Bait tank 101
You will need the following supplies. You can substitute and I would if given a choice between buying something and using what I already had or could get cheap. Be careful that the bilge pump fits in the pipe cap if you substitute that. This tank has worked well with 200 anchovies for the whole day. That is if you have a washdown pump constantly filling it and overflowing. Use the hose divider to control the hose that feeds the tank with one outlet and the washdown hose on the other. When you need the washdown hose shut off the hose to the tank so you can get some pressure. Remove the baits as they die, they make good chum. Scales plug the recirc pump and you will have to remove them if the flow slows down. The recirc pump will get the water moving in a circle to keep the baits from crashing into the sides of the tank.
55 gallon white plastic barrel. Other colors are OK but White minimizes solar heating.
Bilge pump hose, 1-1/8" by 50", the black stuff is cheapest.
4" plastic pipe cap, PVC.
10 ft stick of 4" drain field pipe, PVC.
8-32 by 1/2" stainless screws and nylock nuts, 4 each.
Speaker wire, 14 or 16 ga, length to fit situation.
Scotty power plug, Male. You will also need the outlet installed on the boat.
Bilge pump, Rule, 1100 GPH, compact simple round type without electronics.
Aquarium net approx 8" square.
1/4" shrink tube.
Liquid Vinyl Tape.
Soft foam sheet, used for non skid or silverware drawer liner. 18" by 18"
Garden hose, 10 ft.
Garden hose divider, with individual shutoffs.
Aluminum pop Rivets, 12, 3/16" by 3/4" with backing washers.
Pop rivet gun
1-1/4 hole saw
5/16" drill bit
3/16" drill bit
propane torch or heat shrink gun
Black felt marker
Flat coarse file
Round coarse file
Boat stuff you need
Washdown pump with strainer and hose bib.
Scotty Downrigger power outlet for at least 5 amp service at 12 volts.
Ok so lets start with the barrel. I'll try to explain why I did things the way I did as I go. This may not be the best way and I'm sure you can improve but I did what any experienced DIY person would do. In general I try to make things simple and conserve difficulty.
Figure out what your tank will weigh when full. I calculated that I could tolerate 200 pounds on deck. So I limited the tank to 25 gallons since water weighs 8 pounds per gallon. The barrel I used had the gallons clearly marked with a scale on the side and the tank height worked out to 20 inches and the water level worked out to 14 inches. You can make the tank bigger but consider the weight VS the stability of your boat.
I cut the barrel 21 inches from the bottom using a chainsaw. An extra inch for oops. The chainsaw was just for convenience mainly but I must admit to a certain satisfaction in the roar and bluesmoke of the chainsaw. This makes a huge freakin mess so lay out a tarp or use the wheel barrow to catch the chips.
After cutting the barrel in two, use the skillsaw to remove the rim from the top half. I set the depth on the cut to 1/2" so I would not destroy the barrel if I miscut. Use a coarse flat file to remove the shreds from the edge of the cut. Cut through the waste ring in one place so you can use it as a template for marking the barrel.
Use the felt pen and draw a cutout on the top. You will want a 3" or 4" edge and also to save the barrel bung holes as they strengthen the top and line up the pump housing once you rivet it together. I recommend keeping the plugs. Use one to block the unused bung and slot the other one for the wires going to the pump. Screw them into the holes when you complete the tank. This will keep bait from falling into the pump housing and dying and also from jumping out of the tank. Make your cutout with the jig saw. You can start it by drilling a 5/16" hole at each sharp corner to make the sawing easier. Then clean up the shreds with the files.
Mount the bilge pump to the 4" pipe cap using four 8-32 screw and nuts. Note the offset location. I found the location by placing the entire pump in the cap with the hose on it. You will need to remove the pump from the base for cleaning. Position the pump so that you can do all these things. Cut a notch as shown for the hose to clear the cap when the pump and housing are assembled. Also drill two 5/16" holes in the cap as shown so that you can completely drain the tank when you need to.
Another view of the notch in the cap and the pump and hose.
Cut the drain field pipe to 14-1/2" in length. Snap the pipe cap on minus the pump and hose and mark the large hole. Drill the large hole with the hole saw. Drill out the two 5/16" holes too. Remove the pipe cap. Now assemble the pump and cap and fit it into the pipe. On my tank I have to slide the pump into the pipe, snap the cap on and then snap the pump into the base. Then you can put the hose on. Also at this time connect the speaker wire to the leads from the pump. I solder the connections, liquid tape and then heat shrink the connection since it will be submerged in saltwater. This is very important so you do not zap your bait with 12 volts. Connect the scotty plug on the other end. I would tin the wire ends to make this last a little longer. If you get it backwards .. IE: the pump sucks instead of pumps .. you can reverse the leads here pretty easily.
Finished pump and housing.
Put the pump housing into the lower half of the barrel as shown. The hose is long so you can hang it out and pump the barrel out. This is better than a drain fitting which will break, leak or otherwise reduce your bait tank enjoyment.