Miles Bore Down Under takes his new Rio Grande (also known as Sandrasboat) for a spin around the marina. Miles also has the one and only Blobster.
Contents:
Contact info:
Jim Michalak
118 E Randall,
Lebanon, IL 62254Send $1 for info on 20 boats.
Jim Michalak's Boat Designs
118 E Randall, Lebanon, IL 62254
A page of boat designs and essays.
(1November13) This issue will continue a discussion about modifying boats from the given plans. The 15November issue will rerun the Sail Area Math essay.
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.
Modifying Boats 3
GOING LOOOONGER AND GETTING IN TROUBLE...
I am going to present what I think is about the only way you can get in trouble by stretching a boat out longer (within reason). This has happened in real life several times and needs to be noted.
LET US SAY...
...you have stretched a 12' sailboat to 15' by either the old fashioned way of respacing the forms, or maybe by the instant boat way of laying out the side panel dimensions expanded by a factor of 15/12. So the top views, old and new, might look like this...
Everything including the bulkheads has been respaced by the 15/12 factor.
WHAT'S WRONG WITH THIS PICTURE???
OK, with my boats the mast is usually hung on the forward cockpit bulkhead, and the leeboard pretty much has to be at the boat's widest beam in order to be in water flowing parallel to the direction of the centerline.
It needs to be mentioned and never forgotten that the sail area MUST be centered over the leeboard (or daggerboard or centerboard) area for the boat to handle properly. It is about the only thing with a small sailboat that is sacred. If the sail area moves aft of that, the boat will get more "weather helm" and will try to always steer into the wind. Weather helm is not bad if it is not overdone, a small amount is ideal. But if the sail moves forward of the leeboard area you get "lee helm" and the boat will always try to steer away from the wind. Lee helm is I think always bad and usually very bad. From a safety standpoint, if you fell off a boat that has weather helm, the boat might steer itself into the wind and stop and wait for you if you are lucky. If you fell off a boat that has lee helm it will turn downwind and just keep going away from you and leave you. Perhaps as bad though is that a boat with lee helm may not steer to windward at all or may not be able to tack through the wind to a new course. Essentially you won't be able to steer it. So it is to be avoided! (And, by the way, if you have a boat that is quite lackluster going to windward and you can't really see why, try moving things to give more weather helm - move the sail area aft in particular. A few inches will make a difference.)
So what is very wrong with the above is that the sail rig was designed to have 3' between mast mount bulkhead and the leeboard. The stretched boat has 3' 9" between them and is guaranteed to have lee helm unless something is done. This sort of thing might not be apparent at all to someone who is building stretched without making a drawing of sorts of the new boat with sail rig.
WHAT CAN YOU DO???
You could try to move the leeboard forward 9" to achieve a new balance. Like this...
Now, I don't really know how important that is since I never did tests but you can see if the leeboard were brought forward of the widest beam and still mounted parallel to the side, it would toe inward a bit. You could mount it there but reset the leeboard mounts such that it is now parallel with the hull centerline. But if you assume the waterflow there is parallel to the hull side then your boat still isn't going to want to steer exactly in the direction of the hull centerline (actually it seldom does anyway), or you may end up with a bit of a waterspout and added drag as the water gets jammed between the side and the board as the two converge a bit.
If you use a daggerboard or centerboard you could avoid the above but you still have to move it forward 9" to compensate for the sail moving forward.
You can move the mast mount aft 9" so it matches the leeboard location. This is I think how the problem is usually solved. If you are thinking well ahead you might do that by planning for a new bulkhead installed there. The new bulkhead won't be the same dimensions as the original so you will have to scope that out. But the usual solution has been to mount a new mast step 9" aft of the original and a wide traditional mast partner board securely across the wales such that these together will move the mast aft 9".
ANOTHER APPROACH...
But let us say you did not stretch the hull by respacing forms or expanding side dimensions. You did it simply by installing a straight "plug" at the hull's widest beam. Like this....
I know it may not look elegant but you can see right away all of the advantages. You can leave the mast on the bulkhead where it was and also leave the leeboard the proper distance aft, where it originally was, since the leeboard is still at the hull's widest beam. The hull no longer has its widest beam at just one point - the straight plug has given it a widest beam region that is 3' long. Ah! The experimenter's paradise! The leeboard could go anywhere in that plug if required and you can tinker with different sail rigs to your heart's content and should still be able to get things to balance if you can shift the leeboard along the plug.
I THINK...
...I can put this subject down for a while although it brings up some ideas that could be studied further. For one thing, how is stability affected by lengthening or hull rescaling in general? That should be fairly easy to study with some Hullform models to a good degree of truth...an idea for later.
Piccup Pram
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.
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 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
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....
Hullforms Download (archived copy)
Brian builds Roar2 (archived copy)
Herb builds AF3 (archived copy)
Herb builds RB42 (archived copy)