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Building and Modifying the Kyosho Fairwind For the entry level skippers, the most appealing aspect of the “kit” boats is that they can be bought off the shelf at most hobby stores, taken home and with a small time investment can be assembled and ready to sail. The following is an extension from assembling the Fairwind to Building a Fairwind. Unfortunately (or fortunately, depending on your degree of building enthusiasm), the kit boat manufactures have had to make compromises dictated by profitable production. The good news is that with a little bit of effort, the Fairwind can easily be rescued from it’s sailing and engineering shortcomings. The Fairwind is designed after a full size J 30 and as any seasoned R/C builder knows, “scale doesn’t sail”. There is no doubt that the Fairwind is pretty neat looking boat. However, compared to the efficient developmental class hull, the Fairwind hull falls a bit short. The good news is that with a little work and some relatively simple modifications that are allowed by the class rules, the Fairwind can become an absolute delight to sail and race. And, not to be ignored, is the self-satisfaction of sailing a boat that you built. My background is with the developmental class boats, Primarily the 36/600 and Marblehead. I was the AMYA 36/600 class secretary for 5 years and over the past eighteen years designed over twenty boats…most proving to be clunkers, a few good ones and a couple really good ones. I’ve built close to two hundred boats including over a dozen Fairwinds. As Walrus Model Yachts, I’m currently producing two of Swede Johnson’s 36/600’s, the Orco 2K and the Millennium (both can be seen on my website: http://www.rc-yachts.com/). Because in the developmental classes there are literally hundreds of skipper/designer/builders doing research and development to unlock the genies that make a boat go as fast as possible, I’ve used many of the building techniques used in the developmental high tech racing platforms (that sounds a bit much, doesn't it?) in modifying the Fairwind. Building articles that get so technical in over complicating simple things are dull and for the most part, counter productive to the average builder. My intent is to explain what works on the Fairwind kit and what doesn’t without getting into what size bolt, type of glue, what knot was used etc.. Part of the fun in building is using your resourcefulness and ingenuity. You, as the builder, should be mindful that I’m showing you how I build the Fairwind… that certainly doesn’t mean that what I do is the only way to do it. In most cases, it’s not. Once you know what it is you want to accomplish, don’t hesitate to experiment or try and idea that you have to get you to that point. The Fairwind is a one-design class where all of the boats are theoretically equal…of course; we know that isn’t the case. There will always be some boats that are faster than others. Getting the optimum performance from a boat is the sum of many minor elements that by themselves have little effect. Obviously, this is magnified in a one-design fleet. The most important factors to consider are: weight, weight distribution, balance and sails. All of which will be explored as we build the boat. Because the Fairwind class rules mercifully allow for modifications of the sails, mast and spars, the most significant over all improvement that can be made on the Fairwind. If you plan on racing your Fairwind, I can tell you flat out that without a carbon fiber mast and spars and paneled sails, your Fairwind just isn’t going to be competitive with the boats that have carbon rigs. That’s not to say that if you build the boat exactly as it comes from the kit that the Fairwind isn’t going to be fun to sail, it will, but sorry to say, it just won’t sail up to it’s potential. If you are only going to make one modification to your Fairwind, I strongly advise that it be investing in a suit of good, paneled sails from an experienced sail maker. The dilemma that has vexed sailboat designers from the very beginning is that sailboats must contend with two very different viscosities, water and air. The trick is to make both of these aspects of the sailboat as efficient as possible. Let’s being with the Fairwind hull. As it comes from the box there is a considerable amount of trimming that has to be done along the seams and the hatch opening…one of those production compromises I mentioned earlier. The smoother the hull the less drag so step one is to make the hull as smooth as possible. Unique to all Fairwind hulls is the seam turning to a “trench” at the bottom of the keel and behind the rudder that should be filled. I never recommend painting a hull because of the added weight (painting the hull adds at least one to two ounces to the overall weight). In most boats, this is not desirable however with a minimum weight of eight pounds, (The finished, in the water weight should be no more than the minimum eight pounds) it's possible to cure more ills by painting the Fairwind hull than adding a couple of ounces of weight (everything in a sailboat is a compromise). It’s tough to completely trim the deck seam and I’ve yet to come up with a good solution. The deck is part of the boat’s aesthetics and deserves to be as smart as possible so if you have the energy, have at it. For many reasons, I no longer paint boats, which meant that I had to polish the hull on this boat. I started with 600 wet sandpaper, went to 0000 steel wool, a plastic scratch remover and finally, a plastic fine scratch remover. One tip if you are polishing the hull… when you think that the finish is perfect polishes it once more. Because I plan on handling the hull I’m not going to put in the lead ballast until much further in the construction. The wood braces that go on either side of the hatch are a must if you want the hatch to fit properly. Make sure that any place on the plastic hull that epoxy is applied is well sanded. The cross brace in the middle of the hatch opening that also is a exit guide for the mainsheet isn’t necessary. The less turns in the sheet the more freely it is going to travel. If there is any possibility of hull flexes, the hatch, when in place, will prevent it. Because there is good chance water is going to get into the hull, it’s a good idea to seal any wood with polyurethane or spar varnish to protect it. The designer had the right idea that with the below deck brace under the mast because without it, the deck would compress under the mast. The bad part is that there is considerable flexing of the hull/deck between the mast and the shrouds. This directly effects the integrity of the hull shape and should be reinforced. I’ve made a template of the underside of the deck at the mast mount and have made a brace out of 1/8th inch plywood that extends across the underside of the deck to the shroud attachment points to the bottom of the hull. This forms a triangular truss that will keep the hull from twisting from the torque on the mast and shrouds. This, however, won’t be permanently installed until later in the construction.
