Skiff 9'7" and 11'5"
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|materials needed||experience needed||cost||capacity|
|finished weight||building time||motor||plywood|
|joining plywood||glue and fasteners||paint and stain||fiberglassing|
|building time||sail||oar length||plans|
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materials needed to build the basic boat.
1/4" x 48" x 96" exterior plywood 2 sheets
7/16" x 1 1/8" x 120" clear lumber - 5
#8 - 1" screws - 24
glue, waterproof 16 oz.
woven fiberglass cloth 3" x 90'
resin 1 quart
paint 1 quart primer, 2 quarts color
1/4" x 48" x 96" exterior plywood 3 sheets
7/16" x 1 1/8" x 120" clear lumber 5
#8 - 1" screws - 24
glue, waterproof 16 oz.
woven fiberglass cloth 3" x 120'
resin 2 quarts
paint 1 quart primer, 2 quarts color
The amount of paint and fiber glass will vary with the size boat you build and the amount of area you choose to cloth. I normally cloth the bottom on the outside, running four to six inches up the side boards and the inside seams. Then paint the entire boat with resin. If you only tape the seams and don't paint the entire boat you can get by on a quart of resin. If you cloth the bottom, inside and out, and paint the entire boat you will use one to one and a half gallons of resin. On your first trip to the lumber yard, pick up the plywood, lumber for the rub rails, glue, and screws. Don't worry about getting everything on the first trip. With this basic set of materials you will assemble your boat. Then comes the finishing step. By picking up the finishing materials, fiberglass cloth, resin and paint on a separate trip you will have the benefit of giving thought as to how you want to finish your boat as you build it. I always change my mind several times. The quickest, easiest material to for the rub rails and hog is common "door stop" which is 7/16" x 1 1/8" fir. Molding is generally fir, straight and clear.
woodworking experience needed
Our boat has been designed to be constructed by individuals who have little or no woodworking experience. If you can build a box, you can build our boat. Our plans are drawn as assembly instructions and not as measured drawings, which can be confusing. And, you have us, we are happy to provide support.
The SK-97 will easily support 450 pounds, the SK-115, 550
The Coast Guard formula to compute the safe load of a home built boat is as follows. Determine the amount of weight it takes to "sink" your boat. Put the boat in the water and fill it with water counting the number of gallons it takes for the gunwales to be even with the water. Water weighs eight pounds per gallon. Multiply the number of gallons by eight and you will know the total amount of weight it takes to "sink" your boat. The boat will not actually sink because wood is buoyant. The Coast Guard then recommends multiplying the total weight by a factor of .3 to determine the "maximum safe load".
For the SK-97: 194 gallons of water to reach the gunwales, 194 gallons x 8 (pounds per gallon) = 1552 pounds x .3 = 465 pounds "safe load".
For the SK-115: 232 gallons of water to reach the gunwales, 232 gallons x 8 (pounds per gallon) = 1858 pounds x .3 = 557 pounds "safe load".
It should be remembered that a wooden boat will not completely sink even when filled to the gunwales because of the natural buoyancy of the wood.
The typical weight of the basic SK-97 is 60 pounds and the SK-115 is 75 pounds. The ultimate weight of your boat will vary with the amount of fiberglass and extras such as a dagger board case, oar locks and many other items limited only by your imagination.
In general either boat may be loaded on a vehicle roof top by two people without difficulty. A trailer is not needed.
The following was extracted from the USCG website. Based on this formula, a three horsepower motor would be appropriate. An electric trolling motor is the ideal motor for crafts this size. We do not make a recommendation, different individuals with different levels of skill and different water conditions will effect the safety of a craft under power.
"The maximum horsepower capacity marked on a boat must not exceed the horsepower capacity determined by the computation method discussed in paragraph (a) of this section. (a) The maximum horsepower capacity must be computed as follows: (1) Compute a factor by multiplying the boat length in feet by the maximum transom width in feet excluding handles and other similar fittings, attachments, and extensions. If the boat does not have a full transom, the transom width is the broadest beam in the after most quarter length of the boat.
(2) Locate horsepower capacity corresponding to the factor in Table 183.53. (3) For a boat with a factor over 52.5, if the horsepower capacity calculated in Table 183.53 is not an exact multiple of 5, it may be raised to the next exact multiple of 5. (4) For flat bottom hard chine boats with a factor of 52 or less, the horsepower capacity must be reduced by one horsepower capacity increment in Table 183.53.
