The CRonicle

The legendary Chuck Winder published the first issue of the CR 914 newsletter, then called the CR 914 NEWS, one month after he became the class secretary, in November 1996. The first issue of that desk-top publication included in its 12 pages a report about the 1996 Nationals that had been held in September, minutes of the class meeting held at the Nationals, a discussion about sail cloth, a directory of all 96 members of the class at that time, and the first of what would become a vast and invaluable collection of pithy analyses of the mechanical and electronic components of the CR 914, drawing upon Chuck's long career as a mechanical design engineer in the aircraft engine division of General Electric.

THE CRonicle TODAY
The CR 914 fleet has moved to use digital communications to distribute its news. The spirit of the eCRonicle is the same as that of the original newsletters. -- share information between those interested in the CR 914. All back issues of the CRonicle are available for searching. New articles are part of the web site and can be access by anyone with access to the website. We look forward to receiving interesting formal comment for inclusion on the site or less formal interchange through the CR 914 class forum, also part of the website. 


SAMPLE ARTICLES



Converting to Rechargeable Batteries
by Chuck Winder

THE STOCK CR 914 is set up to use AA alkaline batteries that are disposed of after use. For the owner who sails his boat on a regular basis, rechargeable batteries are preferred.
Batteries

Rechargeable NiMH (Nickel Metal Hydride) cells are the best choice. The Tx (transmitter) and the boat battery box are designed for AA size cells. The Tx accepts eight cells. The class rules limit boat batteries to four or five cells. Using five cells increases the voltage from 4.8 (1.2 x 4) to 6.0 volts and sail servo strength by 20%.

Buy batteries at Wal-Mart or similar stores. An 8-pack of 2500 mAh batteries costs about $18. When fully charged, they will last more than eight hours at the pond.

Battery packs
Battery packs with cells soldered together and packaged with heat shrink is the most reliable arrangement for the boat. The stock Tx is not designed to use battery packs; individual AA cells simply snap into place. (More expensive radios are delivered with battery packs for the Tx though they are usually of insufficient capacity for use with boats.)

To power the electronics in the boat, 4- or 5-cell ready-made battery packs with connectors are available commercially, at RC hobby stores and via the Internet. One source is Radical RC (937-256-7727, www.RadicalRC.com). They also supply 8-cell packs if your Tx uses that type of battery and you want upgrade to a longer-lasting one.

A rechargeable battery upgrade package – Here is a list of what you will need when you decide to climb on the NiMH bandwagon.

Transmitter batteries – Eight NiMH AA cells; you’ll spend about $18 at a Wal-Mart or equivalent store.

Boat battery pack – Choose a 5-cell or 4-cell version. If you order from Radical RC, here are the stock numbers. 5-cell boat pack – SKU Number RRC05H2500F; $22 with connector; Sanyo 2500 mAh 5-AA Cell 6V Flat NiMH Battery Pack. 4-cell boat pack – SKU Number: RRC04H2500F; $18 with connector; Sanyo 2500 mAh 4-AA Cell 4.8V Flat NiMH Battery Pack.
Battery charger – A simple wall charger like the Radical RC SKU Number CMCH84 costs only $14 and takes care of the Tx and boat batteries. It has a three-way plug for Futaba, Hitec/Airtronics or Spektrum/JR transmitters. It comes with a Futaba J connector for boat batteries, but Radical RC will add any connector you need. It charges the Tx at 90 mA per hour, and the boat batteries at 150 mA (four cells) or 125 mA (five cells).
hoConnectors – Make sure you order the correct connector for the boat battery pack and the charger. The stock CR 914 boat battery box has a red "BEC" connector. A universal "Futaba J" connector is more commonly found on chargers and boat battery packs.




Radio Problems
Diagnosis and trouble shooting

BECAUSE MOST OF THE SUBSCRIBERS to the NEWS have already built their boats, the first few subjects I will be covering in this column will involve maintenance and tuning. One of the problems we have in the 914 is the simple fact that water and electronics don’t mix well. Combining them can lead to a number of problems, the symptoms of which range from glitching or twitching to complete failure of the servos and/or receiver (Rx).

