Jim Michalak's Boat Designs
118 E Randall, Lebanon, IL 62254
A page of boat designs and essays.
(1May2013) This issue will present some thoughts about leeboards and such. The 15 May issue will return to the Bobsboat design essays.
THE BOOK IS OUT!
BOATBUILDING FOR BEGINNERS (AND BEYOND)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....
ON LINE CATALOG OF MY PLANS...
...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.
MESSABOUT NOTICE:THE REND LAKE MESSABOUT WILL TAKE PLACE ON JUNE 7 and 8 AT THE PINTAIL LOOP OF THE NORTH SANDUSKY CAMP GROUND AT REND LAKE IN SOUTHERN ILLINOIS. USUALLY THE SANDUSKY CAMP GROUNDS MIGHT BE FULL FOR THAT WEEKEND. BUT SOME OF OUR BOATERS HAVE RESERVED SOME OF THE SITES THERE SO YOU (AND I) MIGHT PASS THAT WAY FIRST SINCE SEVERAL TENTERS CAN SHARE A CAMPSITE. IF NOT, THEN I WOULD TRY THE WAYNE FITZGERRELL STATE CAMPGROUND WHICH IS ON THE MAIN CAUSEWAY LEADING TO SANDUSKY. THEIR WEBSITE SAYS IT IS STRICTLY FIRST COME FIRST SERVE, NO RESERVATIONS ALLOWED. IT IS A VERY QUICK DRIVE FROM THERE TO SANDUSKY. HOPE TO SEE YOU THERE!
Robert Kellock has been sailing his Philsboat in New Zealand for several years now. In this photo he is in a recent "race".....
... came in the email on the same morning. I opened them up one after the other in the space of a few minutes. Both quite interesting from guys who were experimenting and doing a good job of it.
FIRST FROM "MOTORCYCLEJACK"...
hi. it's me again. the experiment is done and the results are in. i thought you might be interested in how it turned out.
here is the record of my experiment. i took the boat's lines and drew a scale picture of the hull and sail. i, then, made several drawings of just the hull, with the different fins, i have tried. that way i have a good idea of the CLR before i build and test a fin. the closer you start, to what you want/need, the less mistakes you have to make before you get there.
the original daggerboard is 21" deep ( below the hull ), 9" wide at the top, and tapers evenly to 5" wide at the bottom. that is 1.02 sqft. the sail area is 40 sqft. this comes out to the daggerboard being 2.5% of the sail area. although i have seen your recommendation of 4% in a few different sources, she always sailed great; pointing at 45% and sometimes better, with little leeway. so, i am happy with that base line.
this is fin1. it is a maximum of 11" deep, tapering to 8", at the front. it is 30" long, at the hull. it comes out to 1.74 sqft. that is 4.3% of sail area. i took her out in moderate winds ( 9 mph ) and in light winds ( 2 to 5 mph ) with borderline heavy gusts ( 12 to 15 mph ) . other than the fact that she seemed a bit less flighty in the gusts and over wakes, i really did not notice much sailing difference. i don't usually slam the tiller over fast, when i tack, anyway. it kills headway. however, you could do that, with the daggerboard, and it would work. with the shallow fin, she did seem a fraction of a bit more gradual feeling, when coming about. however, it could have been my imagination. as i said, i don't normally tack by shoving the tiller over, hard. i usually come over in a nice arc.
lead ended up being around around 10.7% of the LWL. this worked well and i will maintain that throughout the whole experiment. if i notice a gain in weather helm, or the introduction of lee helm( doubtful ), i will make adjustments.
getting her on the water was a bit more difficult, due to the 11" fin. however, it wasn't terrible. i put the plug in the back, hooked up the bow line and put the hull in the water. then i tied her to the dock with bow and stern lines and stepped the mast and set her up, from the dock, with no problems.
