How to Build a Wooden Boat
David C. "Bud" McIntosh
Thomas A. MacNaughton
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Right off we should say that the reader can be confident that the author is one who knows his subject. He also can communicate it clearly, with a light touch, and even some literary style. I like Mr. McIntosh's boats very much. This will tell you how he built them and it would behoove us all to read this carefully. We may disagree with the occasional bit of procedure but we better be smart about it and be prepared to defend our positions because it is very hard to argue with the happiness he has produced with his boats over a long career.
Mr. McIntosh was known to my father and mother, who visited him shortly after he completed his first major boat. I gather they were all standing on the shore looking out to where this lovely little vessel sat on her mooring. My parents were very impressed with the boat but Bud's comment was only "It's terrible to have your first born turn out that way." Since I first heard that story I have had about two thirds of a lifetime of experience with new builders. Mr. McIntosh and the few others whose impression of their own work is always that they could improve given another chance are the ones you can mark as the best people to go to for a boat.
The author is a gentleman darn near worshiped by a great many people whose lives have been touched by his boats or his instruction. I do hope that they will forgive a few of the following comments that is some cases suggest alternatives to some of what Mr. McIntosh has to say. These comments are offered only by way of giving perspective for the new student of boat building.
When discussing lofting the author suggests (p. 4) light colored sheathing paper as an alternative to white painted floor for lofting on. He rejects "experts" who suggest that this results in errors in lofting due to shrinking or swelling of the paper. OK, it doesn't make lofting impossible but nowadays there just isn't any need of it. If you can't paint the floor white and drawn right on it I'd lay light plywood over a floor somewhere paint it and loft on that. Either that or use mylar drafting film which doesn't shrink and swell.
Again in discussing lofting (p. 7) he states that of all the offsets the diagonals are likely to be the most accurate. This is because they cross the sections the closest to right angles of any of the lines thus giving a nice neat point to measure to. This is not only true but very important. If any readers get into design you will find them even more important to the shape of the boat than the builder normally has to consider.
While the author's procedure (p. 9) for deducting plank thickness will be reasonably close in the middle of the boat. Personally I'd use the more accurate methods shown in other books, especially near the ends where the angle of the planking to the section will be more severe. Otherwise the shape of the boat will be a bit different than the intended lines. To be fair in the particular boat used as an example their won't be much difference.
Mr. MacIntosh prefers iron ballast castings to lead ones (p.16). I go the other way, but this is his book. What I would add is that when he says iron please understand that he means iron. Too many keels are not cast of pure iron but rather melted down scrap with enough carbon and other contaminants to really be steel. The point is that pure iron is pretty difficult to get to rust. Steel rusts like crazy. When I was a small boy my father had made up a pattern for an iron keel. He told me that his policy was to take the pattern to the foundry and tell them to pour it whenever they wanted but only if it was the first item cast. His theory was that the pure iron was the first to come out the way the foundry worked that he patronized. This because it was heavier than the impurities. Pure iron is softer than steel and easier to smooth up if you need to. The boat he was working on when we had this discussion is now (1999) about 45 years old. I saw her out of water at about age 30 and there still wasn't any rust deterioration of the keel.
Illustrations on these pages 58 and 59 show the transom edge as mitered to the general hull planking. A lot of people do this but I feel these joints open and let it moisture and are liable to rot. For what it's worth I run the planking by the transom. Also the mitered transom, if varnished, tends to look "weak" in my opinion. I think this is because you get no sense of the structure of the boat from looking at it.
As a designer I was particularly taken with Mr. McIntosh's advice (p. 62) to just do the sheer the way the designer intended. This remarkable attitude that the designer probably knew what he wanted is rare and I commend Mr. McIntosh for his humility. Having said that, this is an area where designers sometimes don't take enough time. If you get the boat set up, and the sheer doesn't look right from some angle, take some pictures of it and send them to the designer. I'd make a model and then look out for sheers that have odd humps and hollows. Most sheers as the boat heels away from you should get straighter and straighter until they become a straight line. As the boat continues to heel the sheer will become a smooth reverse curve. If some part of the sheer looks concave while another part looks convex the sheer probably could use a little work and you should consult with the designer. Various books and our own Yacht Design School lessons get into correcting sheers but Mr. McIntosh is correct that unless you are going to have the builder design the boat this should probably be kept in the designer's lap. When planking you want especially to avoid "losing" the sheer by hanging a plank with the inside edge at the sheer marks and the outside edge of the square edged plank below the inner edge. Some people do this and then trim the top edge of the plank to the outer edge. Instead the plank should be set up high enough so that when you are trimming to the marked sheer the outer edge is at the height marked on the molds.
In his section "Now, about those frames" (p. 66 seq.) I think Mr. McIntosh may confuse some of his readers. Here I think he should state simply that, while strong frames are very important, trying to get strong frames by bending wood to a very tight radius in relation to its thickness weakens the frame dramatically. It may seem as though Mr. McIntosh is arguing in favor of weak flexible frames. I believe that what he really intends to communicate here is that if you can't bend a frame easily to a given curve with steam you'd better laminate it instead. The one statement that bothers me a bit is "even, with square frames, which only a trained naval architect would specify anyway". Since most frames are square in section, I'm not sure what he is getting at here. Square is just a good compromise between weight, stiffness and fastening suitability. I could write a text book on this and some of the engineering is covered in my scantlings rules, but basically the less important weight is the less likely you are to have a designer worrying about deep frame sections. The more you go for lighter weight the more likely you are to see deeper section frames spaced wider distances apart. Presumably you are willing to pay somebody more to laminate up these frames. They certainly are more expensive than the type of framing Mr. McIntosh talks about in this book.
