What does the keel do on a sailboat and how it works
The water and wind act as opposing elements. The wind pushes you forward at the same time as the water resists it.
From this principal thousand of years ago, were believed that the keel was invented in the early days of sailing. and in the modern days, we start to understand what the keel does and how it works.
What the keel do simply:
provides an opposite force from the bottom of the sailboat to the force of the wind from the top to keep the sailboat balanced and not being blown sideways by the wind and it holds the ballast that keeps the boat right-side-up and prevents it from lean too much or tips over completely.
It came in different sizes and shapes from boat to boat depending on the purpose that will fulfill. without further ado let’s start from the beginning.
What is a keel?
The keel is a flat blade that comes down from the bottom-most part of a vessel in the center of the hull and it’s the longitudinal structural element on a vessel. It can vary in size and shape depending on the building process and the purpose that will serve.
The laying down of the keel is the initial step in the construction of a vessel for most shipbuilders around the world. Many refer to it as the backbone which you take literally.
All sailboats have a keel, centerboard, or daggerboard. In general speaking, on larger boats, the keel is longer, a blade-like structure extending from the hull bottom, frequently straight to the boat’s deck.
The keel is built of whatever the boat is built of—usually fiberglass, aluminum, wood, or steel—and the ballast is lead and is either bolted to the bottom of the keel or placed inside it.
Some keels can retract into the boat itself or even be removed entirely. Other keels flip upwards, You generally won’t find these on larger ships. While some can’t be budged in any direction whatsoever.
And while most keels serve the same purposes, some of them are better than others in some aspects. like speed, maneuver, and steering. but first, before we dive in, let’s see what the keel do
How does the keel works
The main purpose of a sailboat keel is to counteract sideways forces from wind and waves and keep the sailboat right-side-up in the water.
The sailboat keel also holds the boat’s ballast and prevents capsizing. Obviously, both very critical and substantial roles. In addition, the sailboat keel provides counterbalance and lift which help the boat perform better.
There is another job that a sailboat’s keel has, to control drifting. When you’re out in the water without any landmark to be seen, it’s very important that you are in the correct direction.
The keel comes into its own when the sailboat is sailing. There are many forces at work, including the structure of the vessels, sails, and the keel. The water and wind act as opposing elements.
The wind pushes you forward at the same time as the water resists it. The keel is making sure you’re not swinging and going sideways. The flat surface and its perpendicular position to the deck make it achievable.
When the wind pushes the sail in one direction, the keel goes the opposite way. The forces are matched even though the keel is smaller.
The density of the water makes up the difference. This element also supports tacking.
That is the maneuver that sailors must use if they are trying to go upwind. Instead of going in a straight path with the wind behind the boat, they zigzagged.
This action allows them to utilize the wind and water energy to create forward thrust. The reason they go back and forth is that they must drag the two forces together to keep moving.
What are the types of keels?
Keels can be fixed or moveable and may retract or be removed entirely. The two most common keels on sailboats are the full keel and the fin keel. But there are many others.
Trying to list every different type of keel available on the market is quite an undertaking. But I will cover a few of the more common types:
Fin keel
It is a narrow plate (of wood, metal, fiberglass, or other material) fixed to the mid-bottom of the boats projecting downward to provide lateral resistance, It”s intended both to steady the boat and to make it handy to steer and providing very little water resistance.
A fin keel is sleeker, smaller, and most importantly If you want to go fast, you’re going to want a boat with a fin keel. Most racing sailboats have fin keels. but the fin keel offers a lesser amount of stability which is something to stay aware of.
Full keel
A full keel runs the length of at least 50% of the hull, ( but most of them more than 50%). The front edge curves vertically while the aft edge often connects to a rudder. it is usually fitted on blue-water sailboats.
It has much more stability compared to the smaller keels, but this makes it slower and a bit harder to maneuver in tight spaces.
The main advantages of a full keel are safe grounding and directional stability. Safe grounding means safer when you lie on hard ground. And provides a robust, stable balancing point for the hull.
And will not tip on its bow or stern when you ground. The boat will lay on the side and take less damage. the full keel provides a line of balance. Be it intentional or not, a full keel has more stability.
A boat with a full keel points well when in the water. It has good directional stability. The full keel has a longer waterline length so it controls the flowing water more than the shorter keels.
And this gives the boat greater directional stability. The full keel is one of the most common types of keels that you are likely to see on most sailboats.