the next experiment was to remove an even 2" from the bottom of the fin ( the above picture ), reducing the area to 3.75% of the sail area. i did this because i wanted to see just how shallow the fin could go, before losing windward performance. it kind of sets up my limitations. also, if the full keel proves to be a bad performer, but fin2 ( this fin )was a good performer, i would choose to go with the shallower board, for ease of launching. i don't think the 2" difference would be noticeable, as far as drag is concerned, but fin2 does have less wetter surface than fin1. the lead did not change.
in fact, truth be told, if fin2 launches sufficiently easily, i may not try the full length keel. it would be greater wetted surface and not much shallower.
this picture was taken with the boat in the back of the truck, but you can see, if you compare it to the other picture, that the fin is noticeable shallower.
ok. that was a success. it was shallow enough to make launching much easier than with fin1. no adverse sailing performance. it may be a tad faster. wind conditions, on this test run, were more stable, than before. approximately 8 mph winds from the north. she tacked between NW and NE consistently, sometimes a bit closer.
she has a normal amount of weather helm. however, before, with the daggerboard, she almost had neutral helm. weather helm only appeared during a gust, and it was sleight. i am going to add 4 inches to the back of the fin. then, to keep the area down a bit, i am going to cut another 1" off of the bottom. it should move the CLR aft, making lead 12.9%. it will also lower the entry depth of the fin and move the deepest part of the fin, aft, making launch easier. it won't make the maximum depth of the fin much less, really. if you take into account the above reduction. this gives me a surface area of 1.67 sqft. 4.2% of sail area. hopefully, it won't make coming about any harder. if it does, i may remove a bit from the both leading edge and the trailing edge.how much, from either edge, would depend on how well she sails with this CLR and surface area.
over all, the performance with the shallow fin has been better than with the deeper, skinny daggerboard. she points and resists leeway the same as before, however, her nature seems a bit calmer and she doesn't seem to heel as much. the latter may be my imagination. i suppose i will know, for sure, when i sail her in 18 mph gusts. lol
towards the end of the day, the wind dropped to almost nothing. however, she still pointed well, ghosting along. she has always done remarkably well, in light airs, and the change from the daggerboard, to the fin, has not changed that.
i tried rowing, at the end, and was pleasantly surprised to find that the fin did not make her harder to row. in fact, she tracks better, now. this type of keel may not be ideal for all boats, but it seems to be great, for this one.
i am very happy, with the results, so far, and i have learned a bit more about boat design. the lateen, that she previously had, was not as good to weather as this sprit sail, and i am not sure the experiment would have been as satisfactory, with that rig.
i finally got a picture of (Bolger's - ed) lady slipper. the keel is interesting. very different than on the micro. i left the bottom of mine angled because i felt that the angle would give the bottom some of the qualities of the leading edge and, therefore, cut down on wash over. i would think that lady slipper's keel, having, really, only a leading edge and a trailing edge, might be much better, for this. however, it's a very deep keel. if i made one, triangular, like his, that was as shallow as my new one, it would lose the benefit of the high aspect angles on the fin and have to make the fin much longer.
so, this is fin3. both shallower and longer than fin2 but close to the same area.
well, that was an awesome test run. the balance was perfect and she had no trouble tacking, despite the extra length. i may angle the fore foot a bit more, but this is the final fin; the one that is going to be made permanent. it was a bit gusty, today, but with good underlying winds ( around 9 mph with 12 mph gusts ). she was rocking and rolling, out there. pointing as close as ever. no noticeable slip to lee.fast as ever. this new keel is a performer, even though everyone said a shallow keel wouldn't work, well.
it amazes me because, on top of being shallow, it's not a specifically long fin.it's not even a third of the LWL.
the daggerboard, deep and skinny, is 2.9% of the sail area and this new fin, really only 6" below the deepest part of the hull ( where the daggerboard slot is, although the deepest part of the fin is well aft of that point, at the trailing edge ), is only 7% bigger. i can sail in extremely shallow water. in fact, it's my rudder i have to worry about, now. that wasn't the reason i did this, but it is a benefit, and, because the fin is so shallow, and towards the stern, i can beach, if i have to, just as well as i could with the daggerboard pulled up. so, there we have it. experiment concluded and successful.
