How does a keel and rudder affect handling and performance?

How does a keel and rudder affect handling and performance?

A lot of energy is spent on fine-tuning and upgrading equipment above the water line but did you know how the keel and rudder critically affects the handling and performance of a boat?

The type of sailing that you are interested in will always influence the type of keel and rudder which will be more suitable for your boat, especially if you have a choice, such as when chartering or considering purchase of a cruising yacht.

Fin Keel and Spade Rudder
A fin keel and a spade rudder is one of the most common modern options available.

The boat’s low weight and wetted surface area combined with a good aerofoil shape reduces drag, enabling a boat to sail close to the wind and tack quicker.

A fin keelboat is a firm favourite with inshore and offshore racers, even those that like to cruise longer distances. It’s light wind performance and ability to plane (surf) downwind reduces passage times, while it’s large size make it pleasant in port and easy to manoeuvre under engine.

Having a large size and light weight design can make a boat tiring in heavy weather as more concentration is required on the helm. The tendency to slam in heavy seas can also make them uncomfortable.

There are also twin rudder variants of this design – be aware that twin rudder configurations are challenging to steer at low speed as the propeller does not push/pull water direct over the rudders. .

Fin keel and spade rudder

Fin keel and skeg rudder
A fin keel and skeg rudder is still a popular design.

Although boats with this keel/rudder combination are not produced anymore, there are countless numbers of these boats still being used for racing and cruising. The fin keel and skeg rudder offer similar handling to the fin keel and spade rudder under sail and engine. The skeg (which runs between the keel and rudder) offers the rudder protection and helps the boat track (sail) in a straight line if correctly trimmed.

These boats tend to be heavier and have a greater wetted surface area due to the length of the keel and skeg than a boat with a spade rudder. Although this does make them slower sailing downwind and in lighter winds because there is more drag, they are comfortable in heavier weather due to the increased weight as they do not slam easily.

Fin keel and skeg rudder

Long keel
A long keelboat is sometimes referred to as a ‘traditional’ long keelboat as they were mainly built before the 1970’s.

Generally, they have a shallower draft compared to a fin keelboat of a similar size with the keel and rudder running the length of the boat. They are still produced today but tend to be one off boats rather than being produced in any numbers.

Due to the weight distribution and the narrower hull, they are much better at handling rough sea weather compared to a fin keelboat. The long keel makes the helm particularly light as it ensures that the boat sails in a straight line.

However, what makes them great at sea also does make them a handful in a marina under engine. The small rudder in relation to the keel can also make them unresponsive under engine particularly in astern.

They are slower than a fin keelboat and due to a narrow construction accommodation below decks, can be limited.

Long keel

Bilge keel
A bilge keel boat has two small keels rather than one.

This design allows the boat to dry out so that they are particularly popular in rivers where boats can regularly take to the ground when the tide is out.

Modern versions have increased their sailing ability, but generally boats with a bilge keel will not sail as close to the wind or be as fast as a fin keelboat.

This boat will not be as stable in stronger winds due to the shorter keel, so they are best suited to sheltered waters.

Bilge keels

Lifting keel
A lifting keelboat is sometimes referred to as a ‘trailer sailor’.

It has a retractable keel so it can be launched and recovered by the owner from a trailer, reducing running costs and the centre of gravity when towing. If you do decide to keep it in a marina or on a mooring, you have cheaper berths available due to the very shallow draft and ability to take to the ground.

Although the performance will never be as good as a fixed keelboat, these boats do offer fast and efficient sailing. Handling under engine is good but can worsen if the keel is lifted. Internal accommodation is also lost due to housing the keel.

Lifting keels
Equinox run sailing refresher days and skills workshops to make sure you are ready for your yacht charter. We also provide support and advice for those considering the purchase of a yacht.

For more information and our 2018 dates please contact us on 020 7002 7676 or email [email protected]