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Old Sep 16, 2007, 03:21 PM
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Bozeman, Montana, United States
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A 4-masted barque pond sailer

The Pamir-Tramp

When I built the Fire Tramp, I was struck by the similarities between it's 3-island hull and the hulls of the great grain racers of the 1930's. I remembered seeing a beautiful model of a 3-island barque in the San Francisco Maritime Museum. These 4-masted barques plied the Chilean nitrate trade and the Australian grain trade. I used the 3 foot hull of the Fire Tramp, and the rigging of the "Pamir". The scale is about 1:100, slightly smaller than HO. The "Pamir" was built in 1905, foundered 1957.

The model is not detailed on deck, so I consider it a pond sailer. I used the ideas of Boyle in rigging the ship. When free sailing on a beat, it is possible to just let the braces hang loose. Boyle's design of the backstays keeps the yards from swinging more than 60 degrees. There are no shrouds to impede the movement of the yards. The yard arms of main and mizzen are connected so that they swing in syncronity, making it easy to change from a starboard to port tack.

An interesting phenomenon I noted: When tacking a real square-rigger, the main and mizzen braces are brought around to the new tack before the fore braces. When tacking my model, with it's free swinging yards, I noticed that if I braced the main-mizzen per real practice, the fore yards would often swing around on their own, assuming the correct position after a short delay. I am guessing that the airflow off the braced main-mizzen set must swirl in the right way to automatically brace the fore yards.

I've only taken her to the pond twice, so am still learning to sail her. Right now, I'd guess I can make about a point to windward (which was typical of some of the larger square-riggers). Only the foremast has both lower and upper sets of backstays; the lack of upper backstays for the main and mizzen means that the upper yards are not constrained, and the royal and topgallant yards for these 2 masts swing more than 60degrees. This excess swing makes the thrust of these upper sails run more or less perpendicular to the ship's course, hurting performance to windward. Boyle recommends 3 sets of backstays. The foremast's upper yards do set correctly with just 2 sets, so I'll add the 2nd backstay to the main and mizzen.

The model uses a fin keel with about a kilo of lead shot ballast. The keel is slotted where it attaches to the aluminum angle keelson; the slots let me adjust the fore and aft position of the fin. With my brigantine, this method of attachment allows me to move the CLR to where it will assist the ship in maintaining a course: forward for a beat, aft for a reach or run. I like this method of setting a course for a free-sailer. No rudder is installed or needed. I have not yet experimented with moving the keel of the barque, since I am trying to learn to sail to windward. Eventually I will RC the braces, and see if I can tack w/o a rudder.

It took about 2 weeks to make the spars and rigging. There is a lot of footage of dowels in a 4-masted barque :-).

Pamir site with a video:
http://www.dsm.de/Windjammer/html/die_pamir.html
Fire tramp:
http://www.rcgroups.com/forums/showt...13#post7990441
Boyle's 1930's square-rigging tips:
http://www.swcp.com/usvmyg/squarerig/sq1.htm
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Old Sep 16, 2007, 04:01 PM
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Movie of the auto-tacking phenomenon. The ship is caught aback in light airs. It starts to sail backwards (hah, try that, you sloops and schooners). The stern goes into the wind. The main and mizzen yards swing to the correct position, followed by the fore yards. The ship then resumes course. Who needs RC? :-)

zipped movie, .mov format, 2.5meg...for once my camera's lack of sound capability is not a problem...Long Live Silent Sailing Movies!

http://1stclass.mylargescale.com/Bro...2autobrace.zip
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Old Sep 16, 2007, 07:02 PM
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Wonderful. I'm so glad our site was a help.

Cheers,

Earl
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Old Sep 16, 2007, 08:30 PM
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Yes, thank you Earl for posting that great article by Boyle.