Plywood Deck Brace Before installing the rudderpost and brace, epoxy reinforcement (small piece of wood) in the middle of the transom. Because the class rules allow for a slightly larger main that the supplied in the kit, the backstay will interfere with the leech on the main if the molded backstay attachment is used. To make an attachment in the transom, bevel the bottom of a part #A-12 and screw into the transom.
Backstay attachment point Installation of the rudderpost is pretty straight foreword. However, it’s most important that it be installed straight. It is a good idea to bevel the ends of the supplied cross brace to better fit the side of the hull. The hole in the hull that part A-1 goes into is quite rough and will need to be sanded flush to the hull. After A-1 is installed, slip the brass tube through the cross brace and then into part A-1 and insert the rudder shaft. More fore or aft to align the top of the rudder to the curve of the hull and tack cross brace at the hull with CA glue. Remove the rudder and epoxy the cross brace to the hull. Generously epoxy around the base of the brass tube in the cross brace and at the bottom of the hull. Before the epoxy goes off, recheck alignment of the rudder to the hull and keel. This is a primary place for leaks so make certain that the you use enough epoxy to permanently seal the rudderpost. Next, install the chain plates, part A-4 and reinforcement, part A-5. This is one of the kit part that is well engineered however it is quite heavy at 14 grams (that’s half an ounce). Because I work with carbon fiber, it’s easy for me to fabricate carbon fiber parts. My carbon fiber chain plate is stronger and more streamlined than the ones supplied in the kit and weights only 3 grams.
Chain Plate The final step in the basic hull construction is to install the drain plug. Don’t even think about using the kit supplied drain plug for two reasons. One, the location in the transom isn’t the most efficient place for the removal of trapped water and, two, the rubber attachment tie arrangement will break easily and then it’s only a matter of time before the rubber plug is lost. A simple hole in the transom with tape over it is a better arrangement than what’s supplied in the kit. I use a combination drain plug/ water splitter at the bow. The drilled aluminum tube collects water at the curve of the bow and the aluminum rod plug rises slightly above the deck splitting water that comes over the bow helping to prevent nose-diving when over powered.
Drain Plug Install the watertight on/off switch where indicated. The top of the switch will have to be trimmed to fit the rubber cover. Holding the hatch cover on with bolts is completely unacceptable. Access to the inside of the boat has to be quick and simple, period. Locate the four chrome cleats (my favorite part supplied in the kit) on the deck, two on each side of the cockpit. These will hold a stretched rubber band over the cockpit, which securely holds the cabin/hatch in place. Access to the batteries. Etc. Is as simple as detaching the rubber bands and lifting the hatch off.
Cleats and Rubber Bands If you are using the supplied aluminum mast, install the supplied mast pulpit (part a-3) on the deck. The 10mm carbon fiber mast requires a part to be made. Using the supplied mast step as a guide, cut a ¼” sheet of Plexiglas to size, drill three 10mm holes in it. I recommend using the pin in the bottom of the mast technique because you can put several holes (mast positions) at 3/8” intervals. Once you’ve established the mast placement, which is the correct location of the center of effort (CE) of the sails, there will be little need to move the mast...it’s just good to have the option.
