Track Leads

[George ( Triton #236 )]

I'm designing and installing the track lead system for the boat over the next couple of weeks. My plan is to have three discreet tracks per side.

1. 5' of track on the toerail for the Genoa lead car.

2. Track along the deck 2" outside the raised cabin. This track will follow the curve of the dog house from a spot in the middle of the aft deadlight to a spot at the forward end of the rear most, side facing, opening port. About 4 - 5 feet of track. This should cover jibs from about 120% down to 90%.

3. A foot and a half of track on top of the lower part of the raised cabin, 2" in from the outer edge, centered on the same rear most, side facing, opening port that was referenced in item #2. This is for the blade jib that was described by the owner of "Good Goose" on the Triton newsgroup.


How does this sound to you guys? I race the boat a lot and need whatever pointing ability I can get.


George
Triton #236 "Ca Ira"

[Tim]

George,

Remember that your pointing ability with overlapping headsails will be more limited by your spreader length than by track placement. You may not be able to sheet effectively to a track mounted well inboard as you describe--the spreaders are pretty long, and the genoa tends to contact the spreaders even with the lead mounted near the toerail.

Also, if the genoa is sheeted too tightly in, you can cause backwind problems with your mainsail. Proceed with caution. Your thoughts on track placement may work fine, but there might be more to it than simply mounting tracks further inboard. Before you commit to drilling all those holes in the deck, be sure that what you propose will actually do what you want. I have trouble visualizing how a sail could be sheeted outside the stays and then as far inboard as you describe, without coming into severe contact with the spreaders.

The Triton doesn't like to pinch. You'll only go slowly if you push it too much. Better to foot off, sail a bit fatter, and go faster. Trying to gain those few degrees may hurt more than it helps.

I think the Triton sails well as-designed, and won't ever point with her more modern competition no matter what you do. Pointing is about much more than sheet leads--the lift produced by the keel is more important, and full keels simply don't produce as much as fins. I'd stack the Triton up against any similar design any day, though, on its sailing ability. And you could be a handicap winner easily, if you sail the boat fast.

Inside leads for non-overlapping headsails do make sense, though. But I think you need to see the sail in place to get a better idea where the tracks have to go. They need to go where they need to go, and one boat's setup may not be ideal for your sail/boat combination. So use the other information as a rough guide for an idea, but don't tie yourself to it till you know it works for your setup.

There is much involved in getting perfect sheet leads, and in sailing fast while pointing as high as possible. Concentrate on proper sail trim and sailing the boat in the groove, and make changes carefully based on actual experience. More races are lost by sailors trying to point too high, which chokes speed; the key to racing success in a boat like a Triton is to sail her the way she wants to be sailed, given the limitations of the design, and not to try to make her something she is not.

Successful racing is about sailing the boat well based on the boat's strengths and abilities--not gear or tricks. Go out, have fun, and learn what the boat wants. Messing with the original setup on a whim may cause more harm than good. There may be some room for improvement--then again, there may not. Time will tell.

Good luck,

Tim

[George ( Triton #236 )]

Hi Tim,

Thanks for the note. I'm going to hold off on the track leads until I finish the sails for them and can see exactly where everything needs to go. You're right about the big spreaders on my boat. They probably will efect the sheeting angles of the headsails and thus the track leads. Thanks again for the great info.

George
Triton # 236

[The Good Goose]

George

My working jib track is 2' long 1" from the cabin side . Starts about 6" forward of the forward deadlight and ends about 6" aft . I think I would go with a three foot piece 1 foot forward of the dead light and even with it aft. I don't have a 120 but I find my working jib a 110 sheets well there.

Talked to my sailmaker about the blade. He said on a fractional rig with a large mainsail that this is the preferred setup. Big genoa for lighter air and a blade for heavier air. he discouraged me from a 130 I was considering. He felt the Blade and full main was better then a reefed main and a 130. Still think I'll get a 130 for cruising some day. My Genoa is a 170 and the boat reallygoes well with that .

Brock Richardson

[George ( Triton #236 )]

Hi Brock,

Thank you very much for the information. I'm going to finish my 155% Genoa and then build the Blade jib next. I agree with you that a Blade jib should provide superior windward performance on a Triton in anything over about 10 knots and is a must for heavy air racing.

