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Old Mar 04, 2013, 03:50 PM
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los angeles
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A note on bracing. When I was measuring the travel of the braces I run the lines from the yardarms to a screw eye on the next mast, and than down to the point where it would enter the hull. I was trying to figure out how I would handle the entry point, when I checked the schematic of how it was done on the prototype. Turns out that in real life the lower sails braces lead not to the next mast, but to the belaying pins by the bulwark. I tried the prototypical approach. It changed the geometry and brace travel. But what is more, when the yard is fully braced, it is set at what looks like an optimal possible angle for the beat. When the brace goes to the mast, it is possible to pull it too tight, too parallel to the hull, so the opposite brace cannot pull it back any more. I suppose when the wind is acting on sails it might help the situation, but I can imagine that it can also make it worse. This situation is physically impossible with braces leading to prototypical locations. Besides, it makes it easy for me to make the brace exit points in the permanent part of the deck, and not at the access hatch.

I remember reading in Jerry Todd's Constellation thread that running the controls prototypically made more sense than any other way.
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Old Mar 04, 2013, 03:54 PM
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los angeles
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Another note on bracing. Would it make sense to run a second set of brace to the uppermost yard and set it so it produces the correct spiral? It is possible to make it so that even if I strike a sail or two from the top, I could relocate the braces to the lower yard.
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Old Mar 04, 2013, 06:32 PM
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Yalex -
A few points...on my brig, and on Gary's Surprise, we want all the angle we can get on the yards to get better maneuverability (pointing higher into teh wind).
Less drastic but more prototypical angles make sailing a pain given the wind conditions and space we sail in. So we modified rigging for maximum yard rotation. This is important, too, to maintain speed going into a tack because you can really come into the wind (more "schooner-like')
Next point - on a real square rigger, where lowest braces go to bulwark, the geometry does work. But a lot of other stuff is going on....the tilt (of the yard is controlle d to keep it level, the brace tension is adjusted both port and starboard, sails are trimmed, etc. On my model, braces running at a downward angle were tried early on (and used until recently on the foretopsl yard), but the yards end gets pulled downward and starts messing up the yard tilt on the whole mast. On a smaller model with stiff sail material, this may not be the case. But on a big model with soft sails, etc, pulling back and downward will likely tilt the yard too much. Also, I couldn't get the angle of rotation that I get if I did not pull the braces from closer to the centerline vs at the bulwarks.
Another point - if you did the test and got so much rotation on the lower yard that it couldn't be pulled back, I'm guessing that you don't have the shrouds rigged yet. If positioned right, they will block the lower yards from over-rotation.
I really believe that model sqr rigger geometry needs to be modified from prototypical to make the model more practical (and fun)to sail.
I've never seen more than minor mast twist on my yards - certainly never to the point where the upper yards are too parallel to the hull vs the lower yard position.
And I still disagree (and I may be wrong) with the idea that the windspeed difference from lower sails to upper sails is significant at this scale. On a real ship you're talking 100++feet. On these models it's only 5-6ft. And it's not that often the topgallants are used anyway.
The biggest issue is not having steady wind velocity, wind direction changes, gusting and having enough sea room and smooth enough seas to tack reliably - all the other stuff to me seems a minor factor because Syren sails like a champ if given anything near a steady breeze.

See these posts for my "paper excercise" on brace pull. The system works just fine and the model measurements are very close to the design excecise. The model is now re-rigged per the drawings, with sliding servos and the foretopsl braces rigged horizontally vs the downward angle pull. I've not sailed her yet, but have run through all kinds of rotation tests, slack measurement, servo amp draw, etc and all looks really good.
http://www.rcgroups.com/forums/showp...&postcount=137
http://www.rcgroups.com/forums/showp...&postcount=138
http://www.rcgroups.com/forums/showp...&postcount=139

I like your plan of starting with fewer servos and only lower braces until actually sailing to see how that works. Allowing as you are for future servo additions and redesign of rigging, you should be good to go. Then optimize rigging over the many years of enjoyavble sailing you will have!
Sorry - long post, but I feel pretty confident about my experience and observations.
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Old Mar 04, 2013, 09:18 PM
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Bracing the bottom and top yard would allow you to get realistic spiral. If you have a fast way to move braces down as you reduce sail, then go for it :-)

As DanL said, shrouds will limit yard swing. They were in the way on the real ships, and on our models too :-). Not until the invention of yard cranes, that move the course yard forward from the mast, were squareriggers able to get decent yard swing and thus work to windward well (or at least better, f&aft ships still excel over squareriggers for beating).

