|By Larry S |
Apr 11, 2013
Just lowering your partner onto a prussik secured to the anchor will get you out of the belay, sure, but you'll potentially get your partner stuck, you now can't lower him out later if you need to. You should know to secure the prussik to your anchor with a load releasable knot, like a munter-mule, so you get your partner back on belay later if you need to.
Edit - He asked for "Essential knots for climbers" that covers a pretty broad spectrum of things depending on what you're doing, and I think we're taking it to mean different things. If you're a beginner and doing sport/single pitch with easy anchors the lists are much shorter, and figure 8 and clove going to be the bulk of what you need, maybe add in an Autoblock for the occasional rappel and water-knot for tying webbing and grapevine for tying cord.