I'm having a few issues with sheeting angles due to the big spreaders on the new mast. Tim mentioned that this might cause a problem and it is going to effect the track lead positions - It appears that they are going to have to be a bit further outboard than the standard 1" from the cabin in order to clear the shrouds.

I'm also unhappy with the ultra high clew position on my 110% "working" jib. I'd like the clew about three inches above the lifelines instead of the three feet necessary to get it to sheet to the same location as the boat's original 170% Genoa. It's good in a seaway but just doesn't get the job done on the Bay. A new working jib is on the list after the 155% and the Blade.

As it stands now I going to have to custom design track locations for the new 155% and the new 110% jib. I seem to be changing too many variables to do it any other way. Although, since I'm building the same Blade as you have, I would think that I can use the track location you have on "Goose". An equal hoist height, clew position, and a sheeting angle inside the shrouds should make it exactly the same as your setup on "Goose".

Thanks again for all the help and the pictures you sent earlier.

George ( Triton #236 )

[Tim]

Triton #100 Sea Witch, the Daysailor hull, has tracks installed on the cabin trunk more or less between the small ports on each side. It's a couple inches in from the edge. The forward end is even with the edge of the port opening; the after end extends about halfway through the after port opening. This sounds like about the same positioning as Brock was mentioning; I only just noticed them today on this boat, since it was covered until recently. These tracks are fairly modern, unlike the other two sets of tracks on the sidedecks, which are original.

Note also an unused set of holes towards the centerline from the coachroof track--perhaps there was once another track there?



Tim

[D. Fox]

Tim, saw your mention of keel lift previously. I see this referenced frequently and have to admit I don't understand it. First, how does a symmetrical body produce lift? Airplane wings are asymmetrical, as are sails, causing lift to be produced on one side. How does it work on a boat? Beyond that, what does it do? How does it affect performance, including pointing ability as you mentioned?

Apologies for the digression, but I haven't been able to find any decent explanation for this. Thanks,

Dan

[Figment]

I'll take a stab at this one...

Simply put, when an object moves through a fluid, that motion causes positive pressure on one side and negative pressure on the other. Differential pressure = lift.

not-so-simply put......

Hydrodynamic lift from the keel operates on the same Bernoulli Principle as aerodynamic lift from an airplane wing, but is not exactly the same. Because we want boats to sail on both tacks, the airfoils and hydrofoils need to be symmetrical (certain extreme cases aside), so we can't use the same shape as an airplane wing as you noted.

The differential pressure required for lift on a boat's keel is produced by it's off-axis angle of attack. When sailing, the boat is always sliding a bit to leeward and therefore never truly traveling parallel to its fore and aft axis. This shifts the "apparent current" to leeward. Because the water traveling past the keel sees more of the leeward side than the windward side, negative pressure is produced on the windward side, as that water TRIES to keep going on that same off-angle, but gets sucked back along the keel to rejoin its leeward companions at the trailing edge.

All that is to say.... leeway causes lift. This is why you don't really NEED a hydrofoil shape to produce lift, you can just stick a plank down in the water and get the same, though less efficient, effect.

Sails develop pressure the same way, but exactly backwards of what I've written above. windward is leeward, positive is negative, etc.

As for the effect of all of this on pointing ability.... I believe what Tim's referring to (smack me down, Tim) is that, to produce a given amount of lift, short deep fins (referred to as "high aspect ratio" are more efficient lift-producers than are our long shallow (low aspect ratio) full keels, and therefore require a less severe angle of attack (leeway), therefore affording better windward performance.

I'm sorry to have to put it in such fluffy terms, but the engineering side of my brain just isn't working today.

[Tim]

Very well put and right on the money! Mike, you saved me a lot of typing today! :<)

Dan--this is all you need to know about lift--and probably more. The main thing to remember, somewhere in the back of your mind, is that the lift produced by the sails and keel actually "suck" the boat forward through the water, much as an airplane wing sucks the craft into the sky.

It's good and interesting to have a handle on the basic physics of sailing, but don't get bogged down by it.

Tim

[D. Fox]

Figment/Tim, thanks for taking the time to write out that explanation. I understand much better now, but want to follow-up....

