Jim Michalak's Boat Designs
118 E Randall, Lebanon, IL 62254
A page of boat designs and essays.
(15December10)This will rerun the bevels essay. The 1 January issue will take a look at mast tabernacles.
THE BOOK IS OUT!
BOATBUILDING FOR BEGINNERS (AND BEYOND)is out now, written by me and edited by Garth Battista of Breakaway Books. You might find it at your bookstore. If not check it out at the....
ON LINE CATALOG OF MY PLANS...
...which can now be found at Duckworks Magazine. You order with a shopping cart set up and pay with credit cards or by Paypal. Then Duckworks sends me an email about the order and then I send the plans right from me to you.
This is Rovie Alford's modified Harmonica. He has lenthened it a bit adding a dedicated motor well area, not a bad idea!
I don't know if there are many topics that cause more confusion to boatbuilders than bevels at bulkheads and transoms. Some slant in and some slant out. Sometimes you can measure them right off the lines drawing but often you can't. To a certain extent the subject has become less important with taped seam construction, but many glue and nail boats are still being built and as you will see, I like to use nail and glue construction in the very early stages of building a taped seam boat because it allows a quick and solid alignment when that is most appreciated, as shown in this photo of Dale Dagger in Nicaragua with a Toto project. At this stage the hull has used conventional construction which required cutting bevels on some of the elements. Dale asked for clarification on one of them.
I did update the Toto drawing to include the full sized bevel drawings shown below. One is for the side edges of bulkhead 10 and the other is for the side edges of the transom.
When I figure out the dimensions of the plywood piece that forms the shape of the bulkhead or transom, I take its dimensions off my lines drawing as if the piece had no thickness.
But the real panels do have thickness. So I rig it such that one face of the panel lies on the plane where I took the panel dimensions and mark that face "Dimensions to Here". Now if the side or bottom panels are sweeping in or out from the dimensioned face, then the other face of the bulkhead or transom will need to be smaller or larger than the dimensioned face.
Let's take the case where the adjacent panels are sweeping outward from the dimensioned face. We'll call this one an "outy". The transom bevel on Toto is as outy. The dimensioned face of the Toto transom is on the plane of the end of the boat and the transom's forward face needs to be slightly larger than the dimensioned face to allow for the outward sweep of the side panels, which measures 10 degrees at that point. How much larger? The Toto transom is supposed to be 1/4" plywood with a 3/4" thick framing stick, for a total of 1" thick. So to allow for the 10 degree bevel each side needs to have 1" X tan10 = .176" extra material which is 3/16" to most of us. But when I build one of these outy's myself, I pay no attention to that extra thickness. See the figure below to see how I do it on my own boats.
I've found the best tool to cut straight bevels is a table saw. First I cut the side sticks on the table saw to the correct bevel. Then I cut the transom (or bulkhead) panel out of plywood to the dimensions with no bevel, just a square cut. Then I glue and nail the beveled sticks to the plywood piece such that a straight edge along the beveled stick will just kiss the "Dimensions to Here" edge. That's it. I haven't fussed with that "extra material needed" measurement at all. This gives a nice straight edge to the right dimensions and it doesn't really get involved with thicknesses - if you use thicker or thinner wood than specified it will still fit.
"But," you say,"there's a little triangular area on the edge of the plywood that isn't right." True. I fill that with glue when the panel is glued and nailed to the side. That triangle isn't very big. On this 10 degree bevel it would max at .045". No problem. To me the glue there is really a hope of sealing the grain on the edge of the plywood, not a strength issue since a lot of that ply edge will be end grain anyway and about useless for glue strenght.
Now let's talk about the inny. Bulkhead 10 on Toto is an inny. (I suspect the trouble Dale had was that he made this one an outy the first try.) The basic dimensions of bulkhead 10 were taken 10' aft of the bow tip of the boat. That is the actual front face of the bulkhead, the face marked "Dimensions to Here". At that point the sides are sweepin inward 7 degrees as they go aft. This bulkhead is also 1/4" plywood with 3/4" sticks for a total of 1" thick. So the aft face of the bulkhead needs to be 1 X tan7=.12" smaller on each side edge than the front side edges.
Innys are a little easier to picture. You could make all the edges square to the basic dimensions and then run them through a saw set to the proper bevel to shave off the extra material. I used to do them that way and still do on occasion. The problem I have is that I use a bandsaw for this which doesn't care to cut straight. And a large bulkhead is a beast to run through the saw all at once. You could try a saber saw or circular saw set to the proper bevel if you think you are good enough at it to keep the blade just kissing the edge marked "Dimensions to Here". I' not.
So I've gone to making the inny bulkhead the same way as I make an outy. First I prebevel the framing sticks with a table saw. Then I cut the plywood panel to shape with no bevel, just a square cut. Then I glue and nail the sticks to the sides of the panel. If the bevel is severe I do try to line up the face of the bevel stick with the "Dimensions to Here" edge of the plywood. Then I will have a small triangle of plywood protruding from the beveled face. I can trim that off later. In the case of a small bevel, I don't do that. I just line up the stick with the back edge of the panel. When I assemble it to the sides there will be a little triangle to fill with glue again. And the panel will be slightly wider than what the lines call for. In the case of Toto's bulkhead 10 the error would be .25" X tan7 = .03". Nothing to worry about.
