Jim Michalak's Boat Designs
118 E Randall, Lebanon, IL 62254
A page of boat designs and essays.
(1 November 2014) This essay discusses "chine runners". The 15 November issue will be about rigging lugsails.
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.
Chuck Leinweber has a Toon19 in the works!
118 E Randall,
Lebanon, IL 62254
Send $1 for info on 20 boats.
Let's turn back the clock to SailOK 2012. I was talking to guru John Wright who had seen Matt Layden's Paradox boats in use (I had never seen one in the flesh) and I asked him about the "chine runners". Now, chine runners are simple flanges on the bottom of a flat bottomed boat, like this:
which are used as a substitute for a leeboard or daggerboard, etc, to allow a boat to sail to windward. The advantages are obvious - simple with shallow draft. But by the usual theories they won't work well. I've written about this before in more detail but the theory and testing I was watching were in a book by Czeslaw Marchaj who is quite a technical wizard. Still I get questions about chine runners all the time.
Anyway, John had seen them in action and commented that the boats had more draft than you might first suspect and that the sail area was further aft than you might suspect and that the rudder was carrying some of the sail load in addition to steering the boat.
So we fast forward to SailOK 2014 and one of the first boats I see on arrival is this, a Layden Enigma...
The chine runners are not visible here - they only occupy the central 1/3 of the chine which is under water in the photo. As I recall they are 2 or 3 inches wide and stoutly built - not just extensions of the bottom plywood. Also note the painted waterline. I believe this boat had no ballast at the time of the photo and in use the boat is loaded to float at that line.
ENTER MATT LAYDEN...
...yes, he was there! Later there was a scheduled meeting of "Ask The Designer". Some of us sat facing the crowd in the Monies Boat Palace and I saw Matt sitting very close. I must admit I get worried about what sort of question might get asked of me to which I might have to admit "I don't know". But at first there were no questions asked and I decided to quickly turn the tables and asked Matt to explain the chine runners. He did so with no hesitation, with chalk and blackboard. He drew a picture on the board that looked something like this...
Almost all the elements are there. To work the boat's draft needs to be 1/5 of the beam, so in a 4' wide cruiser it needs to be about 10". Heeling the boat helps here with a hard chined hull, both in getting that chine deeper down and also I think in helping the flow lines. At least with light weight sharpie sailing I pretty much believe that "flying" the windward chine, that is heeling the boat in the wind such that the windward chine is out of the water, can help speed things up a lot since there is a feeling that water swirling along the chine causes drag. So if you can heel one chine out of the water so much the better. Phil Bolger, who had a huge amount of sharpie sailing experience, taught us this thirty years back in his writings.
Phil also wrote about external chine logs and flanges to slow the swirling of water around the chine of a sharpie, not to mention the use of hull shaping, where the bottom and sides have the same curve. That resulted in the classic "Bolger Box" boats that sail so well but nobody likes to look at. Phil was also big on putting end plates on shallow rudders which makes them more efficient in steering. And in the 1980's endplates appeared on all sorts of airfoils, thus we had winglets on airplane wingtips not to mention a spate of winged keels on boats.
So the chine runners are there to improve the efficiency of the deep chine in resisting the sideways force produced by the sail. Matt said that only the middle third or so of the bottom has the runner and that runners that went the full length of the hull didn't really improve things. But the draft is mandatory in the scheme.
Then Matt added that, yes, the sail area is aft of the usual such that the large rudder carries some of the sail load. Phil also explored this pretty much in the 1980's with boats like the Cartopper which had a very small forward centerboard and a big rudder. But Phil noted the scheme was old in the Mediterranean and lots of tradtional boats there and elsewhere sailed without water boards, instead using deep sharp bows and large rudders.
So, in a few minutes Matt had it all explained. It all made sense. My trick worked and no one asked me any questions in the forum.
...a Layden Paradox was launched...
Note that here the boat is sitting almost down to its waterline and at the stern I believe they are using a hose and pump to fill the water ballast tanks. Both of the Layden boats sailed on that rather crappy day. Here is Matt hisself talking to the owner after taking the Paradox for a spin. Note that it is indeed down to its painted waterline...
I guess that is about it. Details explained. Draft 1/5th the beam, heeling helps. Chine runner 1/3rd of the length in the deepest part of the draft. Sail area aft a bit and a big rudder. John Wright wins again.
