Sorry John (and the Irish), but that reads a bit 'Irish'... Maybe my original post was a bit 'Irish'.
I will not relay your comments to my (Irish) wife
Maybe neither of us were as clear as we could/should have been, but I think we are both saying essentially the same thing - and that it is winston who is 'out on a limb'
I think what I said was being misinterpreted - the 10 degrees was the difference in angle, at the OP's suggested location, between his likely mobile masts.
Indeed, and that was mirrored by me when I wrote:
... My understanding is that the OP has a number of masts within a 10° horizontal spread from his location ...
I said a Yaggi antenna would reasonably easily accommodate that 10 degrees, between the masts.
.. and, again, I was (at least trying to) essentially mirror that when I wrote ...
... and that Harry was saying that it would be difficult to align an antenna (which, in practice is likely to have a horizonal (3dB) 'bandwidth' much greater than 10°) explicitly at one of those masts since, over quite a range of 'pointing directions' of the antenna, the antenna would more-or-less equally well communicate with all of the masts.
My wording was perhaps a little contorted but, as below, I was trying to accommodate the fact that you had used the word "difficult" in what you wrote - but the intent and spirit of my comments was the same as yours - that the antenna would, in practice, have more than enough beam width to accommodate all of the masts simultaneously and that it would be 'difficult' (other than, I suppose, 'visually'), as well as unnecessary, to attempt to point the antenna exactly at any one of the masts.
I said nothing about the how wide the beam width was of the antenna itself, other than that it would work and possibly better than something less directional.
You didn't mention the beam width as explicitly as I did ("in practice ... much greater than 10° ") but it was surely implicit in your saying that it would be adequate to cover all of the OP's masts?
I didn't suggest that alignment would be difficult, all it needs is a compass and a direction to aim for.
As above, you did (I would say rather confusingly) use the word 'difficult' in what you originally wrote, namely ...
... 10 degrees is well within the reception width of your directional antenna - you will find it quite difficult to even align the direction of the antenna that accurately.
... which is why I tried to use wording which reflected that.
So, as I said, I think that you and I are both singing from the same sheet (although we have both written some potentially confusing things!) and that it is winston who has (maybe 'by choice') not understood.
Kind Regards, John