Diy Plywood Boat Plans Youtube,Class 10 Maths Ch 12 All Formulas Index,Intex Excursion 4 Boat Review Windows - PDF Books
31.03.2021, admin
For most amateurs, plywood is the material of choice. Plywood is one of the cheapest and easiest building materials, one that the average do-it-yourselfer is both familiar and comfortable with. Plywood is also, pound for pound, stronger than steel. No exotic tools are required, and with the possible exception of enough C-clamps, plywood boats can be built with the tools in the average home workshop.
Plywood boats are frequently built in school wood shops or by youth groups as individual or group projects. To take full advantage of the material, our Plans and Patterns detail simplified construction methods geared to the abilities of the amateur. No difficult woodworking procedures, such as steam bending, are ever required, and the GLEN-L pattern system makes the difficult lofting procedure unnecessary.
Plywood is used in panels of one or two layers. For a look at the steps in plywood boatbuilding in Diy Boat Plans Plywood Necklace more detail see our Sheet Plywood Pictorial Guide with captions.
The method involves cutting the plywood into strips widths vary depending on curve , and laying up layers at angles to each other, glued and fastened. Epoxy is the recommended adhesive. Multi-diagonal Planking Pictorial Guide. C ertain questions about plywood and its use in boatbuilding crop up time and again. Just as in production boats, top quality is not always demanded, needed, nor expected.
After all, not all boats need to last so long that they become exhibits in museums. A: Basically there are three plywood grades; Interior, Exterior, and Marine. The typical assumption is that plywood used in boats must be made with waterproof glue. However, the accepted standard for such a glue is one whose bonds will survive a boil test.
How many boats are ever subjected to boiling water conditions? None I know of. Fact is, for generations, countless plywood boats have been glued together successfully with low-cost powder-water mix plastic resin glue a urea-formaldehyde product. But it will survive hundreds of consecutive cycles of immersion in water at room temperatures.
The point is, Interior grade plywood is not rated for exterior or marine use where such panels may be exposed to moisture because grading standards permit non-waterproof glues in their manufacture. However, does this mean that such a panel might fail if exposed to exterior or marine conditions? Perhaps not if it is assembled with a highly water-resistant glue such as plastic resin.
Besides, the practice is penny-wise and pound-foolish. For structural members, stick to either Exterior or Marine panels. But I think this is too rigid a rule. The important quality separating Marine grade from Exterior panels is the quality and soundness of the inner plies and their construction both are made with waterproof glues as noted above.
With the Marine panel, there should be no major voids or surface defects, and inner veneer joints if they occur should be tightly fitted. You might be able to save some bucks by using Exterior plywood for planking curved areas. But the problem with lower-quality panels is that you may not always see the voids. And if your panel does break while you are installing it due to hidden voids, you will have to replace it with another, thus making the cost about comparable to what you would have spent on the better Marine panel in the first place.
You may have to make some repairs to the panel e. But in flatter hull areas such panels will suffice for most boats. Exterior panels with any major defects repaired when possible can usually also be used for most internal members throughout a boat without problem for such items as transoms, gussets, bulkheads, etc. But since the boat will probably by sheathed with fiberglass, some builders use the C-side outside and fill all the defects with resin putty prior to fiberglass application; they become invisible once painted.
On smaller, simpler, low-powered boats without a lot of curvature, I see nothing wrong with this practice, and again, have not heard of such a boat disintegrating over time because of it.
A: We generally recommend covering all plywood boats with fiberglass no matter how small. While some complain of an increase in weight, this is seldom more than an ounce or two per square foot of area in the typical application. Then too, even lightweight coverings say 4 ounce cloth are better than nothing. When I speak of covering the outside of plywood boats with fiberglass, I use the term generically; you can use other fabrics such a Dynel or polypropylene, but fiberglass gives the best combination of price, ease of application, ready-availability, and protection in my opinion.
Whichever fabric you select, the reasons for applying the covering are the same; added abrasion resistance, improved durability, extra reinforcing for finish coatings especially at joints , reduced maintenance, better appearance, and to help insure against leaks.
Thus sheathings should be considered as basically cosmetic coverings; their intent is NOT to add strength. In fact, plywood is far stiffer than fiberglass.
Hull strength comes from the plywood hull structure itself, and with proper design and construction, should prove more than adequate. Glen-L carries epoxy , fiberglass cloth and application materials. A: If it is made with Douglas fir a reasonably tough material , surface checking and wavy surfaces will soon occur even if painted. These will be very difficult to alleviate even if the boat gets painted each season. Other plywood types with a more uniform grain pattern will fare better in this regard, but these will still require routine coating applications.
