Mak­ing sure ev­ery­thing is in the right place is an es­sen­tial step to bring­ing your boat closer to per­fec­tion. Get your mea­sur­ing tape and plumb bobs ready.

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Get your plumb bobs and tape mea­sures out. It’s time to see if your mast and ap­pendages are where they’re sup­posed to be.

O No boat is per­fectly sym­met­ric or at max­i­mum/ min­i­mum tol­er­ances when you first pur­chase it. The closer you can get it to per­fect, the bet­ter it will sail. To be­gin, you need to take some ac­cu­rate mea­sure­ments, which can be done with just a lit­tle time and a few sim­ple tools — of­ten a plumb bob, mea­sur­ing tape and a cou­ple of lad­ders.

Once you know where ev­ery­thing is, you can make the nec­es­sary mod­i­fi­ca­tions. The key is to es­tab­lish a cen­ter­line and base­line, and see what you learn about your boat. Then you can de­cide which projects will have the big­gest im­pact, given your time and money com­mit­ment.


If you’re in­ter­ested in mak­ing your ap­pendages line up and par­al­lel to the bow, start by lev­el­ing the boat to the bow since this is the hardest thing to move. Hang a plumb line off-cen­ter of the top of the bow. The forestay pin is the best place. Level the boat by ad­just­ing the cra­dle, shims un­der the trailer tires, etc. Stand back as you’re ad­just­ing it, and you should see the whole bow ver­ti­cal with the plumb line.

Next, hang an­other plumb line down the front and back of each foil. Drop an­other plumb line down from the cen­ter of the tran­som. Fi­nally, take an­other line and put it be­tween two heavy ob­jects (bricks work well), ten­sioned just above the ground and just kiss­ing the bottom of the bow and stern ver­ti­cal plumb lines. This will give you a good idea about the amount of work that lies ahead. From this line you can see if the ap­pendages are ver­ti­cal, par­al­lel to the cen­ter­line, and in line with each other.

If you’re not in­ter­ested in re­mov­ing the keel to ad­just it, which is prob­a­bly be­yond the time and skills of most peo­ple, then for­get about be­gin­ning with the bow and just start by mak­ing the keel ver­ti­cal. Fol­low the same process, with the plumb bob off the trail­ing edge and shim­ming the trailer, etc. You still need a plumb line hang­ing from the bow, ex­cept this time tape it to the cen­ter­line at the waterline and hang it to the ground. Ba­si­cally, if you’re not going to ad­just the keel, start with this as the fixed point and make ev­ery­thing line up with it. If you are more am­bi­tious, then be­gin with the bow and work from there.

If you have a cen­ter­board boat, set the boat on a high trailer, sawhorses or lift so the cen­ter­board and rud­der are in their nor­mal sail­ing po­si­tion. I don’t like to do this work by flip­ping the boat up­side down be­cause then the board doesn’t hang in the case the same way. You may also dis­cover that the cen­ter­board moves a bit in the cen­ter­board trunk. If that’s the case, push it to ei­ther side and make sure the slop is even on each side. You may need to glue some shims in your cen­ter­board trunk us­ing Te­flon or some­thing com­pa­ra­ble to re­duce the play and make the board ver­ti­cal.

Now that the keel or cen­ter­board is ver­ti­cal, hang an­other plumb line off the rud­der. On a tran­som- hung rud­der, you can pretty eas­ily shift the gud­geons and get the rud­der ver­ti­cal or maybe shim the pin­tles where they bolt to the rud­der. For rud­ders where the post goes though the hull, I’ve seen peo­ple cut rud­der bear­ings out and move the top bear­ing over a bit, or fair the rud­der stock where it fits into the bear­ing so that it shifts over a lit­tle bit. You just have to im­pro­vise, as ev­ery boat is a lit­tle dif­fer­ent. You won’t be able to get it per­fect all the time, but you can at least work to­ward that.


Here, ev­ery­thing must be in line with the forestay and the back­stay be­cause that’s what the mast es­sen­tially hangs off. The boat still has to be level off the bow or cen­ter­board/keel. By us­ing grav­ity and lev­el­ing the boat, you can shift the cen­ter­line up to deck level and even back down to the mast step.

Set up a base­line by run­ning a taut string down the cen­ter of the boat, from the forestay ter­mi­nal to the back­stay ter­mi­nal. If you have two back­stay ter­mi­nals, such as on a J/24, find the point be­tween them and use that. Most boats don’t have a flat deck, so put a post or lad­der in front of the boat and an­other be­hind the boat to raise the string so it is not af­fected by the deck el­e­va­tion. From this line you can drop a ver­ti­cal plumb line down any­where and mark the cen­ter­line for other mea­sure­ments, as well as mea­sure out 90 de­grees for jib track, jib lead and shroud po­si­tions.

