Pitch and Pay Style
I changed all the basic inaccuracy by deliberately casting short and setting up the depth much more precisely by letting the line sink untrammelled by drag in freefall. Casting 15 yards sideways and then dropping say 15 yards of backing you control the depth quite precisely and you don't need a stopwatch to play either. The trick is to commence the retrieve as soon as the line goes tight and then to count the number of pulls before the shooting head reaches the tip ring.
If you start at 20 pulls you can double the depth by adding around another 10 pulls of backing into the system (there's already 10 pulls cast out!) Being thoroughly practical, don't try it on with much more than 45 pulls worth of backing because it'll tangle in the boat. I've been out to 70 with braided nylons - but more than that and you'll be untangling for England for most of the day!
With two of you at it, you'll halve the time needed to find the killing depth as long as you both do something different. Normally Jim Clements and me would set off with one on a fast sinker and the other on a 10 yard leadline. Starting shallow and then lengthening off the backing shot after shot. No pulls in the first hour and one would come up and the other go super deep.
You might try changing the fly over from time to time and it certainly can be critical but strange things used to happen - we'd get in of an evening at Rutland having had a fabulous day on white to find that pals of ours had had a better one on black - and we couldn't pull on their colour and they couldn't pull on ours! Black, white or sparklers about 3" long usually does the business - though these days I have been known to use the odd action-implicit lure like a huge Tullis because that thing does provoke a fair few hits and the hits you need to tell you where the trout are.
Overdepth and underdepth fishing
Let us suppose the fish are actually 10' deep, a handy depth for a Wetcel 2 or a medium speed head fished at 30 pulls pitch and pay.
There are other ways of getting the fly to that depth that may be more productive on the day. On a plunge day it is possible to get the fly to dive down by firing a leadcored head as far as you can cast it sideways and then by pulling fast from touchdown.
Semi plunge days you do much the same things with a Fast Sinker - just let it settle in before pulling away. And on a drag day - when they don't want it pulled at all but will only take on a perfect smooth continuous retrieve you may pitch and pay a slow sinker or intermediate and just let the boat tow it along.
On the day you may have to deliberately fish over or under to key the takes - it all depends on what they want - not what you think they should have!
It is a very great pity we didn't have decent echo sounders 30 years ago. The last decade of spasmodically using one from tube and boats has taught me a great deal. The main thing being that trout at depth have two behavioural modes.
They either lie at almost one specific depth which is when they are basically shut off from feeding and are just being quiet - the banding at such a time is typically within a couple of feet. And it is usually a suspended band - say 15 feet down over 35 feet of water.
Feeding behaviour occurs fast and the bandwidth suddenly widens drastically. I have to assume that when something triggers the onset of feeding they start to chase up and down in the water column actively hunting whatever it happens to be. More often than not probably either a buzzer hatch or a daphnia cloud, occasionally a damsel hatch.
Practical fishing styles are basically two but both rely on the fly being in the middle of either band. These days if the banding is tight I don't expect an awful lot of fish but I'll just keep on plugging away in the knowledge that sooner or later I'll provoke one of the quiescent trout into having a go. Boring maybe!
But when the bandwidth expands I anticipate a very sudden bonanza. And this in the olden days we used to refer to as sequencing.
If one or other of us hits a fish the immediate next move is to tell the partner exactly what line we are on and how many pulls of backing are out behind it. "Wetcel 2 and 33 pulls!" and you can bet the partner's gear is on the spot at the right depth within a couple of minutes maximum! Sequencing gets an awful lot of fish into the boat fast. And if you can't do it you are at a massive disadvantage. The feeding spell may only last a few minutes and you have to take immediate advantage.
One very interesting thing we have observed over the years at Toft Newton is that the trout in that very small water almost always occupy just half of it. The other half is virtually devoid of them, which is odd because the place is virtually symmetrical. And it is always the same right through the season. That's what the echo sounder has done for us. Practical experience suggests that most other waters react just the same. There will always be vast stretches devoid of trout and other stretches full of the things.
It is a good idea to be in the trout rich parts when they suddenly come on the feed!