Tracks for Blade Jib

[Fiveslide]

I subscribe to a lot of Dockhead's threads like this one. I hit the subscribe button as soon as I saw this one. I don't often participate, but I follow them. I do this because I know the level of discussions will be high, the number of different solutions will be high, many of which I would never have thought of myself.

There are far, far more annoying patterns and posters on CF.

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[Cheechako]

Originally Posted by UNCIVILIZED

Guys,
Since my name has been brought up again, several times in this thread, with questions as to why I walked away, I'll give folks the story. In order to clear any questions. And if further evidence to back up my statements is needed, it is easy enough to post PM's, etc. to show the full evidence & history behind things.

That being, that the OP (repeatedly) feigned ignorance on this topic & it's solutions presented to him.
He sought out the advice of multiple marine professionals, as well as members here. Acted as if said information was beyond understanding, & sought more information both here & from more marine professionals. Which likely will be treated in the same manner as described above.

This pattern is far from new. If you doubt this, do a search on how many threads the OP created over half a year regarding an info search to pick new sails out. Multiple sailmakers were repeatedly consulted in "endeavoring" to select a new suit of sails. Such was stated by the OP himself. In addition to creating dozens of pages of threads on here seeking advice on the same exact topic.

I walked away from this thread, as I was fed up with this pattern. In addition to the flagrant wasting of my time. And am stepping in now to explain my actions as they were brought into question.
My attempt to walk away & allow the OP to, "save face". As I stated earlier in this thread. Seemingly, failed. And he himself, flat out stated that I'd exited this topic due to said fore stated reasons.

The time of mine which was wasted was not in putting a complex subject into terms which any layman could understand. It was in showing him the resources available, with which someone in Jr. High or High School could decide upon & execute the solution.
For example. I could & did mount hardware for this exact purpose (jib track installation) by the time I could legally vote, in a 48' Nautor-Swan. A boat of the highest repute, which one does not arbitrarily tinker with, with tools.
A vessel with similar loads, & having a far more complex system of construction.

Figuring the task at hand out, & executing it is FAR from rocket science.

I've found that just not commenting or participating in threads that I have nothing to add, or find frustrating is a big help!

[Dockhead]

So the sailmaker has endorsed the idea of a floating jib lead for the blade, saying that the great degree of fine control is really good for this kind of sail. I only wish he had suggested it in the first place.

He says it must be designed properly by a naval architect, and suggested asking Bill Dixon himself to do it. So I've written to him. There's little time, but I can sail without the blade if it can't be done so soon.

As far as structure is concerned, I've taken to heart all the helpful comments made in here about point loads made in here I'm hoping that chainplates at the ends of he staysail track beam will work, but that's now a question for a pro.

[stillbuilding]

Well I am a rank beginner compared with others here but am planing a variant of the floating job for the headsails on my largish steel cruiser. Largely for flexibility over time, preferred impact on the steelwork and cost. Seems to be a very useful concept.


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[Dockhead]

Originally Posted by stillbuilding

Well I am a rank beginner compared with others here but am planing a variant of the floating job for the headsails on my largish steel cruiser. Largely for flexibility over time, preferred impact on the steelwork and cost. Seems to be a very useful concept.


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Can you show us the design?

[stillbuilding]

Originally Posted by Dockhead

Can you show us the design?

In June - I am in HK and boat finishing in Oz.

I bought a rig plus all deck ware off a Maxi racer and am incorporating lots of the same minimalist gear from that boat. Different rationale but same techniques.


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[Southern Star]

Dockhead, it strikes me that the twin track system proposed by Uncivilized will do a far better job of distributing the loads than fixed padeyes and will also provide better sheeting angles when you are sailing off the wind. The structural reinforcement required for the padeyes to be able to handle this kind of load may surprise you!

Due to the staysail stay, you also dismiss the idea of using a curved athwartship track and cars in order to make the blade self-tacking. Is the staysail stay necessary for mast support when you are not flying a staysail? The naval architect/manufacturer of the mast should be able to answer that question for you quite readily. I ask because, if not, it would be possible to use a highfield lever on the inner stay (as you will never be flying the staysail and the blade jib at the same time) and install a curved track and cars.

