Boat configuration advice needed

[870 ExpressMag]

I have an older Meyers aluminum 15ft boat, tiller steer, 58" beam width. I currently have an Evinrude 18hp FastTwin elec start on it. I just purchased a MinnKota EnduraMaxx 55 trolling motor. I currently run the Lowrance Elite 4 fishfinder, and motor starter with a lawn and garden battery, and it works well. However now that i have the trolling motor i need to go to a deep cycle. The battery i currently use is 17lbs, and i put underneath the splash well in the rear center of the boat between the transom stabilizer brackets. The new battery i was looking at is a marine group 24 dual purpose starting/deep cycle, it weighs 65lbs. I am concerned about adding an additional 48lbs to the read of the boat, since i just added the trolling motor. I have lost 60lbs myself since february and it has made a world of difference in boat performance so i didnt wanna weight the rear back down again. I am now down to 265. My problem is where to put things, i dont have much wiring in the boat so now is the time to figure this all out before i start doing the wiring. I have heard that the enduramaxx motors with their power saving feature can mess with the fishfinder when connected to the same battery? anyone experience this? i dont want to have to have two batteries on board for more weight. I also have a bow mounted nav light, and a anchor/stern light on the port side. i also want to add a little panel of some sort to have my light switches and my bilge pump switch on. So, heres what i am asking, do i need two seperate batteries? where to locate my battery? where to locate switches? i usually run my fuel tank just aft or just fwd of the center seat, i really like it fwd, puts some weight up front when by myself. Compartment under front seat has 2 PFD cushions and a small box of tools in it. Heres a few pics for reference.
one more item to note, as i have it configured now, gas tank fwd or center seat, 17lb battery in rear under splash well, me (265#) driving, an anchor and some fishing gear, i can do 20mph per lowrance gps. add my dad (200-220#) in center seat and we plane out about 17mph

 

[onthewater102]

Very nice looking boat - don't think I've seen one laid out like that. If you're concerned about the electronics I'd just give it a try with the deep cycle and see what happens. You can always power the fish finder separately off the lawn mower battery if there's an issue.

I found with my 12' v-hull it planed best with my weight on the middle seat when under way - so if you've already got a good amount of weight in the back I'd put the battery in the middle seat. Just don't put it all the way forward - you want to keep the weight disbursed over the areas that contact the water when you're on the plane. As far as the switches, the trolling motor draws the most power and requires thicker gauge wiring so keep the switches close to the TM so you don't have to run a lot of expensive wire all over.

 

[Ranchero50]

I'd also just buy a smaller battery and not worry about it too much. It all depends on how much you plan on running your trolling motor. The newer Minn Kota's also use less juice. Add in that your motor will probably charge while running and I don't think you need to worry too much about running a monster.

 

[870 ExpressMag]

My motor doesn't have a charging system in it

 

[870 ExpressMag]

I was also curious if i might be able to somehow convert the middle bench seat into storage? i am not sure if it has foam in it or not, i know theres foam up front but not sure on the other two bench seats, but i was thinking if i could cut a trap door in the top of the seat and hinge it, i could put a battery compartment under there and that would solve a lot of issues. Just not sure if it would create more, trying to do it.

 

[onthewater102]

Chances are there is foam in there - which isn't the end of the world - just replace it someplace else, better yet add a combined larger volume of foam forward and rearward of where you remove it.

Foam is just extra weight in your boat until the moment some @$$ hat yuppie buzzes by you too close and swamps you...then it becomes the only thing keeping your electronics and powerhead out of the water.