Battery and Wiring Question

Run the wire up to the dash along with all the other wires going up there from the engine compartment.

Termination at the battery is typically done with a ring terminal under the clamping bolt of the battery cable terminal.

Don't forget fusing the new feed. Closest to the battery is best. Also, besides the new positive wire, you will need a ground wire too. It can be terminated on the engine block.

Ditto what Pete said Otto - that would be the cleanest, most hidden route. Guessing you decided not to add a second battery?   8 ga. is pretty healthy for just a radio ... is this for an amp perhaps? If so, the ground cable needs to be as short as possible so the engine block would likely save you a few feet. Technically most amp manufacturers will suggest 4 feet or less of ground, if possible. But, this is fiberglass boat so you're limited to the closest solid ground available.   

8 ga?
Helluva stereo.

8122pbrainard wrote: MourningWood wrote: 8 ga? Helluva stereo. Maybe maybe not? If he's figuring a "round trip" wire length of 20' and at only a 3% voltage drop, 8 ga. is rated to carry 20 amps.

If he's got the Sony head unit I believe he has the CTA rating is 40 watts x 4 -- The 100 watts peak is at some ridiculous THD of 10% or so (very unpleasant to listen to).   And of course listening volume is going to be directly related to power consumption so drawing max amps at a realistice max 40 watts /ch is not really going to tax an 8 ga. power cable much at all, even at 20'.   Not an overkill mind you, but very stable, IMO.   I've installed, or assisted with dozens of systems in automotive as well as marine.   The smallest system I recall was 60 good, clean usable watts (x4) running about 15-17 feet from the battery to the trunk and since she was on a budget we went for minimums. Hers sounded great and performed well with no power lulls, even at high levels, using 8ga.   
Otto, you'll be fine   

As far as your questions though, I'm not really versed on the interior layout of the 99, but if it's at least similar to my 95 there should be an open channel or chase directly below the captains seat leading to the bow forward of the driver area.    Not sure what you're referring to with those washers, my boats have all had marine batteries & cables - i.e. ring terminals on the cables and wingnuts on the battery studs.

Since it seems, once again, that my 'experience' input doesn't seem to carry much weight, perhaps those that prefer the hard numbers on a page can view this chart and do the math themselves.   It even has an explanation of the formula and use of the chart.
Otto's system is Well within the limits of an 8 ga power cable.



Keep in mind also that 'Total RMS wattage" in this case is figured at the documented CTA rating of 40 watts per channel x 4 channels, or 160 total system watts output (max)   


   Seriously wanting sunny days and warmer lake temps    

My run is 7’ from the battery box to the head unit for the positive ( fuse 6 inches from terminal) and ground is 12’ from the block to the head unit. Crutchfield said 14 gage was pleanty...but I stepped it up! All installed neatly in the channels and looks great.

Sony says max 10 amp draw, so I would have easily been in the 12 gage wire specifications using the chart at 10%.

Tomorrow I will install the speakers.