Dave's musings about setting up and adjusting sails on R/C model Boat.

Dry sailing -set up.

Place the model in a stand. Head the model into them wind.

Things that can be moved, and adjusted: Mast step. Mast rake. Boom vangs. Shrouds. stays. Jumper stays. Head stay/jib stay. Sail shape - loose foot. out-hauls.

Attach the sails to the mast.

Set the sail winches in fully trimmed position while allowing sheets to be slack.

Stand the mast with standing rigging attached in the center step position.

Hook the jib swivel into the middle slot of the jib rack. {The jib boom needs to clear the mast.}

Connect the side stays to the chain plates and adjust so the mast is straight and vertical.

Connect the back stay to the back stay fitting.
The jib stay and back stay will need adjusting to set the mast in vertical position.

Move the out-haul of the sails along the boom to give the sails to have some "belly". Pulling the sails out along the boom flattens their shape. The belly (or shape) of the sails will be determined later and the sail shape will be determined by how windy it is.

Where you attach the sheets to the booms will take into account the type and adjustments available for the sail control. The booms should be full out (90 degrees to the center line of the hull) when the SCU is full out and then the booms should be just about over the center line when fully trimmed in. ( I see 10 degrees as suggested angle to center line). The length of jib sheet trimmed and the length of main sheet trimmed is a factor in setting up the sail control so the sails are coordinated properly when sailing. The SCU handles a much longer main sheet than the jib sheet. The use of jib traveler and mainsheet traveler can help position the sails when fully trimmed in. Unless two servos (SCU's) are used a single SCU has the task of coordinating the positioning of the jib and main.

Turn on the R/C and run the SCU.
Test out SCU setting with the sails full out and fully trimmed.

With the mast set up and sails adjusted roughly in position it time to launch and sail.
--
Setting Sail on the water.

Before launching TURN on the radio on the boat. I have seen many models set loose to sail with the on board receiver and sail controls not tuned on and very unhappy skippers watching as their model sails away towards the horizon.

The initial rigging and sail settings are based in getting the model to sail a strait line while close hauled (sails trimmed in) and sailing up-wind.

Properly trimmed the rig will allow the model to sail it self in a straight line with just a minor tendency to "round-up" (i.e. sail itself dead into the wind). If or example you find you are constantly pulling the tiller (i.e. rudder) hard over to pull the model back on course to keep from heading in to the wind your model has weather helm which means your mast and jib must be re-positioned. When tacking if your model stall's into the wind and won't tack? Try different rig setting.

--
Setting Sails
The art of tuning the rig on a sail boat is detailed in books written for racing yachts and boats.

"DINGHY SAILS"
by Jeremy. Howard-Williams

"The Best of Sail Trim:
A Selection of Articles from Sail Magazine"

"Sail Trim: Theory And Practice"
by Peter Hahne

My observations and commentary on tuning are from an amateur and are at best suggestions not professional advice.

Observation Number One!!
Model sails that are single panel loose footed sails rely on the shape of the sail established by the gap between the boom and the foot of the sail. Model sails with "shape" sewn into the sail fabric still are loose footed. Also the lift of the boom also factors in determining the shape and performance of the sails.

Hauling a sail into the center line and at the same time pulling down on the sail can flatten the fabric and kill the sail shape. I like to use travelers to position the sail to the desired point near the center line. Then you can set the point of maximum driving force and not wreck the sail shape.

On a big boat the skipper can changer the suit of sails to match the cut of the sail with the wind conditions. In the case of a model a skipper can change where the out-haul is along the boom, light air adding belly to increase the drive, heavy air pulling the sail out further changing the sail's airfoil.

The jib and mainsail work as a system. A skipper has all manner of combinations that may be set relating the two sails. If the models did not have jib clubs they could overlap the mainsail. So model sailors have to adjust the "slot" between the jib and the main to get the maximum driving combined air foil.

In heavy air you may want to close the slot and ease the main so that the jib slightly back-winds the main to help the model sail flatter (less heeling).

Don't forget on a model it is easy to rake the mast fore and aft to trim the sailing characteristics to match wind conditions.
--
A digital camera can be a terrific diagnostic tool for seeing what is happening on your model. You can look at pictures and spot misadjustments. Bends in mast, wrinkles in sails etc. Does you model's mast rake forward down wind? Is the back stay bending the top of the mast. How are the jumper/jenny stays adjusted do they balance the tensions between the jib and the back stay?
--
The late Manny Costa of RI always stressed, change one thing at a time to see what changes. He also stressed sailing a pair of models. One model being tuned and sailing against the second to see if the single adjustment improved performance.

