Plugs for livewell fill and drain
I very rarely use the livewells for bait but use them as storage for trash and other less important stuff. I don't want water from the pump or drain in there so I need to plug holes but there's usually some nasty liquid in the bottom that I want to rinse out so I need to open the drain back up every day. I think seacocks on the livewell hoses are a great upgrade to the newer boats (I retrofitted my old boat before selling) but it's a real pain to get in and out of the bilge to operate them on a daily basis. The TH marine plugs that worked on the old standpipe smooth fitting do not seem to work on the newer threaded fitting. I took a risk at ordering the following adjustable rubber plugs and they work great on the standpipe fitting. The livewell inlet can be easily plugged with a 3/4" PVC threaded fitting from your favorite PVC part source (Home Depot etc). Now if only the livewell would drain completely on the trailer like the old setup. Unfortunately I think that will require raising the entire floor of the livewell above the lip of the standpipe fitting.. 
Shaw Plugs 52403 Xtreme Marine Expandable Neoprene Rubber Plug with Stainless Steel Handle and Hardware, 1-1/2" x 1-5/16"
http://www.amazon.com/gp/product/B0085PD2AM/ref=oh_details_o06_s00_i00?ie=UTF8&psc=1

Shaw Plugs 52403 Xtreme Marine Expandable Neoprene Rubber Plug with Stainless Steel Handle and Hardware, 1-1/2" x 1-5/16"
http://www.amazon.com/gp/product/B0085PD2AM/ref=oh_details_o06_s00_i00?ie=UTF8&psc=1

Replies
The ram pressure in the sea chest where the inlet draws its water is what fills up the livewell even without the pump and from my experience is definitely enough to float a five gallon bucket so the bucket opens the hatch and then falls over. Either that or you have Oscar the Grouch living in your livewell.
This plug in the drain:
http://www.westmarine.com/t-h-marine/t-h-marine--drain-plugs--P010126605
and one of these in the inlet worked great for me for years on my 2000 hull. I don't remember the size, maybe it was just the 1/2".
http://www.cheaperthandirt.net/product/6-6501383?utm_source=GoogleShopping&utm_medium=organic&gclid=CK7P8abT3L4CFWYV7AodrGIAgw
I installed seacocks but as I mentioned above they are a pain to get to whenever you want to rinse out the live well compared to just popping a couple of plugs. On my 2012 hull I have a custom shroud around the poling platform to hold lifejackets and keep the fly line out of the motor rigging so it's an even bigger hassle to open and close 4 seacocks every trip.
With the old livewell, I would tie the two plugs together with some heavy mono so 1) the little inlet plug didn't fall out the drain and 2) you could pop both plugs by pulling up on the handle of the drain plug and the inlet plug would get popped out by the tension on the line. The only drawback was trying to keep an eye on friends who would "throw the baby out with the bathwater" when emptying trash from the livewell. Had to replace several of those plug combos that were thrown out, but that's just the cost of being the one with the boat everyone else wants to fish on.
The 152 will work on 1.5 inch threaded openings and they will hold pressure. They will not rust. These are allot less costly than the plug from Amazon. I use them all the time in the swimming pool industry.They are high quality.
**** those plugs are nice and cheap!
Good Score!
That does look like a much more economical plug: at least mine is shiny on top..
Boat: 2015 25' Competition Single 300 Yamaha
Latest Fishing Report - Snook on the Beach
Both wells no longer have standpipes. Water drains in a chest cavity, modeled after Lake N Bay.
Pic of shiny new thru hull fittings, but really to show what must happen to erase chine walking above 63 mph
In that last picture, is that a modification of the bottom that was done?
:thumbsup
I have PTSD about an overflowing livewell as on the old hull an overflowing livewell would guarantee that much of the water would flood the bilge as the seal between livewell and the bottom of the deck was not good. What a mess!
I have never heard of the problem you just mentioned. The baitwell tubs are glassed the underside of the deck after the deck is pulled from the mold. The fix would be to seal the edge with silicone or 5200. If you have an Florida built 18 you can put a small hose from the baitwell gutter drain out to the splash well drain and avoid the water entering the bildge thru the bildge access hatch. Good Luck... Pete
It is simply 1&3/4" OD pvc piping with standard cap, drilled for drain of pump capacity, and a threaded fitting cemented with 5200 into the end. I cut a female thread down to 1/2" and adhered that into the existing drain. That way, the livewell drains completely, as it is flush, and since the units thread into the drain, no more problems. Plenty of flow btw!
You can drill holes in the bottom and the top and not the middle to pull more water up from the bottom of the well! You can black out the wells never worry about bait clogging the standpipe and well overflowing or restricting flow and putting to much demand on your pumps!
Thanks
They baitwell tubes just pull out. You might have to wiggle and twist it so it pulls out.
Thanks. I was worried if I forced them they might break, was not sure if they were sealed in there. I'll give it another try.
Appreciate the advice.
Well that boat is no longer mine.
So i guess that pretty fiberglass molded hatch everyone raved about on the old boats also leaked like a sieve! Awesome!:grin