CD36 staysail sheeting: What was Carl A thinking

[Troy Scott]

when he designed the staysail sheeting system on the CD36? It does seem odd at first glance. I've even heard it described as "weird". But I hate to condemn it without understanding it. It seems to me that it might actually be fairly clever. I was recently given a "lesson" on this board, as follows:

"Moving the traveler to the LEE increases the sheet's downward leverage on the leech, and prevents the sail from twisting off. In heavy air, limiting twist reduces power high in the sail and reduces heel."

Now here are the things I'm wondering about: If the stops are left fairly far outboard, then the sail traveller would find some position on it's own, based on sheet tension, wind pressure, etc. As the sail moves outboard, the "long" side of the sheet "triangle" is pulling the boom to weather, while the "short" side of the triangle is pulling the boom down. I wonder if this action is meant to automatically accomplish what the "lesson" above talks about. OTOH, I wonder if keeping the stops near the center all the time (as some do) somehow partially or completely defeats Carl's plan. I wonder if the stops should really be used for anything other than "preventing" when sailing wing-on-wing, or locking the boom in the center when the boat if moored. I wonder if, in general sailing, the car should be allowed to 'find" it's own position on the track. If anyone has put a lot of thought, followed by trial and error testing of the theory, I'd like to know about it. Are there any of Carl's writings that mention what he was thinking when he designed this sheeting setup for the CD36 staysail? Do other Cape Dory cutters have similar setups? If not how do they differ?

I'm about to start another thread to try and learn if it's practical to try to get old hardware refurbished. Both my travelers could use some attention if I decide to keep them. I'd rather buy new, but the old ones could certainly be made serviceable.

[CD-Sailor]

DELETED

[Troy Scott]

Thank you Clarence!

OK folks, please add to the knowledge base here!

[Len]

I once saw a very nice iteratiion of a NERIA designed by Herreshoff.
I think it was made by MIddleton Marine in Florida, if not mistaken. It had both the staysail and the Main rigged in a similar fashion. The difference being there was no traverler track and hense no stops. The blocks were fixed on either side of the house. This than functioned like Albergs staysail with no stops.Was Aberg adopting a Herreshoff design or one even older?
I have tried sailing wth the stops in the middile and at the ends. How well it works seems to depend on your point of sail.)
Lenny

[Troy Scott]

Len wrote:
"I have tried sailing wth the stops in the middle and at the ends. How well it works seems to depend on your point of sail."
-end quote-

Please elaborate? For example: I wonder if it is actually necessary to move the stops inboard for a close reach. I wonder if moving both stops to one side makes an adequate preventer. Etc...

Is the Robinhood 36 staysail traveler set up the same as a Cape Dory 36 traveler?

[Troy Scott]

but add the traveler?

Does this make sense? I see that Rich and Melissa changed the sheeting as well as the traveler. Would adding a traveler with controls led aft while keeping the original sheeting system defeat the purpose of the traveler? Would it help? What difference would it make?

[Troy Scott]

Folks, I appreciate the information I've read so far, but I really would like to learn more about how the staysail traveller is actually supposed to function (my original question). I've heard various comments ranging from "we always just keep ours centered" to "I go forward and kick the traveller car all the way outboard to flatten the sail". I've heard it described as "weird" and I've heard it described as "genius". Obviously some of you feel strongly about this. Some have replaced both the traveler and the sheet with a more "standard, easy to understand" setup. Others praise the virtues of the original installation. Seriously, I hope someone out there can explain the rudimentary physics involved and tell me (us) how the staysail traveler, as originally installed, was expected to work. I'm very curious.

[Len]

Troy,
Here is how I understand staysail use (which needless to say is not necessarily correct).
For the staysail to work properly , the air flow between the staysail and the yankee must flow smoothly and stay "attached" to the sails. To accomplish this the shape of the staysail needs to be parellel ( same curvature) as the yankee. So if the yankee is full (for example a loose foot and tight leach) the staysail should assume the same shape. The leaches of both sails should run parallel from head to foot. You wouldn't want to have a staysail on its outer stop and hauled down tight while the yankee was flowing freely in a billowy shape. You can recognize when the air flow is not "attached"- the body of the sail puffs while the rest of the sail seems to be correctly positioned.
Therefore my practice has been to set the yankee first and than fill in with the staysail. (even if the staysail was already up before hauling out the yankee.
So now to the question of the stops. I almost always keep the stops in the middle of the traveler. The one major exceptions is when i move the staysail to to the last stop on the traveler in anticipation of sailing by the lee and hoving to. In theory I assume they act the same way as the traveler on the main. I don't routinely go forward to adjust the stops when sailing only with the main and staysail- although I would if I had a crew (I sail mainly single handed) I do adjust the traveler on the main. Come to think of it. If the traveler on the staysail had a "car" setup with line I might utilize it more.
Its a matter of which choices one wants to make. If I were explaining "how to" I guess I would say when you adjust the main traveler adjust the staysail traveler, when you run out of stops reef .
Anyway That is how I see it.

