Jim Michalak's Boat Designs

1024 Merrill St, Lebanon, IL 62254

A page of boat designs and essays.

(15 December 2016) This issue will get to my comments about D'Arcy Bryn. The 1 January issue will be about capsize recovery.



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 Moffitt's Mikesboat on the TX200 a while back. Those same sails were on his D'Arcy Bryn for this year's TX200.



Contact info:


Jim Michalak
1024 Merrill St,
Lebanon, IL 62254

Send $1 for info on 20 boats.



D'Arcy Comments


I have been putting off commenting on Bill Moffitt's D'Arcy Bryn for a long time. I can't totally figure it out and suppose I was hoping for Bill to figure it out in the meantime to clear up issues. But it is time to put down the pencil and hand in the paper. Anyway...


...the self righting situation, as you know. Wouldn't you know he tipped it first time out. It came right up as planned even though it never had its planned ballast. That is not to say it did not have ballast. He had an able crew man on board and all their gear and supplies for the trip and I suppose that was all down on the floor acting as ballast. The amount of stuff was likely considerable. At any rate, the thing I was most concerned about seems to be OK.

I think it is worth commenting on that the boat, as Bill mentions in his letter, was not really being used as it was designed to be in that it really was supposed to be a one man boat. With two and their gear it appears to be down to its lines but not overly so. Boats of this shape can usually handle a lot of weight. Normally I would rate the weight as that needed to sink the boat to its chines and so that the transom just touches. But it can handle way more than that, slower but still safe.


The final assembly of the sail rig was completed in Texas a day or two before the launching and the cruise. An aluminum mast was used in lieu of the wooden mast but that is probably fine. Pains were taken to get the mast rake correct, thus placing the main sail in the planned position and hopefully getting proper helm, (such that the boat will steer into the wind slightly by itself with no hand on the tiller.) You may recall this sketch...

The idea was to get the center of the composit sail plan right above the center of the leeboard. That is a crude way of thinking the boat will not want to steer itself to windward or to leeward when sailing into the wind. The sail area looks large but keep in mind Bolger used the same sail on the 100 pound Windsprint! The sails were sort of a "given" in the design in that Bill already had them on hand, well tested on his Mikesboat...

This is something I did often myself - designed a new boat around a rig I already had on hand. No reason not to and lots of good reasons to do it.

But there is a difference in sail planning between Darcy and Mikesboat. On Mikesboat the lug yawl was an after thought and set up so the main sail area alone was placed above the leeboard, thus the boat could be sailed without the mizzen. The mizzen was there to allow it to sit head into the wind when desired and to allow helm trim changes and a bit of self steering. D'Arcy will not do that. It needs that mizzen area for basic balance and the mizzen sheets will likely need resetting with each change in direction. Still that is sort of standard. It has been my experience that a boat set up that way will have an unavoidable lee helm in light winds. You can live with that but it is a small pain.

Bill said the boat had weather helm, more than desired. Go figure! He thought the problem was in the quicky set up done before launch and later he changed the rake of the mast (by simply changing the placement of the lower hole in the tabernacle) to get less weather helm. This sort of trimming is normal and any boat might need it.


...and this is what puzzles me...Darcy had a pronounced desire to round up when sailing downwind and maybe broaching, although he did not say it did that.

Long, long ago I broached and capsized my old Bolger Jinni. It had the same sort of sail balance as Darcy, that is a main and mizzen yawl with the mizzen required for balance. I was new to all this at the time. I wrote to Bolger.

Phil Bolger was a genius and could simplify things very quickly. You broach when the boat swaps ends, in my case in really large and rough breaking waves. She swaps end because the stern passes the bow, he said. He suggested with the sharpie that if the bow digs in, as it would running down a wave face as happened to me, that is like throwing out an anchor in the bow and the stern will quickly catch and pass it. He suggested furling the mizzen in those conditions and going with main alone, but that is clearly impossible in a small boat in rough going. You can't let go of the tiller for a second not to mention hanging off the stern of a tiny yawl and furling the mizzen. Phil never said it, only constantly hinted at it, but I will say it here. There are times with a small boat when you just can't overcome the rough conditions. You are going to crash. I suppose that is true with large boats too but a larger boat might have a crew with someone to steer as the other guy furls and reefs. With a small boat you can't really reef safely on the water often. But yawls like Jinni and Darcy are supposed to have an out - pull the mizzen in hard to get the boat to head directly into the wind, then attend to your reefing.