Brad

[barnakiel]

It would take a very stiff track to seriously distribute a point load. You will notice when damage done most of the time a single bolt on a track goes first and then .. riiiiiiiiippppppppppp!

A welded on track is perhaps an exception. It is sort of continuously distributing.

So, as I see it, in many cases, the track is there not to distribute the load (so much) as to allow for adjustments (e.g. when a furling sail is not cut for single point sheeting).

Given the difficulty of 'on paper' finding where, athwartships, the best sheeting point is, I would love to have a (perhaps even curved) track on the foredeck.

Possibly, in off the mill designs, the track is not necessary in later incarnations: once the exact best position is found on the proto build.

Cheers,
b.

[Dockhead]

Originally Posted by Southern Star

Dockhead, it strikes me that the twin track system proposed by Uncivilized will do a far better job of distributing the loads than fixed padeyes and will also provide better sheeting angles when you are sailing off the wind. The structural reinforcement required for the padeyes to be able to handle this kind of load may surprise you!

Due to the staysail stay, you also dismiss the idea of using a curved athwartship track and cars in order to make the blade self-tacking. Is the staysail stay necessary for mast support when you are not flying a staysail? The naval architect/manufacturer of the mast should be able to answer that question for you quite readily. I ask because, if not, it would be possible to use a highfield lever on the inner stay (as you will never be flying the staysail and the blade jib at the same time) and install a curved track and cars.

Brad

Thanks, those are all interesting ideas, but:

1. If I were willing to make the blade self tacking, I would just use the existing staysail track, which is extremely beefy. That would solve a whole host of problems. But: a. inner forestay is structural (acts like baby stay; I have swept back triple spreaders), and has heavy furling gear. Not really practical to make it removable. And b. Self tacking headsails can't be properly trimmed in my experience without a lot of barber-hauling - exactly what I don't want from this sail. The point is superb upwind performance, requiring superb sail trim - hard if not impossible to get from a self-tacker.

2. Twin tracks would be astronomically expensive (the cars alone are more than $1000 each, and all kinds of cabinetry would have to be ripped out to get under the sidedecks there), and would obstruct my sidedecks.

3. I agree with Barnakiel that tracks do little to nothing to distribute loads - relatively thin hollow alu profile is nothing to a couple tons of load. On the contrary, they require a huge effort in constructing a proper backing plate over the whole length -- big bronze plates costing several grand each, according to the boatyard.


My sense is that the structural problem is easier to solve in one point than over the length of a track, which is just a bunch of single points, each of which needs to be strong enough to take the whole load. And that I'll get a much wider range of sheet angle adjustment with the racing lead setup. Thats what the sailmaker says. I've asked the original designer of my boat - sure hope he responds.

[Dockhead]

I'm still waiting to here from Bill Dixon, but I think I now have the final solution.

The existing staysail track is a beefy Size 3 Lewmar track, bolted to a massive beam under the foredeck. Structurally way overdesigned like everything on my boat (thank you, Bill!).

As it turns out, the ends of the track are more than 90cm from the centerline of the boat. Since there is 545cm of distance from the track to the tack clew, that makes a 9 degree sheeting angle. That means that my optimum upwind sheeting angle is -- I hadn't realized this -- well inboard of the ends of the track. Provided the track is not too far forward (within the range of how short I can make the foot of the sail, which hasn't been cut yet), then the existing staysail track is the ideal anchor point, requiring no holes in the deck, bronze plates, or expensive boatyard work, at all.

So what I will do is this. I will buy two new Size 3 plunger cars and put them on either side of the existing rolling staysail car. The existing staysail car will lose some range of motion but probably for the good (reducing the basic sheeting angle; I can barber haul any wider angles I might need). I will buy the cars with just a tang, not a block. I will attach to these cars triple blocks, and then buy two Antal Low Friction Rings, and rig those to two more triple blocks. I will lead the line from this tackle along the side decks through clutches on the rail. Through turning blocks on the quarters and back up to the cockpit. I will lead them across the foredeck first so that I can use windward winches which are more likely to be free.