Once you’ve es­tab­lished this cen­ter­line on deck, check the lo­ca­tion and sym­me­try of jib leads, shrouds and mast part­ners. The part­ners are one of the sim­plest mea­sure­ments to ad­just and rarely done. A good lit­mus test to know how care­fully a boat has been worked on is to look at the part­ners. When­ever I get on a boat where the mast is sit­ting per­fectly in the mid­dle of the part­ners, I ques­tion if the boat has ever been mea­sured well. On most boats, you can sand out or fill in on one side, put a shim in there, or use a prod­uct like Spar­tite to get the mast cen­tered in the boat and the open­ing.

Mea­sure out from the cen­ter­line to the shroud bases to see if they’re in the same place. These

are hard to ad­just as they have a lot of struc­ture. But there is typ­i­cally a tang as a ter­mi­nal and a U-fit­ting that goes over the tang. You may find a gap where the U fits over the shroud tang. Us­ing some wash­ers in these gaps, you can shift the shrouds few mil­lime­ters and get the shroud base close to sym­met­ric. If it’s a smaller boat, bend the tangs a bit, or wedge a washer or some­thing com­pa­ra­ble in un­der the deck to move the tang far­ther in or out.

Mea­sure the dis­tance from your shrouds to the forestay, on the di­ag­o­nal, to see if they’re the same dis­tance aft. This is dif­fi­cult to change, but if you can slightly elon­gate a hole or wedge the shroud with a washer, you might be able to get the mea­sure­ments closer. Take the same di­ag­o­nal mea­sure­ment for your jib cars to be sure they’re the same dis­tance aft from the forestay and from cen­ter­line. You might dis­cover that you have to drill some new holes in the tracks or re­po­si­tion the tracks a lit­tle.

From there, be­cause the boat is still ver­ti­cal, mea­sure down from the deck cen­ter­line string to the mast step. Drop a plumb bob to the bottom of the boat in two spots and mark those points. Then draw a cen­ter­line along the bottom that will tell you where your mast step is po­si­tioned, rel­a­tive to the boat’s cen­ter­line. It can also give you a good mea­sure­ment on your cen­ter­board pin lo­ca­tion. My mantra is, “Trust noth­ing.”


With the keel still lined up ver­ti­cally, the next step is to trans­late this to the mast and get the cen­ter­board and mast lined up in the same plane. It’s chal­leng­ing be­cause the hull is in the way. A sim­ple way to mea­sure this is to set up a lad­der well be­hind the boat and hang a line from the top step of the lad­der. Move it so when you step back and look through the line, it lines up with the top and bottom of the keel. Then step back a bit far­ther so you can site the keel and mast with the string. You’ll prob­a­bly have to move closer to the ground to get the an­gle nec­es­sary to align the mast and the string. Ba­si­cally, you’re con­tin­u­ing the line from the foil, ver­ti­cally, up through the rig. On big­ger race boats, we set up a laser line at night to check the align­ment. But for a frac­tion of the cost and en­ergy, you can do it this way and get pretty close.

After you ad­just the turn­buck­les and you’re happy with the align­ment, make sure you take some mea­sure­ments. Use calipers to mea­sure the turn­buckle gap on each side so you can re­pro­duce this align­ment. What you will usu­ally find is that one side is shorter than the other, and that is the num­ber to re­mem­ber.

A lot of peo­ple mea­sure the spreader an­gle with the mast on the ground or on a cou­ple of sawhorses, but that’s not putting the mast in its nor­mal sail­ing po­si­tion, and it’s just not that ac­cu­rate. I al­ways check di­men­sions like that with the mast up. With the mast up and rigged, I find a point on the forestay that is about the same height as the spread­ers and put a mark there. I then mea­sure aft to the end of each spreader. If I want to dou­ble check it, I make the same type of mea­sure­ment from the spread­ers to the back­stay. That an­gle or dis­tance has a sig­nif­i­cant ef­fect on the mast or the rig, so the two sides re­ally need to be sym­met­ric.

How do I get up there to take that mea­sure­ment? I’ve been known to climb nearby trees and tele­phone poles. I’ve used a boat hoist, ty­ing a loop in a rope to put my foot in, putting it on the hoist­ing hook, and then rais­ing my­self up to where I can take the mea­sure­ments. Im­pro­vi­sa­tion is of­ten the name of the game. How to make ad­just­ments is an­other story, and that re­ally de­pends on how your boat is built.

None of these mea­sure­ments are re­ally time con­sum­ing. When I was sail­ing Light­nings, they took only about half a day. And once you mark the cen­ter­line, you can even do other mea­sure­ments over time. With this whole process, you will find a few things that will im­prove your speed and will al­low you to re­pro­duce set­tings much quicker on the op­po­site tack. Q


A day of mea­sure­ments from the rig on down to the waterline is all you need to en­sure sym­me­try around the boat.

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