Jim Michalak's Boat Designs

118 E Randall, Lebanon, IL 62254

A page of boat designs and essays.

(15February 2011)This issue will show a way of mounting a windsurfer sail on a small boat. The 1 March issue will rerun the rowing gear essay.



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.


Bill Lange has this quite modified Sow's Ear cruising canals in the Northeast. Also has a Bolger box type keel added to the bottom. Nice job!




Contact info:


Jim Michalak
118 E Randall,
Lebanon, IL 62254

Send $1 for info on 20 boats.




Windsurfer Sail Mod


...I looked out at the old birdhouse and saw this...

The birds had left but not the rest of us.


This was from Walter Platzer in Bankok, Thailand. Beautiful! Walter wrote:

"Dear Jim,

Attached are some pictures from building and sailing Mixer.Started building in Nov.2009 and finished in March 2010. In Thailand localy manufactured exterior plywood is of good quality but heavy( Keruing wood is used).For the bottom I used 7 mm (35 lbs ! )but for everything else on the hull I used 5mm(22 lbs ! )and the wood for framing the transom and side framing the bulkheads is red cedar(not western).Did not glass the bottom. Mixer completely stripped and ready to put on the car roof weighs exactly 100 lbs. I finished all the spars for a balanced lug but then I built a stub mast(60mm square cross section) and use my old windsurf sails on a bamboo spar which is pulled up to the stub mast through a 2 to 1 purchase.Works rather well. Drawback is no reefing possibility and have to lower the sails and change to a smaller one (have 5 sails from 45sqft to 67sqft).The seats which are demountable make the boat much more comfortable and give you the possibility to outride a little bit.I think Mixer is more stable than you expect and standing up and going around feels safe to me(I weigh 160lbs and my wife 98).I like that Boat.

Hope you enjoy the pictures and feel free to use them anyway you like.

One more thing: In Thailand cartopping is prohibited but if they catch you you pay a fine(quite low)which certainly does not go into the state coffers and the best thing is after you paid they let you continue driving :-)

Best regards

Walter Platzer, Bangkok"

Certainly enjoyed the photos. He added some photos showing this is one of the most tricked out Mixers ever, especially when you know it also was built with the original lug rig plus a bowsprit plus a mizzen...

But what about that a windsurfer sail?? Walter sent some photos of the boat in action...

Now the thing that I have heard about windsurfer sails is that in some places there is quite a surplus of them and they can be quite cheap. Apparently they can be about the right size for a small boat, around 50 or 60 square feet. But they are meant to be used with limber masts that are not supported in the usual way, with a step and partner. They fit in a socket on the surfboard, pivoting freely there in all directions, and are held upright by the skipper who hangs on to the sprit boom, which in the windsurfer's case is a double curved wishbone that can be handled from either side of the sail. What Walter had done was support the windsurfer sail pretty much as it was intended, with a limber mast that was stuck somehow in a flexible step and held upright with a stub mast, in the usual Mixer mast step and partner, in a manner that was both strong and allowed the flexible sail system to work.

I pressed Walter for some details and he quickly responded in words and with photos...


Thank you for the kind words. The system with the stub mast/windsurf mast is very simple. Three issues are important:

-The stub mast must be firmly fixed so it cannot move upwards.I jammed it firmly at the mast partner with the two wing nuts and the wood across.

-The block lashed at the wind surf mast should be alittle bit above the top of the stub mast.Then the halyard holds the windsurf mast down in its mast foot.

-The rope lashing at the lower end of the windsurf mast has to be a little slack otherwise it will have a lot of tension and may cause some damage to the fixing when lowering or raising the windsurf mast.It is actually only necessary when raising it.During raising this mast it may settle beside the mast foot mold but this is not a problem as it easily can be moved into the mold with one hand before the halyard is fastened.There is certainly room for improvement by tinkering with the geometry of the rope lashing.My mast foot looks a bit overbuilt and could surely be in one piece for both masts.

Most windsurfsails around 5 to 6 square meters(53 to 64sqft) will fit a stub mast which is arranged vertical(parallel to Mixers forward bulkhead)with the leeboard down vertical as well.I made some simple wedges to insert in the mast partner changing mast rake. Did not have to use them yet.

Attached are some pictures which make everything clear without comment.Some are from the early mock up stages, others are without the sail.You can use them freely any way you like.

Just finished a curved sprit boom from bamboo and epoxy since I noticed the windsurfsails do not have a nice shape with a straight boom on the "wrong" side.

Regards, Walter"

Now some of his detailed photos. Here are the two masts layed down for inspection.

The stub mast is fairly stout and the sail's mast, or yard I suppose, is quite limber. The halyard attachment detail shows an important feature of the rig....

So when you pull tight on the halyard the yard is raised up into position and once raised the halyard also pulls downward on it to press the yard into its own step

And then is a real clever touch in that there are two steps, one for the stub mast and another for the yard...

Here is a closer detail of the yard step...

Note that it is all rounded, sort of a ball and half socket joint, with a loose lanyard to keep it somewhat in place but remember it is the force of the halyard pushing down on the yard that keeps the ball in the socket. Here is another view of the halyard attachment ....

And another of the yard being hoisted into position by the halyard...

