Jim Michalak's Boat Designs

118 E Randall, Lebanon, IL 62254


A page of boat designs and essays.

(15 December 2015) This issue will take a look at sailing for nonsailors. The 1 January 2016 issue will continue the topic.

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.

Left:

Suddenly it is 1955, again. Bob Mueller has ideas for his new AF4.


Contents:

 

Contact info:

jim@jimsboats.com

Jim Michalak
118 E Randall,
Lebanon, IL 62254

Send $1 for info on 20 boats.

 

 



Sailing For Nonsailors 1

BACKGROUND...

I don't claim to be a great sailor or even a good sailor. There are some good texts out there about the subject. Alas, many texts get you into details so deep you won't see the forest for the trees, or assume you have fancy equipment. So I'm going to try handing out the basics, the minimum you need to know.

This one is for those of you who are going to build a sailboat and have never sailed and don't live in areas where you can expect to get any instruction. There are lots of you out there. Take heart. Here is a full description of my sailing lessons:

Around 1980 I decided to start boating and bought one third interest in an old Hobie 16 with John and his son Greg. John and I had never sailed but Greg, about 20 years old at the time, had a job where he could sail during the day and work at night. One day he took John and me out for our first lesson. He rigged the boat by himself and sailed it with John and me as passengers to a bank about 1/4 mile from the dock, got off, told us he was late for work and left us there! That was it! We had to reinvent sailing to get back to the dock and I guess we did.

If you can get a lesson or two from another guy with a similar homemade boat you will learn a lot. A messabout is a great place to start. I don't really know what to tell you about clubs that race or call themselves yacht clubs. Most of them there won't understand the reason for your homemade boat. Most of them know a lot more than I about sailing but you may get trapped into a racing or drinking scene.

THE VERY BASICS...

Here is a diagram (from overhead looking down) of the wind blowing on a sail:

sail1

The sail here is at an angle of about 20 degrees to the wind and the sail bellys out a bit. The amount it bellys out is called the "draft" of the sail and the draft is typically about 10% of the width of the sail, so a sail 10' wide might belly out 1'.

The wind produces a force on the sail which is shown here as the "net force".

It is possible to show a force, in this case the net force, as the sum of two components. Things like forces have both magnitude and direction and are called "vectors". One of the neat things about vectors is that you can think of them as the sum of other vectors. In this case the net force is shown as the sum of two other forces. One of those forces I'm calling the Drag and it is in line with the direction of the wind. The other force component of the net force is I'm calling the Lift and it is perpendicular to the direction of the wind.

In the case shown the sail is acting as an airfoil and from what I've sketched in it looks like the ratio of the Lift to Drag is about 3 to 1. That might be typical of a low tech sail. (Really high tech airfoils, such as the wings of a sailplane can, I think, achieve a Lift to Drag ratio of 50 or 100 to 1. Occasionally a high tech sail boat is made with a sail like an airplane wing to tap into that potential but they can be too fragile and complex for general use.)

NEXT ADD A HULL...

Here is the very same sail and wind with a hull added underneath:

sail and hull

The net force is also exactly the same magnitude and direction as in the first diagram. But in this diagram I've shown the net force resolved into two forces that are aligned with the boat hull, not the wind. One of those forces is a side force on the hull, and the other is a forward force on the hull.

What you see here is the situation of a boat "sailing to windward" or "close hauled" or "beating to windward". It can't go straight into the wind. In fact it usually can't sail closer than about 45 degrees to the wind. If you tried that the force vector pulling the boat ahead would disappear, you would get all side load, or a big side load and maybe a force pushing the boat aft!

Even as it is the side force on the close hauled hull is a lot bigger than the forward force. A keel or daggerboard or centerboard or leeboard is needed to keep the hull from being pushed sideways. There is no getting around that and the design of such features is very important. The side forces caused by the sail and reacted by the boat's keel don't line up, of course. The sail is way up there and the keel in way down there. The result is that the boat will try to tip over. It usually can't tip over all the way because as the boat tips the buoyancy of the side being forced down into the water increases. The total buoyancy of the hull (which equals the boat's weight) no longer aligns with the boat's center of gravity, the resulting torque caused by the new alignment will balance out the torque caused by the sail/keel situation. See the diagram below. (The same effect can be got by shifting the center of gravity of the boat usually by sitting the crew to the windward side of the hull.)

balance

That small forward force acellerates the hull until it reaches a speed where the drag on the hull is the same as the forward force. More about that later.

NEXT WE "REACH"...

Next the skipper swings the boat about 45 degrees away from the wind such that the hull is at right angles to the wind. In this diagram the sail and wind and net force are exactly as before:

reaching

This is called "reaching". If the skipper were sailing a bit closer to the wind it would be a "close reach" and if he were heading a bit more downwind it would be a "broad reach".

Notice that now we have a lot more forward force and a lot less side force. Reaching is usually about the fastest way of sailing. It is often one of the safest, too. You can stop quickly at any time by releasing the sheet to the sail and letting it swing out to stop the forward force.

Often a skipper sailing on a reach will find his boat acellerating so much that he needs to pull the sail in tighter. Remember that the sail does not feel the wind that one feels when standing still (the "true wind"). Instead it feels that true wind plus the wind caused by the motion of the boat, the total of those two being the "apparent wind". For example if the true wind were 10 knots from the north and the boat speeds up to 4 knots to the east, the sail feels an apparent wind which is the vector sum of those two. In that case the apparent wind would be 10.8 knots from a direction of 22 degrees east of north. Really fast sailing machines, iceboats in particular, generate a lot of their own wind.

wind

NEXT WE "RUN"...

Here the skipper has steered off the wind another 45 degrees. This might be called a broad reach but it is beginning to be a sail downwind, a "run":

running

There is still a small side force but the main push is forward. The hull speed will start to subtract from the true wind speed so the apparent wind will decrease below the true wind speed.

If you need to stop quickly in this situation, you may not be able to do it. You must swing the boat back into the wind.

NEXT TIME...

I'll show some finer points about sailing to windward.

Contents


SPORTDORY

LIGHT ROWBOAT, 15' X 4', 70 POUNDS EMPTY

SPORTDORY

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.

Contents


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:

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/ ....

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.) He is doing the windows now...

Contents


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

1jan15, Sharpie Spritsail, OliveOyl

15jan15, Knockdown Recovery, Dockbox

1feb15, Mike Monies, Laguna

15feb15, Cartopping, IMB

1mar15, WeeVee Lessons, Vole

15mar15, Bulkhead Bevels, Frolic2

1apr15, Capsize Lessons, Riverrunner

15apr15, Hollow Spars, Slam Dink

1may15, Boat Costs, Blobster

15may15, Small Boat Rudders, Roar2

1jun15, Emergency Flotation, RB42

15jun15, Thailand Mixer Cruise, Mixer

1jul15, Rend Lake 2015, Musicbox3

15jul15, Box Boat Stability, Mikesboat

1aug15, Taped Joints, Cormorant

15aug15, Plywood Butt Joints, Paulsboat

1sep15, Navigator Cabins, Vireo

15sep15, Boxboat Stability 2, Philsboat

1oct15, Center of Gravity, Larsboat

15oct15, Hullforms Model, Jonsboat

1nov15, Port Aransas2015, Piccup Pram

15nov15, Hullforms Results, Caprice

1dec15, Sail Area Math, Ladybug

SOME LINKS

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



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