Newbies help with sheeting and rigging

Footy Class General Discussion (Footy)
1

Hello,

I have made the “d” to build myself a Footy. I have been able to drag a couple of work mates into the foray as well so ill have someone to race with. Im excited to start…but…

I have some questions:

What is the best way to setup the sheeting, from the servo arm to the boom? I understand there a probably a thousand ways to do this but i have been able to get a grasp of how it works. Being a complete noob when it comes to model yachts i guess its a ssumed knowledge. I have foud that if a have good photos or a accurate drawing it will probably solve it for me.

Are there any good guides to sail tuning? Same as before i guess this comes down to experience but i guess i would like to have a heads up as to what to look for to get the most out of the yacht.

Any help would be greatly appreciated.

Dont mean to be rude but remember i am completey new to modl yachts, terminology etc.

Thanks in advance

Ace

2

Hi Ace - Welcome to the fold!

First of all it would be helpful to know where you are from. I am writing from NYC in the US. Advice I can give you reflects my bias and materials sources that are available here.

Sheeting for Footies, however, is almost universally a “swing arm” system. This “arm” is basically an extension of the servo horn that serves to increase the “throw” of the servo’s rotation, for us that translates into sheet line taken up. Many setups are what is called “double sheeted”, as opposed to the mechanically simpler single sheeting. In single sheeting the end of the sheet line is attached directly to the end of the swing arm and the amount of sheet taken in is equal to the linear distance the arm travels. In double sheeting the sheet line passes through a hole in the end of the arm and attaches to a fixed point on the boat more or less in line with the location of the sheet’s entry point. This “doubles” the amount of sheet line taken up in the linear distance the swing arm travels. In single sheeting the swing arm is usually pretty long which puts more strain on the servo. Also, since Footies have limited interior space most folks double sheet.

Choosing r/c gear for use in Footies can run the gamut from left over pieces from other projects (usually first boats) to brand new equipment spec’ed specifically for your new boat. With Footies weight is a priority, so when you read the posts on this and other Footy forums a lot of the discussion is about component weight. All top enthusiasts use micro servos just for this reason. Many micros (like the ones that come with most new r/c sets) will work fine for the rudder. The servo for the winch though has to be a combination of power (not less than 50 ounce/inches (3.9 kg.cm) of torque at 4.8v), light weight (under 30 grams), and lastly, price. Being able to extend the winch servo rotation beyond the 60 degrees that come standard is a plus as well.

Servo rotation for winches is important because the more rotation (up to 180 degrees) the more linear distance the swing arm travels and the more line that can be taken in. This may allow the swing arm to be shorter for the same amount of sheet take up thus reducing strain on the winch. Increasing the winch servo throw can be achieved in several ways; using a programable transmitter like the Spectrum DX6i or comparable, using a winch servo modified for 180 degree rotation like the Hitec-225MG (available from Servo City, 31 grams), or by using a Servo Stretcher (also available at Servo City, a device that links into the connection between receiver and winch servo that allows you to adjust the travel of the servo, 15 grams).

I use the first system and my winch (Bluebird BMS-380MAX, 16 grams) travels 120 degrees +/- with the settings on the winch channel on my DX6i set to maximum throw both all in and all out. The other solutions both add weight in comparison to the one I use but can be more economical and the only simple way to increase the winch servo throw with older transmitters.

I would encourage you to use a simple rigging system to start out with. Read the thread “equilibrium rig down under” for an in depth discussion of what is slangly called a McRig. This is a single sail that can be made quickly and also self regulates in wind gusts. There are not many settings so it is a good way to break the ice for new sailors.

For a first boat I would direct you to the plans section of the Official Footy Website (there is a link to it in the Forums section). Bill Hagerup’s Cobra is a good all around boat. I’ve raced against it so I can say it is quite quick.

Also, the Hop2It thread has the panel shapes for this quite attractive boat, I haven’t had any personal experience with this boat but the photographs of them sailing show all the right things.

Most scratch built Footies are hard chine or paneled construction. The best materials for this type of building, and building light, are 1/32nd Balsa or 1/64th aviation ply. The Balsa can be mail ordered but if possible find some hobby location or art supply place that has model building supplies so that you can pick and choose straight grain and matching panels to start with. The 1/64 (.015") aviation ply is available by mail order but doesn’t come in small quantities. The internet has lots of different venders but the ply you want is made by Midwest and usually is offered in bundles of 6 12" x 48" sheets. It can be expensive but since you are undertaking a group project you guys can split the cost. This amount of ply should yield 8 to 10 boats.

