flat.
Step 0 (Base settings, boat has tendency to tip over,
starting to get rid of power)
You are now constantly pulling a good amount of vang on and
flattening out the sail by pulling diamonds on and keeping the head stay tight
with some lower tension (remember, one more hole on the lower shrouds car
tensions that head stay nicely).
Step 1 (getting windy, too much power)
At this stage it’s about finding the right amount of power
in the rig. If you’re having to ease too much mainsheet in order to keep the
boat flat and the main might even be ragging a bit, just put a couple more
turns on the diamonds and primaries. This will calm everything down again.
Step 2 and 3 (should we actually go sailing?)
Now the boat feels like a handful, you might sometimes even
get blown over a bit and loose flow on your foils. But don’t worry the boat can
handle it. Keep working the jib sheet in the puffs to take the worst “bite” out
of it. No need to go crazy on the cunno,
we feel its actually counter productive to have it on too tight. Only bear
away once vang and cunno are well eased or you might loose your rig!