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Author Topic:   Adding Electrical Loads to 170 MONTAUK
sloppyrudder posted 09-06-2008 09:19 PM ET (US)   Profile for sloppyrudder   Send Email to sloppyrudder  
Give me a primer on wiring a 170 the right way. I want to rig a Standard VHF and Garmin depthsounder now, then later [add an audio amplifier and loudspaker system] and courtesy lights. Should I rig two bus blocks? I would like to tie into the accessory switch. I have experience doing 12v, but from scratch not tying into existing wiring....

Here is a link to the schematic. pdf

Barney posted 09-06-2008 09:31 PM ET (US)     Profile for Barney  Send Email to Barney     
I added a small panel of four switches on the flat area above the cup holders. This panel has a fuse holder for each switch included. You can put the right fuse in for each device. The main wire feed for the bank goes to the battery. Ground to ground etc. New wire all the way. Switch_Panels-BLUE_SEA_WATERPROOF_4_SWITCH_ELECTRICAL_PANEL.html

Looking at that panel, I found one that came close to the original equipment look.

seabob4 posted 09-07-2008 07:55 PM ET (US)     Profile for seabob4  Send Email to seabob4     
Your best bet is to run a [10-AWG] [battery positive] and [battery negtative] from the main breaker and the negative bus to the helm. From the looks of that schematic, unless the main breaker is at the helm, you have nothing greater than a 14-AWG wire to pull power from. That being said, run a 10-AWG red from your battery switch common (or positive battery term. if you don't have a switch) to a 12V-positive bus bar or terminal strip. Run a 10-AWG black or yellow to a 12V-negative bus bar, jumpered from the existing negative buss. Use 10-AWG as a jumper. Then wire everything to these two busses. Remember, when you add a stereo, terminate the yellow wire (stereo memory) to a "constant hot" source, or you'll lose all your station presets. An easy way to do this at the helm is to piggyback onto the bilge pump float switch feed, usually brown w/red stripe.

Hope this helps. If you need some good Blue Seas tinned copper buss bars, I have a few here at the house. Let me know. Tinned copper, 10-position each. $15, includes shipping. That's for 2 buss bars.

jimh posted 09-08-2008 12:19 AM ET (US)     Profile for jimh  Send Email to jimh     
I'd keep things simpler:

For the courtesy lights circuit I would use the available switch on the dash panel marked ACCESSORIES.

You can wire the VHF radio positive power lead right to the battery distribution downstream of the main circuit breaker or battery switch. The radio has its own fuse in the power cord and its own power switch. The negative lead goes to the negative bus terminal. You can piggy back on an existing screw if there is not a vacant one. The depth sounder can be wired the same way. If you want to build out a little distribution panel you can loop it off the main circuit breaker.

I would not be concerned about the 14-AWG distribution that Whaler used. The runs are very short and there is little voltage drop. A 14-AWG conductor is adequate for the aggregate current of the existing loads. I am sure the boat meets ABYC recommended practice.

I'd leave the stereo on the dock; get an iPod or build the stereo into a cooler with its own 12-volt battery.

sloppyrudder posted 09-08-2008 07:58 AM ET (US)     Profile for sloppyrudder  Send Email to sloppyrudder     
The project continues to grow. Here is where I am at (at least for now).

1. Add second battery and battery switch.
2. Add Blue Sea 6 Position fuse block under console.
3. Pull lots of wire.

I know I want a second battery down the line, so I figure I might as well do it now, rather than re-configure again later on. The boat is used quite a bit for a month, and then sits for a month so I really like the idea of the battery switch and dual batteries. Any 12V gurus have input on going this route.

Also, I am leaning towards dual Optima Blue Top Batteries. Does anyone have any experience with them?


seabob4 posted 09-08-2008 09:25 PM ET (US)     Profile for seabob4  Send Email to seabob4     
One thing I overlooked: the [audio power] amplifier will be drawing serious power. We wire our Sony's with 8-AWG. So now I say run 6-AWG or 4-AWG forward to power those buses, both positive and negative. 14-AWG I don't think so.

Optima Blue tops have a lot of CCAs, MCAs, and reserve capacity. VERY heavy. Look into Exide 1000 Group 24s.

Hey, Engineer/Build boats for a living. Know a little about this stuff. Don't be cheap when it comes to wiring.

jimh posted 09-08-2008 11:52 PM ET (US)     Profile for jimh  Send Email to jimh     
You have to be kidding with 4-AWG wire. The battery won't be more than two feet from the load.

A 14-AWG conductor is rated for 35-amperes. At 13.2-volts that is 462 watts of power. Exactly how large does an audio amplifier need to be on a boat whose cockpit is about 8-feet long?