Then, I will put padeyes on the rail opposite both of these points, from which I will rig permanent barber haulers to haul the sheet lead point outboard for going off the wind. But I will already have a range of adjustment using the cars up to more than 9 degrees.

It seems to me that this will be simple, elegant, inexpensive, strong, and providing a huge range of adjustment of leech tension, more than simple side tracks could ever do.

What do you guys think?

Here are the geometry issues:

The track is 545cm from the tack shackle on the furler, so according to my calculations, a 6 degree sheeting angle would need an anchor point 57cm from the boat’s centerline. A car will move up to 93cm from the boat’s centerline, so moving a car to the end of the track would give a sheeting angle of more than 9 degrees.

Since there is no limit on how far inboard the car can be moved, this would seem to me to cover the entire possible range of optimum sheeting angle, for sailing hard on the wind, wouldn’t it?

That’s the horizontal plane. In the vertical plane, I will control the up and down position of the Antal low friction ring sheet lead with tackle anchored on the cars. As long as there is the right distance between the clew of the sail, and the track – this will give a large range of adjustment. To figure this out, I need to know what is the possible range of length of the sail’s foot. The geometrical parameters are two, I think:

1. With the sheet lead in the fully down position, the angle from there to the clew of the sail needs to be as acute as we could ever want it for tensioning the leech. So if the distance is too great, we won’t be able to get enough leech tension on. This needs to work with the sail reefed, too. So I guess we measure the angle from the lowest position of the sheet lead to the clew position when reefed – is it acute enough for leech tension?

2. But if the distance is too small, the forces on the sheet lead will be magnified, and we won’t have fine enough adjustment. I guess the greater the distance, the better, up to the point where we can’t get the leech tight enough.


What do you guys think?

[Pete7]

Originally Posted by Dockhead

What do you guys think?

Sounds much better than drilling multiple holes in a perfectly good deck. Chat with the sailmaker next then?

Pete

[Dockhead]

Originally Posted by Pete7

Sounds much better than drilling multiple holes in a perfectly good deck. Chat with the sailmaker next then?

Pete

Yes, I've written to the sailmaker.

[Dockhead]

More very interesting material on sheeting headsails with floating leads:

Jib sheet Twing








These guys use a "twing" to suspend the ring at the end of their regular tracks. Then use an inhauler to bring it inboard.

This is almost exactly my planned new arrangement, except that I will have an outhauler instead of an inhauler. Because the "twing" will be on a car with no limit on inboard adjustment. The car can be set from 0 degrees to about 9 degrees sheeting angle. So the outhauler will only be needed off the wind.

Which is good, because the forces will be huge when sailing hard on the wind, and we will want the twing centered over the car.

In fact, I think my arrangement will work as well as a regular car without any outhauler; or rather, much better than that, since the car can be adjusted athwartships.

Whatever the outhauler will be doing, is something which a regular track cannot do anyway without a barber hauler.

[savoir]

Mauripro are having a sale on Lewmar jib cars including the no 3 size at USD $446.

Lewmar Size 3 S/S T-Track Car (1 1/4 Track) | Mauri Pro Sailing

[Dockhead]

Originally Posted by savoir

Mauripro are having a sale on Lewmar jib cars including the no 3 size at USD $446.

Lewmar Size 3 S/S T-Track Car (1 1/4 Track) | Mauri Pro Sailing

Thanks for that, but I would have needed the towable one, also on sale for $750 vs. $1000, but still a lot of cash: Lewmar Size 3 Genoa Car with Cl sheave (TB) | Mauri Pro Sailing

But anyway I'm very happy with the floating lead setup, which has been blessed by the sailmaker and the rigger and which I think will give me far better control than cars and tracks. And which doesn't require any holes in the deck at all.