Lightning Tuning Guide

VSP Lightning Tuning Guide

There are many proven methods for tuning a Lightning.  The measurements and the settings included in this guide are ones that I have found to be the fastest for VSP Lightning sails. Since crew, wind and sailing conditions and boats vary, you may find that slightly different settings are best for you.

I try to keep the tuning as simple as possible and try to use our “medium air” setting as much as possible.  This tuning guide is being constantly updated so please check back frequently!  Recent changes are made in red.

Please feel free to contact me if you have any tuning or trim questions –

– Bill Fastiggi

Before stepping the mast
1) Make sure all shrouds are securely attached to the mast, and the screws are tight.
2) Make sure the spreader tips are secure to the spreader.  If they are loose, put tape over the ends to secure the tips.
3) Put “trim tapes” on the spreader 2″ in from the tip.

Setting the Mast Butt

The determining factor to finding the proper mast butt position for your boat is the location of the upper shroud chainplates.   Modern Allen and Nickels Lightnings will have the chainplates at or near the maximum forward position.  You should also locate the mast butt at the maximum allowable forward position.  The aft edge of the mast should be 21 7/16″ from the forward edge of the centerboard pin.

Headstay Length 
To measure headstay length with the mast up, we measure a short segment of the headstay at the bow. Simply unhook the headstay from the stemplate and run it down the front edge of the mast. Mark the point where the top of mast band intersects with the headstay with a piece of tape. Be sure to align the top of the tape with the top of the mast band. Reattach the headstay. Remove all slack from the headstay by pushing aft just above the mark. Now measure from the top of the headstay mark to the forward most edge of the deck at the bow. This measurement should be 44.5″ for a Nickels boat, and 45″ for an Allen boat.  When you are sailing, you can “fine tune” this dimension for your own boat by making sure the boom is parallel to the deck.

Shroud Tension
Uppers should be tensioned to 250 lbs. Lowers should be tensioned to 120 lbs. on a Nickels boat and 170 lbs on an Allen.  This should be done with the backstay disconnected and with the mast blocks removed. Using a Loos model A tension gauge, the uppers should measure 29 and the lowers should measure 15 on the Nickels and 21 on the Allen.   This is your baseline measuring position.  If you are sailing a new Nickels boat (15300 and newer) you should use the “Allen” lower tension.  The difference in lower tension is due to the different locations of the lower chain plates.

Check that the mast is straight and centered in the boat.  Pull your tape measure up the jib halyard and measure to each upper chainplate to make sure the mast is centered.  Once this dimension reads the same on each side, sight up the back of the mast and adjust each lower as needed to get the mast as straight as possible.  Recheck that the shroud tensions are still 250 and 120/170 lbs.

Fine Tuning the Rig
Mark this baseline position, fore and aft, of the mast in the mast gate. To do this, mark the side of the mast, approximately in the center, we suggest using a white piece of tape with a conspicuous dark line drawn vertically. Place a mark on the deck that corresponds with the mark on the mast. This mark on your deck is your baseline. Measure 7/8″, 1 1/4″ and 1 1/2″ forward of the neutral mark and place a mark at each. These marks will be used to measure pre-bend in your mast.

Once the mast is straight and centered, tape off the uppers, you won’t need to adjust them again.

Dry Run
In order to achieve proper lower shroud tension on the water, we suggest that you conduct a dry run of the following pre-bend settings in the parking lot. This will allow you to get to a desired lower tension by simply counting the number turns that have been taken off from the heavy air setting. This should be done with the backstay disconnected.

First, block the mast to 7/8″ and measure the shroud tensions. The tension of the uppers should have dropped slightly and the tension of the lowers should have increased to about 250 lbs on the Nickels and 300 lbs on the Allen. This is your heavy air sailing position.   At this point the mast should have about 1 1/2″ pre-bend.

To go from the heavy air setting to the medium air setting, block the mast forward to the 1 1/4″ mark. The tension of the lowers should have increased substantially. Count the number of turns that it takes to get the tension of the lowers back to 250 lbs (300 on the Allen).  On my boat this is two full turns. Record this number in the chart below so that you can duplicate it out on the water.   You should still have about 1 1/2″ of pre-bend in the mast, and the “extra” forestay length should be about 2″.

Finally, block the mast forward to 1 1/2″.  The tension of the lowers will again increase substantially. Count the number of turns it takes to get the tension of the lowers back to 200 lbs (250 on the Allen). On my boat this is three full turns off of each lower.  Record this number below.   You should have about 3 1/2″ extra forestay length.

Mast Pre-Bend and Lower Shroud Tension

Wind SpeedPre-BendLower Tension# of Turns from Neutral
0-5 mph1 1/2″200 lbs. (250) 
6 -16 mph1 1/4″250 lbs. (300) 
17+ mph7/8″250 lbs. (300)0

I draw this chart on my deck next to the mast partner for reference.


Jib Trim
Your VSP Jib is equipped with a jib leech telltale located at the top batten. It acts as an extension of the leech to gauge jib trim off the spreader. When the telltale stalls it indicates the degree that your jib is over-trimmed.   This is the number one indicator that we use to trim the jib.  Our goal is to have the leech tell-tale streaming all the time.