I don't put shrouds on my masts, just backstays (and forestays). This is per Boyle's design. Backstays also limit yard swing, but since they are installed further aft than the shrouds, backstays are less limiting. For my course yards, the swing with backstays is fine, about 60deg off perpendicular to the hull. I actually experimented on the bench to find the best location for the foremost backstay; I wanted 60deg swing, and moved the backstay around to be sure I'd achieve it.

For the higher yards, however, the backstays are not as useful for limiting over-swing of the unbraced yards. The geometry of the lead of the backstays gives them less spread aloft. The uppermost yard can push against them to the extent that the yard shoves them out of the way. The yard is "sweating" the backstay just as a sailor sweats a halyard.

As long as the over-swung yards are not perfectly parallel to the hull, the uppermost sails can still give some drive. But at some point, they contribute more to leeward drift than forward motion. Just as a sloop does not pull it's boom in past, say 75deg, a squarerigger should not swing it's yards past 75deg either. The squarerigger problem is that, unlike a sloop, she can't headup to take advantage of the 75deg royal yard without ending up back-winding the course. Without the ability to headup, the uppermost yard may end up at a stall angle of attack, contributing nothing but drag to leeward. The royal is filled, and looks nice, but is not helping boat speed, nor making it any easier to make progress to windward.

Spiral bracing, in the real ship manner (uppermost yards more square than the course yard), is a refinement for our models, but not necessary. The wind speed vs height effect is real at model scales, however. This can be seen on model sloop sails. A moderate twist of the leach of a Marconi mainsail, model or real, does not make the top part luff. If there was no wind effect, then the head of the twisted leach sail would be luffing all the time. The twist occurs automatically for a gaff fore&aft sail. Sometimes the twist in the leach is too much, and the gaff sail loses power. But the original America's cup racers used gaff mains, and they moved out very fast. So at real scales, over-twist is not such a problem, apparently. Racers use the boom vang to control the twist of a Marconi sail. Most, wrongly, remove all twist, and thus sacrifice some boat speed. Look into my eyes...you will forget what I just said....:-))
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Old Mar 05, 2013, 12:27 AM
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What a lively, informative, educational discussion. I did not dare hope that my modest effort would enspire such dialog. I am truly honored. You are beyond great.

Now, that the flattery is over I need some advise. As I work out the details of control deck, masts, braces, etc. time grows closer to permanently attach the deck to the hull. But there is one detail that I have not finalized yet. I need to attach the shrowds and backstays to the deck.. It is easy to figure out on an XVIII or XIX century boat. Chainplates, deadeyes, and you are good to go. I know they are a pain to make, but at least you know what you are making. But what do I do? If I use close to a hundred miniature turnbuckles, my model boat will cost as much as a full scale one. Plus I need to figure out a way to attach all this to a deck. Any suggestions? Please, please...
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Old Mar 05, 2013, 08:52 AM
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Do you have a pic or sketch of the prototype shroud/deck setup?
How close to prototype do you want it to appear?

A non-prototype approach is attached. Shrouds, length adjusted, are attached to a bar. The bar is tensioned by adjusting screws.

Another approach - use bicycle spoke nipples. Attach threaded rod to end of shroud and use nipple to adjust tension. Google bike nipples and you can find nipples up to an inch long for only 15-20 cents each. Black available too.
Shroud frame can be slotted for easy insertion of shrouds.
(Example: http://www.ebay.com/itm/7075-aluminu...-/200849409190 )

Just some thoughts....
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Old Mar 05, 2013, 01:02 PM
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I try to be a scale-sailing modeler, and am not a scale-appearing modeler. I try to duplicate the real maneuvers as well as I can with a model. I love the scale-appearing models, but don't have the skills or patience to make them. DanL is the man to help with scale details, to be sure.