[Larry DeMers]

First a question. You said this"..."Moving the traveler to the LEE increases the sheet's downward leverage on the leech, and prevents the sail from twisting off. In heavy air, limiting twist reduces power high in the sail and reduces heel."

Moving the traveler to the lee Does pull down on the leech, it Does prevent twisting-off, and it will control the amount of top end twist-off.
But in heavy air, upper level twist is desired to depower the top of the sail. Your statement seemed to be saying the exact opposite. Maybe I am misreading it though...?

I always leave the stops at either end of the traveler, and allow the traveler to determine where the car stops at. If the car moves on it's own, it will balance the vector forces (the long and the short side of the sheet-formed-triangle) that are working on the staysail boom at that time.
Seems to work fairly well that way, but it does highlight a problem; That darn car. The staysail traveler car needs to have a low friction contact with the I-beam that it rides on, in order for it to find the correct position under most wind conditions. My traveler car has a rubbing contact, with no ball bearings at all, and this, in my opinion (I have several) is a weakness that Cape Dory allowed to go through for some reason.

The solution would be to put a "small-boat" car on the track. One that has ball bearings, and is rated for the moderate pressures that the staysail generates. Doing this would allow the traveler to self-locate in winds other than a large blow, I think.

Cheers and Beers,

Larry

[Troy Scott]

Len, as always, thanks for your thoughts! I understand the idea of the sails "matching in shape", one affecting the other, etc.. I'm a pilot, and I've studied the aerodynamics of biplanes, etc.. This is, of course, similar. (and I'm still envious of your elegant dodger...)

Larry, Thank you VERY much. You have confirmed my suspicion (theory?) that the staysail traveller car is really meant to "find it's own position". As for the car, mine IS a roller-bearing Nicro-Fico, and seems to move fairly freely. What brand/style is yours? Even so, I believe a better car would improve both our situations. My track seems OK. I could replace the blocks in the sheeting system (which I need to do anyway) and the boom bales (which I need to do anyway) more cheaply than I can do all this PLUS buy a whole new traveller system with control lines led aft. The reasons for this discussion are (1) to learn how the staysail "combined traveler/sheet control system" is REALLY supposed to work, and (2) to help me decide what to do about it! One problem I know about is that when Garhauer installs a roller-bearing car on a curved track, they usually install two cars, connected flexibly to accommodate the curve. I know that most of these parts have some built-in "looseness", so probably most roller-bearing cars would run on our staysail tracks (they aren't curved all THAT much...). This would have to be determined. John Danicic has promised to do some actual experimentation to confirm or disprove this theory about the car finding it's own position, hopefully this happened this past weekend. I haven't heard back from him. If the results of his experimentation confirm your thinking on this subject, then I believe we're at least approximating the "scientific method" here This will be a GREAT help! IF we can determine that we don't really NEED a traveler control system with lines led aft, than I won't buy and install one, and this will keep the boat simpler, which is the way I like it.

I never listen to opinions like "well, it worked that way a long time, why change it now?" This approach just doesn't work for me. I have to understand things, and base my decisions and purchases on that understanding. Thanks for this excellent and thoughtful information.

[Troy Scott]

Larry, Look what I found:


This is what I found when I went looking for a replacement roller car for the staysail traveller. I have the original Nicro 1159 staysail track on my boat. I have an old nicro-fico roller car, but the bearings are old and apparently slightly "flatted". They run, and the car moves, but it's easy to imagine that it might hang up under load. I want a new one so that it will easily move to the best position on it's own. The Kenyon KT-4510 is apparently equivalent and can be bought new. They have stops as well. My old stops work OK, but I may as well get new ones if they aren't too pricey. They also have parts to convert the whole system to a regular traveller control system, but before I would go to all that trouble I would just buy a ready-to-go Garhauer traveller. You can also go to:

http://www.rigrite.com/travellers/Ken_T ... trvlr.html

and find even more information with some pictures.

Spars, Rigging, and Hardware for Sailboats
Rig-Rite, Inc.
Phone: (001) 401-739-1140 -- FAX: (001) 401-739-1149
www.RigRite.com Ordering/Questions


Kenyon 3/4" Travellers (KT-4540 series) are designed around a hardcote anodized I-Beam Track that measures 3/4" across the top, with an upper lip that is 3/16" (.185") thick. Cars feature SS wheels with SS Ball Bearings in free-floating races for minimum friction. Race design allows easy maintenance with only fresh water rinse. 4-Wheel Cars are suitable for mainsails up to 200-sq. ft. with end boom sheeting.
Cars, Control Ends and End Stops (but not Adjustable End Stops) for Kenyon 3/4" Traveller Track are also compatible with Nicro-Fico NF-1159 (3/4") Traveller Track.