Substitution Strategy

Trouble shooting involves isolating the component that is causing a problem. You will need to borrow the radio system of another 914 that is problem-free. Because we know that this second system works properly, when we substitute one of its components for one in the malfunctioning system and find that cures the problem, we know that we have identified the culprit. And when a substitution doesn’t result in a cure we know we need to keep looking for another malfunctioning component.
Twitching servo

The following steps will identify the cause of twitching, and may produce a cure.

Step 1. Batteries and Connectors – The first thing to do is to try new or freshly charged batteries. When that doesn’t help, check to make sure all of the servo plugs, battery and Rx connectors are as clean as possible. Clean the leads and connectors with an electronic contact cleaner you can get at Radio Shack or Boats US. Sometimes that’s all it takes.

Step 2. Detecting a malfunctioning Tx – The next step in trouble shooting is to determine whether the fault lies in the boat electronics or the transmitter (Tx). First, remove the crystal from the Tx of your problem system and insert it into the borrowed Tx. If the problem goes away, then your old Tx is the cause of the twitching and you can jump to step 5 below.

Step 3. Detecting and treating a bad servo – If the twitching involves only one servo (e.g., #1), first remove the offending servo wire plug from socket #1 of the Rx and plug it into the other servo slot (#2). If the twitching is still apparent, the most likely cause is that the potentiometer (pot) in servo #1 has become dirty and needs to be cleaned, or the servo needs to be replaced. You will find a step-by-step procedure for cleaning the pot on my web site at http://www.rcyachts.com/Build/servorepair.htm.

Step 4. Detecting and treating a bad Rx – After switching the servo jacks, if problem servo #1 no longer twitches, insert servo #2 into slot #1 and see if you now have a problem with this, formerly OK, servo. If the problem has now moved to servo #2, the twitching is probably caused by the Rx, since you have already exonerated the Tx in Step 2. You can confirm this diagnosis by plugging the receiver crystal from your problem boat into the Rx from the borrowed, normally functioning, boat and installing this new Rx in your boat. If that cures your problem then you need to take a look at your old Rx. On the edge of the case you will see a length of tape. Removing it will let you open the case and check for corrosion. A good cleaning with an electronic corrosion cleaner has resurrected a number of receivers that were otherwise unusable. If after a good cleaning the problem persists, it is time for a new Rx.

Step 5. Fixing the Tx – Tx joysticks use the same kind of pots as the servos, and with use they, too, can get dirty. To clean a Tx it is necessary to open the Tx case to get at the pots. Because this is a more involved process than we have room for here, you can contact me and I can walk you through the cleaning process.




Sailing an RC boat with "FEEL"
by Geoff Becker


SAILING A CR-914 IS NOT AS EASY as some full-scale and less experienced RC sailors think. "How hard can it be to sail a toy boat around?" When you consider that a major part of sailing, and sailboat racing is "feel," it becomes more apparent why sailing model boats has its difficulties. When a real sailboat slows down you can feel the deceleration, and when that happens adjustments can be made to get the boat back up to speed. What happens when a model boat slows down, or how can you even tell when the boat slows down?

But experienced model sailors will tell you that they can "feel" their boat while it is sailing. To be honest, if I swap boats with a friend sailing that day, I can actually "feel" the difference between my boat and my friend’s. How can that be? My best answer is something I call "sight feel." Sight feel is simply looking at the boat and translating what you see into feel, by comparing what you see to your other experiences sailing the boat. I can tell right away if the boat is, or isn’t, sailing through the water properly for the conditions.

By using comparisons in my "sight feel" I can at the same time see what might be wrong with the setup of the rig, the trim of the sails or balance of the boat. Basically if it looks wrong, as compared to what I feel is right, I can identify the problem quickly and make the necessary adjustments to get back up to speed.

New sailors, and those who don’t practice, are most definitely at a disadvantage. Practicing for me is strictly to develop and improve my "sight feel." Two very important factors about developing your "sight feel" are:

1. The more you work at it the better you get at it, and
2. Since it is model sailing, you can actually use your "sight feel" when watching your competitors, making comparisons much easier and more accurate.
What to look for

Here is a list of some of the elements you should look for when developing your "sight feel":

· Boat Setup – Does your boat’s mast look like it is in the right position? Is the jib boom the right height off the deck? Mainsheet bridle the right height? Outhauls set properly?

