Can anyone tell me what tension (kg) the shrouds should be on my Parker 235? They have got rather slack on the leeward side on a beat and are still somewhat slack after tightening up a number of turns on the rigging screws.

Should the tension be the same in the upper and lower shrouds?

The tension is currently around 90kg as showing on my Loos gauge.

Andy Sleeman
P235 no. 69

Hello Andy,

You’re right: a cap shroud tension of 90 kg is very slack! The tension on the cap shrouds should be more than 300 kg. The guidance is to set them at 20 – 25% of their breaking strain (which is about 1400 kg) with the backstay off. (Tensioning the backstay reduces cap shroud tension.)

To answer your question directly, the tension on the cap shrouds will be higher than that of the lowers. However, it will depend on the amount of pre-bend you want in the mast, which itself will depend on the cut/age of the mainsail. If your sail is getting a bit too full, more pre-bend will help to flatten it (before you use the backstay to flatten it more for de-powering).

It’s well worth spending the time to set the rig up, ideally using a tension gauge, which you’ve got (that’s the expensive part!). I recommend Ivar Dedekam’s book on the subject, which also considers sails, or, for just the rig tuning, there’s the Selden guide: http://www.seldenmast.com/page.cfm?id=6740 .

Anthony Russell
235/02 Sea Wyche

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Hi Anthony

Many thanks for your advice which is very helpful. I will give it a go and gradually hike up the tension. When I got the boat Bill Parker had set the tension and said it would need adjusting after some use, but it seems that it needs a lot more tensioning than I imagined. I just got the Loos gauge this week so I could get some sort of definitive measurement. The mainsail is in good shape so I will adjust the lowers to keep the mast pre-bend to a minimum.

Andy Sleeman
P235/69 Galatea