Make your puddle duck go fast
Below are some tips for making your duck go fast. The tips are roughly in order of importance, but they are all factors for your consideration.
All Hulls The Same Shape
Our class rules have always been aimed at keeping the lower 10" of the hulls the same, because if they all present the same shape to the water, then all the hulls will have the same performance properties, and it becomes a matter of modifying the other variables to make your hull go faster than your competition. We also have rule 7 so any ducker can confirm their competitors aren't cheating.
Racing Experience
All the talk in the world and chat on the internet is nothing compared to simply getting out there and racing. The more you race, the better you will get. Lucky for you, we have an open membership list so you can directly contact any other ducker and setup time to get out there and go do some racing.
Properly shaped sail
Sailing across the wind is pretty easy, and usually the bigger the sail the faster you can go. The reason it is so easy is because you can rely on the pushing effect on the aft side of the sail. Sailing to windward is more difficult, and that is why most race courses put a buoy straight up wind.
The airfoil shape of your sail has a lot to do with how well it performs when sailing to windward. As for what is the optimum airfoil shape, that depends on type of sail, wind speed, and other factors. I have a general rule of thumb on the sail shape page.
The better the shape of your sail, the higher you can point into the wind -- which after you do the math, you can see that poiting just a degree or two higher than your competition can allow you to arrive at the windward bouy quicker.
Learn to read the luff of the sail
Sails work with the principle of laminar flow and a combination of lift on the windward side, and push on the aft side. You need to learn to look at the sail, and evaluate how the wind is flowing around it. You can use tell tales and other devices, but the most important one is to simply look at the leading edge of the sail.
Try this: pull the boom so it is above the stern corner of the hull, then sail about 60 degrees off the wind. As you sail, slowly turn into the wind, like only a degree or two change per 10 seconds. The luff of the sail will have a very full look to it, and there will be a point where it will stop being full, and start to collapse. That is the point which you have lost laminar flow, and the sail is loosing it's lifting force. Now fall off just enough to fill the luff again, but do not fall off more than that.
As your boat speeds up and/or the wind direction shifts, you will need to pull into the wind occasionally to make sure you are at the highest angle that your sail can point into the wind.
3 Sides sails -VS- 4 Sided Sails
3 sided sails like mutton and lateen sails are able to point much higher into the wind than 4 sided sails. Most of this performance advantage is because 3 sided sails can retain their airfoil shape when pointing into the wind, while 4 sided sails exhibit large amounts of twist in the upper portion of the sail, causing the much of the sail to loose it's lifting qualities.
In the picture, both pdracers are sailing as close as they can to windward. The red sail is a mutton, and the white sail is a 4 sided balanced lug.
Because of the difficulty in sailing to windward, most race courses include a windward leg, and that is usually the place where the winners and loosers are determined.
When going across wind or down wind, the 4 sided sails have an advantage. Because of the geometry, the 4 sided sails usually have more square area, and since they catch more wind, they tend to outperform 3 sided sails on that part of the course.
The best winning combination is to have a 3 sided sail for quick upwind climbing, and then deploy a spinnaker for heading down or across the wind. The spinnaker will give you the extra sail area needed to stay ahead of the 4 sided sails, but the problem is spinnakers are kinda tricky to use. So you will need to practice, a lot.
Sail tension
Each type of sail requires a certain type of tension to make them perform properly, so you need to study what makes each sail work best. I have some good books that cover this subject listed on the sailing books page. The tension they need changes depending on the wind strength & course you are sailing. Some racers use a variety of cam cleats with all control lines in one area, so they can quickly change tensions of various parts.
Figure the best VMG for your sail rig
There is a concept called "VMG", which means velocity made good. This means the closer to the wind you point, the slower you will go, but since it is a closer angle to the windward buoy, you will be climbing up wind faster than someone who is pointed lower (and might be going faster in that direction).
Part of that testing is figuring how to setup the sail, like tension, how tight to pull in the boom etc. Each sail type, and the way it was made, has different a different sweet spot and needs to be tested to figure what works best.
Sailors often do lots of testing with their sail rig and use a GPS to measure the exact speeds, and then chart those speeds and later back at home do calculations to see what will work best for getting to that windward mark.
Read The Course
Racing sailboats is more of an art form that is supported by science. Your situation on the course will be continually changing due to many factors, and the more you race, the better you will get at reading the situation and coming up with productive actions to take. There are many books about sailing and racing that discuss this subject which is a great place to start, and then contact other duckers to learn from seasoned racers. And then go practice, race, practice and race some more.
Learn to read the wind and how it shifts
The wind is constantly changing direction, some times it will help you, sometimes it won't. The wind will make marks on the water that you can read, and also natural obstructions along the shore will create certain predictable wind conditions if you sail near them. So you have to read and predict how the wind conditions are going to change and how that will help or hurt your position.
Leeboard Placement & Balance
Your leeboard (or daggerboard, or whatever) needs to be located in the proper location to balance with the sail rig you are using. If they are not balanced, then the water will not flow past the board properly causing vortexes to swirl around your board, and causes drag. This is one of the neat things about the pivoting type leeboards, you can adjust them forward or aft while sailing to get the perfect balance.
