Just watching a YouTube video of Finbar Furey playing the Lonesome Boatman and noticed from time to time he wrapped his right hand around the bottom of the whistle as though closing or shading the hole. That’s a new one on me!!! What’s it supposed to do? Anyone?
Lowers the pitch.
Try it with any of your whistles. Close all the holes and lower the end onto your leg or a table top (gently, hard to play whistle with dentures…)
Best wishes.
Steve
Really? I can’t get it to work. Furey played with his left hand . . . so only as low as G, and covered the end of the whistle with his right.
Mike
Should have said, “Lower the end of the whistle almost to your leg or the table.” Don’t want to totally block the end of the whistle or it will stop.
If he’s doing something off the G note, maybe he’s just checking for drool levels…
Them’s my thoughts.
Best wishes.
Steve
Is this the video you are looking at?
If so, I do not really know what Finbar is up to with his right hand stopping the bottom of the pipe. I’ll try to figure it out when I have a chance. Finbar Furey’s a maniac on the whistle. 
What Steve referred to is standard whistle technique. On higher whistles you can use your little finger to flatten the first octave bell note. That’s how you get a C# below the D. With some practice you can hit a C. For the larger low whistles you stop the pipe end on your leg as Steve says. It helps to play seated.
Feadoggie
Or at least facing the audience…
I should have mentioned it. This was the video I was looking at. http://www.youtube.com/watch?v=ntGIkGuFBL8
Do you mean where here leans back ? I wonder if it’s ‘microphone technique’.
Where he puts his hand over the end of the whistle.
At 0.39 and 1.29 are examples of what I was wondering might be to do with getting the sound he wants to the microphone.
I see what you’re saying but he uses the technique at other points too when the microphone is clearly not the focus.
At the risk of being a heretic, this was more ‘the loathsome boatman’ IMO..
Steve,
Please tell us this is not your idea of eye candy. 
You “crack” me up!
Cayden
The more I think about it, I believe Finbar is just being theatrical. You know he can be theatrical at times.
http://www.youtube.com/watch?v=ecbgdH8UVeI&feature=player_detailpage#t=44s
Yes, that’s Finbar Furey singing New York Girls in the Martin Scorsese film Gangs of New York.
Either that or he doesn’t want to drop the whistle.
I can find no instance where what he is doing with the bottom hand is effecting the dynamics or pitch of the whistle when I try to do the same. Any body else?
Thanks Feadoggie! Weird.
On the Overton low G whistle closing the bottom end will raise the pitch of F# and E (C# and B in D whistle terminology). Since F# in the second octave is especially flat it may be a useful trick, especially as it is such a prominent note in the piece. You can also get a nice finger vibrato on the high E (B on D whistle) with a finger across the bottom end.
I tested this with my Overton low G (alto G, not bass low low G).
Feadoggie wrote:
I can find no instance where what he is doing with the bottom hand is effecting the dynamics or pitch of the whistle when I try to do the same. Any body else?On the Overton low G whistle closing the bottom end will raise the pitch of F# and E (C# and B in D whistle terminology). Since F# in the second octave is especially flat it may be a useful trick, especially as it is such a prominent note in the piece. You can also get a nice finger vibrato on the high E (B on D whistle) with a finger across the bottom end.
You’re both right but I think in this case the movement in question is more visual than anything else.
Tommy
funny this should come up - I just noticed the other day that xoo oox is noticeably sharper than xoo ooo
on my G whistle closing the end changes the pitch and tone for second octave G, C and C# - though half holing the C as Finbar is doing pitch would seem to be not the important part - closing the end seems to not effect the second octave A or B very much.
I’ve seen whistlers with longer fingers than mine shade the bottom of the whistle with their little finger to get a C with all other fingers on.
I just can’t reach though.
I think he’s just sort of holding the whistle down there, to keep the lower hand out of the way, to show the audience “see? I’m only using one hand!”
BTW from the first time I heard Lonesome Boatman I thought it was clearly derived from Andean kena playing (in melodic style, performance style, and accompaniment style) which was becoming very popular at just the time he wrote that tune.
Here’s what I mean (and no, this song wasn’t written in 1970!!)