I spent a lot of time thinking over the broaching problem. On a big curling wave the top of the wave is going faster than the face, yes? So as you go over the top your stern and rudder might be in water that is actually travelling forward with you, while the bow of the bow ain't. She will want to swap ends. You might lose rudder effectiveness too, especially if the stern if lifting at the wave top. Well, so much for speculation.


...that when running downwind the balance of the sails is really nothing like the neat diagrams used to locate the sails for windward sailing. This is how I figure it. When running downwind with the main sail boomed out to the side, any boat will want to round up. Here is what is happening...

The force on the sail, and it could hundreds of pounds in a big wind, is pushing only forward way off to the side of the boat. That force is balanced by the drag of the hull which is several feet away, and that produces a couple which will always try to turn the boat to the side opposite the sail. That couple is balanced mostly by sides forces on the hull (mainly the leeboard in one of my designs) and an equal and opposite force on the rudder. Now, a 20 mph wind might produce 2 psf on a sail which would be over 200 pounds of thrust on a sail the size of the Darcy main. If the main is boomed say 3 feet of centerline ( I am guessing) then you have 600 foot pounds of couple trying to turn the boat. That is balanced by a equal but opposite couple made by side forces on the leeboard and rudder.

But Darcy is a short boat with the two underwater boards about 7' apart. So the forces on the boards to balance the couple due to the boomed out sail is nearly 100 pounds each. That much side force on a rudder would be very noticable to the skipper - he might not be able to hold it if the tiller is short. Worse yet, the rudder in particular might not be able to produce that much force simply because it relies on water flowing over it to make the force. It might be very noticable in that "cresting the wave" situation if the top of the wave is traveling forward faster than you are in your boat.

I think it is no secret that I draw my rudders too small! That hardly helps this situation.

Well, the Darcy did not broach, at least Bill said he fought it off. Here are things I would try to help the broaching problem. First I would enlarge the rudder and not be a pansy about that. Make it twice as big under the water, as much as you can stand I guess. The rudder on my designs is easily replaced and tinkered with. While you are there, a longer tiller might be in order.

Next I would seriously consider a smaller main in particular. That might be a pain in light wind areas (which would not have a broaching problem anyway) but a smaller snugger rig will help, especially if the sail is narrower and will thus not boom out as far and a wider sail. I also should mention that when I sailed the TX200 with Chuck Leinweber in 2010 that he would rerig his main by shifting the halyard and tack lines more towards the center of the sail, maybe not so good for running to windward, but making it closer to a "square" sail as in days of yore.

D'Arcy is not the only boat to have this issue. Phil Bolger said in his writings that the traditional Cape Cod catboats liked to turn around without control and look you in the eye when running downwind. They had huge gaff rigs boomed way off the side and barn door shallow rudders. Now that I think of it, the only boat I ever sailed that liked to swap ends all the time was my WeeVee with its little gaff rig and tiny shallow rudder. It was fine sailing to windward but the tiny shallow rudder would simply stall out under the sideforce on a downwind. There was no keeping it from rounding up into the wind. I used to tack downwind to avoid it. Then I changed the rudder to my usual deeper drop rudder. Problem solved.


Bill mentioned that the mizzen did not have enough power to hold the boat heading into the wind. Here is a telling photo. She is actually moving forward beam to the wind...

I think a larger mizzen is in order. In the photo the large cabin and the pile of sail on top of it clearly has a lot of drag in a wind. So the bow blows off and the mizzen won't hold it. A mizzen that sets really flat might help too. On a boat like this that would likely mean a stout mast because a mast like this has no choice but to flex aft. Recutting or adjusting the mizzen sail lacing might help here too.





