I bought a Penn Mariner rod today, but my 12/0 stand won't fit into the seat. It appears the seat will not open wide enough. Am I overlooking, underthinking, or poorly matching this combo? I thought these being the same brand and close to the same range in line weights would make this a good combo.

Suggestions?

Thanks

did you try sliding one side in first and maybe tap it in lightly

Yes I did. It's not even close to being able to fit. I had no problems with the 9/0.

I think its a poor match. the 12/0 has a big foot print. If you can return the rod, bring the reel with you when you buy a new one, or take some measurements.

I have both the 9 & 12. The 12's reel seat is the same as the 14/0 and its a larger version than the 9/0, it will not fit period. I had a custom rod built for it and love it. On some reel seats that will accept a 12/0 a 9/0 will fit but it depends on the seat. There is a reel seat made for the 12-14/0 Senators.
I went through the same thing here a few years ago.
I love my father's Seantors, all 1959 vintage and almost like new.
If your serious I can help you find a good rod for your 12/0 reasonable, if you have not done so consider a HT100 drag replacement for it, a huge improvement very cheap also for your 9/0.
Last Oct fishing out of Galveston I had my 9/0 emptied in about 5min of #80 line, I cut it right before the knot came up. I think if I had the 12/0 it would have been the same way also, my 80-120 Senator rod was bent double.

Thanks for the info. You've talked me into the drag upgrade for the 9/0 & the 12/0.

I think I will try trimming down the 12/0 base to fit this rod since I can't return it. It looks fairly easy to do and if it turns out badly I can replace the base for $30.

I'll post some before and after pics.

Thanks for the help.

The 12/0 and 14/0 are basically the same just that the 14 holds more line and the gearing is lower, you can install a 14/0 handle and it makes them about equal except for the amount of line, the 14 is much heavier also. The 9/0 is hard to beat.