i took her out again, today. 10 mph winds with occasional 15 mph gusts. very pleased. a truly beautiful day of sailing. the balance, with the extra 4 inches on the trailing edge, is nearly neutral. sailing along, to wind, there is no weather helm, at all. when a gust comes, she wants to turn up, as she should, but not forcefully. it's just a sleight tendency. the balance is exactly as it was with the daggerboard. i did try slamming the tiller over, in a dinghy racing manner, when tacking today; just to see how she acts. she came about as quickly as ever. i am going to make the permanent fin exactly like this one. i had been going to angle the fore foot more, but i changed my mind. i wouldn't change a thing. the best part is that this fin is shallow enough it doesn't give me any problems getting her on the water.
now, i just have to decide whether to make the keel solid or hollow. solid would add weight down low ( at least a little ) but the weight is noticeable when carrying it. hollow would add a small bit of buoyancy. i have to consider it. if you have any thoughts about that, i'd be glad of the input.
AND NEXT FROM TOM STEINMETZ...
Back in January, I sent you a letter stating that I had built a Paradox (Morning Glory) and was having trouble getting it to sail properly.
At that time, I was thinking of selling it and building something else. That's when I decided to oder the Fatcat2 from you.
The idea then was to build the Fatcat2 and then sell the Paradox.
When I got the plans for the Fatcat2 I studied them and wondered if I could use the leeboard on Morning Gloring.
I built and installed the leeboard and Monday got the chance to take it out on the gulf.
I was on a run and low tide out of the harbor and had the board up. When I got out in the channel with some depth I got the board down and that didn't seem to bother running at all. When I got out into deeper water, I headed off to a broad reach and it seemed to track straighter and point better. Then I came to the first tack, I swung the tiller over and the boat came about with no effort. That never happened before without a fight or start the motor. I thought to myself, OK don't get excited let's just sail back and try it again. This time it came around again with ease. And that's the way it went the rest of the day. I could sail the boat any where I wanted in heavy wind or light. I was delighted.
If was such a relief off my mind that now I could sail this boat and all the work paid off. Morning Glory is planning many adventures.
Thomas S. Steinmetz
WELL, WHAT CAN I SAY...
Motorcycle Jack's boat is he thinks a "Moth" of sorts from years ago, a 10 footer with a daggerboard originally. Jack gave it a new spritsail in lieu of its lateen. The boat is so small Jack wanted to get rid of the daggerboard because the case simply took up too much room in the tiny hull, (and daggerboards are probably the most compact solution to this sort of problem). So he did what I thought would never work well - he tried a "full keel". He said he always launched from a dock so the flat bottom he was losing was not an issue. I've written a lot about this subject and in theory and the usual testing a shallow keel is not usually an efficient way to go. And I'm not sure how Motorcycle Jack got away with it but it certainly sounds like he did, with very quick and thorough building and testing I might add.
SO YOU MIGHT THINK...
...to do the same and the theory stuff is all wet. Until you read Tom Steinmetz letter. He took a design which is intended to sail on it side hull area alone (and maybe the rudder area too), found it didn't work well for him, and added a Fatcat2 leeboard and it seems to have solved all his problems! So now we think again that deep and narrow is the way to go....
...the proof is in the pudding. But you have to do like these two did and do a live taste test.
BLOBSTER, SAILBOAT, 16' X 6.5', 750 POUNDS EMPTY
Blobster has a lot of features I like in a boat. Lots of volume for its size, sort of like Micro or Scram Pram. The multichine shape is almost exactly like Scram's but this one does not have a Birdwatcher cabin. It has the more traditional cabin with a raised watertight deck behind. Also it has one feature I would love to have in my personal boats - a step-through bow so that when you beach you can go forward through the cabin and out the front without going into the water or climbing over the bow. The cabin also has a slot top roof.