· Jib Trim – When sailing upwind is the jib boom pointed at the shrouds? Lower or upper? How is the twist of the jib leech?

· Main Trim – When sailing upwind is the main boom close to center? How is the twist of the main leech?

· Balance – Does the boat sail in a straight line or do you have to compensate with the rudder control?

· Tracking – How is the boat sailing through the water in general? Bow down or bow up? Is the internal weight placement right?

· Change – MOST IMPORTANT! Know what each control changes in the image and performance of your boat. Outhauls, boom vang, sheet settings, backstay, fore and aft position of your jib boom downhaul, etc., etc.
How to practice

If you are alone when you practice it is more difficult to get boat-to-boat speed comparisons to add to your "sight feel." When alone, sail the boat and develop a mental picture as to how the boat sails through the water, upwind, downwind, reaching, big breeze, and light air. It really doesn’t matter much if that picture is right or wrong, just that you have one to use as a comparison later. Once you have developed this picture in your head you have the beginnings of "sight feel" and the next time you sail with another boat you will quickly be able to compare what you see.

If you are able to sail with other boats when you practice, make sure you focus only on your boat at first, until you are comfortable with your own "sight feel." Then sail near other boats and see how your boat does. Compare what you know about your boat to what you see on the other boats and compare any differences. I think it is OK to ask other skippers questions about setup, but using your eyes to see what differences there are on the water is the best way to quickly get your boat up to the speed of faster boats.

Practicing depth perception is also a large part of model boat sailing. Watch your boat go around marks and behind other boats to get a better "sight feel" for how close you are. Looking at mark roundings and crossing situations from different perspectives can also be helpful. Just change your location on the dock or pier to get those perspectives and help you improve your "sight feel."

Remember, the better you know your boat the easier it will be for you to fix something that is wrong. Have fun sailing!




SEVERAL YEARS AGO, THE EDITOR was sitting in the shade drinking beer at a post-regatta party, when the disk jockey began to play a Jimmy Buffet ballad entitled “Barometer Soup,” from which the title of this column derives and the lyrics of which capture perfectly that laid-back feeling you get after a hard day of racing.

So what’s that got to with building, tuning, tinkering with, sailing and racing your CR 914? Just this: there is a lot more to savor about our wonderful sport. And that’s what I want people to think about here, and then begin to contribute stories, ideas, humorous anecdotes, and anything else that will enhance the enjoyment of sailing and sailboat racing.

Since our recipe for hot mulled wine in the last installment failed to stimulate anyone to submit ideas for this issue, here’s another one from the Martins’ sailing cookbook.
Portable Soup

Mulled wine is great after you finish racing on a cold day. Here’s an idea for a satisfying pre-race noon meal before venturing forth to race on a brisk afternoon.

A staple of the Lewis and Clark expedition was “Portable Soup,” a dried concoction of various beans and vegetables that Lewis was enthusiastic about (although it appears that his men would eat it only as a last resort). “Portable Soup,” he wrote to a provisioner for the expedition, “in my opinion, forms one of the most essential articles in the preperation [sic], and fearing that it cannot be procured readily in such quantities as is requisite, I...take the liberty to request that you will procure two hundred pounds of it for me... I have supposed that the soup would cost about one dollar pr lb; should it however, come much higher then quantity must be limited by the sum of $250 as more cannot be expended.” In the end, Lewis spent $289.50 on 193 pounds of the stuff, by far the largest sum for any area of provisions, and even more than he had originally planned to spend for guns and ammunition.

Last year Carole and I found Portable Soup for sale at the Camp River Dubois Visitors Center in Wood River, Illinois. Having read about it in Stephen Ambrose’s book, Undaunted Courage (and expecting the worst, based on Ambrose’s description of the stuff that they ate on the Voyage of Discovery) our curiosity made us buy a bag of the dried mix and try it.