Mast Step To secure the pin in the base of the mast, sand the inside of the mast, pour in about 5/8” of resin. Mask off the bottom, stand the mast in a corner and let it cure. When it has gone off, sand smooth, drill a hole in the center and ca in a pin that extends slightly less than ¼” to fit into the holes in the pulpit. Since the mast will be moved minimally, the mast step shown is a bit over done. The molded jib pivot at the bow isn’t even close to where it should be. To properly create a balanced pendulum (the jib club) the pivot should be at about 25% of the length of the jib club. That moves the jib club attachment to the deck to about 90mm (3 ½”) from the bow. This has to be reinforced below deck. Drill a small guide hole, sand off the seam on the underside of the deck and epoxy a small piece of wood using a pushpin through the guide hole to locate the right spot. Since all of the major hull handling is over, the ballast can now be added. Because the class rule specifies that lead shot must be used for ballast, to get the weight as low as possible, I recommend using the smallest size shot as possible to minimize the air between each bb and thus the total volume. The instructions call for 1.7 kg, which is about 3 pounds 12 ounces. This will increase, as weight will need to be added to get to the minimum 8 pounds total weight. Cement the initial ballast with good ‘ol Elmer’s glue. Epoxy the mast support truss to the inside of the hull. Use a lot of epoxy at the top under the mast position to seal any gaps between the truss and the deck. The same goes for the base. The hull is now completed. Probably the single worst part of design in the Fairwind kit is the Mickey Mouse radio tray. Even if you only plan on sailing for pleasure, don’t even consider this method of securing the winch and rudder servo! There are several good ways to make a radio tray as long as attention to the weight is considered. I suspend the winch, rudder servo and receiver between two support beams. The radio gear, tray and battery are heavy (about 5 ½ ounces). This weight should be placed as low in the hull as possible without touching the bottom of the hull. This is to keep the bottom of the winch and servo above any water that may get in the hull. Regardless of what anyone may say or do, a servo won’t work as a winch. Though the Fairwind sail plan is very low aspect, there is still 587.5 squire inches of measured sail area. That’s comparable to a 36/600 and the one meters. For sail winch, I recommend the Futaba s3801 arm winch but there are several other arm type winches available that will work well in the Fairwind. A single arm can be used, however, I prefer to use a double arm because the torque is more evenly distributed than on a single arm. Blocks can be used at the sheet feed on the arm but not necessary.
Servos & Double Arm The radio tray is located at or just forward of the center of balance (just aft of the front of the hatch opening) so the battery can be placed low, behind the radio tray. This concentrates all of the weight of the radio tray and battery pack low in the hull at the center of balance. To secure the batteries, Velcro the battery pack directly to the winch. The antenna can be taped inside the hull along the tumblehome.
Installed Long rudder control arms such as supplied by the kit, open the door for flex causing rudder slop. Taping each end of an aluminum rod, inserting a 440 threaded rod and using clevis makes for a stiff, light and adjustable rudder arm.
Rudder Arm Running the sheeting is pretty simple it’s just one of those things that seems intimidating if you’ve never done it before. The object is to have enough travel so the jib club and boom go out 90 degrees to the hull. The marked sheet exits can be used so half of the job is done for you. Tie off the mainsheet at the rear of the hatch reinforcement rather than the Rudder support to keep the sheet well above the rudder arm to prevent snagging. For the jib sheet tie-off, drill a small hole aft of the jib club attachment on the bow, bring the jib sheet through it and tie off at the jib club attachment. When the sheets need to be replaced, the tie-off is accessible. Using a carbon fiber mast and spars saves close to four ounces over the aluminum rig supplied by the kit and eliminating weight aloft is critical! I used the kit supplied mast crane because the weight difference in carbon fiber was negligible. The carbon fiber mast that I used is quite stiff, mainly because the class rules specify that the mast be a “constant section, 10mm max diameter”. Because of the inherent stiffness, it was only necessary to use one set of shrouds with a carbon fiber spreader. Because paneled sails generate much more power than the nylon kit sails, if you use the aluminum mast with paneled sails, it’s advisable to reinforce the center mast section to prevent mast bend, which kills sail shape. I do this by making aluminum spreaders with the section that attaches to the mast acting as a brace by making them extend about three inches down the mast over the joint. If vinyl covered wire shrouds are used only one shroud is needed. Spreaders, Crane & Rig There are several types of goosenecks available and several “how to” articles in model yachting on various goosenecks if you want to make your own. Mine is all carbon fiber and weighs less than half an ounce. Carbon fiber spars are recommended and are simple to work with. There are several ways to rig the sail adjustment on the jib club and boom with the main concern being quick and easy sail trim adjustment. I use sliding bowsers where ever possible. If holes are drilled in the carbon spars, I suggest sealing it with ca to prevent splitting.
