Jim Michalak's Boat Designs
118 E Randall, Lebanon, IL 62254
A page of boat designs and essays.
(15jul01) This issue will repeat the essay on making a weighted rudder for your small sailboat. Next issue, 1aug01, I hope to review some happenings at our last Midwest Messabout.
SEWN SEAM BOAT BUILDING IN 1909...
...Reader David Beede found an excellent Russian website (in English) put together by Misha Naimark where you can learn how to make clinker boats with no nails, as was done in Northern Europe right into the 1950's. The technique predates the Vikings use of nails. The planks are hewn out of logs and sewn together with tree roots, as the fellow above is doing ( I think he is hammering in a peg that secures the lacing, not driving iron nails). Misha describes doing this without a saw since saws were advanced technology then. So he goes into the woods with an axe, a knife, a drill, a sharpening stone, and he comes out with a lapstrake boat! (And no doubt he is several pounds lighter for doing it.) I'm thinking CLC is making modern lapstrake boats with sewn seams and I'm just wondering...
John Bell's building an AF4.
SMALL BOAT RUDDERSBACKGROUND...
Here is an article I wrote a while back that appeared in the great paper magazine BOATBUILDER. I've included copies of it in my prototypes catalog since then. The article shows how I've made rudders for my own small boats.
Where I sail only a kick-up rudder works well. It's not because once a year you might strike a ledge and break off a fixed rudder. It's because our waters are generally shallow and a fixed rudder would require endless fussing on every trip. With the weighted kick-up rudder shown here you just blast along without giving the kick-up blade a second thought.
I have also tried kick-up rudders that weren't weighted, but were held down by lanyards. Nearing a shore or shallow I had to play the thing like a puppet and quickly ran out of hands because the tiller, sheet, and board all needed handling at the same time. The weighted rudder blade is much better. In this article I'll show you how I build a kick-up rudder from the ground up from plywood. This sort of rudder can be suitable for boats up to about 22 feet length.
The best way to make the blade is to laminate it from thinner plywood. I've seen warped blades made from a single piece of 1/2" plywood, but I've never had a problem with a blade built up from two layers of 1/4" plywood.
Cut out the plywood blanks and butter one up with glue. I prefer plastic resin glue. It comes as a dry powder and is mixed with water to the consistency of regular white wood glue. It's best to spread the glue with a notched trowel like you use to paste down floor tiles. Place the glued-up blanks together on a flat surface protected with plastic or paper, and tap a couple of light nails through them so they can't slide around on each other. Apply clamping pressure with weights like concrete blocks placed atop the blanks. Now stay away until the glue has set good and hard.
Now give the blade a final trimming and streamline the edges where required. (If your rudder, daggerboard, leeboard or centerboard vibrates in use, streamline the edges some more. That almost always cures the ailment.)
I called this the "counterweight" in the drawing but "sink weight" is a better term.
The sink weight should be slightly heavier than the buoyancy of the immersed blade. Wood is about half as dense as water, and lead is about 11 times denser than water. It works out that the area of the lead weight should be about 1/16th the area of the immersed blade, or maybe 7 percent of the area to give a slight negative buoyancy. For example, a blade that is 10 inches by 15 inches immersed is 150 square inches. The lead weight could be 150 x .07 = 10.5 square inches, which would be a square 3.24 inches per side. Cut a hole in the blade for the lead to the proper size, preferably toward the tip and toward the trailing edge. Bevel the hole's edges so the lead will lock in place by forming flanges around the blade. Also place some rustproof nails or screws around the interior of the hole to further lock the lead in place. Clamp the blade to a flat metal plate and place it level on the floor.
To figure the weight of the lead required, multiply the area in inches by the thickness in inches and again by .4. In the example, if the example blade is 3/4" thick, the weight of the lead required is 10.5 x .7 x .4 = 3.15 pounds.
To melt the lead, I use a propane camp stove. I place it right next to the job so I woun't have to tote molten lead around the shop. For a crucible I use a coffee can with a 1/2" pour hole drilled about 3" above the bottom of the can, with a long metal handle bolted to the side of the can. The crucible goes on the stove with enough lead wheel weights inside sufficient for the pour.
