On Wednesday, January 3rd, I was told that the ice thickness between Smith Point and Ferry Point, where trail 301 intersects the lake was 6" plus!
That water froze December 28/29, so ~ 6 days for 6", makes sense and not considering the impact of the snow I estimate that today it is 9/10".
I find it hard to believe that the water south of Pot Island would not have frozen before the end of the year, so know it would be ~6"
Should be OK but to play it safe cross from Laconia to Sanborton north of Pot Island where the lake narrows and then follow the shoreline south.
I will be up there next Saturday and can port actual information, if that helps