Rig Tension - Tuning Guide

Most people know what their rig settings should be, but don’t know the forces

they are putting through the rig and the hull. We will try and help you get a bet-

ter idea of what forces you are putting through the rig using the Spinlock Rig-

Sense.

We know the fundamental job of standing rigging it to hold the rig up, however

we can affect the performance, safety and longevity of the rig and boat by having

the rig over or under tensioned.

To start your rig tuning, you need to get a good starting point. Download the

settings from your class website, sailmaker or rig manufacturer. This will show

you how to step the mast, adjust the mast so it is straight, with the right amount

of pre-bend and rake (depending on the type of your rig).

Download our App

We recommend using the Spinlock Rig-Sense App to import, log and share your

rig settings. This can be downloaded for free via the Play Store or Apple App

store.

Download the Rig-Sense App for iPhone and

iPads

Download the Rig-Sense App for Android

phones and tablets

Once you have the mast up and set to BASE settings, you can attach your Spin-

lock Rig-Sense. The numbers at the bottom will be in kilogrammes…but what

does this mean?

Wire cable measures its strength by breaking strain, approximate numbers can

be found in the table below:

Most dinghy and keelboats with fractional rigging set their cap shrouds to 20% of

the breaking strain of the wire.

For example, if you are using 3mm 1x19 wire, (breaking strain = 790kg) your

BASE shroud setting should be approximately 158kg at 20%.

This might seem a small amount compared to the wire breaking strain, however

you must consider the strength of the other fittings attaching the wire to the hull

and the mast. Over tightening the shrouds will cause a lot of compression

through the mast, potentially creating permanent damage to the hull (do not ex-

ceed 25%).

An under tensioned rig could lead to a mast failure. If you are unsure about the

right tension, contact the boat, rig or sail manufacture for more advice.

When measuring the tension of your rig, we recommend the following:

Position the boat head to wind, on flat ground with your mainsail down or

up (as long as it’s the same every time).

Always attach the Rig-Sense at the same place, at least a metre away from

any terminals. We recommend eye level with the KG scale, then mark with a

permanent marker or electrical tape.

Once attached to the rig, push on the base of the gauge, so the pointer

points at 0kg and release.

If adjustments need to be made, this can be done with the Rig-Sense still

attached to the rig.

Repeat the other side of the rig to confirm settings. If possible, measure the

tension on your forestay. This will highlight any issues with the rig setup.

Once you are happy with the tension of your rig, head out sailing and see how

the boat feels. If possible, sail alongside a similar boat to yours and look at your

speed and height compared to your partner. Here are some common problems

relating to incorrect rig tuning:

Sail too full with sail controls on (Kicker, Outhaul Cunningham) – Try more

pre-bend

Not pointing upwind very well – Try more aft rake

Slack leeward cap shroud – Tighten caps shrouds equally on both sides

Mast has an ‘S’ curve – Adjust lowers and intermediates

Excessive slag on the forestay – Tighten forestay/backstay on a masthead

rig, tighten cap shrouds on a fractional.

Poor performance downwind – Try raking the mast forward

Once you are happy with your performance, log the settings in your Rig-

Sense App for easy access.

Mark your wire or rope for repeatable settings:

Use the Rig-Sense to measure jib halyard tension:

For more information, we recommend the RYA Speed Sail and Rig Tuning DVD or

this article by Practical Boat Owner.

*Settings will vary depending on rig type and material.

**Remember not to leave your Rig-Sense gauge on the rig for long periods of time

and in direct sunlight.

Spinlock Ltd

41 Birmingham Road

Cowes

Isle of Wight

PO31 7BH

UK

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