Jim Michalak's Boat Designs

118 E Randall, Lebanon, IL 62254

A page of boat designs and essays.

(15Dec03) This issue wil look at messing with motors in 2003. The 1jan04 issue takes a closer look at Bayard Cook's AF4.



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....


...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.


Bayard Cook & Co. go for an AF4 ride.




Contact info:


Jim Michalak
118 E Randall,
Lebanon, IL 62254

Send $1 for info on 20 boats.



Messing With Motors 2003

I did a fair amount of messing with motors last spring and summer. You might recall the web issues where we measured prop pitch and then with Max's handy tach and my ever handy gps we figured out prop slip. Then came fuel tests and finally my thrustometer that measured thrust at the prop as the boat sped along. I got my money's worth out of the AF4 again.


You might recall I had some small free Elgin motors from the 50's that I could not keep running for lack of a convenient source of parts. I gave two away and put the other two in the corner where they will be forgotten. One has a bad bearing and the other a sorry ignition.


The 3.5hp Scott, actually sold as a Wizard by Western Auto in the 60's, wasn't used at all. Never did find a recoil starter or carb linkage for it but haven't given up on it.


This one has a Clinton power head that uses common Tecumseh ignition parts so I've been able to keep it running. If it has a problem it is that the lower until won't hold lube long although that is a cheap thing to keep up with, if inconvenient. I do have another lower unit that ought to swap. . Here it is beside my Goodyear 12.


The white motor in the photo is my Goodyear 12, about 1956, that I picked up at a swap meet last year. It got a fair amount of use this year being well suited to my AF4 especially when I'm solo, which is the norm. An older motor that is noisy. At reduced throttle it is a nice sort of noise, a throb, but at full throttle the noise will quickly remind you that high power is stressful all around. No problems with this old winner.

More or less identical to the Goodyear 12 is my Sea King 12, also Gale made in 1956 but with different paint and cowling appliques. These two motors are so alike that I wonder if a blindfolded user could tell them apart in operation. As I recall from the testing we did, the performance of these two is also identical. "Well," you say, "of course they should be." I agree but as you will see later motors identical on the outside can be very different in use. Here is a photo of the Sea King 12.

SEARS 5....

The small white motor next to the Sea King 12 is a Sears 5, really an Eska I think. It has an air cooled Tecumseh power head that uses ignition parts from the lawnmower rack at the hardware store. Iin the past were first it blew out its water pump impellor. A water pump on an air cooled motor? Yes, the Sea King 3.5 has one also and they cool the exhaust system. But Max showed me that older similar motors did not have the pump, instead using a tube pickup behind the prop that uses the boat's forward motion to ram water up into the exhaust. So I converted the Sears over that way quickly and easily and it works great. With direct drive the boat is always moving when the engine is running so the water is always pumping. I suppose if you had a boat that wouldn't exceed 2mph or so at full throttle the pumping system would not work, not the case for the AF4 which perks along nicely at maybe 6 mph at 2/3 throttle with this one. Very cheap with fuel then, maybe 1/3 gph and I often use this as a slow speed cruiser (with a seat cushion stuck in front of the cowling to deflect the noise).

Because of its light weight and good power and economy this has been my main backup motor on AF4. But there was always a problem starting it cold. My current theory is that this motor was designed to be stored in the trunk of your car, with shutoff valves everywhere and a drain on the carb bowl. That drain always leaked on mine so I epoxied it shut. Even though I don't store it in my car's trunk I do close off all the shutoffs. Now I figure that once the shutoffs are opened it takes a good while for the carb bowl to fill, thus the hard cold starts. I used to pull on the rope ten or fifteen times and say "What's the use." and Max would come over and pull the rope once and off it would go. I thought then it was due to his way with motors but now I think it just takes that long for the carb bowl to be full and ready. So I open the shutoffs when I launch the boat even if I don't plan on using the motor. And it went a lot better this year.

SEA KING 15....

Another Gale product from about 1963. These Sea Kings were all sold by Montgomery Wards. This one has full sound proofing and I would guess is half the noise of the two Gale 12's. Better vibration isolation too. Also a much better cowling design than the 12's. One latch holds the cowling on where the 12's need minor surgery removing nine screws as I recall to look at the insides. The extra 3 hp is nice when taking on a passenger, remembering that a planing boat usually needs another horse for each 50 pounds of load. Fairly fuel efficient. Since it is so civilized this became my main AF4 power.

The only problem I have with this motor is water leakage into the lower unit. It was repaired by a previous owner with epoxy putty and probably once had water freeze in the prop region. Still it leaks to the point where I feel I have to check the lube there every couple of trips to the lake. Not expensive but a bit of a pain. It got worse during this past year and I took a long look at it and saw another crack forming above the gear torpedo. I filled that one with epoxy putty. Seems to be better but didn't have a chance to scope it out at the end of the season. It would be great to find that fixed it since that is really the only thing wrong with this motor.

JOHNSON 5.5,,,,,,

Also from 1963 as I recall and a real sweetheart. This one never pushed the AF4 as quickly as did the Sears 5. It found its way onto the stern of my Birdwatcher where half throttle gives 5 or 6 mph, faster than you can sail in a good breeze. At half throttle this one is so smooth and quiet that 'tis better than sailing usually. My usual plan now with Birdwatcher is to go out in really light winds and motor to windward say 5 miles in an hour and then set sail and drift on reaches and runs all day.

This motor gave me no troubles at all this year. Remember is past years she threw a rod and had lots of problems with odd power losses (besides throwing the rod). I replaced all of the fuel hoses and clamps and that seems to have fixed that. I think it was ingesting air at loose hose fittings from time to time.


