Building and Equipment ArticlesBuilding and Equipment Articlesby Peter Follansbee
As you may know, Fleet Nine had a very good showing at the 1993 Frosty NAs, taking the top two spots. That sucess is due mainly to the very competitive nature of our fleet racing, which has forced us to optimize our boats, boatspeed, and tactics. While it is true for all classes, it is particularly true in the Frosty class: a little extra boatspeed can make you look pretty smart. This is probably not a huge revelation, but on a short course it cannot be overemphasized. Speed is king, and some of us up here spend a lot of time in pursuit of it. This effort has produced what I believe to be a fast, durable boat that is easy to sail. What follows is the Fleet Nine philosophy of setting up a Frosty, a philosophy that with minor variations defines our top boats.
Beyond the obvious goals of a light, stiff hull, there are certain speed-enhancing characteristics that can be built in during construction. One should strive for a hull that is at or near maximum length and has all the forward chines radiused. Maximum length presents the longest sailing length and therefore the highest theoretical speed while, at the same time, allowing the greatest separation between the centers of effort and lateral plane. This is achieved by locating the daggerboard trunk max aft and the mast partner hole max forward under the rules and helps balance the boat, especially in a breeze, when getting a Frosty to bear off around the weather mark can be a real chore. Adding a bit of aft rake rake to the board can also help alleviate some of the helm. In addition, an adjustable mast step further allows one to optimize balance according to the given conditions. Rake the mast forward to reduce weather helm and vice versa. The key is to keep the boat balanced.
In the blade department we feel stiff is fast. Frosty boards are highly loaded in a breeze, and any flexing costs you distance to weather. As far as foil section is concerned, I use the NACA 00XY series with a straight leading edge. But I feel this area is wide open due to the thinness and high aspect ratio of the board and the Frosty's high angle of leeway. Consequently, foil-section design is a continuing process in Fleet Nine.
When it comes to the rig, simplicity and strength are the guiding principles. Aluminum rotating masts combined with stiff booms are derigueurin Fleet Nine. The sail shape advantages of a rotating rig are clear, but it reduces the loads on the mast step as well. And like a stiff daggerboard, a low-flex boom can only be faster. This rig, when fitted with a powerful sail can be extremely fast in any kind of a breeze. Though in general the latest generation of Frosty sails looked quite good, I thought our sails were particularly fast given the conditions we encountered at Hyannis. It is essentially a moderately full sail with perhaps less twist than other sails, a shape that develops a lot of power while being quite close-winded.
So how do we in Fleet Nine harness our light, stiff, maximum-length Frosties that point practically into the wind and are always traveling at hull speed, you ask? I don't know about the rest of you, but we don't like going forward to make sail-control adjustments, particularly offwind in heavy air. Leading control lines aft where they can be easily adjusted makes changing gears a lot easier. I have led the vang and Cunningham to the after edge of the foredeck where they can be reached even when hiking hard. My outhaul remains on the boom, but it is easily accessible. Obviously there are many possible permutations, and there were several boats at Hyannis that addressed this issue effectively.
Having an easily adjustable vang is particularly important to those of us who prefer a mainsheet bridle over a traveler system. With a bridle, the mainsheet acts solely to control lateral movement of the boom. Twist is controlled through the vang. This system requires both a powerful vang and a stiff boom, but it is particularly effective when it breezes up, since it allows the main to be quickly depowered while maintaining leech tension. This system of vang sheeting makes it very easy to keep the boat on its feet and moving at top speed. It works less well in very light air, however, when leech tension needs constant attention. In general, we strive for sail-control systems that are both accessible and have adequate purchase.
Well, that's the Fleet Nine Frosty in a nutshell. It is not a static entity. Rather it is constantly evolving in the search for yet more speed. But whatever its configuration next year, it will undoubtedly exhibit the characteristics outlined above.
by David Heinke
[The following tips from master wooden-boat builder David Heinke are the first of a series that will appear in successive issues of the newsletter]
Once the hull has been wired, it's time to glue it together, using WEST System epoxy throughout. The first step is to tamp down all the wires on the inside seams with a wood chisel, being careful not to break the wires. Next, build the daggerboard trunk, sand square, stand it over the D/B slot, and mark the back of the trunk for location of the mid-station support. Remove D/B trunk and wire the bulkhead into place, tamping down its wires.
