Jim Michalak's Boat Designs
118 E Randall, Lebanon, IL 62254
A page of boat designs and essays.
(15APR98) This issue has (at last) some photos and test results of my new AF4. Next issue, about 1May, will continue the sail force discussion.
TEXAS MESSABOUT NOTICE... Tim Webber is putting on a messabout near Houston on April 25 and 26. For more info see his page at http://www.infohwy.com/~tbertw/messabt.htm
A NEAT WEB SITE...
One of the advantages of the web is that ordinary folks can put up a page that has really good information, the sort of information you might never read in a slick magazine or web page. I can recall the first time I read that great paper magazine, Messing About In Boats. Bob Hick's lead time for articles was maybe 4 weeks instead of 4 months or maybe a year, if ever, for the same info in a slick magazine. Quickly I dropped my subscriptions to the slick magazines since everything there was dated. Not only that, the slick magazines had their professional writers interpreting the information while MAIB printed the original authors' letters and articles. So, with that in mind I turn you to John Bell's page at www.mindspring.com/~jmbell/boatyard.htm. I especially found informative his tale of his first sail in his Windsprint. (John's page requires a frames capable browser.)
In a way Alison's Fiddle No 4 was born on this web page back in December. If you weren't a reader then you can go to the index towards the end of the page and brush up on why and how it was designed. I kept track of things as I built and tested, to a certain extent, and here's the latest report.
My rough records show I spent 120 hours and less than $500 on the AF4 project up until I launched the boat.
She was built to the largest extent with materials from the local lumber yard, although I caved in to the epoxy agents and bought a 3/4 gallon kit of epoxy from RAKA and used it for fortifying the chines both with a double layer of glass tape on external corners, and a fillet of thickened epoxy around the inside corners in hopes that it would seal things and prevent water in the cockpit and cabin from seeping up into the end grain of the plywood. We'll see how effective it is.
The plywood I got from the lumberyard was unlike anything I'd used in the past. In the past I had used AF exterior fir which is usually three equal plies with the usual problems with voids and splits and holes to be filled. Never had a problem with the exterior glue and the panels were perfect as far as length, width and squareness. I had also used lauan underlayment. That plywood had very thin, but nice, outer plies with a center ply with no voids. Nice to work with but be careful when laying out shapes because the lengths of the panels was not a constant 96", not even sure if it was really square. Well, the latest 1/4" (actually it about .20") plywood is stamped "exterior" from a US mill, but it has the characteristics of lauan in that all the plies were about perfect and free of voids. But there is no lauan. I don't know what kind of wood is in there but it looks like fir on the thick inner ply and something like birch for the very thin outer plies. It cost $20 a sheet and is the best exterior ply I've ever worked with with no waste due to voids (or anything). The 3/8" (acually it's .34") has two thick plies of fir with a single very thin face of that nice mystery wood. Again no voids except those obvious on the thick fir ply that shows. Again, you need to double check the length of the panel. $22 per sheet so I had about $200 in plywood in the boat.
For framing lumber I used ordinary pine white wood. The lumber man gave me a hint on getting the best stuff. The best wood comes in the larger boards, say 2 x 8 by up to 20' long, used for steps and such. Not really that expensive per board foot but the board is huge, probably too much for a man to horse around by himself in a shop. He had a large amount of this wood, a lot of it about clear. I couldn't handle the big board but the lumberyard with rip it for a modest fee. I bought smaller boards like 1x10's and 16 feet long. I had to scarf pieces to get out the wales and chine logs for this 18' boat. Maybe I had $100 in lumber.
For fasteners I used galvanized nails from the yard and that was probably a mistake. They're very cheap and strong but you must be careful not to sand them and I'm sure I've sanded a lot of them. Bronze nails might have cost another $10 or $20 and I could have sanded away with no concern. I used about 3 pounds of Weldwood glue. And that RAKA epoxy for the chines and tought spots. For the most part I worked in temps of 40 to 50 degrees, well below the advice of the glue folks. At times I'd fire up the kerosene heater and cover the project with a tarp and tried to get the glue to set. Seems OK. One problem I did have was with the epoxy. I used the fast set hardener which is supposed to be good down to 40 degrees. But some areas seemed to not cure and I think the problem is that at cold temps you can't rely on getting everything mixed well (I really tried). Later I went to heating the epoxy bottles in a cabinet before pouring and mixing. Then let it cure in the cold. That worked much better. I had no troubles with the Weldwood. I'd say I spent $100 on glue and fasteners and glass.
For paint I used the local paint store stuff, two coats of oil based primer topped with latex color coat. The kerosene heater helped a lot. The dark green bottom took four coats to cover and the light buff top took only one coat. The interior cabin walls are white and the floors are all varnished with three coats of oil based spar varnish. The varnished floors and wales show wear far less than any painted surface and will be easy to touch up. The boat really needs more paint as the work was done in the winter shop with poor light. I hope to give it a light sanding and another coat when the testing is done. I spent about $60 on paint.
