Some of the plans shown in this catalog have been specifically designed to be built of waterproof marine plywood. Each of these is identified in the contents by a . In general, it is not recommended that the professional or amateur builder use plywood unless the design has been developed expressly for its use, as the curvature to which the flat sheets may be bent determines the forms that can be achieved in construction. However, in some cases the lines of a flat bottom or V-bottom hull are relatively simple so that the builder might adapt the construction to use plywood in sheet form. Occasionally, this will require some ingenuity.
Since plywood is sometimes stronger than conventional planking, thickness can be proportionally reduced, but each plywood thickness has its limitations with respect to the minimum bending radius. Sometimes, two, or more, thin plywood laminations achieve the desired result. In other cases, several wide strakes can be applied to topsides with battens at the seams. It is feasible to cut the individual planks of a lapstrake hull out of plywood sheets. Strakes, or planks, may also be spiled in the manner of traditional planking. There are some excellent plywoods available on the market. Some of these, as MDO, are covered with a resorcinol overlay over the dense, void-free laminates. Resin impregnated cellulose facing, over solid core laminates tends to eliminate the undesirable characteristic of "weather checking" of the outer wood laminate. Fir plywood, of the nature of that used on round bilge, lap strake Chris Craft's "sea skiffs" is still, in many instances, in extremely good order. Over thirty years have proven this particular plywood to be a most amazing, long lasting material. When properly maintained these hulls are still in remarkable condition in many instances. To be sure, the vertical plywood cabin sides, coamings and decks, subject to fresh water penetration, are subject to deterioration.
Many of the European solid core, marine plywoods have proven to be first class materials. Various epoxies and other waterproof glues, are providing first class adhesion, combined with solid core. Those V-bottom hulls, power and sail, shown here planked in a traditional manner, can be planked with two, or more, thicknesses of waterproof marine plywood -- laid on a diagonal, one over the other, to obtain the desired thickness in areas involving hollowness, or shape in the topsides and similar hollowness in the hull's underbody. In areas of rather extreme wine glass section, relatively thin plywood, or laminations, can be utilized.
Both the professional and amateur builder should consider the fact that the fitting and securing large sheets of plywood is often a physically difficult task. Means of proper clamping and otherwise holding the panels in place, in the process of permanent fastening, is a consideration.
My own 22 foot V-bottom utility boat is planked with Virginia white cedar, lapstrake on the topsides and European solid core Regina plywood on the underbody -- laid in two lengths, butted amidship. Batten seam construction, using plywood, has proven practical in many instances.
It is tremendously important for the professional or amateur boat builder, when using plywood, to purchase only the highest quality available. I strongly advise against the purchase of exterior fir plywood, many of the Oriental plywoods, as Lauan and similar poor, generally less expensive, plywood deteriorates in the weather. Consider time, that rare commodity, as well as money -- both professional's and amateur's -- in undertaking the building of your yacht, power or sail, small or large. Many letters come along each year from builders who have purchased "cheap" plywood, only to discover their poor judgement and experience disappointment.
While there continues to be a reasonably "adequate" supply of traditional boat building materials, the world over, for the building of a limited number of boats, or single boat, good quality, long proven woods are increasingly difficult to find. Air dried, as all boat building materials must be, lumber of the nature of flitch sawn Virginia white cedar is rare. But it is available, albeit very expensive. Here in New England and in other areas of the northern midwest, etc., we are blessed with a fair supply of oaks, and other native woods, proven practical for boatbuilding -- often available from small sawyers tucked away in the back country. Lengths are often shorter than desired for large boats, and proper scarfing -- and ingenuity -- are essential. Maine white cedar, though usually small in diameter and knotty, is also available in limited quantities. Such is entirely acceptable for smaller boats. Good quality Eastern pine and other pines are suitable for boat building -- other pines are not, so great care must be taken in determining the proper species. Clear Alaskan (yellow) cedar, Port Orford cedar, select fir and Oregon pine is plentiful on the west coast and northwestern areas of this country and Canada. Good quality fir and Oregon pine is used for keels, planking and decks in these areas.
