Melges 20 Tuning

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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!