Round-Robin racing in pairs is an excellent way to evaluate how your model performs.

Curved mast -- tuning a mainsail

From: Philgeren@aol.com
Sender: Star45@yahoogroups.com
Date: Wed, 22 Nov 2006 06:58:53 EST
Subject: Re: [Star45] Curved mast -- advantage ??


Curving a mast so that it bends convex forward (concave aft) moves the luff edge of the sail forward and reduces the camber of the sail in the section where the mast is bent (if bent half way up the mast, the camber in the up/down center of the luff of the sail is reduced). In a blow, this reduces power, reduces leeway force, reduces weather helm, allows the boat to increase its speed.

Generally, the minimum position of mast bend is considered to be a curve equal to the luff curve designed into the luff edge of the mainsail. For very light air and for heavy air, maximum mast bend is used for maximum speed. For very light air, less camber makes it easier for air to stay attached to the leeward surface of the mainsail as the air passes aft. For medium air and for waves, where maximum power equates to maximum speed, minimum mast bend is used to get maximum designed camber.


By use of all the tuning controls on a mainsail, one can obtain a certain amount of control over the distribution of camber over the length of the mast, and there will be an optimum camber distribution for any particular sail and set of wind conditions. Pretty complicated to get it perfect, however outstanding sailors like Stuart Walker are on record as saying it is of paramount importance to use this against competitors who are using it. Otherwise, in a one-design competition they win.
My two cents.

Working with Fiberglass "SAFETY" is Important !!

Always work in a well ventilated area. Resins, hardeners, and solvents are flammable and toxic. MEK60 is impact sensitive. Some people are ' especially sensitive to any and all components. Avoid excessive skin contact. Avoid inhaling concentrated fumes. Wash well and keep skin clean from these chemicals. chemicals follow manufacturers instructions. DO NOT SMOKE or have open flame around when working with fiberglass chemicals. Select an appropriate work area. Protect furniture, floors and other surfaces from spills and spatters {.o prevent permanent damage from these substances. Remember that the fibers of the fiberglass are irritants and commonly cause skin itching and irritation. When sanding, use a barrier cream or gloves, protective clothing and sanding mask and clothing and careful clean up methods as you work.

Fiberglass is just that, GLASS, and it will cut if you are not careful. When you sand, cut or trim anything made from fiberglass keep in mind that it can be as sharp as anything known to man.

Fiberglass Cloth, Matt -- polyester resins

This is a guide to assist the model builder in building model sailing boats from kits with fiberglass hulls and associated components.

"FIBERGLASS"

Fiberglass is the common name for glass reinforced plastics, GRP. The strands are produced in a non-woven cloth called matt and in a woven cloth called fiberglass cloth, boat cloth, tooling cloth and woven roving. After the cloth has been saturated with resin and the resin cured (hardened) we have fiberglass. Fiberglass matt and cloth are sold by the yard in small lots by retailers and by the pound by wholesale suppliers. Matt and cloth are designated in thickness by referring to their weights. Matt is weighed by the square foot with 3/4 to 3 oz. matt being most common. Cloth is also weighed but unlike matt it is weighed by the yard. Thus a 9 oz, cloth has the same glass content as 1 oz, matt. Matt and cloth have different handling characteristics and different conformability as well as different impact and strength factors. Working with matt using brush-on resin requires skill and experience to avoid developing one big mess of glass fibers and resin. You will find with a little practice that matt conforms well when worked with a resin-covered surface with a constantly wet brush. A matt called surfacing matt can be used to work the regular matt in place and squeeze out air bubbles and excess resin. This matt is hard to obtain other than from wholesalers. A layer of cloth works well for surfacing if you can stand the added weight. Fiberglass cloth put up in tape form is widely available. It is a convenient way of getting high quality cloth in small quantities. It is important for the glass resin combination to have as high a glass content as possible for strength. Fiberglass cloths used in boat building must have a special treatment called Chroming to make the glass compatible with the resin. Do not use industrial or auto grade fiberglass cloth unless it is treated.
Fiberglass (GRP) laminates will absorb water through the capillary action of the glass fibers. The problem of water absorption and surface abrasion is overcome in the molding stage by adding a specially formulated resin known as gelcoat. Although gel-coat is available clear, it is usually pigmented to give the surface resin a molded-in color. Polyesters and lay up resins can be pigmented giving the part a solid color throughout. This is an inexpensive way of molding color in but it presents two problems - hidden air bubbles within the laminate and exposing glass strands.