PICCUP PRAM, SAIL/ROW PRAM, 11' X 4.5', 90 POUNDS EMPTY
Piccup Pram was the first boat of my design to get built, back in 1990, I think. I still have the prototype and use it regularly. I designed it to be the best sail/row boat I could put in the back of my short bed pick up truck. But I found it to be a good cartopper, too. It has capacity and abilities I had previously thought impossible in a 90 pound cartopper. The photo above shows the original 55 square foot sail on Pensacola bay a long time ago. Piccup is a taped seam multichine hull which can take a fair amount of rough water.
Piccup continues to be one of my most popular designs and I get nice photos from builders. Here is one of Richard Donovan hoping for more wind up in Massachusetts.
Richard's Piccup has the larger 70 square foot sail that prefer myself. It's the same as the original but is 2' taller. This balanced lug sail sets on a 12' mast and rolls up easily for storage on its 9' yard and boom. The idea was to be able to store the rig easily in the boat during rowing and it works. There is a pivoting leeboard and kickup rudder on the boat and they can be left in place raised while rowing. Converting to full sail takes a couple of minutes as you step the short mast, clip on the halyard and tack lines, hoist the sail, lower the boards, and off you go. And the balanced lug sail reefs very well although reefing any small boat is best done on shore.
Here is a Piccup by Vince Mansolillo in Rhode Island, a nice father/son project. Piccup will be large enough to hold both of them. You can see the large open frameless cockpit, large enough for sleeping. And you see the buoyancy/storage boxes on the end.
But Piccup will take two adults as seen in the photo of Jim Hudson's boat. Jim's boat has a polytarp sail as does my own Piccup.
These boats have proven to be good for sail rig tinkerers (be sure to read and apply the Sail Area Math essay before starting). Here I am in Piccup with a polytarp sharpie sprit sail. The rig is different from the originals but the hull here is totally unchanged (except for paint) from the original shown on the beach at Pensacola.
I think my own Piccup has had about six rigs of different sorts and was always the test bed for the polytarp sail experiments. But, hey!, that's nothing compared to the tinkering the late and great Reed Smith did with his out in California. Here is his Piccup rigged as a sharpie sprit yawl!
Here is Rob Rhode-Szudy's yawl rig Piccup that was featured in his essays about building Piccup that you can access through the old issue links.
Here is another by Doug Bell:
This one is by Jim Islip:
And this one by Ty Homer:
Piccup Pram uses taped seam construction from five sheets of 1/4" plywood.
Plans for Piccup are still $20.
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 to the point the builder can sit and relax in it and imagine boating. You can follow the builder's progress at http://moffitt1.wordpress.com/ ....
AN INDEX OF PAST ISSUES
THE WAY BACK ISSUES RETURN!
MANY THANKS TO CANADIAN READER GAETAN JETTE WHO NOT ONLY SAVED THEM FROM THE 1997 BEGINNING BUT ALSO PUT TOGETHER AN EXCELLENT INDEX PAGE TO SORT THEM OUT....
THE WAY BACK ISSUES
15nov13, Sail Area Math, Caprice
1dec13, Stretched Stability, Ladybug
15dec13, Trailering, Sportdory
1jan14, Cartopping, OliveOyl
15jan14, Width/Stability, HC Skiff
1feb14, Hiking, Shanteuse
15feb14, Dory Stability, IMB
1mar14, Scram Capsize, Scrampram
15mar14, Bulkhead Bevels, Frolic2
1apr14, Capsize Lessons, RiverRunner
15apr14, AF3 Capsize, Sneakerbox
1may14, Paper Capsize, Blobster
15may14, Prismatic Coefficient, Roar2
1Jun14, Roar2 Repair, Piragua
15jun14, Rend Lake 2014, Toto
1jul14, Mast Tabernacles, Musicbox3
15jul14, Sandell Tabernacle, Mikesboat
1aug14, Taped Seams, Cormorant
15aug14, Plywood Butt Joints, Paulsboat
1sep14, Rowing 1, Vireo
15sep14, Rowing 2, Philsboat
1oct14, Guessing Weight, Larsboat
15oct14, SailOK2014, Jonsboat
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