Begin the pour as soon as the lead is molten. (The steel clamps on the wheel weights will float to the top and not pass through the pour hole.) Take your time and be very careful with the pour, but it must be done all at once. Overfill the hole in the rudder blade somewhat to allow for shrinkage on cooling. Shut off the stove and walk away from the job for a few hours. Lead stays very hot long after it has solidified.
If the weight gets loose in the blade due to shrinkage, you can tighten it by placing the weight over an anvil and hitting the lead with a hammer. That squeezes the center and expands the perimeter.
Now contemplate what it's like to pour a thousand pound keel!
Laminate this exactly as you did the rudder blade. You need to add the downstop and it's amazing to me how sturdy this part needs to be. A block of hard rubber or phenolic plastic bolted in place might be best.
Don't make the tiller too short! Make it too long and shorten it later if needed. The tiller should fold neatly along the back edge of the rudder for storage.
Use light braided line, about 3/16" for the lanyard. Tie it to a small hole in the rudder's trailing edge. The hole needs to be located about where the raised rudder meets the aft end of the tiller. Then pass the lanyard through a hole in the back corner of the tiller, then forward to a small cleat on the top of the tiller. Pass the lanyard through a small hole in the base of the cleat and tie and loop for your fingers. To raise the rudder, yank on the lanyard and belay it around the little cleat. To lower the rudder, uncleat the lanyard and let the blade drop kerplunk against the stop.
This works very well on smaller sails that don't require multipart main sheets. Screw a fairlead solidly to the tiller's top face. Place the fairlead right above the rudder hinges so the sheet loads won't affect steering. Run the sail's sheet through the fairlead and forward along the tiller. You can secure the sheet merely by wrapping it a couple of times around the tiller's grip under your steering hand. Then you can steer and hold the sheet with the same hand. To release the sheet in a puff you need only slacken your grip without letting go of the tiller. You can also belay the sheet around the rudder lanyard cleat if you are feeling lucky.
I haven't figured out hinges yet. I think the best ones are welded up from stainless steel, but I'm working towards building boats totally from lumberyard stuff. Stevenson Projects used barrel bolt locks for hinges. Payson used eyebolts and rods. Dick Scobbie used door hinges with big cotter pins for pivots. Seeing those, I tried some door hinges on a dink rudder and was quite satisfied, especially since they came from the scrap bin. Most door hinges won't mount as simply as real boat fittings - check out the angles they swing through and do some head scratching.
One thing I'm sure of: Don't rely on gravity to keep your rudder on your transom. In a knockdown the rudder may unship and leave you with a very wet boat and no rudder. Also, with the sheet fairlead on the tiller as I've shown it, the sheet can produce a large upward force on the assembly in strong winds and lift the whole thing out of conventional fittings. Both of these things have happened to me. Now I secure conventional fittings against knockdowns and sheet loads by drilling as small hole in one pintle below the gudgeon and putting a cotter pin through the hole.
THE CARY HINGE...
I wrote the above a few years ago. But very recently I got letter from Ted Cary in Florida. He has a way of making effective rudder hinges from scrap seatbelts.
Here is his description:
"Thought you might be interested in my solution to the rudder pintle problem. My first experience trying to hit two gudgeons with the pintles in a big chop, while hanging over the transom, disqualified that system for me. I came up with a simple track and slide system, then epoxied up the slide and rudder stock around pieces of connecting webbing strap. The stap flexes when you steer. You can bend a seat belt a lot of times before it breaks, and nylon doesn't corrode in salt water. I found that you must align the strap longitudinally across the direction of the flex, and you must not allow the epoxy to harden on the strap where it has to flex. But the ends of the strap have to be well saturated to hold the slide and the rudderstock halves together. The most successful way I've used to avoid glue where I don't want it is to get the parts all glued up and assembled with clamps, keeping the glue off the flex line as much as possible. Then use a syringe or squirt bottle to saturate the flex line with vinegar, working it through the fibers, before the glue starts to set. The acetic acid neutralizes the amines in the epoxy hardener, so it won't polymerize. The clamped parts won't allow the vinegar to reach the glue on the strapping between them, so it goes off where you want it to."
