In reply to devontwig and Tim.
I do lots of pruning, as well as removals.... tall conifers to spreading hardwoods. The maple in the vid actually had about a 90ft spread, for example.
So, lets use a pruning situation as an example, starting with access. No need to isolate a limb, just put the line straight through a high point in the canopy and base tie it. Away you go, work that side of the tree on the way up using your 1:1 ascent if it suits, bottom up. If you’re not comfortable with a base tie then you can easily use a sling and carabiner to girth-hitch your rope in the canopy at any given point. Base ties do add some extra risk into any climb, so has to be thought about beforehand and remembered throughout. Its as well that they’re somewhat of a taboo subject, because they seem to getting a healthy respect as a result thus far.... nobodies cutting themselves out of trees yet it seems. The possible force multiplying effect from a base tie to the high point/redirect in the tree needs to be factored in also....but, its really not difficult thing to plan for and mitigate.
Once in the tree, its all about navigating the canopy, whether up, down, in, or out. There’s not much else to it. Whether base tied, or using a canopy anchor of some, you have the option of setting the exact amount of line that you require to work the tree. No excess might allow for easy movement or less to no chance of the tail being snagged, damaged or even just getting in the way of the ground workers. With DdRT, there is usually always the climbers rope on the ground in something’s or somebody’s way. Having a chipper anywhere near a climbers excess line is always a major concern too. Canopy anchors/redirects also can also be placed anywhere, without the need for a crotch. 2 or 3 redirects for example can be used to add strength to the working anchor, which would otherwise require additional support lines via DdRT.
When using DdRT, the climbers chosen route around the canopy is largely dictated by the need to keep his line free running, free from obstructing branches or redirects in that sense. Friction savers are all the range these days, but at some point, perhaps after your line is rubbing on 3 separate limbs on route to your target, it starts getting like hard work. SRT, on the contrary, can be routed through or around an unlimited amount of limbs and have zero effect on your mobility, because its only you hitch that moves, not the rope. And whats more, at any such redirect, a sling/carabineer combo can be positioned whether to provide a better line angle for work positioning, or lessen a swing in the event of a fall/arrest scenario. The point is being able to access more of the tree without having to re-route.
DdRT has some advantage in returning from limb walks as its easier to keep you’re weight in the rope using the 2:1 advantage already in place. You can set up a similar system but 3:1 at any point of an SRT line in seconds, if you so wish. I’ve personally never felt the need for this, but I know some people do. If the limb is descending too steep for me to pull my own weight back up it, I simply click on the foot ascender. Where the 2:1 system fall short is that you’re moving half the speed for the amount of rope that moves through the system. Lots of wasteful arm over arm movement but actually going nowhere fast, an illusion of sorts. The 1:1 ratio of SRT whether inward or upward is obviously more efficient by its very nature.
The option of Spur/spike ascenders, chest harnesses and other such SRT specific add ons also offer many advantages....but I just wanted to stick with the basics of climbing for now. Thats all I have to say really.