Centerboard
The centerboard keel has a base keel with a dagger that rotates downward. the dagger comes through the base outwards and offers the stability and balance of a fin keel. known as a centerboard case.
The retractability allows the centerboard to be raised to operate in shallow waters. And When the water is deep, you take the dagger down and sail with a fin keel.
With the centerboard the difficulty is maintenance. As with any moving parts, problems arise. The centerboard has to be well maintained all the time.
Dagger Keel – Daggerboard
Dagger keels are a retractable centerboard used by various sailing craft. These keels are retractable and stored in their own compartment when not needed.
While other types of centerboard may pivot to retract, a dagger keel slides in a casing inserted through the center of a vessel’s hull, usually amidships. This means you can brave the shallows with ease.
Not to be confused with a daggerboard, which is entirely removable and generally found on one man vessels like catamarans. While Dagger keels are usually found in small sailing craft.
Bilge keel
A Bilge keel is one of a pair of longitudinal plates that like fins. (one for each side of the boat). on big ships may have more than one bilge keel per side, but this is rare. projected from the sides of a ship or boat and run parallel to the center keel.
Bilge keels minimize the draft of the vessel compared to a single fin keel thus enabling it to negotiate shallower water. and provide additional stability and keep the vessel from rolling in rough waters.
They also give a boost in speed if the boat is moving windward. Bilge keels increase hydrodynamic resistance to rolling, making the vessels roll less. Bilge keels are passive stability systems.
Bilge keels are usually fitted to commercial ships and cargo ships, and some smaller boats and sailing yachts.
Bulb keel
A “Bulb keel” is a fin keel that contains a ballast-filled bulb at the bottom, usually teardrop-shaped or torpedo.
This keel works the same as a fin keel does. but The purpose of the bulb keel is to place the ballast as low as possible, therefore gaining the maximum possible amount of leverage and thus the most righting moment. You’d typically find them on racing sailing boats.
Wing keel
The wing keel is a regular fin keel with small wings projecting to the sides at the bottom tip of the keel. it is another kind you’ll see on high-performance vessels.
It resembles the tail of an airplane, These little wings serve two purposes: They provide more leading-edge length and they create less drag from tip vortices.
Tip vortices directly relate to drag, and reducing these will reduce drag. Reducing drag will directly result in an increase in speed and higher performance.
The wing is another shoal alternative to the deep fin. which gives you the privilege of higher performance on deepwater and shallows.
While a wing keel may sound like the perfect solution to a sailor who is searching for a high-performance vessel with a shallow draft, the wing keel has a serious drawback.
It is the most difficult to free if you are grounded in the mud or between rocks. The wings act like shovels and wedge themself into the ground. and freeing out a wing keel can be very difficult.
Canting keel
The canting keel mounts on a hinge, suspended from a rigid canting strut beneath the boat, which can be swung to the windward of the boat under sailing. when the boat heels, racers hydraulically rotate the keel to windward.
Rotating the keel away from your healing direction generates a force that both rights the boat and propels her forward. the canting keel handling the ballast functions, lateral resistance, and the steering can be managed separately using such as daggerboards.
The main purpose of the canting keel is to allow the boat to sail closer to a level that generates maximum balance and speed. this keel best suited for racing sailboats. It is the future for racing but not perfected yet.
The downside is the maintenance and complexity associated with the canting keel, hydraulics, and other moving parts. but one day it will become the norm in the future of boat racing.
The first patent for a canting keel device was granted by Douglas Beardy on May 8, 1900.
Skeg
The skeg is an aftward extension of the keel intended to keep the boat moving straight and to protect the propeller ( inbound or outbound engine ) and rudder from anything beneath the surface of the water that could cause damage to them.
A powerboat often has a skeg only on the hull which serves the same purpose.
The idea is that it will protect the prop from any floating objects in the water before it can get to it. and If it gets damaged, the vessel will have a tangible wobble when underway.
Conclusion
Sailing is a challenge and fun. Sailors constantly adjust sails, boat position, and onboard weight to find the perfect balance between winds, tides, currents, and boat characteristics and use these components to get the highest performance of the boat in the safest-efficient possible manner.
The keel is a fantastic piece of the sailing mechanism that many people don’t give a second thought. It needs care and maintenance from time to time.
Because most new sailors think the keel’s there just for ballast, and without the sailboat keel the Modern sailing would never have progressed to the point that it has.
you can read this article ( When was sailing invented? ).
But now you know better. and If anyone asks you, what is a keel on a boat, you can say it is its backbone. It’s really a wing, flying under your boat.