Table 183.53--Outboard Boat Horsepower Capacity
[Compute: Factor = Boat Length X Transom Width]
If factor (nearest integer) is.............. 0-35 36-39 40-42 43-45 46-52
------------------------------------------------------------------------------------------------Horsepower Capacity is.............................. 3 5 7.5 10 15
The basic difference between marine plywood and exterior plywood: marine plywood does not contain voids (edge voids are easily filled with wood putty). Taping the seams and edges with fiberglass will effectively seal exposed edge voids. Both marine and exterior plywood contain essentially the same glues. Because boats of this nature are not left in the water for extended periods of time and the difficulty in obtaining marine plywood, we feel that exterior plywood offers distinct advantages. Exterior plywood is considerably more economical and is a standard stock item at most lumber yards. We have had good results with both fir and pine. The choice is determined by comparing quality and local availability. Many small boat builders use Lauan Mahogany plywood Lauan is which is actually five millimeters.. Lauan is pretty, easy to work with and very economical.
How is plywood joined to make longer lengths?
Plywood is easily joined using a scarf joint, overlapping the separate pieces. Scarfing plywood is easily accomplished using a belt-sander or a sharp hand plane. An electric plane, or sandpaper wrapped around a piece of 2x4 may also be used.
Getting the angles (proper beveling) to match is very easy, stack all four sideboard pieces on top of each other with a scrap piece on top. By doing them all at the same time, they will all have the same angle. Each piece is offset from the one below by 2". The formula for scarfing is 8 to 1. If the material is 1" thick, the scarf would be 8" long. Using this formula will result in a joint as strong as the rest of the material. I tack them to my work table, a solid core door, with brads so they will stay flat. Then I use a random orbit sander with 60 grit sand paper and grind them down. One of the biggest mistakes people make is when gluing up the joints they apply too much pressure which can squeeze all of the glue out resulting in a weak joint. When I glue up, I put wax paper on the work table, put the first piece down add glue and put the top piece in place, more wax paper and then put a 2 or 3" wide piece of scrap plywood over the joint and shoot it down with a brad gun. Come back the next day and pull the brads and sand off the excess glue. What about using a "butt joint". Some individuals prefer to use a butt joint. Quicker and easer but not a pretty and more difficult to hide. To use a butt joint, simply butt the two ends together and fiberglass both sides with four to five inches of cloth. The strength of a butt joint is more than adequate. It is not necessary to use a 'plate' when you glass both sides.
There are numerous waterproof and water resistant glues on the market. For the most part, glues, nails and screws hold the pieces together prior to fiberglassing. Once the seams are taped, the fiberglass will provide a strong waterproof joint. For this reason, the type of glue is of less importance than fiberglassing the seams. The glue we use is Titebond II, a one part waterproof woodworking glue. It says "not for marine applications" on the label. But after the seams are fiber glassed the glue will be incidental. It's not necessary to purchase expensive exotic glues. I've found that sometimes the 'exotic' glues are exotic only in price.
screws and fasteners
We have used both brass and stainless steel with good results. Both are rust and corrosion resistant. Stainless is harder and is usually somewhat more economical than brass. However, I routinely pull the screws after the glue dries and fill the holes prior to finishing. I use utility screws, or as they are more commonly known, "sheet rock screws". If you do not have enough clamps to glue the rub rail in place, you may very well consider brass or stainless and leave the screws in place.
paint and stain
Epoxy resin needs to be protected from sunlight or it will degrade. Paint is easy and durable. Common exterior house paint works best, 100% acrylic exterior latex (water based) paint, found at any building supplies store. Water based paints adhere well to epoxy where some solvent and oil based paints have adhesion problems.
Polyester resin contains a wax that rises to the surface as the resin cures. It is necessary to remove this wax prior to painting. This will prepare the surface for painting with either oil or water based paints.
Stain, if you wish to stain your boat for a natural wood finish, you should use a water or alcohol based stain and not an oil based product. Allow the stain to dry thoroughly before applying the resin. A good marine varnish will protect the resin and show the beauty of the wood. This method requires more careful selection of wood and greater attention to detail, everything will show through a clear finish. Because varnishes and polyurethanes may have problems adhering to resin Wipe the surface with acetone and then sand with 180 to 220 grit paper before applying the clear finish.
