Boat fishing in July, after the first week, can suddenly become very hard. If the fish continue to rise in the evening then all is well, since dries are likely to succeed. However sometimes they fail even this. Don't be alarmed - calm days will produce sporadic daytime rises easily coped with small dries #16 to #20, hot flies can work especially well.
I often go down and find the fry feeders. It's usually with the intermediate, although with wind it could be a wetcel II. Flies are simple; mini-fry pattern on top dropper, mini catswhisker on middle and an appetiser fishing the point.
Cast as far as possible and allow the flies to sink down to your required depth (vary depth until fish contact is made and then stick with it until fish contact is lost). Bring back very slowly and hang flies on the lift. Takes here can be so vicious that you can get broken. The only answer is to expect the take. The other main taking area is when your flies suddenly begin their ascent.
I find that the angle the flies are retrieved through is absolutely critical. This is what makes lure fishing from boats so subtle when correctly applied. Fan your casts. If you find a good angle and your boat partner can't, then you may have to swap sides so that both anglers get the sport.
I carry a wetcel II but only use it for this method.
It is possible to follow the fish up through the water until they appear at the surface.
Then there is what I call the Muddler Trick. After dries, this method catches me more fish than any other. It works especially well during cloudy days. The set up is a big greased up muddler on the top dropper (#10 l/s), followed be a Cove pt (#10) - which has a dual role, to catch fish and to sink the point fly - which is either a damsel nymph, an appetiser or a black lure depending on what the fish want.
Long line the whole thing and bring back figure of eight. Don't strike - apart from takes on the drop - just keep retrieving.
Play the angles and fish the dibble out. The dibble is three times more effective with a change of direction.
Sometimes it's a good idea to just stop the flies as they reach the boat. When the muddler disappears or moves backwards then you had better strike. If the fish actually takes the muddler static and dry, strike like a floating fly, ie give plenty of delay.
Muddler fishing is dramatic and very few people fish it any more, they're just too preoccupied with their dries. The only objective I have to this method is that it can be just too effective. Muddlers sometimes outclass all other methods from the beginning of July until mid September. And that can make the fishing pretty dull.
Some people recommend fishing the muddler on the point, this I believe is a huge mistake, most fish get turned on by the muddler but fail to take and then turn around and snap the other flies.
It can be very entertaining to watch the fish's reaction to the muddler, some leap out of the water, snatching it as they go, others zoom past it, turn around and wait for it, yet others leap out of the water and land on it. And then there are the others which just pluck it about 90 times and never get hooked. Steve Parton devised a muddler with a trailing treble to take these fish. However on many waters you can only fish three hooks and so you lose out on the trailing flies.
And lastly there is the booby trick for the fish which have seen it all and couldn't care less.
It goes thus; intermediate line, with lure top dropper (may I suggest a black minky?), leaded lure or leaded shrimp in the middle, with a booby lure on the point (orange can be the one).
This set up can be lethal - and a real bitch to cast - fish very slowly with plenty of pauses. Use the angles and I prefer to save it for windy days when anchoring is essential for controlled fishing.
You can also turn the whole lot into imitative flies in September; daddy long legs, leaded shrimp / leaded hares ear, with suspender buzzer / floating fry on the point.