The author expends a good deal of effort on describing how and why boats develop problems and what to do about them. To me this is one of the great strengths of the book. A lot of boat builders seem only interested in getting the boat done and pay no attention to what will happen to the boat later in life. It is very nice to read a builder's thoughts on why boats have problems and how to correct them. This will save your customers or yourself a lot of grief a few years down the road. I also like that he says builders go on making mistakes but once they've done repair work on those mistakes they don't make the same ones again.
Of course nowadays admitting you made a mistake is positively un-American. The attitude nowadays, when so few people understand making things at all, is that the consumer has the right to assume the builder is infallible. Even a builder who wants to fix something a customer brings back to him, because he can see what he did didn't work the way he thought it would, may be told by his lawyer that he can't say he did it wrong. The lawyer won't even want him to say he'll fix it for fear of lawsuits.
Then there are some of the production builders who have a permanent staff of lawyers on salary whose job is to defend the company against failures of horribly built boats that they have no intention of building any better. The poor boat owner is often left searching for somebody like Mr. McIntosh who is smart enough to know he can make a mistake and is willing to fix it. When you find somebody like this have him do your boat building. If you hear somebody wants to sue him rally round and help him out.
Mr. McIntosh points out (p. 103).that you can hang all the planks, being as careful as you want, and they'll still show light through the seams when you go back a day or so later and look. He is right that it doesn't matter as long as you worked hard to get them tight as you hung them. They'll swell just fine and you aren't going shove any caulking in through that tiny crack and mess up the caulking job. However it is worthwhile to mention that the reason you virtually never get the seams really light tight is probably not a lack of craftsmanship. My father taught me that what is happening is that no matter how nicely seasoned a pile of lumber is when you pull a piece out of the pile, if you cut a plank out of it and hang the plank, the air can just get at the wood better. It is going to lose some more moisture and shrink a bit. Even the very slightest shrinkage will let you see light.
Do, please read the section (p. 117) on bunging over fastenings. Bunging is simple but so often done wrong. He mentions using a very sharp chisel with your other hand as a mallet. I've had good results using a very large very heavy chisel, called a "slick" with a two handed handle and an absolute mirror finish on the edge. This has enough weight that you can turn it with the bevel down and just slide it against the bung. The sheer weight of the slick will cut off neat shavings. You quickly get the feel for adjusting the angle slightly with each pass until you are shaving just proud of the surface a tiny fraction, when you can switch to coarse sand paper.
As he begins discussing fairing the planking (p. 121) Mr. McIntosh suggests a loaded gun to use on anyone trying to help you fair with a power tool. I am inclined to agree. However there is one tool that is the woodworker's equivalent of international terrorism. This is a true weapon of mass destruction. I refer, of course, to the power grinder. This destroys fairness and can literally require replanking the boat. You often hear people say they are only bad "if misused" or "in the wrong hands". I have had a number of people suggest to me that they were so skilled that they could use this tool. All I can say is that, after several decades of working on boats, supervising people working on boats, and observing others working on boats, I now automatically fire anyone who insists they can use this tool for fairing hulls. It's just too dangerous to have them around as sooner or later they decide to "show you" by tackling the planking of a customer's boat. The resulting thousands of dollars in damage will not amuse your insurance company. We narrowly avoided this a year ago, before we sold the yard, when I was out of the yard. The office manager stopped the guy and I got rid of him as nicely as I could the next day.
Anyway Mr. McIntosh's exposition on fairing caulked seamed carvel planking is very good. This method is actually pretty fast once you've done it a bit. I did note that he says he'd use a disc sander with a soft pad on the underbody instead of hand sanding because he was older. I don't insist on hand sanding but never use a running edge type sander like he's talking about here. Use a random orbit sander of some sort and keep it moving. You'll note he was apologizing here. If you stay with random orbit sanders you won't need to.
I really like his remarks (p.124) on caulking. People who don't know how to do this try to invent all sorts of amazing ways to avoid it. All you have to do is find somebody who caulks and have them show you how to do it. It has never taken me more than 15 minutes to teach anybody to caulk. The last person I taught was a middle aged woman who had never done anything more complex on boats than paint them before. She had absolutely no problem learning the whole process in 10 minutes. We barely spoke. I caulked a bit, handed her the tools, and she caulked a bit. I said, "OK you're now an expert, come get me if you have any problem with it." That was it.
The author's remarks on ceiling (p.131) are excellent. I'm not much of a ceiling person. I normally don't use it. However, his remarks on how and when and why are excellent.
His description of the conventional caulked seam carvel deck (p.151), which includes a nod toward unglassed plywood decks, is an excellent exposition on conventional methods. He even includes a brief ascerbic remark about bare teak decks, which should certainly get some negative press once in awhile. The only thing I can add that can be said in favor of conventional laid teak decks is that they absolutely require somebody to live aboard the boat full time to keep them wet down either by sailing or with a bucket. This means that even though the owner is probably working to pay the bills on this fancy yacht at least some young man or woman is actually being paid to liveaboard and maintain the boat and have a good life.
In his section on masts (p. 213-215), which contains a great deal of good perspective on traditional methods there is a least one piece of innovative stuff. This is his solution for flaws in an otherwise good mast. This is very much like the Scotsman method we evolved for repairing frames and other structural members. Anyway we have done destruction tests that have proved to our satisfaction that Mr. McIntosh's method will do a good strong elegant spar repair very inexpensively.
All in all this is a book you should have in your library if you build, repair, or own wooden boats.
255 pages, profusely illustrated, WoodenBoat Publications, Inc., 1987
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