Thoroughly clean the area and let dry. Mix up resin and hardener, planning on 2 pumps per seam area (total 5 of seam areas). Mix in colloidal silica and Microlight (50/50) until a creamy peanut-butter consistency is reached. Only work on one seam at a time. Start in the center, being careful not to put any of the mixture in the area where the D/B trunk is to be placed, then do the sides, the bow, and the stern. Apply the mixture as a fillet in approximately a 3" dia. circumference. When the fillets have semi-cured, wet them out with resin and lay in 4" fiberglass tape in the seams, continuing to wet out. Let cure overnight. Sand thoroughly with 80 grit. Reposition D/B trunk to mark location for deck strut. Always measure to be square. A string (waxed thread) attached to the center of the bow works well for a measuring aid. Also mark locations for aft strut and aft deck strut (use the aft deck to mark location of strut. Cut pieces to fit, then glue into place, using screws to fix. Measure for all stringers, cut, and glue into place. Finally, glue the D/B trunk into place.
Fair cockpit seams with Microlight, let cure and sand. Apply barrier coat(s) to interior, let cure and sand. If you choose not to install flotation tanks, prime interior, paint or varnish, and move on to the next step.
by Bob Durand
[The newsletter invites responses of all kinds from its readers: comments, queries, corrections, and additions. Such contributions will appear in future installments of the ongoing "Frosty Forum."]
As an adjunct to David Heinke's articles on construction, consider the end before you start at the beginning! How will your finished boat look? If your plans call for a clear deck and inner hull, consider the following tips.
Finish of the inner hull: First apply 3/4" wide masking tape around the inner circumferential boundary of the "bottom" and "side" blanks. Also apply tape to the bottom where the center bulkhead will attach to the bottom and the daggerboard trunk. Next finish the bottom and side inner surfaces with semi-gloss polyurethane varnish, wet sanding with 180 and 220 grit abrasive paper between coats. Three or four should be fine. Pull the tape off when done, using an "Exacto" or flat construction blade if the tape sticks along the varnish edge. Next re-lay 3/4" masking tape just inboard of the previous boundary tape. Leave just a little bit of varnish showing. You are now ready to join the bottom and sides. After wiring the pieces and applying the epoxy fillet, you can easily remove the tape before the epoxy sets up firmly. The result is a neat professional-looking joint. A quick touch-up of varnish along the epoxy joint edges will insure that no site is present for water to creep into the wood.
Deck finishing: The deck inner surface can be finished in the same manner as the sides and bottom. The outer surface of the deck can be finished without taping. After assembly with the sides and removal of the wire ties and back filling the wire holes, you may want to consider applying a masking tape strip about 3/4" inboard of the deck edge. The outboard band can be attractively painted in a color band, concealing the seam joining work. One or two final clear top coats, and you have a really sharp-looking Frosty!
While all this may seem like a lot of extra work, you will find that the finishing work is completed on your terms: in the flat and in the open where you can get at it without breaking your neck! On the other hand, the Hermit Crab approach is still perfectly acceptable.
by David Heinke
[This is the second in a series of tips from master wooden-boat builder David Heinke]
Fairing the hull is possibly the most critical step in developing your boat's overall performance (i.e., speed and handling). Although many theories exist on hull design, none of the conventional ones has anything to do with a Frosty. It certainly doesn't sail like a dinghy so the hull doesn't need any planing shapes. A Frosty is more akin to a two-ton IOR boat. Actually, the Frosty is more like a potato chip than anything, a Pringle, perhaps. The Frosty is going to push water, unlike a Soling or a catamaran that slices the water. So shape of the rails should focus upon how the hull pushes the water and how much.
Without going into numbers, the idea is a smooth entry with a sharp release. By fairing off more in the bow, gradually adding harder rails toward the stern, you can achieve a smoother entry and cleaner release of water moving under the hull. Also, softer rails forward of the mast decrease resistance to lateral movement, aiding in allowing the hull to spin when tacking. The harder rails toward the stern add lateral resistance and help the boat track. The balance is hard to pinpoint due to changing conditions, but there is a rule of thumb for shaping the rails. The first third in the bow is soft, the middle third around the daggerboard increases in hardness, and the last third has hard rails with the stern being a sharp corner. All along maintain a constant flow of gradation--no drastic changes. The important thing to remember is to have a fair hull. All voids, scratches and gaps must be filled with microlight and a Bondo squeegee and sanded fair. All bumps, overlaps, and protrusions must be sanded down and faired. Use an electric planer and grinder to fair edges and 80 grit sandpaper to "clean" up the hull. Be sure to sand and refill until the hull is completely fair! Once you are convinced the boat is beautiful, then apply the glass, the subject of the building tips in the next issue.
by David Heinke
[This is the last in a series of tips from master wooden-boat builder David Heinke]
Glassing is easy if you can keep your cool when working with large amounts of resin. Prepare enough six-ounce glass cloth to cover the bottom of the hull. After double checking to make sure the hull is absolutely fair and clean, lay out the cloth over the bottom. Don't worry about cutting anything now except the length. Leave an inch or two of overlap at the chines, for once the resin cures, the cloth can easily be cut with a utility knife. Smooth the cloth from the keel line out.