Woode boat Construction -- glues and adhesives

John F. Howard (Star-45 discussion forum, July 31, 2006)

"Gorilla Glue does foam a bit, but nothing like foam-in-a-can and has minimum stink. Forget trying to smooth things out, the foam is very, very sticky and keeps growing until it sets up (about an hour) at which point it will still be a little soft (keep clamped for 3-4 hours). Any squeeze/foam out once hard, can be cut, chiseled or sanded smooth. Run a strip of tape along the edge of the glue line and most of the foam out will end up on the tape. The best joints are tight ones that use a minimum of glue. For narrow or thin pieces (planking), squeeze out a little puddle (just enough to use in 15-20 minutes) and use a Popsicle stick to spread along the edges. Wear gloves, the stuff stains and is sticky. GG is great for laminating larger areas (spread with an old credit card or playing card)."

"If you use epoxy resin such as West Systems (best, you can adjust the cure rate with the different hardeners) or one of the 30-minute or longer (5-15 minute never gets hard and remains rubbery) such as sold by Great Planes or Tower, stink will not be a problem. The polyester resin does STINK in a big way, it what you can smell in a new fiberglass hull.
CA glues are ok for "tacking" stuff in place until the epoxy sets up, but watch the fumes. CA will fail if used in a wet location for long and also cause a problem with the wood accepting stain. Work with plenty of ventilation and or respirator and wear gloves with any of the above glues and resins, staining of the skin and sensitivity, either skin and or breathing can occur."

"These are base on my experience with the glues mentioned (full size boats, cabinet work and models). Yellow glue such as Titebond or Elmers Carpenter Wood Glue (not waterproof) works fine when encapsulated with epoxy (cedar strip canoe builders use it all the time)."

{ http://groups.yahoo.com/group/Star45/ }

Phil Geren adds a warning note about Glue Fumes:
I have a serious allergic reaction to CA fumes - causes fluid to build up in the lungs, like pneumonia. I still use it, but with a fan blowing air between me and the work. Trying to avoid it.

Phil Geren on Gorilla Glue:2006 August 1
Is it rock hard or rubbery when dry?
I bought some, but have the same reservations as Dave M about foaming, trimming, and sanding. If it doesn't sand well, the finished product won't be as good as what I am aiming for.

Fiberglassing materials -- vacuum baging etc

Breather fabric is a lightweight, polyester blanket that provides excellent air passage within the vacuum envelope while it absorbs excess epoxy.
60" wide x 2.7 yd, 60" wide x 10 yd. 60" wide x 200 yd rolls:

Release Fabric is a tough, finely woven nylon fabric treated with a release agent. It is used to separate the absorber, breather and vacuum bag from the laminate in vacuum bagging operations. Excess epoxy bleeds through and is peeled from the cured laminate along with the release fabric. Peels easily and leaves a smooth textured surface, ready for bonding or finishing. 60" wide x 2 yd,. 60" wide x 10 yd rolls

Vacuum Bag Film is a Clear, heat-stabilized, modified nylon resin film, tough, stretchable film for high vacuum pressures. 60" wide x 2 yd, 60" wide x 10 yd,60" wide x 20 yd. 60" wide x 333 yd rolls:

Vacuum Bag Sealant; a mastic tape sealant for airtight seals between vacuum bags and molds. Easy to work with around difficult angles, patching small leaks in the system. 1/2" wide x 25' rolls:

Techniques Book on Vacuum Bagging, West System publishes this definitive guide to the principles and application of vacuum bagging techniques for laminating composite materials
with epoxy.

Fiberglass Mat is a Chopped Strand Fiberglass Mat, Offers great conformability with low cost.

Veil Mat 0.09 oz/sq ft

Fiberglass Mat, 3/4 oz/sq ft, 1.5 oz/sq ft, 2.0 oz/sq ft

Fiberglass Cloth 4-, 6- and 10-oz per square yard.

