AC/DC . . . no, not that - the ship's power - Help!

[Mikey]

I am totally verklempt. Trying to design the electrical system for Dreamsicle. Here's where I am. Pair of 6BTA-300's. That's it. I can do anything at this point and have spent restless days on the internet and sleepless nights trying to figure it all out. I'm planning this as a day boat, day fishing on the Bay (no off-shore runs for tuna) and a picnic boat/creek cruiser. Possibly rare over nights.
1. Do I need 8D's on each of those beasts or will 4D's work? Do I need a separate house battery?
2. I would like a battery management system that leaves the human element out as far as making decisions about which batteries to use, which need charging, etc. Have spoken to several manufaturers and all insist that their top-of-the-line system is necessary. Not to be skeptical of the salespeople but . . . money doesn't grow on trees in my yard. One did suggest that with the use I project that I wire for a third house battery but at this point use just the two big beast batteries, one to start and one for house with a momentary switch for backup if the start battery needs a boost.
3. One suggests an isolation transformer in place of the galvanic isolator and polarity indicator. Sounds a bit over the top for my application. I've drawn the schematics for all that I plan but still feel overwhelmed by this battery management.
4. Isolating everything from everything is a concept I understand in theory but in application I'm still trying to put the pieces together. Every manufacturer I speak with sells me on the practicality of his or her products, but when I ask that they lay it out (Schematic) so that I know where things go they all balk. No one in our litigious world wants to take resposibility. How do I get there from here?
Damn, guys, I've designed and installed entire wiring systems in houses and cars for forty years and with boats I feel like a total maroon. There are three systems, all interconnected and sitting in salt water. Whew!
There are probably other questions I should ask but at this point I'm not sure what they are.
Alright gang, let the fun begin.

[In Memory Walter K]

Mikey-I can tell you what I have that has served me well since I put in my diesels. I put a 4D on the outside of each of my Cummins as starters for each with a switch that allows me on "all" to start either if one goes bad. I put two 12V "regular" high amp hour batteries put in parallel for even longer amp hours and have an isolater on them so they cannot be drained if any individual battery goes bad. I use those batteries for my electronics. I do connect my bilge pumps directly to each 4D and my AC/DC Norcold fridge directly to one of them.
All the batteries are lead-acid and are charged by a Trucharge 40 "smart charger" that I mounted on the port outer wall under the dinette table. It is dry and visible by looking under the table. having rusted out chargers over the years, this one after 3 years, looks like it just came out of the box. My AC 3 wire 30 amp line comes into a marine 30 amp 3 pronged receptacle then to a 30 amp circuit breaker box, then runs to two strategically placed double 110 wall plugs for lamps, toasters, heaters as necessary. It is a simple, no big deal set up, but has served me well. I too have used the boat as a day boat for fishing only, but have stayed overnight on her, but at a dock with the shore current plugged in. Walter

[Bruce]

Mikey,
What Walter described will meet the needs of 90% of the 31 owners. Simple and effective.

The only thing I would add is a 30amp marinco or other brand zinc saver(isolator) to the AC system. An isolating tranformer is not really necessary for the 31.

Don't connect any grounds, ac or dc to the bonding system only to the panel.

Have the bonding system checked with a galvanic meter so you can see if you are okay, over protected or under protected.

That's it.

If you come to the Lauderdale show next week, grab me and we'll talk and draw up a system.

[Chiles]

Mikey,
This is pretty much what I have as well. The big difference is that I have two isolators so that no matter which engine is running, all my batteries are getting charged. I used the Charles Marine 5000 series smart charger and Charles Marine sealed switches. I still have a brand new 30A isolation transformer that is new in the box. It retails for 300.00 and I will let you have it for a small donation to this site. Hell, I'll even deliver it.

What do you think?

Chiles

(Timmy started it)

[Kevin]

Bruce,
I need "guidance" on my set up too. In fact, after looking at my goat rodeo of wiring I was hoping that maybe I could leave the boat with you for a couple days. The only wires left that go to the bridge are for the new Steyr panels. Yanked all the nasty dated electronics and starting fresh. I was leaning towards the "if you have the time, I have the money," saying just to get the bilge pumps and main switches with some bus bars hooked up. I can do all the other 12 volt little stuff. Bilge pumps, float switches and the wires that go to the bridge for the momentary switches confuse the heck out of me. I will be bringing a dewatering pump with me if you know what I mean. Kevin

[thuddddddd]

hey Stew, if Mikey don't take it I will. Don't know if I'll ever use it, but probably be worth something on ebay in the future "off famous hyundi powered bertram 27 project" second owner.

[Chiles]

Timmy,
Your more then welcome to see if it will work on the Hatt. I think there may be some compatibility issues.

1. It works.

2. It does not leak

3. It is new and desireable.

4. It has value.

Come to think about it... it may be a great addition to your boat. It will make it worth something. :)

Your money is still good. The donation to the site stands.

[thuddddddd]

Funny Stew, looking at your list, and applying it to you, the answers are just like what you'd get if you applied them to the tubbbbb
Thudddddd

Stew started it.

[Sean B]

Mikey,

Get Nigel Calder's book. It's got answers to all your questions, plus answers to questions you didn't even know you should be asking.