Should I go uplocking or downlocking on the size 20 Fuji graphite spinning reel seat. Its going on a Black Hole 8' blank for large yellowfin tuna.

For many years I was in favor of uplocking on spinning rods. In latter years, I have come to favor downlocking and I will usually remove about a half inch of the threaded barrel as it's rarely needed. Check for reel foot fit before you do similar, however.

On that type rod you'll almost certainly employ a foregrip.

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I always go down locking.
Norm

Mark,
Guess what - You can make an executive decision on your own and then own the decision with its final results.

At the end of the day-
Each way works just fine.

Best wishes

Uplocking puts the seat hood up so a nice smooth transition to the foregrip is possible, with the threads down and most of the time out of the way of the hands. Mock it up to see which you like the best.

I have to vote for down locking.
The way I hold the reel seat, in between the middle two fingers, tends to cause the hood to loosen on an up locking seats.
I also will remove part of the threaded barrel...and no foregrip.

Chris, I've heard that comment on loosening before, but I don't get it on DPSSD size 17 Fuji seats. I've fought some very nice smallies and a couple pretty large barracudas, but no tunas.

For a heavy duty rod like this, if there is any question, downlocking might be best.

I'm with Michael, seems to me to loosen a reel seat you have to exert a force similar to what you used to tighten it, I just grip the rod, I don't twist it, I guess.

On the mock-up the blue trim ring looks soooo much better in the up locking position. I've always fished and built with the down locking position so I'll probably go with that. The 6500 spinning reel barely fits into the seat with the nut all the way up so when screwed down only about 3/4" of the thread is showing. The main reason for the question was that I was thinking the reel would be in a more secure position with the front foot against the static cup of the seat. With up to 30# of drag being exerted, would it be better up locking? Maybe I'm just over thinking the simple process.

Mark,
It all boils-down to personal preference and there are valid pros and cons for either up or down locking seats. I certainly do not think you are “over thinking the simple process”. For large fish and rods (Tuna), for reasons you stated, I feel more secure if the seat is up locking with the main force against the stationary hood, more so with a spin reel (no clamp) versus conventional (with clamp) and, as Michael mentioned, provides a smooth transition between seat and foregrip (needed). For smaller freshwater fish (Trout), I prefer down locking because I infrequently use a foregrip (not needed) anymore.
I do not know what size YFT you are seeking, but may I suggest you reconsider employing such a small (size 20) seat. You already mentioned that the reel feet “barely fits into the seat” = go with a 22 or 24, remember there are no clamps. To be honest, the majority of anglers would prefer a conventional reel over a spin reel for 100lb tuna.

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

Thanks, Mark. I'm building the rod to Black Hole specs. The build sheet has a 20 seat as well as rear and fore grip sizes. It also has the guide spacing included. YFT up to 200#. but most likely 50-80# on a top water plug.

Mark,
It is impossible for the “build sheet” to know what size reel (and feet in your case) will be employed. Especially considering the feet of your reel barely fit into the size 20 seat and that there are no clamps, it may (probably will) prove foolish to not upsize the seat. Hopefully you are using the provided guide spacing as merely a starting point before performing a 2-line static load test to determine the most efficient guide positions / spacing.
Just out of curiosity, why are you building a spin rod for tuna rather than a conventional rod? I am certain that large tuna have been caught with a spinning set-up and suppose anything can be done but it certainly is not the norm.

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

Black Hole builds and sells this exact set up for experienced tuna fishermen around the world. No need to reinvent the wheel. These rods will be for a 38' Freeman fishing in the Gulf of Mexico. They target and land many pelagic species such as 800# blue marlin, 80# wahoo, 560# bluefin tuna, 600# mako shark, 300# grouper, and of course yellowfin tuna. The captain and crew have every type of blue water rods and reels imaginable, except for these. It is built specifically for tossing top water plugs into a school of marauding surface feeding yellowfin.

Mark,
Thanks for the description of what you are attempting to accomplish. You are obviously a better man than me fishing for “800# blue marlin, 80# wahoo, 560# bluefin tuna, 600# mako shark, 300# grouper, and of course yellowfin tuna” with a spinning outfit; those are lofty goals indeed. Personally, I’ll stick with a spiral-wrapped, conventional reel set-up.

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.