Mix up the West epoxy resin--you'll need approximately two 5-6 pump batches. Start in the center on the keel line and pour a bit of resin onto the cloth and begin LIGHTLY working the resin into the cloth with a plastic squeegee. Keep it up, you'll get the hang of it; don't freak, but work methodically. Push all air bubbles out, always working from the center out. Once the cloth is fully wetted out, it will become transparent but slightly matted. Tip off with a cut foam roller brush (see illustration).
When the epoxy sets, trim the excess fiberglass away from the chines. A lap of anywhere from flush to four inches is adequate. When the resin can take another coat (approximately 2-4 hours) roll on a barrier coat of resin to the entire hull and then another when the second coat is ready. Let cure overnight. Wet sand the hull with 80 grit, then 120, and finally 220 until fair. Fill any non-fair areas with microlight and sand thoroughly.
by Larry Christian
With the addition of side tanks and a bulkhead forward of the trunk, the common Frosty can be transformed into a boat with enough flotation to be righted practically free of any water.
The pitfall of the extra lumber involved in construction is, of course, extra weight. The minimum class weight of 34 lbs. should be one main objective of the scrupulous builder, but not at the expense of strength or stiffness. These boats take lots of torture when pushed hard. A 180-pound skipper fully hiked in a six-foot yacht really loads up the torque. Weak spots will soon surface as cracks or splitting caused by deflection of buckling panels.
Building a light, stiff hull begins with the selection of plywood. One must start with the lightest wood possible. Occume Marine is the best material but is dear to the pocketbook. The days of good quality cheap Lauan are history, but with careful selection lumber-yard Lauan will do the job nicely. Builder beware: the weight differences in these 4 x 8 panels can range from 16 to 25 lbs. Stay away from sheets with dark cores. I don't know what's in there, but take my word for it--it's heav-v-v-y. Also inspect the center core for voids. These voids tend to run straight through the panel. Voids spell disaster in bendy panels and weak spots; worst of all, eventually water will find its way in. Be fussy and pick the pile over if the yard attendant will let you. Just tell him you're building a Frosty! How can he say no?
After wiring your hull together, it's time to get creative and build some sort of jig to hold this bowl of jelly. Make a male or female mold that will hold it straight and level. Get it where you want it and keep it there; then fillet and tape the joints. This step prevents torque in joints and distortion of hull panels. Bending and twisting the hull panels after the joints have cured does weird things to the shape.
Stretch a string from center of bow to center of transom. Plumbing trunk and mast step location is a piece of cake off the string. What we're looking for here is a symmetrical boat with good alignment between mast, board, and rudder. Make your measurements off the string, not the boat.
After installing the trunk, it's time to fit a solid bulkhead against the forward edge of the trunk. For this I used 1/8" Luan (doorskins) to save weight. Filleted and taped, this thin membrane adds tremendous stiffness-to-weight ratio while sealing the bow compartment from flooding during a wild downwind submarine dive. An inspection port is essential to keep an eye on your mast step and vent your hull.
Side tanks can now be butted to the bulkhead. Cut templates from cardboard so the tankside intersects at the chine fillet. This forms a rigid triangular beam in the fore and aft direction of your ship. Again I used 1/8" skins with the addition of two web sections in the hiking area of the deck. These tanks should be vented to avoid condensation and change in pressure.
The one engineering problem you have to work out is a watertight mast socket, similar to a Laser's. I sealed the bottom of the 1 1/2" aluminum mast stiffener with a wooden plug. The tube is permanently fixed to the step. It could easily be done with PVC pipe. At last the deck: on Tinka I glued small gunwale and inwale strips to the hull and tanksides. This method gives extra glue surface to a now inaccessible area inside the compartments. It also makes clamping a one-piece deck to the hull easy. Now trim off the fat with a router and bearing bit. Voila! the coffin is sealed.
Tinkabelle tips in at a slender 35 lbs., and to date shows no signs of fatigue after two seasons of vigorous racing.