Wiring Aluminum Boat

[Chester]

Hi, I have a 20ft aluminum boat, enclosed cabin, self draining back deck and bracket for motors. There is a 60 gal gas tank under the aluminum floor. The box containing the batteries is located at the transom and has access to the bilge and to the cabin. I would like to replace the existing wiring as it is not marine grade wiring and also the negative side needs some work to properly isolate it from the hull. Would it be up to code to run a pvc style conduit from the transom to the cabin along side/ on top of the fuel tank for the positive and negative leads from the battery to the fuse block in the cabin? Also any suggestions for isolating all metal electric wiper motors from the hull? There is a negative current in the outside housing and the bracket for attaching the motors. Even bolting the motors to the hull has problems as the negative would transfer to the hull through the bolts. Any suggestions? Thanks. I use the boat in salt water.

[gonzo]

PVC conduit is fine. I suggest you install an active electrolisis protection. Something similar to Mercathode. They make aftermarket units.

[Specmar.Aus]

Hello Chester,
We have used the ABYC Guide and US CG Guide when we have Exported Boats to USA from Australia. They may be available from your local Library.
They are easy to read and use even for someone the first time.

We always use Plastic and sometimes Metal conduit or cable tray, however the rules only require that you tie the wires up at certain intervals with an approved method.

Outboard motors can be bolted above ground by using plastic spacers and fibre washers ECT. Note that the Morse (Throttle) control head also needs to be above ground also. Small bolts can be enchased in a heat skink tube and the washers packed with a fibre washer also.
Please be careful running any wires through the bilge area special rules apply here and at the junction of fume tight bulkheads.
Hope this is of assistance to you.

Specmar.Aus

[Chester]

Thanks,
I have zinc's on the hull and on the outboards. Thanks also for the info on wiring.

[lazeyjack]

Hi, I have a 20ft aluminum boat, enclosed cabin, self draining back deck and bracket for motors. There is a 60 gal gas tank under the aluminum floor. The box containing the batteries is located at the transom and has access to the bilge and to the cabin. I would like to replace the existing wiring as it is not marine grade wiring and also the negative side needs some work to properly isolate it from the hull. Would it be up to code to run a pvc style conduit from the transom to the cabin along side/ on top of the fuel tank for the positive and negative leads from the battery to the fuse block in the cabin? Also any suggestions for isolating all metal electric wiper motors from the hull? There is a negative current in the outside housing and the bracket for attaching the motors. Even bolting the motors to the hull has problems as the negative would transfer to the hull through the bolts. Any suggestions? Thanks. I use the boat in salt water.

Dont even try to isolate
Bang your neg batt stright down to the hull,
Fact Hamilton jet co will not guarantee their jet units unless the hulls are grounded to neg You cant possibly isolate your outboard anyways
in 27 years building alloy yachts and all manner of craft we always did this, no problems TAke a look at www.alloyyachts.co.nz AND OTHER MAJOR YARDS, USE SAME system people confuse the boat electrics with electrolysis caused by disimilar metels Sure get everything isolated by way of gasket, but dont try to buy all 2 wire gear
Eventually your untinned wiring will cause problems, with big voltage drops on load

[Not A Guest]

lazeyjack ---

There is a difference between isolating the electrics from the hull and bonding (grounding) the metal components.

I don't do electric work on boats, but I believe that it is required that electrics be isolated from the hull and the engines and the other metal parts be bonded.

[lazeyjack]

lazeyjack ---

There is a difference between isolating the electrics from the hull and bonding (grounding) the metal components.

I don't do electric work on boats, but I believe that it is required that electrics be isolated from the hull and the engines and the other metal parts be bonded.
Look the only different metal you bond to alloy is an anode, If you bond anything else then the hull becomes an anode, correct? you isolate machinery , bits and pieces with sleeves on bolts screws etc and gaskets.
you will never ever in a squiilion years stop current going to ground on hulls, for instance you have hydraulic hoses with wire in em, you have engine feet that carrry current(even soft ones.) so we, and all other major builders , put the negative to the hull in one place you may cover the boat with zinc and you are throwing away money, minimum zinc is better, if you are going to have trouble it will happen right from start
Anyways I ,m just trying to save a monumental headache, In all my years we never ever had trouble .Smiles Stu

[Oran]

Sorry folks if this is going off on a tangent. But I just spent All day today trying to fit a hamilton 274 jet to an alluminium hulled RIB. We got it in OK despite the manual's instructions. However getting the flange , o ring and jet to play ball has stumped us. We tried by hand, as per manual using vegetable oil as lube, then we used long stainless steel bolts and started tightening them down. It still did not do the job and in fact we snapped the bolts to remove them. You mentioned Hamilton Jet, any experience in this area.

Oran