Sportdory is an attempt to improve upon the Bolger/Payson dory I built about 15 years ago. This boat is slightly smaller than my old dory. In particular the bow is lower in hopes of cutting windage. the stern is mostly similar. The center cross section is about identical. This boat has slightly more rocker than the original Bolger dory.

The hull is quite simple and light, taped seam from three sheets of 1/4" plywood, totally open with no frames. The wales are doubled 3/4" x 1-1/2" pieces to avoid the wale flexing my first boat had. I've added an aft brace to stiffen it up and give the passenger a back rest.

Mine once covered 16 statue miles in four hours. In rough water you will feel the waves are about to come on board but they won't. But if you try to stand up in one it will throw you out with no prayer of reentry.

The prototype was built by John Bell of Kennesaw, Georgia. Here is a photo of John's Sportdory under construction. You can see the sides and bottom, precut to shapes shown on the plans, wrapped around temporary forms and "stitched" together with nylon wire ties in this case. I'm quite certain that with this design one must leave the forms in place until all the structural elements like the wales and cross bracing have been permanently installed. If they are removed before then, the assembly will change shape and you won't get the same boat. In particular I think the nose will droop to no one's benefit.

One might wonder about a comparison of Sportdory, Roar2 and QT. They are all about the same size and weight, a size and weight I've found ideal for the normal guy. They are small enough to be manhandled solo yet large enough to float two adults if needed. They are all light and well shaped for solo cartopping. Roar2 is probably the most involved to build and the best all around of the three. Sportdory is simpler and lighter, at least as fast and as seaworthy, but most likely will feel a little more tippy and less secure. You shouldn't really try standing up in either of these two. QT will be the least able of the three as far as speed and seaworthiness but may be the easiest and cheapest of the three and is stable enough to stand up in. So take your pick.

Sportdory plans are $20.


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.

We have a Picara finished by Ken Giles, past Mayfly16 master, and into its trials. The hull was built by Vincent Lavender in Massachusetts. There have been other Picaras finished in the past but I never got a sailing report for them...

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:

Another prototype Twister is well along:

D'arcy Bryn is done and sailing here on its first voyage, on the Texas 200. I never suggest you should test a new boat on a trip like this but it worked this time. I will print a full story in a future issue.

The first Jukebox3 is on the (cold) water. The mast is a bit too short - always make your mast too long. A bit more testing will be nice...

A brave soul has started a Robbsboat. He has a builder's blog at http://tomsrobbsboat.blogspot.com. (OOPS! He found a mistake in the side bevels of bulkhead5, says 20 degrees but should be 10 degrees.) This boat has been sailed and is being tested. He has found the sail area a bit much for his area and is putting in serious reef points.






1jan16, Sailing For Nonsailors 2, OliveOyl

15jan16, Sailing For Nonsailors 3, Robote

1feb16, Sharpie Sprit Rigging, Laguna

15feb16, Trailering Plywood Boats, IMB

1mar16, Hollow Spars, Slam Dink

15mar16, Bulkhead Bevels, Frolic2

1apr16, Capsize Lessons, RiverRunner

15apr16, Wood Vs Aluminum Spars, Mayfly16

1may16, Scarfing Wood, Blobster

15may16, Prismatic Coefficient, Roar2

1jun16, Figuring Displacement, Mayfly14

15jun16, Rend Lake 2016, Mixer

1jul16, Ballast Calculations 1, Dorado

15jul16, Ballast Calculations 2, Robbsboat

1aug16, Ballast Calculations 3, AF4

15aug16, Taped Seams, Cormorant

1sep16, Butt Joints, Vireo

15sep16, Old Outboards, Philsboat

1oct16, D'Arcy Ballast, Larsboat

15oct16, D'Arcy Ballast 2, Jonsboat

1nov16, D'Arcy Ballast 3, Piccup Pram

1dec16, Sail Area Math, Ladybug


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

Puddle Duck Website

Brian builds Roar2

Herb builds AF3

Herb builds RB42

Barry Builds Toto

Table of Contents