Could you define what you mean by the boat's axis and angle of attack. I take axis to mean a direct fore-aft line along the centerline of the boat. I take angle of attack to mean the boat's heading. Aren't those going to be the same - won't the boat's centerline always point toward its heading?

I think you're telling me that leeway causes the boats boat's axis to not be parallel to its direction of travel (course) through the water, causing the keel to present an asymmetric shape as it travels through the water, creating lift. The lift sucks the boat to windward, improving pointing ability. Is that right?

If so, this creates a paradox in my mind - a boat that makes more leeway will create more lift, causing it to sail more closely to the wind.

[Figment]

you're telling me that leeway causes the boats boat's axis to not be parallel to its direction of travel (course) through the water,

Right.

causing the keel to present an asymmetric shape

not exactly. The keel doesn't really present an assymmetric shape. Rather, by diverting the water along its length at an angle, it creates differential pressure. When you were a kid, did you ever "fly" your hand out the window of a moving car? as you changed the angle of your hand, it would lift up and down by the pressure of the air moving under/over it. The shape of your hand wasn't changing, just it's angle of attack to the wind. Same forces are at work on the keel.

a boat that makes more leeway will create more lift, causing it to sail more closely to the wind.

Yeah, that's a paradox alright. My little quip about "leeway causes lift" is an amusing little tidbit, but it's not a true direct relationship. More accurate would have been "The skewed angle of attack caused by leeway is what makes lift possible"
Keel lift is still a function of the shape (both in section and in profile) of that keel. Some leeway must be present to allow ANY symmetrical keel to generate lift, but some shapes generate more lift than others.

It's also worthwhile to note that "pointing ability" (the ability to sail at a close angle to the apparent wind) is not the same as "windward performance" (the ability to make way toward the true wind). A boat that is able to point very high may not make way to windward as rapidly as a boat that sails faster on a lower course.

[dasein668]

A boat that is able to point very high may not make way to windward as rapidly as a boat that sails faster on a lower course.

Mike makes a really good point here that we should all remember. Too often we (sailors in general) concern ourselves too much with pointing ability, rather than true windward performace (course made good to windward).

And this is true not only for keel lift, but also for lift from the sails. Even if the sail doesn't appear to be stalled (luffing) often you will get better lift if you crack off a couple of degrees and sail just a bit fuller. I can't give you an aerodynamics engineering lesson in why exactly this is so --Mike?-- but I can say from experience that it is often true. Optimum windward performance results from a fine balance between a high pointing angle and optimum laminar flow over the sails....

There's my 2 cents!

[Figment]

oh, and I fogot to clarify this....

I take angle of attack to mean the boat's heading.

"angle of attack" (as I'm using it to explain the way water moves past the keel) can conveniently be defined as the angle of difference between the boat's heading (along fore and aft axis of the vessel) and the boat's actual course, or progress through the water (different because of leeway).

Nathan, as for your thing about how you can point high and appear to maintain flow, but heading down a bit is better......

One can head up fairly high and still have some flow over the sails (according to the telltales), but let's face it; the reason telltales are telltales is because they show even the lightest breeze, and because of that they can fool you into thinking that your sails are drawing tons of air when really the flow is barely there.
We need flow on our sails, true, but what we're really after is pressure. Heading down that little bit allows MORE flow, which in turn develops more pressure.

This is why we used to sail drills in college with the skipper blindfolded.... sometimes we just get tunnelvision on those damned telltales! The "feel" of the boat will tell you much more than the telltales.

Further digression: I'm reminded of a story I once read about how N.G. Herreshoff's brother (from whom he'd learned to sail) went blind later in life, but still stayed active with the boats. Once, when taking the helm of a large new schooner on builder's trials, he remarked "the topsail is choked". The crew looked up, and he was right.

[Tim]

The telltales on the sails are there only as a guide to wind flow. They are a helpful tool in getting maximum performance out of the boat, but are only one of many tools--and not the most important one, either.

There's a definite feel when the boat is sailing correctly, particularly upwind. It's called "the groove", and we've probably all said it and felt it. There's no question that an experienced sailor on board a boat can tell, even when he/she is not steering, when the boat is in the groove. Nothing feels worse than a boat being pinched, or sailed too heavy.

