Which tip should I use?
This is a question I get asked often when we're out on a guided steelhead trip. There are a lot of different answers based on numerous variables and preferences, however this blog post will try to break down things by season and by tactic. This post is biased towards steelhead, but could be applied to trout.
Summer and Fall
The water is warm, let's say it's anywhere between July and early November. The water temps range from high 40s to high 60s; I would recommend using a scandi setup with a mono leader. It's a very classy and enjoyable way to fish, where you don't need to worry about the depth of your fly, and active fish will move towards it. I will note that I've seen steelhead take surface or wet flies in colder temps, they just have to be comfortable and receptive.
For a mono leader on a two handed rod I would recommend a 12ft steelhead leader of 16lb paired with at least 3ft of 12lb fluorocarbon tippet.
What about poly leaders, versi leaders, or sonar leaders? If you're throwing really large dry flies or skaters, you could use the floating and intermediate varieties since it 'takes mass to move mass', but for the most part I find that they're a crutch for people who are stuck "skagit casting a scandi setup" or for people who are constantly blowing their anchor when casting. Occasionally I'll use the floating tips for someone who's having a hell of a time casting into the wind.
If you're more concerned with fishing productivity or if you don't have confidence in a dry line, I would recommend switching over to a skagit setup with a sink tip and a wet fly or an unweighted tube fly. This setup can be used when the water is really cold, the weather has changed drastically throughout the day, whenever the sun is on the water, or over the course of several days you're full of doubt and just need a change of pace.
If the water is really slow or shallow you can use a MOW tip that's half floating and half T8 or T11. Otherwise if you're on a larger river I would use 10ft of T11, that's perfect for most cases. In either case I would pair that sink tip with 3 or 4ft of 12lb fluorocarbon tippet.
With summer steelhead you're likely to see two groups of anglers; those that have fully subscribed to the scandi/dry line and stick to using it all day, or those who will use a scandi in the mornings and evenings when the sun is off the water or indirect, but will switch over to skagit in the afternoon sunshine.
Neither is wrong, remember that fishing is subjective and at least they're not nymphing. :)
Winter and Spring
The water is cold, let's say it's anywhere between November to mid April, and the water temps range from sub 30s to low 40s. I would highly recommend using a skagit setup with 10ft or 12ft of T11 and an unweighted tube fly. Pair that sink tip with 3 or 4ft of 16lb fluorocarbon tippet and you're good to go in 90% of all situations. Seriously, don't overthink things, just buy that one tip and use it all the time.
In the winter or spring there's only a few exceptions to the T11 recommendation.
If the water is super dirty and/or high I would advise using T8 in order to swing your fly a little closer to the bank (this tip sinks slower than T11).
If the water you're targeting is very deep I would recommend using T14 (this tip sinks faster than T11) and a weighted fly, sometimes even on a longer length of tippet. Your tippet has a narrower diameter than your sink tip and with a weighted fly it will drop into the zone faster.
If your water is both deep and fast maybe switch from a floating skagit to a multi density skagit like an Airflo FIST or a Rio PickPocket, both are built with sections of floating to intermediate to S3 sinking line, in order to slow your swing down.
For the adventurous folks, there's a time in the late spring when the water temps are slowly rising up to the 40s and there will be the odd steelhead that is aggressive enough to take a skater. It takes a certain person to do it, but it can happen.
Tight Lines!
NOTE: Thanks to my boy Eric Leininger for a quick proof read on this for a sanity check.