jackstays and tethers will usually keep you attached to the
boat, but don't expect them to keep you standing up on the
deck. At 10 knots, you separate from the
boat at the rate of 300 metres a minute. A stay and tether means no separation and so an improved chance of staying alive. Increasing the tension on the stays won't do a lot to improve the situation. In the past I used a double tether and hooked onto solid objects. In rough
weather I don't set the
jib or do much to make me go forward. My
current rule is: if I need to use a tether, I should be back in port.