People who follow their telltales too closely tend to pinch their boats, therefore going slower. A few degrees down, and the boat would pick up substantial speed, while barely sailing a lower course. The speed more than makes up for the couple degrees. After a point, of course, if you keep falling off you start to lose VMG and hurt your overall windward performance. Falling off too far with closehauled sails will also adversely affect performance. Telltales are useful to help guide sail trim when you start cracking off onto a close reach.

When I bring people out for sails on Glissando, I often let them steer. I have lots of helm time by myself, so I'm happy to give others a chance. (Right, Nathan?) But in many cases, through no real fault of their own, my guests (not Nathan) are horrible helmsmen, and I have to bite my lip to keep from saying anything. But I can feel the boat moving sluggishly, and feel like I'm physically being held back. But virtually all guests sail the boat far too close to the wind, mostly because they generally lack sailing experience that would help them understand that. They don't know how to feel for the groove.

Only experience teaches you what the groove is, and what it feels like. Once you know, you always know, regardless of the boat you are on. Of course, in a new situation, it can take several minutes or longer to get the feel for a different boat, but you can always get there once you know how.

Note also that the faster you sail through the water, the higher you can efficiently point. That's the beauty of apparent wind--as you move faster, you create more apparent wind, which typically allows the boat to sail just a bit closer. Large, powerful racing designs excel at this.

The only way to find the groove in your own personal boat is to sail it frequently, and get used to how she feels. Pay particular attention to sail trim, and find out what makes things feel the best. What feels good is usually good.

Sailing is mostly an art. The science is there, but very few technical sailors are ever on top of local racing fleets--rather, it's the ones who sail by the seat of their pants.

Now, go down to your boats and go sailing! Find the sweet spot and discover why it's the sweet spot, and then look for it on every tack. You'll be surprised. Oh, and trim the sails properly. You don't need books or technical knowledge for this--mere practical experience tweaking things is the best.

The moral of the story is: sail often! Work--who needs it. Sailing is better for you. ;<)

Tim

[dasein668]

When I bring people out for sails on Glissando, I often let them steer. I have lots of helm time by myself, so I'm happy to give others a chance. (Right, Nathan?)

Not just "more than happy"; some might say "downright pushy" about it! ;-P

Very generous with the helm, he is.

[Figment]

Backing away from our aeronautical fumblings......

Back onto foresail lead points and tracks:

My current dilemma (see recent post in "Ramblings") is that I evidently bought #78 with sails that don't fit. The boat has one set of tracks, mounted along the foot of the house, running roughly the length of the forward deadlight. Both genoas that came with the boat are too big to be sheeted inside the shrouds, and they need to be led farther aft than the track runs anyway.

I'm guessing that these sails are 150% genoas? and that the tracks are for a 130% or less? These numbers are totally wild guesses, so please jump in and correct me if you think otherwise.

The track that's on the boat is semi-modern (looks just like the track on the forward part of the house in Tim's photo of #100 above) replacement of the original little track (farther aft in Tim's photo), which came with the boat's box of spares. Because I'm a cheap bastard, I'm contemplating mounting this old smaller track out near the toerail to get a fair lead.

Is this old track up to snuff for the larger loads imparted by the oversized sail, or am I getting myself into trouble?

George, how has your track layout (the start of all this longwindedness) worked out for you?

[George ( Triton #236 )]

The track I use is the standard 1" black anodized t-track for toerails. To completely eliminate current and future problems with improper track location I just installed two 7 foot sections on either rail immediately forward of where the standard 170% genoa track on our boats ends. A real pain in the butt to install all that track and its 40 1/4-20 bolts in the proper bedding. However, it has worked out really well because it handles my 155% as well as the 110% jib and gives me a set of movable fair leads for my spring lines. It will also cover the 130% when, and if, I make it. I use Ronstan spring mounted series 50 blocks and matching slides with the track in all locations.

The blade jib I made uses two 18 inch sections of toerail track located on the forward part of the raised cabin top. These are the same locations as Brock uses on "The Good Goose". The blade jib is a thing of beauty when the wind gets much above 10 knots just because of it's ability to point so well.

When I made the 155% for #236 "Ca Ira" I designed it specifically for sheeting on the toerail. A toerail track sheeting point equals shallow camber sails, track closer to the centerline equals deeper draft. This way I still have a strong attack angle to the wind even though I have to sheet around those giant spreaders I have. This sail gives me a combination of strong pointing ability and good drive for the PHRF racing I do.