Fiberglassing is an intimidating process for the novice builder. There are two types of resin, epoxy and polyester. Epoxy resin is the best, polyester is the most economical and the easiest to obtain. Polyester resin can be found lumberyards and auto parts stores. Simply put, you mix two liquids, put the cloth where you want it and saturate the cloth with resin. At a minimum, you need to cloth the seams on both sides. The next level would be to cloth the outside bottom running up the side boards six to eight inches. Stepping up to the next level you would cloth the floor inside running up the side boards. If you cloth the entire boat you will have a fiberglass boat with a plywood core. The final decision can only be made by you based on your needs and your budget.
If you use polyester you will typically spend fifty to seventy five dollars, with epoxy it will be close to two hundred. Although epoxy is somewhat more expensive than polyester it is more forgiving to use, is stronger and more stable.
A good source for epoxy may be found from www.raka.com. Larry Steeves, owner of RAKA INC, a supplier of Epoxy, Fiberglass and associated products recommends: "
(1) 2 gallons of epoxy, this should be enough epoxy for all gluing, filleting and epoxy coating and saturation of the fiberglass.
(2) 1 pound of maple wood flour, this is more than enough for all gluing and filleting the seams etc.
(3) 8 yards of our 3.25 oz. x 60" wide fiberglass cloth. This material is very light, thin and strong. We recommend glassing the entire outside and the inside bottom and 4" up the insides. With fiberglass on the inside and outside there is no need for fiberglass tape.
The cost of these materials is about $200.00. Extra materials, you might consider are mixing pots, a squeegee spreader and latex gloves." RAKA's site is located at www.raka.com When you call Larry (772-489-4070) and tell him you are building our boat, he will explain the options and supply the materials and instructions you need. If you ask for the "Uncle John's Special", they will give you a 5% discount.
In general, actual assembly time for the basic boat is 12 to 20 hours for the average builder. As a weekend project, on Friday the sideboards and bottom would be sized and scarfed. On Saturday the boat would be assembled. On Sunday the seams fiberglassed, the boat would then be ready to be sanded and painted. The time required is determined as much by the time necessary for the glue, resin, and paint to dry between steps. Although it's possible to build the boat in a weekend, two weekends and the evenings between is more realistic. More often than not individuals will choose to add extras like breast hooks or small decks or gun rails and take a longer building their boat.
The skiff is easily rigged for sail. There are several rigs shown on my website. Plans for two sails are included. We also sell the sail shown on the left. click here to view our sail.
The best formula I have found for oar length was in the May 1994 issue of "Cruising World:
Oar length = 1.5 x width of boat + 1" for each inch of freeboard greater than 9" + 1" for each foot of boat length over 8' + 3" to 6" for rower strength + 6" for a sliding seat. based on the formula 1.5 x 47" = 70.5"
+ 5" for freeboard factor = 75.42" + 1.5" for boat length over 8' ....a total of 77" or 6' 5" which is equal to 6.5', slightly over the 6.13 you calculated. This difference is primarily the freeboard factor.
This does sound some what complicated and in the article, they conclude that there are so many variables that the rower should use an oar length that is comfortable. The best way to determine where to mount the oarlocks is to sit in the boat and see what feels 'right'. Attaching the oar locks is the last thing you would do to finish the boat so find the sweet spot with the boat in the water. Hold them in place with c-clamps and try different locations. When you find what feels right, run in the screws. Depending on the type of oar lock you purchase, you may or may not need to add a pad to attach the oar lock. Just do what seems right. After all, at that point you will have built a boat. This photo shows the lock I use on my boats, buy them at the local sail boat shop. I use screws that are as long as possible with out coming out the inside. Haven't had any structural problems.
View the building plans using Adobe Acrobat. Please be patient, it may take a moment for the plan to open. You may save the file to your hard drive to view offline or to print.
SK-97, our 9'7" skiff 460KB
SK-115, our 11'5" skiff 442KB
If you need to download Acrobat, it is free from Adobe.
cost of building the skiff
Your total cost will range from $200.00 to $450.00. The actual cost will be determined by the the quality and amount of paint and the type of fiberglass resin used. We recommend tapeing the seams inside and out, some builders choose to glass the entire bottom, some the entire boat. The type of fiberglass resin used will have the greatest impact on cost. Adding the sailing rig will also be a cost variable, you can build your own sail (see our plans) or you can purchase finished sails. You may or may not choose to add oars and oarlocks.
We are happy to provide support.
Additional questions or suggestions?
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