My last recommendation here is to invest in a gram scale. It is important to know how much each part of your boat weighs and to keep track of overall weight as you proceed through construction. Accurate notes will help immensely as your group builds up its fleet. Also, the design trend seems to be moving to lighter boats while trying to maintain the same ballast to overall weight ratio. That puts an emphasis on light building techniques and honing building skills.

I would encourage you to scour this Forum and the vast experience accumulated in the threads and posts. Much of the information that you will need is already covered there, but it may take some digging.

3

Nice job, Niel. Good advice, indeed.

I’ve found that, as you have done, taking advantage of the DX6i programmable end points really helps. I’ve been able, by locating the servo, the fairlead, and the sheeting point on the boom at optimal points, to get enough travel to avoid the need for the double haul…but it’s close.

I haven’t published the plans yet for the Cobra versions you sailed against, so I recommend building Razor3…I think it is so close to Cobra3 that it’s hard to decide the difference, and Herb won our Region 1 regatta with it.

Bill

4

Thanks very much for the information, it will be a great help.

Does anyone have any photos or diagrams of the double sheet method at all? I guess i can understand things a bit more especially not knowing the sailing jargon as of yet.

Many thanks

Ace

5

Here’s a sketch showing typical sheeting arrangement.

Bill

6

That makes a big difference, i can see how things work now.

I have found another picture specific to the Una Rig. Is there a particular way the arm should be orientated when fully sheeted in or out?

Also from the screw eye to the servo arm, i am assuming that all in under the deck. Are my assumptions correct?

Sorry for the frustrating questions

Ace

7

Actually, in your attached drawing, I think the forward location of the adjustment bowsie is an indication that the servos are mounted so that the arms, sheet, and rudder linkage are all above the deck. This has been a trend on some of the recent Footys, especially the narrow hulls. If it were below deck, having the bowsie in the bow would make it hard to reach if you had to adjust it.

Regards,
Bill

8

You are right, i have noticed that some yachts have the servos poking out the top. I also did think it may be difficult to change anything with the bowsie underneath the deck, silly question really.

Ill have to have more of a look around for a decent photo. There is soooo much info around here, its hard to sort through all of it.

Great forum though

Cheers

9

Bill,

You know what would be really helpful would be a set of line drawing showing “single sheet” and “double sheeting” set ups. I learna lot form seeing then reading. Sometimes the eyes work better then the brain. Currently I use a single sheet with my Macrig. I have a DX6i but have not figured out how to program the darn thing - so I 'm using my DX6.

Thanks Big

Ted

10

Boutique en ligne. Tous les hommes Lacoste Polo T Shirts,Ralph Lauren T Shirts sont de qualit?et de la mode. Notre prix tous les prix de gros. Si vous achetez plus de 3 seront Livraison gratuiteLacoste Polo Shirt Lacoste Polo T ShirtRalph Lauren polo Shirt Lacoste Polo T Shirt MenWomen Lacoste Polo Shirts

11

After having a better look around i have found some pictures that may help some other complete “noobs” like me.

The setups are pretty easy to figure out from the pictures, all of them are for a MCRig at this stage. The .pdf drawing posted earlier is probably the best pic for other rigs.

Thanks to those people who own these pics, i hope you dont ming that i have posted them here :smiley:

Hope it helps

Ace

12

Here are some ideas that may help.

13

Well, the layout is nice but the statement about maximum force on the servo at “all in” is bunk. Sails generate the most force on a broad reach not on a beat. Also, while the diagram shows that the sheet’s all the way in position should be in line with sheet’s entry point into the hull this arrangement takes up less line than one that is equally divided on either side of the perpendicular to this vector. Taking up less line means having a longer swing arm to take up the same amount of line as the afore mentioned equally divided setup. More swing arm length translates to more leverage the sheet line exerts on the servo.

The advantage of the layout in the featured diagram is that as the sheet line approaches the “all in” position for upwind work the amount of line take up diminishes thereby providing finer adjustments in sail position for playing wind shifts on the beat. Of course, with programmable transmitters, this same effect can be achieved by tinkering with the exponential feature.

14

One other thought - I have never had trouble pulling the sheet line in from a beam reach to the beating position. But many of us have experienced the winch stalling when trying to round the leeward mark and trim in for the beat.

The layout in the diagram puts the running position perpendicular to the “all in” vector from the sheet entry point to the servo’s pivot. This loads the winch swing arm at the point of maximum line take up to pull the sails in from an all out run. Its sort of like flooring your gas pedal from a standing start. Not something you would want to do every time you accelerate.