"Dropping the triangular section slide down the transom track installs the rudder in a fraction of a second.This hinge rig has been working great on several dinks for over 4 years now."
Well, I must try Ted's system sometime. I think model airplane guys have been using flexing plastic hinges for a long time. My only comment might be that I would also lock the slide it to prevent it from unshipping in a knockdown.
I review the happenings at our last Midwest Messabout.
PIRAGUA18, SWAMPBOAT, 18' X 3', 90 POUNDS EMPTY
I reviewed the 14' Piragua last issue. Here is the same boat stretched to 18'. The width of the boat remains at 24" maximum on the bottom flaring to 30" maximum inside the wales, too narrow to stand up in. It is intended to be paddled with a double paddle like a kayak. The stretch creates more weight carrying ability. While the 14' Piragua will take two adults in a pinch, Piragua18 will float 500 pounds before its bow and stern start to drag the water. The empty hull should weigh about 100 pounds leaving 400 pounds for people and gear and that should be enough for two grown men.
I've also shown on the drawing how I would rig a boat like this with an electric trolling motor. A typical trolling motor and 100 amphour trolling motor battery will together weigh around 100 pounds and this hull will handle the weight of the rig better than the shorter boat. I'm thinking that is no need to get a large motor. The smallest I've seen for sale lately was 30 pounds thrust which is usually rated at 1/2 hp. That should drive the boat about 5 mph. Better would be to throttle to about half power which should give about 4 mph. The battery has to be a full sized deep cycle trolling battery. There batteries should never be deeply discharged, in spite of their name, and for long life they should not be discharged more than 70% of their capacity, and they should be promptly and fully recharged after use. At full power the 100 amp hour battery should give about 1.25 hours of endurance for a range of about 6 miles in calm conditions. At half power the battery should give about 3.5 hours endurance for a range of about 14 miles. Note that at high rates of discharge a battery has inefficiencies that prevent it from delivering its full charge. Anyway, power and hull should together weigh about 200 pounds, still leaving 300 pounds for folks.
This hull might be a good starting point for a beginner's sliding seat rowing boat. It has the length and light weight and wide open interior that would take rails for the seat. She's way too narrow for rowlocks mounted on the wales. You would have to add riggers. No doubt the best approach would be a drop in unit that has rails and riggers and foot braces all bolted together. You would have to secure it to the hull somehow but that could be done in such a way that the unit could be removed and the boat returned to its canoe configuration.
Anyway this is powered I think it would be a good camper's boat assuming there is no real rough water about. The ends are boxed in with buoyancy/storage volumes and the center 9' wide open for sleeping. The hatches into the storage boxes are small, only 6" wide, in order to make them less likely to take water in an upset.
Construction is simple nail and glue like the original Piragua. Three sheets of 1/4" plywood will do it. I don't think these boats need epoxy coatings if they are stored under cover. The chine corners need to be armored with fiberglass set in epoxy and the inner seams given a fillet of epoxy putty to keep water from creeping into the seams.
Plans for Piragua18 are still $15 until one is built and tested.
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.
Caprice: Chuck Leinweber of Duckworks Magazine has finished the prototype Caprice. I got a ride and some photos at the Midwest Messabout and will have a full report soon.
Normsboat: This is an 18' sharpie being built by Cullison Smallcraft in Maryland. You should be able to check on it by clicking through to his web site at Cullison SmallCraft (archived copy, actual site no longer active). He is presenting an excellent photo essay of how to assemble a flattie. This boat has been launched and I'm waiting for photos and a test report.
Family Skiff: A Family Skiff has been started in Virginia.
HC Skiff: One of these is going together in Massachusetts.
Electron: An Electron has been started in California.
Mayfly: A prototype of the original 14' Mayfly is going together in New York state.
AN INDEX OF PAST ISSUES
BACK ISSUES LISTED BY DATE
Mother of All Boat Links
Messing About In Boats
The Boatbuilding Community
Kilburn's Power Skiff
Bruce Builds Roar
Rich builds AF2
Herb builds AF3 (archived copy)
JB Builds Sportdory
Hullforms Download (archived copy)
Plyboats Demo Download (archived copy)
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