Battery and wiring

ok I just picked up a motor and now I think I need to change some plans do to the fact that it is electric start with an alternator. first let me ask about the wiring.

I have from the battery 8ga wire to this battery switch


to this fuse panel


and then from the negative bus bar on the panel back to the battery with 8ga wire.

So will I be able to hook the positive side to the battery switch and the negative side to the bus bar? and is the 8ga wire heavy enough?
or will I need to get thicker wire to the battery switch, hook the positive motor wire to it, and then run the negative motor wire all the way back to the battery?
Next I need to know about batteries. I was going to get a group 27 deep cycle but now with the starter will I need to get the dual purpose one? Will it power my livewell and trolling motor the same? I can't have 2 batteries so I need to know which type will do the job the best and what the real differences are?
heres some motor porn.

 

how many amps does the starter draw? I know it has either a 10 or 12 amp alternator so the 8 ga I already bought would work just fine since according to that chart it is rated for 80amps, but I would like to be safe. An electrician I work with thought the 8 would be just fine as well and the 4 would be over kill, but didn't know about the actual starter. Keep in mind my battery is in the front of the boat so it has to be run atleast 11-12ft. what to do? :-/

 

called yamaha dealer today, the tech said 4 should be fine, I hope it wll fit through my pipe chase

 

it might be overkill, but if the yamaha tech says use 4ga, Imma gonna use it. I picked some up this morning and it's not as thick as I thought so it should still fit nicely in my pipe chase. the only think is they did not have red, only black in stock so I'll have to mark one of the lines.

My plan now is run 4ga to the battery switch, then to connect the positive side of the motor to the battery switch, then splice the 4ga into the negative side and run that all the way back to the battery. sound good?
My other electronics will be 8ga (gotta use it somewhere) to the fuse panel, then 8a from the negative bus bar back to the battery. I hope this is the last time I need to revise this all.

 

if you look at the fuse panel picture I posted you can see it already came with a bus bar for the positive and negative sides, however it has a smaller stud on it like a number 10 so i feel more comfortable just running it all the way seperately.

 

I am running the 4ga to the battery cut off so if I got a stud I would only need one. as far as protecting the bus bar goes why would I need a fuse to protect a fuse panel?

I am running out of time, where can I get one of these studs locally? (pepboys, discount auto parts?) I am starting the wiring tomorrow and don't have time to wait for internet orders.

 

I understand this, thats why I was going to run the negative by itself back to the battery. and if I don't the negative side would not be bolted to the batery cut off, that would actually negate the cut off switch all together wouldn't it. the battery switch would do the same job as the post for the positive side which is why I don't see the need for it.

it's a 6 fuse switch block, 4 will go to the switches for the livewell and lights, 1 to the bilge pump, and 1 to the depth finder/gps eventually, but all will be fused through the block, if I need to add anything else later on I'll just add an inline fuse for that.

Ii need further clarification on this one. would just a 1/4" bolt covered in liquid tape work? if not how else do I insulate the bolt without directly bolting it to my boatside?

Problem is there are no local marine supply shops here, closest one is west marine which is almost an hour away.

Thanks for the help, I know this is a headache, especially since this is the 4th time I've revised my plans for the electrical system.

 

My battery will be in the front along with the gas tank(see my build blog for pics of the supports). so I can't do as your suggesting. I already have the wire for my accessories along with the fittings. I have pipe chases to keep the fuel and electrical completely isolated from each other. basically the negative setup for the motor is the last piece of the puzzle for me.