This one was a freebie. Some one gave it away at an antique motor meet. Called a Golden Jet 400 which I thought might mean 4hp. Would not run beyond an occasional pop. Back to the lawnmower rack at the hardware store for another set of ignition parts and now it runs. Not much power though, I would say no more than 2 hp. Maybe the "400" means 4 cubic inches? Here is a photo taken on my thrustometer:

Funny thing is that the Sears 5 with its fancy, but pain-in-the-butt, cowling removed looks identical to this one. But surely it has twice the power. This little one has gone into storage since it doesn't have enough power to push the AF4 in a meaningful way.


I don't know which chain store sold the Buccaneer brand but this one is another Gale 12, no doubt from 1956 also. I saw this one at the motor meeting also but paid $80 for it. It appeared to have had little use and with such good luck from the other Gale 12's I shelled out and took it home. Unlike the other 12's this one has full sound proofing. Its cowling is even more complex than that of the others.

Once home I noticed it would not go into reverse. Removing the plate on the lower unit to get access to the shifting rod showed the gears would indeed shift in and out but for some reason the shifting lever can't be adjusted to do the job. Eventually I got it adjusted to work but it is clearly way out of spec in some way that could only be determined by removing the power head for a look see.

I changed the water pump and the points and condensors as directed by the guru and it started and ran in the test barrel at part throttle. Once out at the lake it started hard and would barely go above idle. The guru quickly found it was running on one cylinder. Back home I took it apart a hundred times, replacing points again, checking gaps over and over, even using a fancy timing fixture. Both plugs will throw a spark across the room so it can't be the ignition, right? Can't be the carb because one cylinder runs fine. The reeds look fine. Compession checks at 95psi in both cylinders which I'm told is perfect for this motor. Stumped and still stumped! The guru is the type of guy who replaces all and think the coils and wires are next, firing when you test spin the motor but not under cylinder compression. Maybe so. Another mechanic says the bad cylinder might have a leaking crankcase. Maybe so. Good thing I have other good motors and can put this one aside for now but it would be a nice thing to have running. Looks like the power head will have to come off in almost any case since the only way the shifting could have gotten screwed up so much is when someone had it off before (although the paint on all the screws and nuts is intact and seems original). Like I said I'm stumped with this one.


Got lucky and stumbled onto another 5.5 Johnson. Since the first was so ideal for Birdwatcher I picked this one up. It seems identical to the first except has different trim. Or so I thought.

I put this one on the AF4 for a test run. Remember that the other Johnson 5.5 on the AF4 maxed out at maybe 7mph. This new one put the AF4 on plane! 11mph on the gps at full throttle. I really thought we were onto something close to perpetual motion here! Then I put the fuel milage gear on the new one and found it burns maybe 50% more fuel than the other 5.5. Same power head and same lower unit and prop. It isn't the carb tuning since Johnson's are pretty easy to tune by ear - you can quickly find the best tuning position of the needle valve. Go figure!


...we look at Bayard Cook's AF4 delux.



af4 lines


AF4 is a simple low powered cuddy cruiser intended for protected waters. Kilburn Adams of St. Louis brought a boat similar in spirit to AF4 to our Midwest Messabouts and it was easy to see what a good idea this is. Kiburn's boat was a modified Sturdee Amesbury power dory with a small cuddy added and a new 4 stroke Yamaha 10. He thought the empty boat weighed about 600 pounds ready to go. It planed quite well with two men on board at about 13 knots. He made a 60 mile trip on the Mississippi (above the Alton dam where the current is small) burning about 4 gallons of fuel. It's quiet and cheap to operate. It's a good idea now that smaller 4 stroke motors are more common.

Here is an AF4 by Barry Targan. I think he is using a new 8 hp 4 cycle.

AF4 is supposed to do about the same job. Its simple hull shape won't handle rough going like the dory, but it's very easy to build and roomier. This boat has an open bow well for anchors and junk. The cabin is 8' long and 3' deep and 4' wide for minimal camping. It should be comfy for one and snug for two. it has a slot top to allow stand up boating in good weather. You cover it with a snap on fabric piece in the rain and cold. The cockpit is a full 6' long and 4' wide and totally open. You could lounge there too with a folding chaise. Aft of the cockpit is a draining motor well which will take the standard 6 gallon fuel tank and then some.

For power I used to say 10 horsepower maximum but now I would say 15. My boat has gained gear and weight over the past three years and is more comfortable with the extra power. A light AF4 planes with an old Sears 7-1/2 horse (single cylinder, air cooled, for $50 at a yard sale) as you can see here:

Here is John Bell & co. in his AF4. I think John is using a 20 hp four stroke having tested the boat first with 25 hp and found it too much.

Here is one by Rhett Davis at the last Rend Lake meet.

And here is another by the motor guru Max W at sunrise during our last campout.

Bayard Cook built this delux AF4 in Florida:

AF4 uses the simplest nail and glue construction. It takes five sheets of 1/4" plywood and four sheets of 1/2" plywood.

There is also a shorter 15' version called AF4Breve, the prototype shown here built by Bruce Given.

Plans for either AF4 or AF4Breve are $30.



Prototype News

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.

The Tennessee Shanteuse is rightside up now on a trailer:

Out West the Picara project gets its bottom. Winter approaches:

The Deep South Skat is getting done:

Another Picara, this one with a 1' stretch in the middle, going together in Arkansas.





Mother of All Boat Links

Cheap Pages

Duckworks Magazine

The Boatbuilding Community

Kilburn's Power Skiff

Bruce Builds Roar

Dave Carnell

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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