Setting sail with accurate data: load cells on racing yachts

Published On: June 17 2022

For those of us brought up on “Swallows and Amazons”, sailing still holds a sense of adventure and excitement. Around 100,000 of us take to the water to enjoy sailing every year, whether in small dinghies or full-scale club racing yachts.

Load cells for all sailors

According to a fascinating article in Yachting World:

“Strain gauge and load cell technology has already started to filter down from the world of elite racing to become useful for club racing boats and cruisers.”

Apart from the various uses of load cells we discovered, we also had to look up a lot of rigging and sailing terminology. It’s another world out there on the water!

Load cells are most often used as strain gauges to sense load and monitor tension on rigging ropes. For example, specially designed load pins can replace the normal pins that attach rigging to the boat’s deck or hull.

Bottle screw gauges can also be retrofitted to load pins to monitor loads on the forestay (a piece of rigging that attaches to the bow of the boat and stops the mast tipping backwards.)

Load cells are also used to monitor tension on non-structural cabled sails, and to measure load in running rigging for the mainsheet. Increasingly, strain gauges are being integrated into sails, usually to measure the luff tension.

Quick terminology explanation. The luff is the leading or front edge of a sail. Luff tension is the force exerted along the luff (vertically) mainly by the halyard (a rope used to raise or lower a sail).

What we particularly enjoyed what the explanation of how data from the various load cells would be used by the sailor. A major use is safety, with the ability to monitor safe and maximum loads for rigging even as conditions shift and change. Load cells can also indicate if a boat is overloaded,:

“This is particularly useful in cruising catamarans which, when loaded up with extra weight in the hulls, can feel stable and mask the signs it is time to reef leading to damage of sails, mast or rudders.“

(Sailing terminology: to reef is to reduce the surface area of a sail by folding or rolling one edge of it. )

Sail tension consistency

Load cells can help establish an optimum tension for actions such as furling headsails which can be replicated each time. This avoids either an unsuccessful furl where a cable may be too slack, or over-tensioning which can damage the mast. The same applies to sail trim:

“By measuring the force going through running and standing rigging we are not reliant on marks on ropes, or the deck or memory of sail shapes to sail well. This makes it easier to record and return to fast modes.”

Data transfer and interpretation

In a fast-moving sport such as sailing, the ability to see and interpret the data during a race is important. Modern racing yachts usually have an instrument cluster with multi-screens that can display load cell data in graphical form. This can make interpreting the data for unexperienced or amateur crew as simple as seeing if a graphic “dial” is green or red.

For more on load cells and elite racing yacht testing, see our 2019 blog “Load cells and destruction testing”.

Load cells for marine environments

Load cells need to work reliably in harsh marine environments, including:

Need load cells for marine environments?

Contact us. We design, manufacture and distribute a wide range of load cells here in the UK.