In short, I like my new track and I think that the track you already own is more than strong enough for any sail you want to put on the boat. I'll try to attach a picture of the boat from the last trip so you can see the track locations. Oops, can't seem to do it. I'll post a couple on the Triton newsgroup. If you want the non-compressed image so you can really see the detail let me know and I'll e-mail it to you.

I'm leaving first thing in the morning for a race in Deltaville, VA and will return Sunday night. Talk to you then.

[Tim]

The boat has one set of tracks, mounted along the foot of the house, running roughly the length of the forward deadlight. Both genoas that came with the boat are too big to be sheeted inside the shrouds, and they need to be led farther aft than the track runs anyway.

Mike,

With the wide spreaders and outboard position of the shrouds on a Triton, any overlapping headsail will normally require a sheet lead on or just inside the toerail to draw properly with appropriate sail shape. I'm guessing the inboard (and forward) location of your tracks is someone's misguided or uninformed attempt to change the way the boat sailed or pointed--or, as you guess, you simply received sails that are mismatched to the current track setup. Who knows why, or how someone sailed the boat in the past?

I have trouble seeing how any overlapping sail on a Triton could be led to tracks set up the way you describe yours to be. I sail with a 130% LP genoa, and it leads to a track mounted just inside the toerail. There's no way it could ever lead to a track near the cabin trunk--way too far in.

A proper sheet lead should generally allow the luff of the sail to break evenly along its length. In general terms, this means that the fullness and draft of the sail will be relatively even top to bottom. If you choose a position for your track so that this supposed "ideal" is about in the center of the track, you should then have ample room for adjustment fore and aft should wind conditions dictate a slightly different lead setup. Once you have the starting point, some tweaking of the final lead position on the track is easy and fun.

The original position of the outboard tracks on most Tritons (starting at about the forward end of the cockpit and leading forward) is optimized for the 170% and 150% genoas that the boats were designed for, and often sailed with. Using a sail such as a 130% will likely require that the tracks be mounted further forward--and most definitely along the toerail. My 130% leads to a point on the toerail roughly opposite the aft end of the forward deadlight.



I recommend picking a relatively light air day (about 5 knots) and hoisting your genoa. With the sheet in your hand, you can hold it down to the deck in a few locations along the toerail to see about where the proper lead should be, moving it forward or aft as necessary to make the shape look right and to break more or less evenly along the luff while closehauled. By playing around in this manner, you can pretty easily determine the centerpoint of your new track location for installation.

I further recommend that you install a track that allows a range of adjustment. I use 4' tracks on each side; with care, you can get away with 2' sections, though this can limit the utility and adjustment capability. I would not use the tiny, cold-formed track (like that originally installed for the working jib) for a 135% or 150%; it seems terribly lightweight for such duty.

George's long track installation on the toerail itself is the most ideal situation, really. It allows a multitude of adjustments and will allow for proper sheeting of almost any sail. However, you need not go to this extent if you choose not to. 4' of track, when optimized for the sail you use all the time, is more than enough. It just depends on how you use the boat and what you're looking to accomplish.

Phew.

[Figment]

I spent some time straightening up the shop last night for an upcoming project, and I happened across a box of odds&ends that the PO gave with the boat. Among the dozens of old drawer pulls and robe hooks were two 24" lengths of bronze 1" T-track! digging a bit deeper unearthed a pair of cars to match! SCORE!!!!

Some fasteners from Jamestown, some stock to make backing plates, and I'm in business. Some bronze blocks would be nice, but that cart's way before the horse at the moment.

[George ( Triton #236 )]

Hi All,

I have recently been re-thinking my desision to go with 6 foot lengths of toerail track in addition to the 4' pieces we already have on the Triton. While I love the versitility that this track gives me. After the race on Saturday I noticed that water had been leaking in under the new track on the starboard side. It's impossible to determine where the leak is along the track so I'm faced with re-bedding the whole thing - all twenty bolt holes. This is going to be a royal pain in the butt. I'm starting to think that breaking up the track into more manageable sections might have been the way to go. Strictly from a maintenance point of view.

George
#236 "Ca Ira"