If a car driver uses ‘cruise’ to control a car, the vehicle will achieve its maximum performance efficiency. To do something similar for a sailing boat, you would need to calculate the hull speed. This will give you the average speed that suits the type of craft you are sailing. That’s why you need to know how to work out the average speed of a sailboat.
What is a Sailboat?
It’s a boat that primarily uses wind to propel it forward. There are other factors, such as tidal direction and design of the boat, that also help to move a sailboat. For the wind direction, a sailboat uses sails instead of an engine. Although some sailboats are also fitted with small engines to help with docking, among other things.
How Do You Calculate a Journey?
In the 15 century, Columbus’s Caravels sailed across the Atlantic at an average of 8 knots. We haven’t moved on much at today’s average speed of a large schooner, which is around 10-12 knots.
Remember that 1 knot is about 1.15 mph.
Sailing a boat is a challenge and takes skill to start, and significant talent to excel at, with specially built racing yachts achieving much faster speeds. A large schooner can cover up to 200 miles a day, but the speed will depend on a few important factors. See our article on how long to sail 100 miles for more information.
For top speeds sailing boats rely on the ocean current and the wind. It takes time and patience to plan for both of these factors to flow in the direction you want to sail.
The initial calculation for a long journey can be made with a simple calculation.
- How many miles you are going?
- Divided into how much time you want to take to complete the journey.
But, for a sailing boat, whether that calculation is ‘do-able’ will depend on three very important factors:
- The length of the sailing boat.
- The type of hull.
- The wind speeds.
These three factors are vital in calculating the average speed of a sailing boat.
Why Does Length of the Sailing Boat Matter?
Generally, the longer the boat, the faster it can cut through the water. A large boat is considered to be over 50ft long. For instance:
- A 16-foot boat can move up to 5 knots per hour.
- 50 ft boat can move up to 7 knots per hour.
- 244ft boat can move up to 16 knots per hour.
Showing that size makes quite a difference to speed when it comes to sailing boats.
What are the Two Main Types of Hull That Affect Speed?
There are two main types of hull, that play a major role in the speed of a sailing boat.
A ‘mono-hull ‘is used in an everyday sailing boat. You may also hear it called a ‘displacement hull.’ It’s also a single hull and is placed under the water. This type of hull pushes the water away from the boat, so the craft can move smoothly as it cuts through the waves.
To move faster, the hull needs to above the water level. This is also known as a ‘planing hull.’ The situation of this hull makes the craft quite buoyant, so it’s less stable. That’s why a sailing boat with a planing hull needs more than one hull, which is known as a multi-hull. Catamarans are common multi-hulled sailing boats. You may find pontoon boats as well as others that fit this category as well.
These are the favorable hulls for racing boats.
What Does Wind Power Mean?
One benefit of using wind to power your craft is the beauty of how you can utilize nature instead of an oily engine. Going faster with wind power means it will not harm the craft in any way if it’s done right.
What is the Average Speed of a Sailboat?
There are a ton of variables that go into the average speed of a sailing vessel, including the wind and water condition, the skill of the sailors, the type of boat, etc. But we can give some general ideas using the following estimations.
To calculate the average hull speed of a monohull, the length of the boat is the most important factor. When we talk about the length of the boat, it is the waterline length (LWL) that matters, and not the overall length (LOA).
The LWL is the part of the boat that sits at the waterline level. Also, note that the LWL is always less than the LOA.
What is the Scientific Calculation for the Average Speed of a Sailboat?
This is where you’ll need that scientific calculator so you can work out the square root of the LWL.
Let’s take a boat of 35ft in over length (LOA).
It’s LWL, from bow to stern and not including the rudder, will be approx. 28ft.
First, calculate the square root of the LWL, which for 28ft is 5.3 (rounded)
Next, multiply the square root of 5.3, by 1.34. (This is the accepted scientific measurement of the wave crest between the bow and the stern. The wave crest creates the bow wave in the wake of the boat).
Our calculation now looks like this:
5.3 x 1.34 = 7.09
The average speed of a 35ft (LOA) sailing boat is 7 knots.
Here’s the same calculation for a 15ft (LWL)
Square root of 15 = 3.9 (rounded).
1.34 x 3.9 = 5.189 which gives us 5.2 knots. (rounded).
To increase speed, you would need to learn how to harness the wind and the tide in your favor.
Speed, for many, can be a real adrenalin hit. The present world record speed for a sailing boat was achieved in 2012 at 68 knots (78mph).
Whereas, the average speed of a high-end racing sailboat is around 15 knots (17mph). This type of sailboat tends to be lighter. Plus, it will most likely have a double, or even triple (tri), hull, hence the planning effect.
But a cruising sailboat tends to go at an average of 5 -8 knots.
The longer the sailboat, then the larger the crest wave. This results in it moving forward at a bigger distance than a smaller boat creating a smaller crest wave.
The shape of the hull also affects the speed. Imagine a fat-tub of a hull to a boat; it’s going to move much slower than a slimline hull, even if they’re equal in length. Design plays an integral role in speed.
Plus, regular maintenance of your sailing boat too. This also helps to ensure its efficiency to reach top speeds. Sails must remain intact with no tears or holes and be properly tensioned. The mast must be solid. The skill of the sailor is also an essential element in achieving top speeds for a boat. Only a skilled sailor can take advantage of the winds and tide.