Having said that, a 3 foot bottle screw assembly (threaded rod ends plus the bottle nut itself) would only be about 1/2" long at your scale. Once your ship is at sea, I doubt anyone could tell the difference between a scale bottle screw and a simulated one. Thus, perhaps it would be adequate to simply wrap the lower end of the shroud or backstay with something that simulates the shape of the bottle nut? A wrap of thread around the lower end (a serving), covered in medium or thick CA to smooth out the wrapping, then painted silver or white would probably look fine. Heat shrink tube would also work, but I'd be afraid of hurting the strength of the shroud by getting it too hot. A short length of aluminum tubing, glued in place, would also be an option. Be sure to deburr the ends so they don't cut into the line, of course.
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Old Mar 05, 2013, 05:40 PM
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what great ideas! I did not think of spoke nipples. Maybe I can use the spokes for shrouds. May look right. After all, they are made of steel cables. But seriosly, I liked how Dan's shrods are tensioned with bungee and deadeyes. I cannot do it on Kruzenshtern, but maybe I can bungee-load the shrouds at the mast end. I am thinking of running thre shrouds to a screw eye at the mast, but not attaching them there. I can collect all the shrouds together, use the screw eye as a sort of a turn block, attach a strong bangee to the collected shrouds, and run the bungee down the mast and attach it near deck.
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Old Mar 06, 2013, 01:38 PM
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I was looking at my rudder setup just now. It should work OK, but I am not happy about having two tiny openings that I would have to use for any adjustments or repairs. I should have thought of the servo placement that is used on SC&H brigs, where the servo is connected directly to the rudder shaft. I'll try to re-design my setup this way. The problem is the connector. I would need to manufacture a precise metal part that would fit onto a servo on one side, and to a rudder post on the other. I have not lathe, no mill, not even a drill press. Nah, will probably leave it as is.
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Old Mar 06, 2013, 08:18 PM
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Rudder setup

Here are some ideas....

On the gear drive, you may have to flip the servo (have it upside down vs what the pic shows.

Tons of linkage hardware available from www.servocity.com

Gears http://www.servocity.com/html/servo_mount_gears.html
http://www.servocity.com/html/32p_hitec_metal_gear.html
http://www.servocity.com/html/48p_hi...tal_gears.html

Couplers http://www.servocity.com/html/set_sc..._couplers.html

Servo to shaft couplers (probably what you want)
http://www.servocity.com/html/servo_..._couplers.html
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Old Mar 06, 2013, 11:40 PM
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los angeles
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Dan, this is exactly what I need! Pricy, but perfect. I'll be ordering one. I will also be redesigning the hatch so it can cover the servo. Or, maybe, I will look for a low profile servo they use in airplane wings.
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Old Mar 07, 2013, 01:57 PM
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4 masted barque Sea Cloud photo, base of shrouds showing bottle screw. They painted theirs black.
http://www.seacloud.com/en/die-schif...new-glory.html
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Old Mar 07, 2013, 02:13 PM
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Kruzenshtern chainplates, or what passes for them
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Old Mar 07, 2013, 05:53 PM
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There was a thread over on the Sailing forum discussing standing rigging failures due to improper crimping of the loop in their wire rigging. To think, they could have employed 4 seizings, per your photos, and not had failure *smiles*.

Seizing were used not only because they worked, but also for safety. It is difficult to chop through wire rigging if necessary (say in a knockdown, when the masts must be sacrificed to right the hull). A fiber seizing could be cut with knife or axe. Even a wire seizing would be easier to cut (with cold chisel) than the shroud itself.

A survivor of the Pamir knockdown & sinking (1957) remembered seeing the bosun trying to cut the shrouds with an axe. The ship sank before he could accomplish his mission. I presume he was working on the seizings; cutting a wire shroud under tension would be a good way to lose your head :-/ The Pamir is an example of failure of leadership. The captain refused to give orders to save the ship, and retreated to his cabin. The cadets (Pamir was crewed with 52 cadets, plus 34 professional seamen) had no orders to launch lifeboats or anything else, apparently (no officers survived). There were only 6 survivors; the German inquiry was a whitewash, by modern standards, sigh.

http://en.wikipedia.org/wiki/Pamir_%28ship%29
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Old Mar 13, 2013, 11:54 PM
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I have been working on my brace geometry. I tried the scaled approach, and Dan was right. The winch does pull too hard down on the yard. Besides, there might be problems with interference from other sails. So far, I am working on Foremast. The main sails might be in the way if I run the braces in scale manner. I switched back to running them to the mast, and the problems went away. Experience is everything.
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