The ship actually looked very pretty at sea with more wind. When I arrived at the pond this morning, the wind was just right: nice heel, good speed, steady course with all squares set. Oos and Ahhs from adults and kids on the beach :-). I spent the next hour following the ship in my kayak, learning to sail her. By the time I got ready to take some photos, the wind had practically died, naturally. The best shots are known only to me and Davy Jones :-).
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Old Sep 16, 2007, 09:53 PM
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Brooks -
I'm more of a scale model builder than a sailor, and just from your terminology, etc, I know I have alot to learn. Your 4-master is awesome, and the fact that she sails herself really amazes me. I'm still trying to get the hang of RC sailing the brig.
Bottom line, I need to learn a lot more about sailing!
Suggestion on sail material - Supplex (DuPont) that SC&H supplies, is a great material. Some stiffness, wind proof, strong, easy to work with.
Have fun,
Dan
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Old Sep 16, 2007, 10:34 PM
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DanL, Your brig is Awesome. Thanks for the sailcloth suggestion. The barque sails itself primarily because the rigging is not scale, but rather is adapted to the needs of a free sailer. Boyle is quite opinionated on the subject *grin*.

I think the neatest book on sailing square riggers is Harland's "Seamanship in the Age of Sail." I've mentioned it before in other threads, but thought I'd repeat since it's the bible, as far as I am concerned :-). I see that Amazon has it at little over half price, $45.

The standing rigging is made using 20# Spectra, one of those non-stretch fishlines. I'd like to get it in something other than moss green, but once the ship's at sea, the color is immaterial. Most everything on the ship is supposed to be practical and inexpensive, eg. the button bowsies, the aluminum angle fiferails, etc. This philosophy detracts from the scale end of the hobby, of course. I would love to have the ability (and Patience) to make the scale details you have put into your Brig.
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Old Sep 17, 2007, 10:35 AM
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Very nice Brooks...is she the first in a long line?

Next thing you know you will have ships of the line in battle formation shooting at each other...what fun that would be...eh!

Capt. Slick
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Old Sep 17, 2007, 04:46 PM
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Quote:
Originally Posted by Brooks
The standing rigging is made using 20# Spectra, one of those non-stretch fishlines. I'd like to get it in something other than moss green, but once the ship's at sea, the color is immaterial.

Try "Hang-em-High" kite shop - they use Specra for kite line and you can get a variety of weights up and over 100# strength. Maybe try a kite shop if there is one near you - at least you can "fondle" the stuff before you buy.

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Old Sep 18, 2007, 04:53 AM
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DickL, thanks for the Spectra site. I'll be ordering some line in natural and white. I have some Ritt fabric dye, and will experiment with changing the line's color.

The barque has RC square sails now. If the rain lets up this week, I'll give it a try.

Re self tacking: I seem to remember Dana saying something in his book along the lines of 'if you time it right, the yards practically swing themselves' (on a real ship). The scant crews carried by merchantmen lead the sailors to learn and use all sorts of tricks to reduce their workload. On the Rose, I remember one of the professional crewman urging us neophytes to time our hauls to the roll of the ship. It was neat how you could reduce the force we needed to apply if you caught the roll just right.
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Old Sep 18, 2007, 09:45 PM
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RC steering by differential sail bracing

RC square sails, first cruise : Not enough wind, the perpetual complaint ... and an hour before I could head to the pond, I was thinking "I wonder if I should strike the royals and t'gallants?" :-). The goal was to use the sails to steer the ship. A sharply braced Foremast (relative to the Main-Mizzen pair) causes the bow to fall off the wind. And vice versa.

There was enough wind to let me wear ship (turn 180 degrees by turning downwind). But not enough wind to tack...or maybe the neophyte skipper was lacking in skill? *grin* As the Brig Skippers have reported, if you are too far away to see the set of the yards clearly, it's hard to adjust the braces to meet the conditions. When I was close enough, I could tell that steering via sail control is a much more subtle process than steering via rudder. One has to sail the ship around to the new course, using the braces to adjust the appropriate yards to a "sails just shivering" position. This requires repeated minute adjustments of the joysticks as you change course.

The RC setup: For the RC braces I used the Parallelogram Method. The brace is attached to the yard and to the servo arm at the same distance from the center line of the ship. When the yard is braced square, the yard, braces, and servo arm form a rectangle. When the servo is rotated, the yard rotates the same amount, the whole forming a parallelogram. The advantage of this system of bracing is it's simplicity. The disadvantage is that it not at all scale since the braces lead to an interior position on the yard (1" from the mast for my barque); in real ships, the braces lead way out to the yard arms. Another disadvantage is that the yards move very quickly, both looking dorky and also risking damage to the rigging; slowly moving the joysticks is a solution. Blue Point Engineering makes a device to slow servo rotation, but I have not tried it.

