Checking and replacing the tendon on your mast base

It’s that time of year to check out your gear. Cold water sailing is fun and exhilarating but a little more care should be given to safety. Here is a quick guide to checking and changing one of the most critical parts of the rig. The mast base (Universal joint). I have three. All three of the tendons holding it together needed to be replaced. I am changing them twice a year now. They cost $25 a piece but can save you and your gear. When they break… often the board gets damaged at the same time. Imagine loosing a part of your gear… sail or board!!! Spend the money… its worth it. Bruno at 2rad has them in stock.

Dont forget to check the line that holds it all together. You can sail back with this setup even if the tendon breaks.


To check the mast base tendon you need to disassemble it. Mine are done with an Allen key.

Checking tendons for wear

 Insert a thin screwdriver shaft into the hole that holds the screw.

Insert screwdriver and bend

Bend the screwdriver up and down and check for cracks on both sides of the hole. This is a fairly huge crack, If you even see a nick, its time to change it.

Replace if cracked

6 thoughts on “Checking and replacing the tendon on your mast base

    • Thanks for the post. Sometimes you need to hammer the screw through as the new rubber can be a bit stiff. I suppose lock tight is always a good idea. I dont use it though and have never had this come loose on north or Chinook mast bases. You just need to tighten reasonably. 🙂

    • Sorry for the long delay to reply. Had not seen this. For me I just tighten them snug, but this may depend on what type of mast base you have. I’m sure lock tight is a good idea.

  1. Yes same goes for rubber hourglass, bend it to see if there are any cracks developing,if so replace it now. I had one let go in Hatteras as I forgot to check them. but the strapping held and got me back in, plus it was Hatteras Sound, and I could have walked back in worst case. Not to funny though if the strapping isn’t there and your in cold deep water.

  2. Pingback: Checking and replacing the tendon on your mast base (via Windandbigwaves’s Blog) « Windandbigwaves’s Blog

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