Either the Voyagers’ palates were very finicky or, more likely, the mix that has been created by “Lewis and Clark Provisioners, Purveyors of Fine Foodstuff” is much better than what Lewis bought for his men 200 years ago. Today’s Portable Soup, when mixed with water, simmered for 8-10 minutes, and served with about four drops of Tabasco sauce per bowl, turns into the most delicious and satisfying corn chowder I have ever tasted.

You can obtain Portable Soup mix much easier than Merriwether Lewis could. It is sold by the Chalet Market in Belgrade, Montana. It costs a little more than Capt'n Lewis paid, however: $6.99 for a 6.1oz bag that makes about a quart of soup. But it’s worth it. Prepared with just the right amount of Tabasco, it’ll keep you warm for a full afternoon of frostbite racing, right up until you are ready to top off the afternoon with Carole’s Frostbite Fuel at the end of the day.

Remember, now, this column isn’t just about sailing food and drink (although other recipes will be welcome); send the editor any ideas that have helped you enjoy the sport of sailboat racing.



TUNNING A CR 914 IS OVER-RATED. Although your boat needs to be properly tuned to be competitive, the mechanics of doing so are simple. Tuning the driver is much more complex, interesting, and fun. That is the focus of this semi-regular column.
Windshift Geometry

If you watched the telecasts of the 2003 America’s Cup, you are familiar with the "ladder rung" method of displaying the relative positions of boats beating to windward, as shown in Figure 1.

Three boats that are even with each other at the bottom of the playing field are sailing at the same speed and tacking angle to windward up the "gridiron." As long as the wind does not shift they will remain on the same ladder rung together—that is, a line drawn perpendicular to the wind direction touching the bow of one boat touches all their bows—and they will all get to the windward mark at the same time. (For clarity, this diagram overlooks the fact that the act of coming about causes a boat to lose some ground, but if all the boats tack the same number of times they will end up on the same rung when they get to the top of the ladder.)

Since ladder rungs by definition are perpendicular to the wind, a wind shift changes their orientation, as shown in Figure 2.

Figure 3 shows the effect of a 15 degree right-hand shift on three boats that had been dead even before the shift, as indicated by the fact that they were on the same (dark gray) ladder rung. Tilt your head 15 degrees to the right to improve your perspective of the new wind and ladder rungs. The shift (lighter gray wind arrow and ladder rungs) lifts each boat equally. But notice its effect on their positions relative to the new ladder rungs and to each other. The right-hand boat has gained on the boats to her left.

Draw yourself a ladder diagram like this one to see what happens when the wind shifts to the left. You’ll find that the left-hand boat gains relative to the boats to her right in exactly the same way, and you will have discovered a fundamental principle of wind shifts: [1] Boats that are closest to the side of the course toward which the wind shifts gain relative to boats that are on the "wrong side" of the shift.

There are two other important conclusions to be drawn from this type of analysis. Make several more drawings, varying the magnitude of the shifts and the distance between the boats. You will discover that: [2] The amount a boat gains or loses as a result of a shift is proportional to the magnitude of the shift, and: [3] The amount a boat gains or loses relative to another boat is proportional to the distance between the two boats.

There are other fascinating insights to be derived from spending an hour with pencil, paper, a straight-edge and a protractor analyzing windshift geometry. Such as, if you are sure that the next shift will be a big header and that it will be the last shift before you reach the windward mark or finish line, you should bear off and foot as fast as you can to gain separation to leeward of the fleet before the shift arrives. Here’s another: Say that you are about to start a race in a wind that can be counted on to shift several times back and forth 15 degrees on either side of the mean wind direction of 360 degrees (due north), but you cannot predict how many times it will shift before the fleet reaches the windward mark. During the last 30 seconds of the count-down to the starting signal the wind direction is 345 degrees. At which end of the line should you start?

You’ll find the surprising answer to that question and the reasoning behind it in a future installment of this column, along with other pearls such as When in Doubt, Let it Out; Understanding Overstanding; Go Right, Young Man, Go Right; Reach for the Gold; Join the Conservative Party; Coast to Victory; A Recipe for Scallops; and more.


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