This shape of boat with multichines has proven good in rough water and with fair speed in spite of its blobular proportions. Blobster has about 600 pounds of water ballast in its belly and should be OK to 90 degrees heel although such depends mostly on weight distribution of the crew, something the designer has little control over. On the other hand, if the crew jumps overboard the boat will be almost assured of righting without their help. Then the problem becomes reboarding. Be prepared!
Sail rig is a large but simple 139 square foot balanced lug on an 18' mast. Mast is stepped off center to allow you to walk upright down the slot top and out the front. Should be rigged in an instant with no one going on deck ever. All very low tech built with common materials but effective.
The prototype Blobster was built by Miles Bore in Australia. He had built several boats prior, including a Micro, and did a great job of it using very nice materials.
Outside and on its trailer for the first time, the likeness to Micro is clear. But you can see it was meant to be much easier to trailer and launch.
Then he used it for a while as a low power motor cruiser while he finished the sail rig. You can see how easy the boat was meant to use from the beach with its step through bow transom.
Then for the rig and off for a sail, shown here with ballast tanks full. Miles reports it sails with no vices so far. No, he hasn't capsized it yet.
Miles got this photo of the inside. The living platform you see is 7' long and 6' wide max and about 42" at its deepest from platform to slot top. With the slot top cabin and step through transom it is a pretty airy home. Maybe not the little cruiser that Micro is but clearly much easier to use in general and a good choice for a daysail when you have but a couple of hours at the lake.
Great job, Miles!
Blobster uses taped seam construction. Five sheets of 1/4" plywood, eleven sheets of 3/8" plywood and one sheet of 1/2" plywood.
Plans for Blobster are $45.
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 out West.
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:
Another prototype Twister is well along:
And the first D'arcy Bryn is taped and bottom painted. You can follow the builder's progress at http://moffitt1.wordpress.com/ ....
AN INDEX OF PAST ISSUES
A NOTE ABOUT THE OLD WAY BACK ISSUES (BACK TO 1997!). SOMEONE MORE CAREFUL THAN I HAS SAVED THEM. TRY CLICKING ON...
which should give you a saving of the original Chuck Leinweber archives from 1997 through 2004. They seem to be about 90 percent complete.
15may12, Electric Boats 2, Electron
1jun12, Messin With Motors, AF4
15jun12, Rend Lake 2012, Toto
1jul12, Prop Thrust, Brucesboat
15jul12, Making A Hull1, Mikesboat
1aug12, Making A Hull2, Paulsboat
15aug12, Olympic Thoughts, Cormorant
1sep12, Making A Hull3, Hapscut
15sep12, Making A Hull4, Philsboat
1oct12, Figuring Sails 1, Larsboat
15oct12, SailOK 2012, Jonsboat
1nov12, Capsize Lessons, Piccup Pram
15nov12, Figuring Sails 2, Caroline
1dec12, Figuring Sails 3, Ladybug
15dec12, Hull Shaping, Sportdory
1jan13, Bulkhead Bevels, OliveOyl
15jan13, Drawing Boats 1, HC Skiff
1feb13, Drawing Boats 2, Shanteuse
15feb13, Drawing Boats 3, IMB
1mar13, Figuring Displacement, Paddleplank
15mar13, Drawing Boats 4, Frolic2
1apr13, Drawing Boats 5, RiverRunner
15apr13, Drawing Boats 6, Picara
Mother of All Boat Links
The Boatbuilding Community
Kilburn's Power Skiff
Bruce Builds Roar
Rich builds AF2
JB Builds AF4
JB Builds Sportdory
Puddle Duck Website
Brian builds Roar2
Herb builds AF3
Herb builds RB42
Barry Builds Toto
Table of Contents