Walter has several windsurfer sails of different sizes ready to hoist but points out the problem of not being able to reef it. Nothing really new there as the old sharpie sprit sail is also difficult to reef, just to name one. But Walter's rig has an advantage there in that with the release of the halyard, the sail and its yard all drop down relieving the boat of all that weight and windage up high.


... some traditional rigs that are similar. I suppose the Gunter rig is related and maybe the Solent lug rig too. He sent this copy from "Gary Dierkings book "Building Outrigger Sailing Canoes" showing the set up with original mast,boom and universal joint".





IMB features a "Birdwatcher" cabin, full length with panoramic windows and a center walkway slot in the roof. Everyone rides inside. This style of boat was invented by Phil Bolger in the early 1980's.

These boats can be self righting with minimal, or no, ballast because crew weight works as ballast. They sit low looking out through the windows (although standing in normal winds is quite acceptable). The cabin sides provide lots of buoyancy up high to ensure a good range of stability. IMB, which is small with a light bottom, should reliably self right from 60 or 70 degrees and in the test described above self righted from a full 90 degrees of roll.

These boats are operated from within the cabin, like an automobile. No one need ever go on deck. For boating with children I can see no equal.

These are usually cool inside. The tinted windows cut the sun's power. The crew can sit in the shade of the deck. Downdraft from the sail cascades through the walkway. (By the way, at the Conroe messabout two boaters with Lexan windows noted that mosquito spray will ruin Lexan with one application and they noted belatedly that the back of the spray can says so.)

IMB has an 8' long cabin on a multichine pram hull. The prototype was built to perfection by Gerry Scott of Cleveland, Texas. At the Conroe (Houston) messabout I got a chance to look over his boat plus the only other IMB I know of built by Bob Williams. Both boats were quite true to the plans. Both had added low inside seats which made them more pleasant to use to the point that I will show some seats on the plans. I was worried when I drew IMB that the headroom would be minimal so drew no seats thinking the crew would sit on the floor, as with the original Birdwatcher.

While I was sailing with Gerry, Bob's boat came out on the lake with four adult males and no sign of bogging down, showing that these fat pram shapes, very much like my Piccup Pram, can handle a lot of weight in the 13.5' length.

(Later they rescued a mermaid and returned to the dock with five total.)

I don't know if either boat had ever been weighed and the 350 pounds I quote as the empty weight is just a guess. One of the ideas behind the boat was that it might be towed behind a compact car and I was glad to see that Gerry tows his behind a 1500cc mini SUV.

Both men adjusted well to the lug sail/leeboard rig. Gerry's has the blueprint 104 square foot sail and Bob's uses the 114 square foot Bolger Windsprint sail available from Payson. I used to worry a bit about running a leeboard on a full cabin boat like this since handling must be done by remote control, so to speak. No problem. Both boats have the leeboard lanyard running to a cleat on the aft deck. The leeboard position is plainly in view at all times through the cabin window. In use these leeboards need only lanyards to pull them down. Once down they will usually stay down until they strike something. Then they pop up and you will need to pull them down again. I've never seen a need for a lanyard to pull the board up although I've seen several rigged that way. The Dovekie design had elaborate cam operated levers in the cabin that operated the leeboards and I thought that all very clever. But in talking to some Dovekie owners I found the internal levers are not universally loved since they can often be in the way. Anyway, my idea was not to run the down lanyard to the aft deck but rather through a small hole in the side of the boat, say 1/2" for a 1/4" lanyard, so it could be operated totally from inside the cabin.

Both Gerry's and Bob's boats used electric trolling motors. The plans show rowing ports and no provisions for a motor. A boat like this won't be a fast row boat but it might be useful in a calm. Even the 24' Birdwatcher would row about 2.5mph in a calm. But I'll admit that adding a motor to Birdwatcher makes it a much more useful thing.

IMB takes two sheets of 1/2" plywood, eight sheets of 1/4" plywood and one sheet of 3/16" Plexiglass. Taped seam construction using no jigs or lofting.

IMB plans 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.

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...




1mar10,Wood Vs Aluminum, Blobster

15mar10,Rigging A Lugsail, Laguna

1apr10,Beefing A Mast, Frolic2

15apr10,Rigging Sharpie Sprit Sails, Sportdory

1may10,Small Boat Rudders, Blobster

15may10, AF4 rebottom1, Catbox

1jun10, AF4 rebottom2, Ozarkian

15jun10, Rend Lake 2010, Vector

1jul10, AF4 rebottom3, Wooboto

15jul10,Texas200a, Mikesboat

1aug10,Texas200b, Family Skiff

15aug10,Texas200c, Cormorant

1sep10,Texas200d, Trilars

15sep10,Texas200e, Philsboat

1oct10,Texas200f, Larsboat

15oct10,Sail Area Math, Jonsboat

1nov10,Sail Oklahoma a, Piccup

15nov10,Sail Oklahoma b, Caprice

1dec10,Taped Seams, Trilars

15dec10, Bulkhead Bevels, Raider

1jan11, Mast Tabernacles, OliveOyl

15jan11, Knockdown Recovery, DarcyBryn

1feb11, Knockdown Recovery 2, Caroline


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

Hullform Download

Plyboats Demo Download


Brian builds Roar2

Herb builds AF3

Herb builds RB42

Barry Builds Toto

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