Gooseneck Sail trim adjustments on the spars must do several things. On the main, adjustments for luff downhaul (halyard), out haul, down haul and boom trim. Other controls can be added but none of these should be omitted. Because there is little room at the top of the mast between the sail head and the mast crane, I put the halyard adjustment at the tack. Tension here will control the tightness of the main luff. The outhaul at the clew controls the camber at the foot and the downhaul, in conjunction with the vang, controls the tension on the leech. For simplicities sake, I’ve used a hook on a sliding rubber grommet to act as a combination downhaul and out haul. The sheet attachment slides on a bowser so trimming the boom in or out is easily done. To achieve the perfect sail trim, all of these elements must be in harmony...sounds easy but takes time to be able to correctly achieve the prefect trim for the conditions. Part of the fun of sailing. Sail Adjustments The same basic trim adjustments are on the jib club. Because the jib luff is quite short, rather than using a jib stay (standard on my 36/600’s) I attached the tack to the jib club with the up haul (halyard) at the top. A topping lift can be used however there is a chance of fouling. I have a difficult time sailing across the pond without tell tales on the backstay so I strongly recommend using them.
Halyard Improving the sails on the Fairwind is one biggest
improvement that can be made in its performance. Sails are a sailboats
“motor” and unfortunately, the single panel nylon sails supplied with the
kit are lacking in many critical areas. Well-shaped sails, along with hull speed
are a major factor in obtaining maximum speed. Fitting the Fairwind with paneled
sails will greatly increase the speed and performance. The kit sails have no
built in shape and only have artificial camber created by a positive luff curve.
The rip stop nylon is unsatisfactory as sail material on any boat because it
will stretch after only minimal use. There are several materials that work well
for sails such as Trispin , clear mica film and polyester film. Sorry, if you
are thinking of making your own sails, drafting Mylar is way too stiff. I use a
1.4 mil opaque polyester film, this is the material now being used on the most
competitive boats and the same material used on the Wakicki Skalpel (arguably,
the most dominate 50/800 racing today).
The
panels are put together with adhesives rather than sewing which makes for a
completely smooth surface allowing for an uninterrupted air flow. Because of the
relatively short luff length (44.25” on the main) no more than three panels
are needed to create efficient sails. If anyone suggest more than three panels,
I assure you that they don’t understand sails, sail function, sail shape or
sail efficiency.
Sails The fundamentals of sailing in the back of the instruction booklet (page 18) are quite good. As a skipper, understanding these fundamentals along with knowing your boat and it’s sailing characteristics and how to tune it for the conditions are what combine to make you sail fast When setting up /tuning your Fairwind, remember, if you have custom sails, they should hang on the mast with no wrinkles or creases. It’s common to mistakenly tighten the sails way past where they are functional which usually causes creases in the sail when not under load. For every action there is a re-action. If, for example, you tighten the backstay to take slack out of the jib, if you go too far, the mast bends and there goes the shape of the main. There should be some camber in the foot to create sail shape, not unlike an airplane wing. The lighter the wind, the more camber needed. In heavier wind the sails should be trimmed flatter. Because the trim adjustments on the spars are very simple, it’s easy to experiment with different trim to find what’s fastest. Congratulations! You’ve just finished building a competitive Fairwind. Have fun and good sailing! Comments: Some of the kit parts that should be modified: The radio tray ...the rubber bands just aren’t going to last. Rudder arm...wire is too weak. It will flex when the rudder is under load. Clevis for rudder arm... Too weak Rudder arm... Too weak. All of the deck trim and do-dads...really neat stuff but it will foul sheets Hatch screws...much too difficult to open hatch. String shrouds...will stretch. Sails ...very low efficiency because of no sail shape, material material will stretch. Aluminum mast and spars... Too heavy.
Observations: The class rules allow for minimum and maximum sail dimensions. The rule reads: spars may not exceed the dimensions of the originals max include end fittings. However the max length allowed by the rules is a couple mm more than the original. If the jib is at the maximum allowed, there is very little slot, the distance between the jib luff and the mast. This is important in controlling airflow off of the jib and onto the main (Bernoulli principle). Perhaps the jib would be more efficient if it was a bit smaller. Certainly worth trying.
Web page by: Rick Moynahan Page last modified: February 27, 2004 |
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