I'm looking for a good longer rope (e.g. 70m or so) to use for rappeling during canyoneering trips. Most of the ropes on Amazon or REI are dynamic, and my understanding is that static ropes are generally preferred for canyoneering.
Most of the lighter ropes I see (7.9mm or 8.5mm) are only rated twin or half. Presumably these would be usable when rappelling double-rope, but wouldn't be advisable for single-rope rappels due to low friction?
In short, for the described purposes, what kind of specs should I look for in a rope?