In the first paragraph of my previous post I mentioned that a balanced setup, with the swing arm’s rotation equally divided on either side of the vector running from the sheet’s entry position to the servo’s pivot, is more efficient. It also reduces starting torque on the servo in the “all out” position when the sails have the most resistance to being pulled in on a dead run.

15

The point I was trying to make is that, at the all-in position, with the pull of the sheet in line with the servo arm, no force is exerted on the servo which would require the flow of electric power from the battery to maintain this position. Equally, at the all-out position, the servo arm will be at the extreme end of its travel. I do not know specifically if force exerted on the arm in this position would require electrical energy to maintain the position. I do know that normally the arm cannot be turned past this position even with power off. ( I just checked the turn angle of the sailwinch in my Soling, and it will not turn past its end point with power off)
In most “modern” racing, the boat is usually sailed either on an up-wind beat or on a down-wind run. The amount of total time spent on a reach, with the servo arm in the centre of its travel is probably minimal. The electric power consumption in this central position would, of course, be at its maximum to maintain the position. I do not have any numbers to support the argument that the force exerted on the sheet in the all-in position is greater than that at mid way (reaching), but the direction of pull is downward (towards the deck), while in a reach, the pull is more nearly horizontal.
It is also obvious that the pull on the sheet while running is at a minimum because the boat is moving with the wind, thereby reducing its apparent velocity and consequently the pressure it exerts on the sails.
As with most mechanical systems, the proof is in numeric test values, which I don’t have.

16

Hi Rod - The first sentence contradicts the last sentence in your first paragraph. If you pose the proposition that at the extreme “all in” position that there will be no drain on the battery and the servo cannot be turned manually at either extreme then why would the servo at the extreme “all out” drain battery power? I think that you are assuming that having the “all in” position in line with the vector of the sheet entry to winch servo pivot somehow reduces the pressure on the servo. In fact, where you set the swing arm in relation extreme ends of the servo’s travel doesn’t make any difference, the servo requires electricity to hold any position.

You are mistaken about wind pressure on the run as well. Sailing upwind and on close reaches you are sailing at an angle to the wind, using the wind’s speed to create lift and forward motion. As an airfoil the sail deflects the wind it is in, never presenting its full area to it. As wind speed increases the lift and therefore the boat speed increases as well, without adding much extra load on the sheets.

On the run, even though the boat is moving along with the wind, the sails are presenting their full area to the wind. Drag slows the boat down so the wind, moving at a greater clip, is putting more pressure on the sails than the boat can use to generate forward motion. The sails act less like an airfoil and more like a bed sheet. This disparity increases as wind speed does. Thus my recommendation of easing the starting torque when trimming in from a dead run.

If, in the beating position the force you are exerting on the sheet line is downwards then you are trimming in too hard. Footies, particularly ones sporting McRigs, like to be sheeted out about 7 or 8 degrees from center.

Finally, we can agree to disagree. There are as many ways to set up the sheeting system in one’s boat as there are people setting up sheeting systems in their own boats. Swing arm systems date back to the dawn of radio control in sailboats. I know because I was there.

One last thought - Whichever system a person devises the milli-amps that modern batteries rate are well up to the task of controlling Footies in any conditions.

17

As in any discussion where theoretical assumptions are being made about any system, the point arises where theory must be tested by actual measurement. This is, indeed, the very essence of the scientific method.
At the scale of Footy boats, any measurements that one tries to make require rather precise measurements of quite small forces, and small electrical currents. While a good ammeter is routinely available to almost all of us, an accurate apparatus for measuring the force on a Footy main-sheet, or the force exerted upon the hull by the rig, is not so easily obtained. This indeed is precisely the problem that I have run into in trying to make accurate measurements of the drag of a Footy hull in the range of 0-1.4 Knots. There are no weigh scales adapted to this purpose–even digital fish weighing scales for sport fishermen weigh up to 20-40 Kgms, with an accuracy +/- 50 gms. Any attempt to construct an amateur apparatus to do the job runs into the effects of friction. It is not for nothing that aero-and hydro-dynamic measurements of full size aircraft and yachts cost many thousands of dollars.
These measurement undoubtedly need to be made, and this is a challenge for all of us, yet I don’t think any of us has unlimited funds to carry out this kind of work. It is, I suppose, one of the reasons why we race boats–and cars–and planes–and bobsleds…

18

Current draw of servos and sail positions aside, thanks very much for the diagram. Its an easy to follow diagram to follow and gives the complete noob (like myself) a good idea of what is required.
Very soon i will have a footy to try out and test out each theory one by one. No doubt i will be old a grey by the time i have tested them all.

Soed anyone have any tips for fine tuning for better performance? What things should i keep an eye out for?

Thanks again

Ace