Floating Line with Bob Fly  & Wet Flies : Tube & Boat differences
Traditional lough fly fishing for stillwater trout involves using a bob-fly to make a surface wake. This draws fish up where they often take the bob fly. Other times they slash at it, and miss, or refuse and veer past. It is relatively common for these fish to take one of the other two more natural looking nymphs on the dropper, or tail position, as they move back and away from the bob-fly that brought them up from a deeper level. Dibbling at long range is not necessary because the trout will rise consistently closer to the tube than they will for boating anglers. Trout are not afraid of your tube. They will rise under your hand if you dance a fly from your arm with no rod, and rising at a half rod length is very common.
That means that there is no need for the high seat that a boat provides. The boat angler can dibble further out due to his higher position. This gets the trout up further out and appears to be an advantage when a trout takes at a safer less exposed distance.
However, a boat's big dark profile above water level scares fish. So the boat angler has to lift off sooner and re-cast farther away again due to a "dead zone" near his boat. In contrast, a tube does not scare the trout anywhere as much. So we from our lower seat, dibble at a nearer distance.
Our float tube variation in presentation is to cast shorter, and dibble more often, closer to us,  than the comparable boat mounted fly fisher. What we lose in "effective dibbling distance" we gain back by increased casting frequency. The fishes reaction to prey is instantaneous, so a take is immediate. Any "followers" would not have taken (mostly) with a longer retrieve.
When a trout takes too close to strike due to the vertical rod position at the end of the cast, just do a roll cast, and the trout will be hooked by the weight of the line in the rolling loop.
Tackle choice takes account of this shorter range fishing. We prefer a tip and middle (medium-through action) fly rod.

Four midwater presentation styles
Tactically speaking,  fishing a bobfly is effectively a way to catch trout on the surface, fish that maybe were already surface oriented. But possibly they were feeding on food situated a little below the surface in midwater. It is usual to regard lack of surface action as a possibility that fish are feeding below. However at this point a choice opens up. An alternative. We can bring them up, or go down.
Option 1 is to put on an intermediate, or Wet Cel 1 slow sink, and go down into the shallow midwater zone, probably using chironomid pupae, corixae or olive nymphs, maybe damselfly nymphs in summer. retrieve as appropriate for the food item above the bottom or weeds. In calm to ruffled water this is usually a productive choice. You cover a small area of water this way.
Option 2 works better if the water is calm. This choice is to use a floating line and strike indicator or bushy dry fly. The flies hang almost vertically down from the fly line's end and floating indicator. The leader and team of flies covers three depths. You drift and wait for the trout to find your offerings, and they will. Then the indicator sinks and you are in business. Pick a good spot because not much water gets covered due to the infinitely slow presentation.
Option 3 is the one for the day with a good wave, but is not fishing in the feeding zone. Rather it attempts to draw the fish up to the surface. Leave the floating line on, fish traditional lough wetfly style, and dibble a bobfly with a trailing team of two wet flies or nymphs. The wake fly grabs their attention and brings the fish up. Then either it, or the middle dropper, or tail fly receive a take. This method allows the fishing of a wide area of water.
Option 4 if a bob fly's wake in the surface can get trout up from midwater, then a dap will do it even more effectively. Get a long rod and the floss line and start making the surface disturbance with a vertical presentation. The number of rises will increase and possibly the size of trout too. This depends on wind to work well. I feel that dapping from a boat is better, as the tube mounted angler with his lower seat needs a good wind to get the line out, and that wind will make tubing an energetic affair over a couple of hours.

Longer Casting with full Sinking Line
Now if the trout are feeding in a zone below midwater, the sinking line is the better choice.

(There is an exception. In very shallow water the bottom feeding trout is still within striking distance of the surface)

However if they have their head down, as in the early season when digging for Assellus water louse or Gammarus shrimps, it can happen they won't notice a surface fly, even if it is within inches of them. When a few food morsels bolt and flee, the trout will go after them, and that is when the fly just below the top has it's moment, with a fast take.

A Wet Cel 2 line is suitable for this work, and is a versatile line for alternative uses. It will take nymphs down to 10 feet, troll slowly at 15 feet, or present a fast retrieved lure fish imitation in 4-5 feet.

Cruising trout taking chironomid midge pupae: camera in rear position looking forward

Carefully stalked and covered

A grown on stockie comes aboard for a brief visitn