To get the desirable 60deg rotation of the yard, it is simplest if your servo also rotates 60deg to each side (120 deg total). There are 4 ways I know to get this rotation out of the normal, 45deg/side servos:
a) add resistors to the pot in the servo.
b) install a "servo stretcher" from Blue Point Engineering between the servo and the Rx.
c) Use the "travel adjust" function of your radio to increase rotation. My Hitec HS-81MG Metal Gear Micro Servo/Spektrum combination required +/-150%; (the Spektrum adjusts each side separately, thus the + and - designations). The BPE servo stretcher roughly doubles servo travel; you end up getting about 90deg/side, so you have to use the travel adjust feature to reduce servo rotation for this setup (for me, that worked out to about +/-50%).
d) change the pots in your Tx (sort of tricky, I've only done it once).

To get the maximum fidelity of yard rotation to the servo rotation, several criteria must be incorporated in your design:

1. As the servo rotates from square, the braces move inward. If they are not allowed to move inward, you lose some of the parallel motion; the yard does not swing as much as the servo arm. To allow this inward movement at the yard, I made a "traveler" on the mast. This is simply a brass rod suspended between screw eyes that are stuck to a plywood spreader. Wheel collars keep the traveler rod in place. The traveler allows the braces to seek their own position as the servo rotates.

The same inward motion occurs at the servo, but fixed screw eye fairleads seem to work ok here. Perhaps this is because the traveler is close to the yard (2"), but the screw eyes are not as close to the servo (3")? I could not detect a loss of motion even when using only 1 screweye. There is probably a loss of motion, but it was apparently not big enough to worry about. A traveler would be appropriate here, though.

2. The brace must lead horizontally to the yard (and to the servo) if you are to get maximum brace movement. The traveler at the mast, and a pair of screw eye fairleads at the servo, fulfill this criteria for the barque. If the brace is allowed to run at an angle up from the deck directly to the yard, you lose brace motion as the servo turns. If the brace runs at an angle, the brace travels the hypotenuse of the triangle, using up some of it's motion. At a 45deg lead, you'd only get 70% of the servo motion to swing the yard, for example. You can easily demonstrate this effect to yourself: hold the brace vertically above the servo; you will see hardly any movement of the brace as the servo turns. As you lower the brace, you get more and more motion, until it maxes out when the brace leads horizontally from the servo. The same geometry applies at the yard.

Interestingly, it does not matter how the brace leads between the 2 horizontal sections. If the string moves an inch at the servo, it has to move an inch at the bitter end. The only reason for the horizontal criteria is to ensure that that inch does an inch's worth of useful work for us, namely moving the yard in a horizontal plane.

3. Fairlead position at the servo is important. The fairlead(s) must be located in line with the servo arm at it's max travel position. This can be either max clockwise or max counterclockwise, whichever places the pair of fairleads most conveniently on your deck. For the barque, the forebrace fairleads fit best forward of the servo, while the fairleads fit best aft of the mainbrace servo. The fairlead can be located closer to the centerline of the hull than the extended arm position, but not farther out from the centerline. Otherwise, you will get reversal of brace travel as the servo turns; it pays out line until the arm passes the fairlead, then it takes in line. A fairlead lined up with the arm when braced square would allow the servo to do nothing but take in line, oops. :-)

4. I found it best to make a scale drawing of the yard/brace/servo geometry of my particular ship to help me visualize where to place the fairleads. For one thing, the fairleads must not put the braces in a position where they would foul the yards of another mast. This is why I used the "hourglass configuration" for my servo fairleads, rather than using a traveler. This fouling potential is unique to each vessel, so even with paper planning, it is still wise to check the actual model before drilling holes :-).

Blue Point Engineering:
http://www.bpesolutions.com/rcequip.html
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Old Sep 18, 2007, 10:26 PM
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Thanks for the clear diagrams and pictures. I want to install a square sail on a schooner and I will probably make good use of your research. However, in my case, the square sail braces mustn't hamper the free move of my mizzen gaff sail.
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Old Sep 18, 2007, 10:48 PM
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Your braces could run up the foremast, then aft to the spreader, then forward to the yard (for a yard hung from the foremast). Provided the 2 horizontal criteria are met, any geometry (as far as I know) is acceptable between the servo and the spreader. The more angles the line has to negotiate between servo and yard, the more friction, of course.
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Old Sep 19, 2007, 06:07 AM
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Fore and Aft sails run from Square sail servo

If your servo is powerful enough, you can run your fore and aft sail sheets off the same servo as you run your square sail braces. As the servo arm rotates to brace your yard for a beat, it will also take in the F&A sheet, flattening these sails for a beat also. The F&A sheet will be taken in no matter which way the servo rotates (per the "oops" comment above).