Imported Philippine "Mahogany" -- truly a cedar -- if rich and red in color has long proven to be practical for planking and joinerwork. Most unfortunately, resin-rich, long leaf yellow pine is virtually used up and impossible to obtain in this country.
Strip-planking might well be the next, or another, practical method of building a round or a V-bottom hull. These have proven as strong as any hull, depending on design and materials used.
Conventionally, round bilge strip planked hulls are built on the station forms, with the frames steam bent and installed within the finished planking. Thus a "monocoque" hull is fashioned, much after the manner of a cold molded hull. Frames may be on far greater centers -- and ribbands, with strip planking, are not required as utilized in traditionally planked hulls. A V-bottom hull is strip planked directly to the sawn frames, as no station forms are usually used. Strip planking though more time consuming, provides all manner of methods in achieving the desired strength.
The cold molded method of building a round or a V-bottom hull must also be given consideration. As the building of a proper frame work, not unlike ribbands, setting up the work, time involved in gluing, clamping and stapling various thicknesses of laminations is required. I am well aware that there have been a good many highly successful heavy and moderately heavy yachts built using the cold molded method and respect its virtues. However, I conceive of cold molding as being best suited for relatively small, light displacement cruising/racing yachts, day sailers and similar boats.
Great care must be used in finding the specific gravity and weight per pound per cubic foot of any wood used in boat building. It is essential to maintain the weight of a particular hull. It is most ill-advised to increase the weight of scantlings of any design. The performance of a yacht depends upon her resting on the designed waterline. Increasing the weight, or dimensions of scantlings -- as well as all other primary weights -- is often responsible for poor performance of a sailing or power yacht, thus a great disappointment for all involved. Best results may always be expected when the builder adheres rigidly to every detail of the designer's specifications, without change.
Steer clear of kiln dried materials of any kind for boatbuilding -- particularly pressure treated "lob-lolly" pine, birch and similar woods that have proven to be short-lived in the salt and fresh water environment. Encouragingly, there are a great many Central and South American woods, as Cabbage Bark, Sapodilla, etc., which are strong, hard and long lasting. Santa Maria is a relatively light cedar-like wood, Lagart, etc., all make fine planking. African iron bark, greenheart and white oak head the list for long lasting qualities, followed by Sabien, Jarrah, Kurrie, blue and red gum wood for all major timbers as keel, stem and stern post, planking, decks, etc. Well maintained these materials are good for as long as thirty-five years, and often many more years. Philippine mahogany (cedar), larch. Juniper, Oregon pine, etc., are about evenly long lasting and twenty-five to thirty years can be expected. The Far East provides Yaca1, Kiaki, hard and soft camphor, Menehe (which is a grand, clear grain wood much as our red Cypress) are but a relatively few woods available in great abundance in the far off corners of the world.
It is my conclusion that any practical method of boat building, professionally and well done, is entirely acceptable. I do not advocate the covering of plywood, stripped plank or cold molded hulls with synthetic cloths. While this is done -- my experience has indicated such covering is subject to failure, in various areas and conditions of swelling, etc., and I see no need for further complications.
The above is intended only as alternate methods of construction, thus not detailed. It is recommended that those not familiar with boat building, and that many who are, obtain any number of excellent books on the subject. Bob Steward's Boat Building Manual -- originally published by The Rudder magazine in the late 1950's -- is presently in its third printing by International Marine Publishing Co., Camden Maine. I am fortunate in having not only one of the original books, by my friend Bob Steward, but have, in fact, copies of each edition published over these past 40 years -- each autographed by the author.
Bud McIntosh's Boat Building Methods published by Wooden Boat magazine, Brooklin, Maine and well illustrated by Sam Manning is also an excellent book on a11 manners of practical methods for boat building. McIntosh, a wooden boat builder with years of first hand experience, has recorded his procedures in building a proper yacht. A man of great ingenuity, Bud McIntosh's book should be in every boat builder's library.
Howard Chapelle's Boatbuilding published by W. W. Norton of New York, over many years, is the "old standby" on the subject. The book often covers the construction of working and commercial vessels, rather than yachts, and procedures used in older days. It contains data not necessarily included in other books of this nature, therefore of great value.
There are, as well, a number of fine books on cold molding -- as well as the building of boats in steel and aluminum.