This boat has almost no fittings, especially compared to a sailboat. I guess it has two cleats, oarlocks, and three line guides, all of which I had on hand.
THE FINISHED BOAT...
I weighed my trailer with no boat on it and it weighs 200 pounds. The boat and trailer combination weighs 500 pounds with no gear, so the empty boat weighs 300 pounds. It's a bit lighter than I had thought and I'm tickled about that. The motors I have weigh between 30 and 60 pounds and with a bit of gear aboard you would think the rig weighs about 600 pounds. The idea was to tow the rig behind my Escort but I haven't done that yet. The car has towed that much before.
The photo below shows the cabin. The chair in the cabin at the time is one of the low "beach chair" sort, about 9" off the floor and there is enough head room for a man to sit on that chair. It's quite nice for someone used to camping in a more open boat. Not shown is a cover sewn from polytarp and held in place with "lift the dots" that covers the open slot and the doorway. When rolled up it is very compact. By the way, when you sew up a cover like this remember that you need to be able to button it up from the inside and also get out fairly easily. On AF4 and Birdwatcher I've sewn a small PVC pipe into the ends with a bungee looped through. And there are tangs located near the ends on which to hook the bungees. So when camping, the cover is secured with snaps (or equal) except for the ends, which are left free to the extent that you can get in and out. Once inside the cabin you grab each bungee and hook them over the tangs.
I was able to salvage my old Jinni trailer although the 18' boat clearly has maxed it out. (I think the trailer is really supposed to be for a 12' power boat. The AF4 is well within the 600 pound rated capacity.) I pretty well followed the trailer instructions given in a previous issue. I converted it back to longitudinal bunks, which work well for a boat with a flat run. The first trip with the trailer was a bit of a bother. I added goal posts from PVC pipe, greased up the bunks, and lowered the bow eye for the bow tie as low as possible. I found I can get by easily without a winch. My bow post has cleat welded to it. My bow tie is fastened to that cleat, is passed through the boat's bow eye, and back to the post. So it approximates a two-to-one effect as long as things are kept slippery.
Testing is still going on but I've got a few numbers I can hang on the boat. All testing was done with me solo so the all up weight is about 550 pounds.
With my old Clinton engine (1970?), at half throttle, about 1 hp, she went 5.7 mph. At full throttle, about 2 real hp, she went 7.5 mph. No fuel consumption runs yet.
With the Sears 7.5 (1970?) I did more testing. From runs on my boat Twixt last year I though this motor really peaks at less than 5 hp. Full throttle on AF4 gave 12 mph. I also ran three fuel consumption tests over a 12.5 mile loop to see how things agreed with earlier predictions. Speeds mentioned in the tests are averages over the loop. At a throttle setting just above idle (I see no point in going slower) AF4 averaged 5.8 mph and 18 mpg. At 6.9 mph average speed she got 15 mpg. At 10 mph average (really about full throttle slowing for no wake zones, and rough water) she got 14 mpg. Not too bad. This engine is old technology and a newer motor might do a lot better. The big fuel economy payoff predicted by slowing down really didn't show. I figure the engine simply is not as efficient throttled way back. But at full throttle the fuel ecomony is actually better than I expected.
With the Johnson 10 (1956) the boat really flew but I have no timed runs yet because I can't get the engine to run at full power long enough. I think it has the wrong carb float. Anybody know where I can get the proper float? I emailed the "Marine Parts Finder" after finding them with a net search. They didn't answer my email. Still tinkering and making progress. I think the idea is for this motor to be THE motor for this boat if I ever get it running right.
Here is a photo of AF4 at full throttle with the Sears 7.5 at about 600 pounds total weight:
The bow rises a bit as you see when she planes. It's not a sudden rise and it stays at about the angle you see at all speeds above 6 or 7mph. From watching the wake I'm pretty certain the biggest waves occur at about that speed and then she climbs up a bit and the wave action is reduced.
TO BE DONE...
There's quite a bit to be done yet. Maybe fuel tests with the Clinton, and speed and fuel tests with the Johnson. Also towing behind the Escort. And a few campouts. And rough water testing. Will report on these things as they happen.
(14 April. Was able to get the Johnson 10 to run at what I think was full throttle and it pushed the AF4 at 17mph. The boat levels out some at that speed, the bow dropping down a bit. )
AF4 PLANS ARE NOW $30...
You get the blueprints, keyed instructions and a blow-by-blow essay of how I built mine.
JONSBOAT, POWER SKIFF, 16' X 5', 200 POUNDS EMPTY
Someday I may get to put my full catalog on the net. For now I'll put one design in each issue.