The amount of sheet travel will be, for a 60deg rotation, about 1.0x the distance from servo center screw to the point on the servo arm where the sheet attaches. You could double this pull via the usual block&tackle method, yielding a pull of 2x the distance, if the servo will take the added stress. The sheet could run direct to your centerline fairlead; I've run it along the gunwale in the drawing to keep it clear of deck protrusions.

The braces are always tight enough that you don't need to worry much about them fouling anything. The F&A sails and sheets are floppy, though. It might be wise to install a rubberband along the run of their sheet (tugging to pull the sheet tight from servo to rubberband) to make sure any slack is only allowed where it can do no harm. I'd put one along the horizontal run of the sheet, out near the turning fairlead, for instance.
-------------
Followup: While installing my latest wizz-bang notion, controlling the spanker sheet with the main brace servo, I discovered I should have read my own writing :-). You need to position the first fairlead off the tip of the servo arm *as close to the arm as possible* to get the full benefit of the 1x movement. The farther the fairlead is from the tip of the servo arm, the less movement you get in the sheet. It's the old hypotenuse problem again. Also, the use of the block and tackle to double the sheet movement did not deliver the full 2x, probably due to positioning errors and line stretch. With only 1" of servo arm distance to work with on my setup, the tolerance for placement of the first fairlead and b&t items was tight. The rubberband did work, though :-)
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Old Sep 20, 2007, 12:55 AM
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Good and bad at the pond today -

Good: breezy with intermittent rain and overcast, perfect square rigger weather :-) The 2gal ziplock bag to protect the Tx was off and on a bunch; it's much easier to apply tiny joystick movements w/o the bag's interference. I removed the springs on the joystick axes that control the sails; to keep the sticks from flopping about, I stuffed a U of silicon tubing under the gimble.
http://www.mylargescale.com/forum/to...chTerms=gimble

The barque definitely goes to windward, but only about a point. I could sail back, eventually, to the launching beach. Yay!

The Vacutug can tow the ship, though not directly upwind (well, it's very slow). But the tug can easily tow her on a beat, zig-zagging the 2 ships back upwind to the beach. Lots of fun to try to keep ahead of the barque to keep the towline snug. Running 2 ships from one Tx is a hoot - talk about "dumb thumbs" LOL. I could also use the tug to assist tacking turns by pushing against the windward stern near the jigger mast. With the overhanging yards, I did not wish to risk breakages by pushing anywhere else.

Bad: No sail-only-powered tacks or even wearing today. The sheets had loosened a bit. This let the yards twist more than last cruise. Attempting to shiver the sails to turn ended up with spiraling yards, with lower yards aback and upper yards still drawing. Rather than using differential bracing to turn, like before, the attempts today failed, just resulting in heaving to. I could detect no difference in steering with the new RC spanker sheet. Still experimenting with that setup.

I could still reverse course by boxhauling. According to Harland, that's a perfectly legitimate maneuver. Another one to try next time is "tacking with a stern board"- here the ship stalls head to wind and then gathers sternway. Leave the foremast sails on the last tack, haul the aftersails to the new tack, and reverse the rudder. The ship should back and turn just like a 3-pt turn with your car. This method supposedly loses less ground to windward than a wearing maneuver because you gained some ground to windward during the initial turn. Since I don't have a rudder, I don't know if this will work for the barque, though.

Upshot - learning to sail an RC square rigger is not the same as reading the book. You Brig and Topsail Schooner Captains have my respect!
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Last edited by Brooks; Sep 20, 2007 at 01:14 AM.
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Old Sep 20, 2007, 02:26 AM
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Don't you think a rudder would be a legitimate accessory ? You can steer a dinghy without rudder but :
-it's much more difficult
-you need to move your body around in the boat to change the position of its gravity center
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