I'm wondering why a line tip should start sinking when it has not gained any density, in theory it should never sink waterlogged or not, anything with a density lighter than water should float regardless, no?
Think about it. The core of the line is the same diameter all the way through its length. The line itself is not the same diameter throughout its length. Starts thin, gets thicker & gets thin again. There will not be the same amount of material that makes it float at the thin end as there is at the thick part. Therefore the tip two or three feet have less to hold them up and therefore will tend to sink, or rather fish just under.
I've used dozens of different fly lines over the years from mill ends at a fiver up to top of the range Scientific Anglers at £70 and the one thing they all have in common is that the tip sinks sooner or later. You can seal the cut end with superglue, but the tip will still sink. Slather it in mucilin and when it washes off the tip will still sink.
Thanks Bob that makes sense, it's not something that's ever been a problem for me being primarily a wet fly fisher, last season was the first I had any real interest in fishing dry.
I assumed it was my taper that was pulling the tip section down, last season when i was drifting onto the dries the tip was sunk on my barrio but it didn't create any problems?
Falkus was an advocate of having the first few feet of his line sunk while fishing his surface lures at night. He suggested that the joint between his line & leader created a "V" wake similar to what his tail fly was trying to achieve to attract sea trout.
Back around 1980 or so Cortland brought out a floating line with a bright red indicator tip. This section of the line was about 6" long and twice the normal thickness of the line at the tip. This indicator tip was supposed to float and enable us to detect subtle takes. Full of enthusiasm as I was getting into fishing nymphs deep under an indicator I bought one of these lines and guess what? The b*gger sank! For some odd reason that line rapidly disappeared - sunk without trace you might say.