RAIDER, ROW/SAIL BOAT, 24' X 6', 500 POUNDS EMPTY
Norm Wolfe built his Normsboat to my design so we were acquainted. He visits the Baltic countries regularly and had participated in a "Raid" in Finland and was going to make it a regular thing, maybe with his own boat. A Raid is a pseudo race with boats that row and sail, over a fairly long course taking several days. But the racers don't sleep in their boats. Instead they do a stage each day, sleeping and partying on shore in nice prearranged places each night. So the "racers" need carry no gear except what they need during the day and a rescue boat is always nearby. I think each boat must have at least two crew. So what sort of boat do you take? A true sailboat will be helpless in calm and a true rowboat will get left behind in a breeze. Norm wanted something that would row well but convert quickly to sailing and even do hitches with oars and sails together at the same time. He wanted four oarsmen.
I sat with him at McDonald's one day and we sketched this:
The idea was a boat long enough to take four at the oars, with a folding rig that could be left up while rowing or quickly taken down and up again as the winds advised. I suggested a V bottom as it would row the best and beaching was not going to be a problem. The lugsail was lifted from the Normsboat. (I see we were thinking at the time of offset oarsmen each with a single long oar but it was first rowed with pairs of oars. I have been told that rowing with single long oars is preferred in rough water but that way you will always need an even number of oarsmen.)
The plan was to build in Europe and leave the boat there, so the drawings had to be in metric dimensions. I had never done metric because I found when I first started that metric tapes and scales were not commonly available in the US, still aren't, so I stuck with English measures. But I did draw this one in metric and was always worried about real goofs going unnoticed by me. I don't know if there were any. The boat was built in Estonia, I think, in the back of a car repair garage by a non boatbuilder. But that is OK. My boats are designed to be done that way. I never heard from the builder concerning any mistakes although I suspect he is the type of guy who forges ahead regardless and gets it done. I thought he did a fine job and I should say that there are some major twists in the panels in the bow area to deal with. I can see small changes from the plans but nothing I might not have done myself. He has a slotted gunnel. And he used a modified flag pole to replace the wooden one shown on the drawings. I should mention here that I am pretty sure a buoyant wooden sailrig is a safety factor for a sailboat in that it will prevent a capsized boat from turning turtle by my experience. I still say wood is the best material for a small sailboat. But if you have the proper flagpole at hand......
I used my usual pivoted leeboards, with one hitch to the usual. I thought she needed two, one on each side, to have enough lateral board area in a tough slog to windward. In the photos you can see the guards on the gunnel.
The Raider was finished in time for the 2008 Finnish Raid. Norm jetted over a bit early to sort it out or at least get used to it. He took along his Normsboat sail. The race was apparently its first time in the water, more or less. Here it is being paddled out for a sail:
And here it is with some of its rowing crew:
Norm assures me these are hardy men, Vikings all! That is Norm, I think, in the bow seat with no oars urging them on. Can't you hear him yelling, "Come on! Pull! Pull! Break your backs!", just like in Moby Dick. Looking at the photo I thought they might do better by sitting a little higher on say a flotation cushion and maybe with longer oars, but you never know. I gave each man a meter of space as I recall and that looks to be enough. You can see the folded rig is OK. Norm thought he might revise it to fold a bit lower.
Well, I can't tell you how Norm and crew did cuz I don't know. But they did it!
Raider is a taped seam boat, needing ten sheets of 3/8" plywood.
Plans for Raider are $40.
Some of you may know that in addition to the one buck catalog which now contains 20 "done" boats, I offer another catalog of 20 unbuilt prototypes. The buck catalog has on its last page a list and brief description of the boats currently in the Catalog of Prototypes. That catalog also contains some articles that I wrote for Messing About In Boats and Boatbuilder magazines. The Catalog of Prototypes costs $3. The both together amount to 50 pages for $4, an offer you may have seen in Woodenboat ads. Payment must be in US funds. The banks here won't accept anything else. (I've got a little stash of foreign currency that I can admire but not spend.) I'm way too small for credit cards.
I think David Hahn's Out West Picara is the winner of the Picara race. Shown here on its first sail except there was no wind. Hopefully more later. (Not sure if a polytarp sail is suitable for a boat this heavy.
Here is a Musicbox2 I heard about through the grapevine.
This is Ted Arkey's Jukebox2 down in Sydney. Shown with the "ketchooner" rig, featuring his own polytarp sails, that is shown on the plans. Should have a sailing report soon.
And the Vole in New York is Garth Battista's of www.breakawaybooks.com, printer of my book and Max's old outboard book and many other fine sports books. Beautiful job! Garth is using a small lug rig for sail, not the sharpie sprit sail shown on the plans, so I will continue to carry the design as a prototype boat. But he has used it extensively on his Bahamas trip towed behind his Cormorant. Sort of like having a compact car towed behind an RV.
And a Deansbox seen in Texas:
The prototype Twister gets a test sail with three grown men, a big dog and and big motor with its lower unit down. Hmmmmm.....
Jackie and Mike Monies of Sail Oklahoma have two Catboxes underway....
Tom Wolf has completed the first Toon2 that I know of and was waiting for some good testing weather...
AN INDEX OF PAST ISSUES
BACK ISSUES LISTED BY DATE
Mother of All Boat Links
The Boatbuilding Community
Kilburn's Power Skiff
Bruce Builds Roar
Rich builds AF2
JB Builds AF4
JB Builds Sportdory
Hullforms Download (archived copy)
Plyboats Demo Download (archived copy)
Brokeboats (archived copy)
Brian builds Roar2 (archived copy)
Herb builds AF3 (archived copy)
Herb builds RB42 (archived copy)
Barry Builds Toto
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