And because many species of plywood are not as tough as fir, they will more easily suffer damage without sheathing. If you absolutely insist on not sheathing your plywood boat, Diy Boat Plans Plywood Size consider using medium-density overlay MDO panels. These still require routine coating, but the overlay prevents surface checking and presents a smooth paint-ready surface.
These do cost more and may not be readily available, however. Q: Epoxy resins sound great but they cost too much. Can I use polyesters for sheathings instead? A: We quit offering polyester resins for sheathing application years ago simply because we no longer believed in them anymore for this purpose. Finish results with either otherwise appear the same, but polyesters are less flexible and resilient so tend to crack more easily over time.
When this occurs, water can creep behind the sheathing and cause problems. As for the encapsulation process where all wood surfaces inside and out get coated, do NOT substitute polyesters this way in place of epoxies. See the epoxies available from Glen-L.
A: Because the stresses on a plywood boat are ultimately transferred to joints in the hull, a hard-setting glue rather than a flexible mastic, for example is required. As a result, glue choices are few. But as discussed above, plastic resin glues can work successfully in plywood boats for all practical purposes.
Currently resorcinol costs more than epoxies, and offers no benefits over plastic resin glue in my opinion. Unlike epoxies, both need well-fitted joints, specific limited temperatures, heavy clamping pressure, and leave colored glue lines. This uses a powder-water mix along with a second liquid component, dries clear, and has some gap-filling properties. Once popular with kit airplane builders, it may still be available from suppliers in that field.
Q: Can I increase fiberglass thickness in order to get by with thinner plywood or compensate for lower quality plywood? Primarily it involves the fallacy that plywood is weaker than, and inferior to, fiberglass.
Keep in mind that while fiberglass is strong in tensile strength, it is not very stiff. Conversely, plywood is actually stronger on a weight basis in both tension and compression. More to the point, the modulus of elasticity stiffness is actually much higher for plywood than fiberglass for the same thickness. Then too, for some reason many who ask this question think fiberglass is lighter and will thus save weight.
This myth is quickly dispelled when a piece of each material gets thrown into a pond of water and the fiberglass sinks like a stone while the plywood floats. So the simple answer is that if you reduce plywood thickness and make up the difference with fiberglass laminate, you get not only a more flexible panel, but one that weighs a lot more. It will also add considerably to your cost and effort. And if this question is asked because thicker panels are not available, the answer is to use a double thickness of plywood rather than attempt to make up the difference with fiberglass.
Environmental and economic factors, coupled with very modest demand should warrant even higher prices in the eyes of producers. On a cost per square foot basis, many common materials are considerably more expensive than plywood, such as carpet and resilient floor coverings.
Compared to all the other boatbuilding materials an amateur may use, only steel is cheaper than sheet plywood. A: This is generally poor practice in the framed plywood boat for several reasons.
First, a main reason for using solid lumber for frames is that grain gets oriented in the direction we want for strength. If plywood is used for frame members instead, because of the alternating grain direction of the plies, there is no strength in those veneers in the cross-grain direction.
In other words, a plywood frame will need to be nearly double the thickness to have the same strength see Fig. Second, longitudinal strength members e. If the frames are plywood, the edge grain of frames at such intersections will hold fastenings poorly, and if other than Marine panels are used, there is a possibility of voids at a point where they are least desirable. Third, attempting to bevel or fair such frames when necessary is difficult because of the alternating grain pattern at edges.
The tendency is to splinter the frame edges instead. On the other hand, using plywood for joining sawn frame members via gussets, floor timbers, and the like is excellent because the alternating grain at such connections reduces splitting that would occur if solid wood members were used see Fig.
The reason is that a plywood stem is more dimensionally stable due to the cross grain. Such reduction in expansion and contraction reduces any tendency for movement or cracking along the centerline where planking halves join. While it could be argued that the plywood stem presents edge grain for the planking fastenings, in reality the bevels required here allow fastenings to set diagonally to the grain for a solid grip if long enough see Fig.
An acceptable alternative is the stem made with a core of plywood and solid wood on both sides see Fig. FIG 3 � A section through a plywood stem A shows that because of the bevels required, fastening into edge grain is largely avoided. An alternative is a stem with a plywood core and solid wood either side B. Stitch-and-glue boats that depend upon glue bonded junctions reinforced with fiberglass tape Diy Boat Plans Plywood 70 often show pure adherence to such principles.
However, not everyone is willing to trust their fate only to glue bonds; many still favor the extra security that fastenings and some internal framework can provide.
After all, such construction has been proven strong and durable for generations whereas stitch-and-glue is still the new kid on the block.
This candid examination is the clear proof that allows students to see which judgment yotube themselves. Will begin re flooring this week end. Supplement 1 in?
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