Kenyon 3/4" Traveller Cars
Basic 4-wheel Traveller Car: KT-4510:
Basic Traveller Car for Kenyon 3/4" I-Beam Track is constructed of aluminum alloy and features SS wheels with SS Ball Bearings in free-floating races for minimum friction. Car has removable eyestrap for attachment to mainsheet block. Car is 2" long with a maximum width of 1 1/2". -1
Eyestrap for Kenyon 3/4" 4-wheel Traveller Cars: KT-SB-131:
SS Eyestrap is used on all standard Kenyon 4-wheel Cars. SS Eyestrap is 3/8" wide x 1 7/8" long with (2) 3/16" holes on 1 3/16" centers.


Kenyon 3/4" Traveller Ends & Stops
Aluminum Track End Stop: KT-4500-4:
Extruded aluminum Track End Stop for Kenyon 3/4" I-Beam Track covers track end and attaches to track with (1) #10 RH screw.

Adjustable Track Stop: KT-30331A:
New style Adjustable Track Stop for Kenyon 3/4" I-Beam Track features SS Spring Pin and rubber bumpers to cushion car impact. Used on free-floating car systems without end controls, especially for jib and staysail boom Travellers. Anodized aluminum Track Stop is 1 1/4" long x 1 1/8" wide, and has a 3/16" plunger Pin.

I'll order one KT-4510 and two KT-4500-4 if I decide to repair and reuse the present system. I think I might prefer the KT-30331A adjustable track stops (because they have the rubber bumpers) but the note above says they are not compatible with the NF-1159 track (I can't imagine why...). I would also replace all the sheet blocks with Garhauer. I think this would really slick-up the original system while maintaining the original idea and function, and eliminating the need for a new traveller with control system. Thoughts?

[Larry DeMers]

Troy,

Whoa ..doing a Garhauer traveler for the staysail would be EXXtreme Overkill in my mind. Use the new car with no flattened bearings, and adjust to it's ways, so that this simple system can work for you. No need to go expensive, and rather large solutions for this problem.

I appreciate your research for the car. I will have to follow-up on those, and find my fix. I do like using the staysail, but I have to admit to going the lazy route and leaving it doused when it would have been useful.

One feeling that I enjoy, is the comparison of the boats movement and "feel" in too high winds for the sails set, to the same after reducing sail to reefed main and staysail only. There is 'Peace' in the middle of the malestrom.

Cheers,


Larry

[Troy Scott]

Hey Larry,

I tend to agree that a full control line traveller for the CD36 staysail is overkill. As I wrote earlier, I had already suspected that the function of the staysail rolling car/sheeting system was/is more clever that seems to be immediately apparent to most CD sailors. Then you came along with your description of how it works for you in practice, which reinforced my thinking. When John Danicic clues me in on the results of our little "experiment" which hopefully will have involved actual observation of how a "free-floating" car works on various points of sail, I will have more ammunition (confirmation). I'll be grateful if I learn that our thinking is actually the way it works in the real world..., or I'll be perplexed to learn that what seems to be a good idea really doesn't work well enough to keep.

Today I found the price for the Kenyon equivalent for the out-of-production Nicro Fico car that I have. The damn thing is $179 from Rig Rite! I guess I shouldn't be surprised. That inspired me to call and talk with Guido at Garhauer. I was hoping to find that their MT1 traveller track is 3/4" wide, like our Nicro Fico staysail track, and that the roller car they install on that track would work for me (us) and be a lot more reasonably priced. At first I was disappointed to find that their narrowest track is 1 1/4". But then a little light came on in my mind while I was talking with Guido and looking at their catalog. I suddenly realized that their MT1CT traveller system would look much like our ancient Nicro Fico staysail traveller if it was missing all the blocks, cam cleats, etc.. I explained my thinking to Guido, and he immediately understood what I was getting at. He said he could make me a special "stripped" version of the MT1CT with just the track, the double (hinged) ball bearing car with the eye strap, and the end stops. In other words, eliminate all the blocks, cam cleats, etc., both on the car and at the ends. He would adjust the price accordingly. The MT1CT is usually $475. He would build this special one, with the curved track and matched mounting holes for $300. But, for the month of July only, they are offering a 20% discount on all travellers and traveller-related parts. That means this ALL NEW staysail traveller would cost (only)$240 That's not much more than the new Kenyon roller car! And the Garhauer setup would probably be much smoother than my old setup would be even with the new Kenyon car. Thoughts? I'm getting all new Garhauer blocks for the staysail sheeting system anyway. All this new, very low friction stuff should allow the original Alberg/Cape Dory design to do what it was probably meant to do all along. And there would be no extra lines to run aft. Very slick, clean and neat. Thoughts?

I guess at the same time I would order the MTUB2 traveller (with dodger conversion) for the main, and the UR2 risers to mount it on. That's what John Danicic used and he is in love with it.

Now I just have to figure out where this next boat-unit is coming from, considering these extra medical bills I have now.

All this thinking has made me tired! It's bedtime.

P.S.: I too have been impressed with how the world seems to calm down when you reef or heave to. It's wisdom that usually comes with age and/or experience. In my case I learned after several stressful knock-downs many years ago. Like I wrote before, I've never had a sailing lesson! I need some!