What gauge wire rewiring 18 footer?

[steve yates]

Is 16 enough? I'll be rewiring both my longbow and bradwell 18, while I guess the longbow may need more substantial stuff, is 16swg enough for the little in? Will have interior lights, depth, sat nav vhf , plotter, compass, navy lights and USB chargers, running off an 85ahr battery with a 60w solar panel.
Thx

 

[lpdsn]

It depends upon the current in each circuit and the acceptable voltage drop. Easy to find data to calculate voltage drop online. Suppliers will tell you the maximum rated current, but generally voltage drop will trump that. Remember to consider the voltage drop on the negative too.

 

[PaulRainbow]

Is 16 enough? I'll be rewiring both my longbow and bradwell 18, while I guess the longbow may need more substantial stuff, is 16swg enough for the little in? Will have interior lights, depth, sat nav vhf , plotter, compass, navy lights and USB chargers, running off an 85ahr battery with a 60w solar panel.
Thx

AWG is an american measurement (A stands for American), we use mm here Steve and most sites will list cable in mm. 16g is a touch under 1.5mm csa and 15mm would do for the stuff you listed, as long as cable runs are not daftly long. It'll also do for a lot of the equipment on the Longbow, again if the cabling isn't too long. Some 2.5 will be OK for the other equipment on the Longbow (obviously not bow thrusters, windlass etc, before anyone starts).

 

[Neeves]

Cannot quite resist the question - how many 18' yachts have bow thrusters? I must be getting old

Jonathan

 

[PaulRainbow]

Cannot quite resist the question - how many 18' yachts have bow thrusters? I must be getting old

Jonathan

There's always one

 

[ghostlymoron]

You need to be methodical and size each circuit to take the maximum current for the equipment connected. Its not simply related to the length of the boat. Begin with a schedule of electrical equipment, then draw a wiring diagram, then calculate the cable size taking voltage drop into account.
As a guide, I found that 1mm was sufficient for everything on my 19 footer except connections to the batteries and charging circuits.