Dynel Fabric is a popular laminate fabric with great abrasion resistance used for museum-quality restoration work on wooden boats. It's strong and supple like a true woven fabric, with no fibers to irritate your skin.
Size Weight, 5 oz

Carbon Fiber lightweight, strong composite can strengthen any project while adding minimal weight.
Plain Weave 5.8 oz
Twill Weave 5.8 oz
Unidirectional 9 oz

Carbon Fiber Tape a unidirectional reinforcing tapes are used
to improve tensile strength and stiffness in one direction with minimal weight.

--

You can learn a lot about boat building by reading catalogs for example: www.jamestowndistributors.com/
Many of the same materials are also used in model boat building.

The Jamestown site has several links to model builders, AMYA and other organizations

Fiberglassing information and comments

Polyester resins are formulated in many make ups. To change the liquid resin to a solid you must add a hardener to catalyze the mixture. Whenever resin is referred to in this manual it is intended that it be properly catalyzed before use. The resin you choose for your model should be pre-accelerated. This resin will commonly have a purplish hue in the liquid stage and may change color to indicate states of cure. Resins should be at room temperature (60�-90�F. ) for curing. Among the polyester resins `available are the air, inhibited types. Lay up, spray, and gel-coat resins are formulated so their surfaces will not cure readily while exposed to air. This is advantageous if several layers of glass are to be laminated over a period of time. However, it may present a problem to the unsuspecting buildr who finds the surface of his resin "forever tacky". Sometimes, applying a layer of hard .bowling, alley wax will solve this problem. Gel- coat resins therefore, are' not used as a finish coating on completed boats because they are air-inhibited.

Finishing resin or hand-lay-up resin is commonly a waxed resin. When special waxes are formulated in the resin they will move to the surface as the resin cures. This is an advantage if this is the outer surface. If you want to bond to: this, surface you must first sand it thoroughly and then '" prepare, the surface with acetone or polyester solvent.

Polyester resins may be thinned with acetone and styrene. The common polyester hardener is methyl ethyl kettle peroxide (MEK60). -Resin and hardener 'must' be handled most carefully and in strict accordance with the manufacturers -instructions. The amount of hardener or activator in conjunction `with the room or ambient temperature determines the jel time and the cure' rate' of the resin. The jel time is the period that the resin remains liquid until it turns to a jelly just before curing hard. Resin has a "pot life" and is only workable for the time before it jels; this may vary from seconds to several minutes. CAUTION-DO NOT use too much hardener. Styrene will thin the resin' and become chemically part of the cured resin. Acetone will thin the resin but will evaporate during cure. Acetone will change the characteristics of the cured resin and may result in brittleness and other unwanted characteristics.

Polyesters may be filled with a 'number of components from sawdust to pecan shells. Most common fillers are Cabosil and micro-balloons and macro-balloons. This filling may make the resin thixotropic and filled resin may vary from a slurry to a heavy paste. Macro-balloons and micro-balloons are used to make a foam-like putty that will work as a flotation foam.

Polyester will bond nicely to polyester. We stress that surfaces must always. be cleaned and prepared for bonding. The bond between two fiberglass parts, such as keel and shell or hull and deck, will be enhanced if the interface between bonded surfaces is filled with a layer of saturated matt, cloth, or filled resin. Polyester resin is frequently used to bond to wood as a glue. However among wood glues, polyester rates poor. The initial bond to wood may look all right but it has a history of delaminating. We will not rule out its use for model building. However, there are better wood glues and the best of the waterproof glues are better, many epoxies.

Fiberglass is not at its best under tension. Spread or distribute any tension . load over a wide area. The same goes for compression loads that should be spread out also. This fiberglass found in models will tear if pulled on so always spread the load - more on this later.

You must remove all waxes in order to bond to fiberglass and you can reverse this and coat surfaces with hard floor waxes during building to protect surfaces from accidental spills. Also remember to use only resin-resistant tape such as Scotch brand Cellophane tape which is inert to resins; regular masking tape may be used if not in contact with resin or solvents.

Fiberglass has the outstanding feature that when molded in curves it has very high strength imparted to the part because of the curves. On smaller models the curves of the hull provide sufficient strength for the model. On larger models you will need stiffeners. These may be ribs or bulkheads which add support to the hull. These can be of the aircraft framework type. Another stiffening method is to make a sandwich. Here the strength of the GRP is achieved by laminating a light weight core between two layers of fiberglass.

