Jon Boat Frequently asked questions
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View a set of plans |
capacity |
finished weight |
experience
needed |
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cost |
tools needed |
materials
needed |
glue and fasteners |
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fiberglassing |
plywood |
joining plywood |
paint and stain |
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motor size |
support |
cost of building the skiff
Because the materials required will vary with the size you build, a normal materials list has not been included . The boat may be built with a 30" bottom, from 10' to 12' long using two sheets of 1/4" plywood. And, up to 15' 8" with four sheets. The amount of fiberglass cloth and paint as will the length of the material used for the rub rails will be determined by the length of the boat. The number of screws needed will be determined by the number of clamps you have. We do not recommend building less than 10 feet.
Your total cost including the Jon boat 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.
Materials Needed
Because the materials required will vary with the size you build, a normal materials list has not been included . The boat 10' to 12' long with a 30" bottom, may be built from using two sheets of 1/4" plywood. And, up to 15' 8" with four sheets. The amount of fiberglass cloth and paint as will the length of the material used for the rub rails will be determined by the length of the boat. The number of screws needed will be determined by the number of clamps you have. We do not recommend building less than 10 feet.
woodworking experience needed
Our plans have 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.
tools needed
You will need to rip the plywood into the various parts, (table saw, skill saw, jig saw or hand saw). You will need a sander (a random orbit sander like the DeWalt is very handy, a belt sander or pad sander works well). A jig saw is the tool to use cutting the bottom and of course the ever handy drill.
capacity
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 Coast Guard then recommends multiplying the total weight by a factor of .3 to determine the "maximum 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 wood.
finished weight
It's impossible to estimate your finished weight, because our Jon boat ranges from 10' with a 32" bottom to 15'6" with a 48" bottom. In general, a 10 footer will weigh 60 to 70 pounds
motor size
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
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plywood
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.
glue
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 fiberglassed 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 polyurethane 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
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, paint the entire boat then 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 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. Cloth increases the strength and durability of your boat, the more area you cove, the stronger your boat will become.
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
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 http://www.raka.com When you call RAKA (561-279-8929) and tell them you are building our kit, they will explain the options and supply materials and instructions.
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(please note, the plans are complete but don't include dimensions)
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