by Robert Ferguson
| EXPRESS 30 Rig Tuning for Racing (and Cruising maybe) 🙂 Make sure you know your class rules, etc. Don’t go lengthening your for-stay or changing things until you check all the applicable rules. There is an infinite combination of shroud configurations, but basically your boat should have the shrouds in line with the mast. Boats with a swept back configuration would be tuned differently. We will assume you’ve got a fixed mast base. Starting at the bottom, check that your mast is in line with your keel. You only have to do this once and it should be good from the factory but check it anyway. When your boat is on a cradle or in the mooring slip, you can use a plumb bob, a measuring tape, straight edge and/or the halyard. The boat doesn’t have to be sitting level in the cradle or the slip to get the mast in line with the keel. You can use a laser to do this too if you feel really anal (buy a laser level from Home Depot etc), but you can also clip a halyard to the base of the mast at a point straight in line with the keel blots and tighten it to create a straight line to compare to vertically. You aren’t worried about rig tension at all here. Make it snug, and make it straight (from side to side). Using the keel bolts as a guide also ensure that the mast base or sole plate is in line with the keel. If you find that the sole plate has moved then some major work is needed to fix the problem. The plumb bob is good for checking the position of deck stepped sole plates. The sole plate might be fine but the bottom of the mast may have to be shimmed to meet proper position. This is also the way to check for alignment where the mast goes through the deck. Once you have the mast basically in line with the keel, you can use your mainsail halyard and a fishing type scale to set a reference point. Attach the scale to the halyard so that it reaches down to just above the chain-plates. The scale is used to tension the halyard (straight) so that we can achieve the same measurement from the top of the mast to the top of the chain-plate. Don’t change the height of the halyard, and using the same weight setting as before swing it over and check the other chain-plate. Keep adjusting the top/outer shroud tension until they are the same measurement. Shroud tension may be measured in two ways, with an expensive gauge or by eye. For the eye setting adjust the tension until you have the same deflection (movement left to right) of the shroud at approximately the same height from the deck. For the by eye setting start with ½ inch at 6 feet above deck. Harken has come out with a new electronic and easy to use rig tension meter that can be purchased at any good marine supply store. So now you have a good starting point. Your mast is vertical from the keel to the top and sort of from side to side. Now we have to straighten it from side to side. To straighten it we use the bottom and intermediate shrouds. Using the main halyard and the scale again attach it so that it is in line with the sail track slot. At the top and the bottom. Adjust the tension on the shrouds until the main halyard is centered top to bottom on the slot. Tension on all of the shrouds should be checked and be about the same from side to side. Also recheck the top for centering. Now, check the pre-bend (only IF your mast requires pre-bend, or if you have swept back spreaders, otherwise skip this). Again, you can gage this by clipping your main halyard to the back of the mast at the base and tensioning it. Call the boats manufacturer and ask what it should be. If they can’t tell you or they no longer exist, then it’s going to be by feel, and you’ll have to figure it out while you go sailing. Keep in mind that more pre-bend means a fuller mainsail. If you find your boat is typically underpowered, don’t go with a ton of pre-bend. If you find yourself overpowered all the time, then more isn’t a bad thing. Pre-bending the mast does limit you though. I find that I set the rig to the “minimum” pre-bend I think I’d ever want. On most mast head rigs we can use the backstay to power or de-power as needed. For the express 30 I find that just snug is good so that I can really change the tension on the for-stay for pointing. This is usually to suit the water and wind conditions. Now we’re at the point where you take your boat sailing. The first thing to do is go out in a moderate air day. Obviously, you want your mast as vertical as possible even when the wind blows. So go upwind. Your leeward shrouds will very likely hang loose. This isn’t a good thing on most keelboats. Because if they’re loose, that means the mast has moved in that direction and is no longer on the same vertical axis as the keel. Tighten the leeward shrouds a turn or two, tack, and do the other side. Continue the process, tightening both sides equally, keeping track of the turns on the turn buckles. Always check later to ensure they still have the same tension. Not guitar-string tension, but definitely snug. Picking the right tension for all round use is always a problem. Too tight and the boat will not perform in light air, too loose and it will be no good in moderate to heavy air. I try to pick a setting that will be best for the majority of the season. Note that if you have shrouds that are swept back, the backstay will affect them as well. In that case it’s a smart move to fully tension your backstay when you do these adjustments. Otherwise when you pull it on in a breeze you’re going to lower the tension on your stays and your mast will fall off to leeward a bit. Now we have a mast that is going to stay vertical in a breeze. You’ve fooled around with your settings, so double check using the main halyard as a guide that that mast is still where it should be versus the keel. Also recheck that you have the right amount of pre-bend. If your lower shrouds are swept back, then you should use them to control the pre-bend of the mast. So, we think we’ve got the mast straight, and we think we’ve got the right tension on the shrouds and pre-bend. Now go sailing again on a medium / light air day. Preferably one with very little chop / wave action. Note the angle you have to hold the tiller / wheel at. Most boats want 5-7 degrees of windward helm when going upwind (i.e., you should have to try to keep the boat from heading up with the helm). If you’re below 5-7 degrees and you sail in medium air predominantly, you need to rake your mast further back to induce windward helm. If you have to pull the tiller further than this, you probably want a little less rake. Ease your forestay to add rake, and tighten it to reduce rake. This is where many people run afoul of the rules. Please read all applicable rules on your allowable forestay length, especially if you are racing one design! So now we think we have the rig where we want it CHECK IT AGAIN. Go up wind again. Ease your backstay fully. Check that you’ve got the most sag you’d ever want. Check that your pre-bend is correct. Check that the mast has no bend to it side to side. Pull the backstay on full. Make sure the head stay goes to ZERO sag. Make sure the pre-bend is the most you’d ever want it. Make sure the mast still has no side to side bend. Finally, go back to the dock and check with the halyard and scale that the mast is still straight vs. the keel. Now you should be done! A note on pre-bend. If your sail maker can’t tell you what the beginning and final bend should be in your mast, then you’ll have to guess. If the front edge of your mail sail is luffing, then you could probably use some more bend. If it’s not luffing, then you’ve probably got enough. That’s a good rule of thumb if you’re guessing. (Either that or your genoa is over trimmed). Note that this is a process. You may touch your shrouds a hundred times before you get it to the place you think it should be. Also note, all that time you just spent on your rig is wasted if you can’t drive etc. If you are in a semi competitive fleet and are not in the top 25%, you shouldn’t be worried too much about your sails and rig. You’ve got other problems. |