Here is a plain vanilla boat if there ever was one. Since I designed Jonsboat I've learned a few things about these light flat power boats from AF4. In particular, a 10 horse motor will push one as fast as anyone with good sense will want to go, something I didn't know before AF4. They can get by with very small motors in small waters, too. Here is the current writeup in the catalog of prototypes.
Jonsboat is just a jonboat. But where I live that says a lot because most of the boats around here are jonboats and for a good reason. These things float on dew if the motor is up. This one shows 640 pounds of displacement with only 3" of draft. That should about be the load with the hull, a small motor and two medium sized men. The shape of the hull encourages fast speeds in smooth water and I'd say this one will plane with a 10 horse motor and one man aboard. With two aboard she will do well also, but "planing" with that weight might be more in the eye of the beholder. I kept the center of this one wide open as I usually like to do but another thwart could be added straight away.
There's nothing to building Jonsboat. There's five sheets of plywood involved and I'm suggesting 1/2" for the bottom, deck, seats and transom, and 1/4" for the sides and seat frames. It's all stuck together with glue and nails using no lofting or jigs. I always suggest glassing the bottom and chines for abrasion resistance but I've never glassed more than that on my own boats and haven't regretted it. The cost, mess and added labor of glassing the hull that's out of the water is enormous. Some folks figure complete "encapsulation" with epoxy traps water and encourages rot. I don't believe that myself, but I've avoided complete encapsulation because my pocketbook and my patience won't stand it. Glassing the bottom is different, by the way, because it doesn's show and need not be glassy smooth. No fussy finishing required.
I usually study the shape of the commercial welded aluminum jonboats. It's surprising to see the little touches the builders have worked into such a simple idea. I guess they make these things by the millions and it's worth while to study the details. Anyway, this Jonsboat is a plywood copy of a livery boat I saw turned upside down for the winter. What struck me about it was that its bottom was a constant width from stem to stern even though the sides had flare and curvature. When I got home I figured out how they did it and copied it. I don't know if it gives a superior shape in any way but the bottom of this boat is planked with two constant width sheets of plywood.
I'd use a 9.9 hp motor on one of these to allow use on the many beautiful small lakes we have here which are limited to 10 hp. But I'd say she'd be happy with a lot less - you might consider shortening her to 12', build all from 1/4" ply, and cartopping.
Plans for Jonsboat are $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. (If you order a catalog from an internet page you might state that in your letter so I can get an idea of how effective this medium is.) Payment must be in US funds. The banks here won't accept anything else. (I've got a little stash of foreign currancy that I can admire but not spend.) I'm way too small for credit cards.
Anyway..... Anytime a design from the Catalog of Prototypes starts getting built I pull it and replace it with another prototype. So that boat goes into limbo until the builder finishes and sends a test report and a photo. There are three boats in that catagory right now.
The Texas Scram Pram, a 16' multichine Birdwatcher type, is being touched up and registered and should be back in the water by the time you read this. Should be at Tim Webber's messabout near Houston.
No new word on Skat . But the West Coast Spy who sends me Skat reports will soon start the prototype of a very recent design I did called Sportdory, 15' x 4' for rowing only. It's of the usual size and shape but this one is designed from the get go to be taped seam. I think there are fewer than 20 pieces of wood in the hull and that counts the usual butt plates I like to use. Three sheets of plywood. The Spy says he plans it to be a 2 day project. He's built two of my boats before and may get away with it. But you can't put a finish on a boat in two days.
The Way Up North AF3 project got a growth spurt over the Easter weekend with sides attached to the bulkheads, chines and bottom in place. Waiting for the bottom glass work to finish and the boat is probably flipped upright by now. Normally I don't publish the names of the prototype builders as work is underway but this man is Herb McCleod up in Edmonton. He has a neat web page and is talking about the AF3 there. No need for me to be hush hush.
Harmonica (ex Fusebox) is back in progress. I take it that the builder has finished the bottom and flipped her upright because he is tinkering with the windows and fitting out the interior. This will be a very detailed boat with elaborate Victorian motif, something I hadn't dreamed of when I designed it. Nothing wrong with that and I'm looking forward to seeing his interpretation.
I got this nice paper letter the other day from the Houston area (boy you guys are active there!):
Just a note to let you know IMB is alive and looking good. I turned the hull over last Sunday and started on the topside and inside. About 95 hours so far in 39 days. The boat looks beautiful. I think my final weight will exceed your 350 pounds number by something but I don't expect a problem. I wonder how much weight is required to sink her to 7 or 8 inches. Might be good to know. I have grand plans for this boat.
The building process has been pure fun. Your plans are great with only one wrong number . (He didn't say which one.)
So another IMB is on the way. The last one was sold before launching or any photos.
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