From: "Mitch Martin" 2006 August 1

Working with WEST is similar to polyester resin, but it is stronger, doesn't smell bad, and hardeners can be selected for your application. For example if I was mixing the epoxy for glassing a hull that would eventially be painted I would select the extra-slow hardener 209 which has a pot life of 45 minutes. That's much longer than a polyester resin pot life. The down side is the cost, it's pretty pricy stuff. Another trick is to mix in the graphite powder and it gives the finish a carbon fiber look.

from John 2006 August 1

The pot life with the 105/209 is 40 min or so. I have used that
combination when doing vac bagging and it allowed plenty of time to wet
out the fabric on a 60" boat, then apply mastic, then the bagging
materials, then pull the air out. I have also done 72" long 10R's and had
no issues with the pot life. Now I am usually about 70 deg, so that slows
it down some too.

Now the 105/205 can be more in the 10 to 20 min range depending on temp.
Also how deep the container is that you mix the epoxy will influence the
cure time. Deeper is faster.

Billie Geisler's comments regarding Epoxy:

I use strips of cardboard scissored from breakfast ceral boxes for mixing and applying the epoxy. I use aluminum beer cans for containers. I cut the bottoms off about an inch up the can with a curved exacto knife. I find that I can get a pretty good mix of resin to hardener by cutting the mixer cardboard the same size, then use them to measure the epoxy and hardener.

I dip the cardboard mixer stick into the resin and scrape off all that will remain on the stick, after I wind up the strings, into the beercan. Then I use another fresh cardboard mixer stick, and dip it into the hardener to the same depth as I dipped the first stick into the resin. I let it drip once before I scrape it into the beer can. The difference in viscosity seems to get the ratio about right, even though it seems that no way is the little bit of hardener that stays on the dipper is going to be enough to work. The cardboard mixer sticks are inserted vertically into the resin and hardener, and scraped on the edge of the beer can.

You can pretty accurately go from a hot mix to a slow mix by simply varying the depth of the mixer stick in the hardener. It works on very small amounts, and about two dips from a half inch wide cardboard mixer stick will be enough for a plank on each side.

I use small jars to contain the epoxy components that I am working with, and label both the jar and the matching lid as resin or hardener. That way, if I happen to dip the used hardener dipper into the resin, or mix up the lids, I don't loose my whole supply. I like horshradish jars from Kraft.

Experiment with your epoxy before smearing it on your hull, as my epoxy is about 20 years old and the ratio of hardener to resin may work differently with yours. Just vary the depth of the hardener dip relative to the depth of the resin dip, until it works for you. It doesn't take long to learn to mix very small amounts with reliable cure results.

Billie Geisler's comments regarding Epoxy:

I use strips of cardboard scissored from breakfast ceral boxes for mixing and applying the epoxy. I use aluminum beer cans for containers. I cut the bottoms off about an inch up the can with a curved exacto knife. I find that I can get a pretty good mix of resin to hardener by cutting the mixer cardboard the same size, then use them to measure the epoxy and hardener.

I dip the cardboard mixer stick into the resin and scrape off all that will remain on the stick, after I wind up the strings, into the beercan. Then I use another fresh cardboard mixer stick, and dip it into the hardener to the same depth as I dipped the first stick into the resin. I let it drip once before I scrape it into the beer can. The difference in viscosity seems to get the ratio about right, even though it seems that no way is the little bit of hardener that stays on the dipper is going to be enough to work. The cardboard mixer sticks are inserted vertically into the resin and hardener, and scraped on the edge of the beer can.

You can pretty accurately go from a hot mix to a slow mix by simply varying the depth of the mixer stick in the hardener. It works on very small amounts, and about two dips from a half inch wide cardboard mixer stick will be enough for a plank on each side.

I use small jars to contain the epoxy components that I am working with, and label both the jar and the matching lid as resin or hardener. That way, if I happen to dip the used hardener dipper into the resin, or mix up the lids, I don't loose my whole supply. I like horshradish jars from Kraft.

Experiment with your epoxy before smearing it on your hull, as my epoxy is about 20 years old and the ratio of hardener to resin may work differently with yours. Just vary the depth of the hardener dip relative to the depth of the resin dip, until it works for you. It doesn't take long to learn to mix very small amounts with reliable cure results.