Leeboard Location (centered, offset, or side)
I know it looks strange to have your main fin (leeboard, daggerboard, whatever) not in the center of the boat, but it really doesn't make much of a difference when put over on the side. There are problems with having the daggerboard in the middle, it gets in the way and many ducker complain about banging their knees on it.
Foil Shape (leeboard and rudder blade)
A lot of hype surrounds the foil shapes, but in real life the difference between shape 3 and 4 on the keel page is not that significant. On high performing boats, there has been a lot of testing to try and create perfect foils, but our ducks are so slow that I am not sure how much of that applies to our hulls.
The perimeter shape of the foil is significant though. Tall skinny blades perform much better and are called "high aspect". They produce less drag than "low aspect" foils such as bilge boards that are short, but extend the full length of the hull.
Rotating mast with teardrop cross section
The mast is right there in the front of the sail, so having a mast shape that doesn't mess up the wind is important to laminar airflow. Marchaj discovered through wind tunnel testing that a 3:1 teardrop shape is the optimum mast shape. This teardrop shape must rotate so it is oriented towards the flow the apparent wind. If you want to see a prime example of this type of mast, look at a Hobie 16. You can also create the teardrop shape by using a sleeve type sail. Laser sailboats have round masts with a sleeve luff which the sleeve is just the right size to form the teardrop shape.
Mast that isn't too bendy
We often taper our masts to reduce weight aloft, but a problem is that the masts end up being thin and more flexible. When a nice gust of wind comes along, we hike out and try to utilize that extra burst of power, and what does our mast do? It bends and destroys that nice airfoil shape, and spills all the good power that mother nature just handed to us. So the stiffer your mast, the better it will perform.
Hull Weight
Intuitively you would think that a lighter hull would make a faster boat, but in reality it isn't that simple. Most hulls are around 125 pounds when fully rigged, some have been made as light as 40 lbs, and some up in the 180 or 200 lb range. The biggest variable is actually the crew weight. Some duckers are tiny little people barely weighing 80 lbs, while some are big people like me in the 300+ pound range, but most fit somewhere inbetween.
In light winds, because of my size, I can almost guarantee that I'll loose a race. But as soon as the wind picks up to 10 mph or better, then I have a significant advantage. Being heavier allows you to more smoothly control the boat, and also when hiking out I can apply much more pressure keeping the mast upright, so I can extract more force from the wind, making me go a lot faster.
Sail The Hull Flat
Flat bottom hulls perform better when they are sailed flat, as in level fore and aft, and from side to side. This is something that has been proven amongst many other boat classes, so much that there is an entire book written about the subject called "sail it flat". See the racing section in the sailboat book pages. Our puddle duck having a flat bottom, performs best when sailed flat.
Prevent Pig Rooting and
Don't Drag The Stern Transom
To explain this, first you need to understand what the bow wave is, and how it is formed. As any sailboat hull travels through the water, a wave is formed at the bow, and the trough of the wave is under the hull. The faster the hull goes, the bigger the wave.
Regular sailboat hulls have a shape that is intended to form fit inside that wave, and keep their stern transoms out of the water. If that stern transom drags in the water, then it creates vortexes and causes resistance to the hull moving through the water. But also regular sailboat hulls when pushed really hard, will dig down into the wave and can't go above what is known as displacement speed. For an 8 foot long boat, that displacement speed is 3.7 kts.
Powerboat hulls work on a different principle, they are very flat hulls with abrupt stern transoms. When you drive them at slow speeds, it takes a lot of force to push the hull because the stern drags in the water very badly. If you push the hull hard enough, it will create a bow wave, and then get up on top of that bow wave and skim across the top of the water. A regular sailboat hull is incapable of this, because of it's round hull shape.
The puddle duck has a hybrid hull shape (often called semi-displacement) that allows her to travel at both displacement speeds, and get up on a plane when pushed really hard. Most duckers are able to get their pdracers up to 6 miles per hour, and the fastest a duck has ever gone on wind power alone is 9 mph. For those that use outboards, a 3hp can push a duck to 7 mph, and I do not know of anyone that has used a 5hp or larger. The trick with outboards is to move forward on the hull after you get to planning speeds.
Most of the time you will be travelling at low speeds, it is easy to keep the stern out of the water, espeically if you have a flat top duck, you can use that flat top as a reference to see how level she is on the water.
The problems you will run into, are the speed ranges where the duck is trying to transition from displacement speeds to planning. The bow wave starts to get pretty big, and you need to adjust your weight so the hull does not pig root. If she does pig root, don't worry, you won't flip, it will just slow down the hull a bit and you need to adjust your weight so that you aren't plowing water anymore. At this same speed, you will start to drag your transom, but thats OK, because she is trying to get up on a plane. If you get good at this balancing act, you can push your hull up on top of the wave, and start to plane. It takes a lot of wind and good balance to do this, but with some practice, you can get your duck to go 6 miles an hour on wind power alone.