I think you're trying to sell ANCOR wire on commission.

sloppyrudder posted 09-09-2008 08:21 AM ET (US)     Profile for sloppyrudder  Send Email to sloppyrudder     
Today is the day that the install starts. I decided on the Bluetop's - I have heard nothing but good things about them and the weight seems to be in line with conventional batteries. I went with 4-AWG tinned wire for the batteries and switch. I am going to run 6-AWG to the bus, and 14 for any runs from the bus to equipment. FYI, I am not planning on running a discrete amp - just a head unit and a pair of speakers.

Now, another question. Inline fuses, should I keep them or rely on the fused bus block? I am inclined to NOT use the inline fuses, as I have had problems with connections in the past. Any input on whacking the in line fuses and doing it through the buss?

davej14 posted 09-09-2008 10:11 AM ET (US)     Profile for davej14  Send Email to davej14     
The only negative I can think of for removing the inline fuses is that you will probably void your equipment warranty. That being said, I removed mine and use only the Blue Seas fuse panel with a fuse sized to the original inline that was removed. One fuse per each piece of electronics. Don't forget to label the fuse panel as you go because tracing the wires later is no fun.
Chuck Tribolet posted 09-09-2008 07:11 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
I don't think removing the inline fuses will void your warrantee
because, if you send the unit in, that wiring will stay with
the boat. The mfg will never know. And the purpose of a fuse
is to protect the wiring and prevent fires, NOT to protect the

Think about your house. That little wall wart transformer
pulls something less than an amp, but it's "protected" by
a 15 or 20 amp circuit breaker.


seabob4 posted 09-09-2008 09:38 PM ET (US)     Profile for seabob4  Send Email to seabob4     
We use Sony's XM604M 60X4 Amp, 33 Amp draw at full power. Not to mention the head unit itself, plus what ever electricals may be running, especially on one battery.

No Jim, I don't sell Ancor wire for a living. I just know that our electrical systems don't give our owners any issues when they commission their boat. Besides, we use Pacer wire, just like about any other boat builder here in Florida.

I will NEVER trust a 14 gauge wire to feed an amp. 10 minimum, 8 preferable, and if someone wants SERIOUS power, 6 or 4.


jimh posted 09-10-2008 09:15 AM ET (US)     Profile for jimh  Send Email to jimh     
If you want to follow Bob's advice, you better start re-wiring the whole boat. Boston Whaler feeds the battery positive to the main breaker using only 10-AWG wire. According to Bob's theory, this conductor, only about two feet long most likely, should be increased to a 4-AWG conductor in order to properly run a small audio amplifier. Increasing a conductor to 4-AWG from 10-AWG has the effect of increasing its current capacity approximately eight times. I really do not think that an audio amplifier will increase the current draw from the battery by a factor of eight times.

When calculating the size of conductors there are two considerations:

--the maximum current the conductor can safely handle
--the maximum voltage drop the circuit can tolerate

In the case of a conductor that is only two feet long, there is not much concern about the voltage drop. When conductors are in open air environments their current rating is higher. Current rating is based on the heating of the conductor by its current. A conductor suspended in open air will have a higher rating than one bundled in a cable or conduit with many others.

The primary distribution from the battery to my helm runs on 8-AWG conductors and travels about 15-feet. It is fused at 50-amperes. If following Bob's guideline, I think I need to increase that to 2-AWG if I plan to ever run a audio amplifier.

Also, it would be interesting to look inside the audio amplifier to see what gauge wire the manufacturer uses to distribute the 12-volt power; it is probably no larger than 14-AWG.

sloppyrudder posted 09-10-2008 11:25 AM ET (US)     Profile for sloppyrudder  Send Email to sloppyrudder     
Thanks for everyone's Input and Help. I finally have my game plan together. As I mentioned before, all the connections between batteries and battery switch will be 4-AWG tinned wire. From the Battery/Switch to the Buss panel is going to be 10-AWG tinned wire. (The wire run is going to be a grand total of about 18 inches, 2 feet tops. From the Buss to the electronics I will use 14-AWG. Again, I am not running a separate amplifier, just a head unit. FYI, I have a 400 watt amplifier in my truck is 10-AWG and it has never been a problem. Again, thanks for the help...I will post a few pictures once I get my head out from underneath the damn console!
swist posted 09-10-2008 06:19 PM ET (US)     Profile for swist  Send Email to swist     
God save us from all these people who parade around in vehicles and boats with 400W or more amps shaking the windows of adjacent cars and otherwise annoying the hell out of people who need some peace-and-quiet in this world already too full of gratuitous noise.

Install your amp in your house and keep your doors and windows closed. You can probably even get the electric company to drop you some three phase power so you can really rock!


seabob4 posted 09-10-2008 08:12 PM ET (US)     Profile for seabob4  Send Email to seabob4     
Sounds like a good plan. Big wire equals great efficiency. It also equals more cost, but you're not talking 30' runs.

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