Can I hook 2 fishfinders and the livescope to a switch panel and then to a one 12volt marine battery? I tried  this and the fuse 20 amp fuse which I put in line to the  positive post on battery it keeps blowing, can some one help ?

You have three different posts on the same subject. All of those together should not draw anything near 20 amps. If you are blowing a 20 amp fuse there is a short circuit. Something is not connected correctly. It is near impossible to troubleshoot from a forum.

Let me just say thanks for giving me some info on what might be wrong, I'm new on here so I apologize for listing this 3 times I wasn't sure where to post the first 2 times, the 3rd time I tried to make it more clear what I had tried to do, I realize it's almost impossible to track the problem on a forum but I don't have many options, taking the boat to a boat dealer I'm guessing would cost hundreds of dollars that I don't want to spend. I already tried all the YouTube etc. and I  do not have friends that fish are own boats.

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20 amp fuse which I put in line to the  positive post on battery it keeps blowing

If a fuse keeps blowing, it's trying to tell you something. It's tempting to keep replacing it and trying again, but each time you do, you're gambling (damage to equipment, or fire).

 

I'd try to do more isolating, debugging, double checks on connections, etc. You don't necessarily have to have a friend who fishes or boats, just someone with some electrical know-how who can throw a meter on there and help figure it out. Or maybe ask a dealer for a quote or tell them to not spend more than an hour on it etc...who knows, could be a quick fix.

 

Is everything located in the bow? Multiple electrical connections should be via a terminal block by running a larger size 12 gage marine tin plated stranded wire, both power and ground, from the battery to the terminal block. Add a inline 20 amp fuse to the power wire. You need a water proof area for the terminal block in the bow area, then run your seperate wiring to each component that should have it's own fuse. Use red and black wires to identify power and ground.

Tom

Great info thank you!