In light air, the jib leech is normally trimmed right on the spreader tip.  If it is light and choppy, you will probably find that trimming 1″ or 2″ outside the spreader tip is best.  If the leech tell-tale isn’t streaming, ease the jib, and if it is streaming, try trimming it until it stalls, and then ease back out just a touch.

The jib is generally easy to trim but in light and spotty conditions, as with all jibs, it requires constant trimming to keep the leech telltale streaming. In this condition, the top batten should be anywhere between the tip of the spreader and 4″ outboard. You’ll find the lighter it gets the further outboard you will need to go to keep the leech telltale streaming. This will keep you powered up and going fast!

In medium air, the leech telltale should be streaming and the top batten should be trimmed to the 2″ mark inside of the spreader tip.  If it gets a little lumpy or you find you need a little power, ease the jib sheet about 1″.  If it is flat water, or you need a little extra height off the starting line you can trim a little tighter, but never more than 3-4″ inboard of the spreader tip.

In heavy air, the top batten should be outside the spreader tip except for the lulls. As the wind increases over 20 mph, the top batten should get further and further from the spreader-up to 4″-and the leech telltale should be streaming 90-100% of the time.

Jib Lead Position
The placement of the jib lead is found by measuring the distance from the forward edge of the bow, straight over the splash rail to the jib track.

Wind strength0-78-1516-2020+
Lead position97″98″99″100+

Jib Wire/Halyard
Your jib wire adjustment is best described by comparing the tension on the wire to the tension of the headstay . In all conditions, the jib wire should be tensioned so that it is tighter than the headstay.  We’ve found that the VSP jib works best with a lot of wire tension.  When we are sailing upwind, if the luff of the jib seems at all unstable or “bounces” we add more tension to the jib wire to remove this “bounce.”  In lighter conditions, this can mean pulling the wire on as much as 3 or 4″ tighter than the forestay.  If you feel like you aren’t pointing well, pull the jib wire on harder.

Jib Cloth/Jib Cunningham
This control is relatively easy to adjust and is effective in moving the draft placement in the jib. In light to moderate winds, 90% of the wrinkles around the snaps should be removed. When the wind is consistently 15 mph and above, all the wrinkles should be removed.

Mainsail Trim

In most conditions, the mainsheet should be pulled tight enough so the top batten is parallel to the boom on a vertical plane (this can be checked by sighting directly up the sail from under the boom). The exception to this rule is in high winds when the upper leech needs to twist off to depower the sail plan.

The boom should be on centerline up to 10 mph and then dropped to leeward in 1-2″ intervals as the breeze builds until the bridle is all the way to leeward. In smooth water the bridle does not have to be dropped as soon as it does in choppy conditions.

Bridle height (from the deck) should be set for the desired main leech tension. The objective is to get the mainsheet between 1″ and 1/2″ from being two blocked, at a desired sail trim. This extra sheeting capability will allow the main to be over trimmed at critical times.

Another sail trim indicator is the top telltale located at the end of the top batten. In light air the top telltale should stall about 40% of the time, and in medium air it should stall a maximum of 60%. In breeze above 16 mph, the top telltale should be streaming most of the time because the backstay has most likely been pulled on to depower the main.

In light and medium winds, the backstay should be pulled on slightly to stabilize the rig and to prevent The rig from bouncing around.  When the wind picks up, the backstay should be the first control used to depower and relieve weather helm. In smooth water, you will pull the backstay more than you will ease the bridle to leeward. When it is choppy, the bridle will be dropped to leeward earlier to keep the boat driving through the waves.

The backstay tensions the headstay/jibwire when it is pulled on. In heavy winds, a tight headstay is desirable because it will flatten the jib making a faster heavy air shape.

Main Cunningham
This control is relatively easy to adjust and is effective in moving the draft placement in the main. In all conditions, remove about 90% of the luff wrinkles.

Outhaul The VSP Mainsail is designed very flat in the lower section so the outhaul has more effect over the shape of the entire sail. In most conditions, the outhaul is adjusted so that the shelf foot is just taken out while going upwind. In light air, the bottom half of the sail should be flat (which is why we put in so much pre-bend). This keeps the jib slot open and reduces backwind. In medium breeze, ease the outhaul slightly if you are looking for more power. As the wind increases, pull the outhaul towards the end of the boom but be aware. Because of the design of the sail, it is possible to over-tighten the outhaul.

Boom Vang
Upwind in windy conditions, the vang should be tight so that when a puff hits, the main can be eased without losing leech tension. If you don’t apply the vang in higher winds, the boat will become very unstable.  Otherwise, just remove the slack from the vang while sailing upwind.   In higher winds, be sure to ease the vang before turning downwind or you might break the boom.

Leech Line
The leech line should be completely slack until the leech starts to flutter. Tension the leech line until the fluttering stops. Remember to ease it off as the breeze drops or your leech will hook.

How to reach us

Via mail:
Vermont Sailing Partners
150 West Canal Street
Winooski, VT 05404

Via phone:
(802) 655-7245
(802) 655-SAIL

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