Grounding electrical items?

[huntinfool]

New to the forum and so far I like what I see. I've got a 1648 Lowe that I have rebuilt (rotted transom, many holes in the transom and back section of the boat) I've added an extension and made a bigger front deck. I've completely wired it with lights a fuel tank under the front deck, where I will also add trolling motor batteries. But I see where several people have said not to ground any electrical items to the hull. WHY?

I have done this in the past for several boats and never had an issue. I always run any positive line through pvc or rubber hose to keep it protected...so what else am I missing. Is it because it can cause oxidation?

Thanks for the heads up and as soon as I can figure out how to post pics I will get some up here of my boat.

 

[Quackrstackr]

Corrosion via eloctrolysis.

It turns boats into pincushions.

 

[huntinfool]

Is that only if it is in salt or is it the same for fresh? Again I have done this on a few boats and never had a problem. But none of those have been in the salt.

 

[Quackrstackr]

I happens in fresh water too.

It happens more rapidly if the boat is moored at a marina but it still happens. There are posts on here of boats that it has started happening to or purchases made before it was discovered to be swiss cheese.

A few extra feet of ground wire is pretty cheap insurance against scrapping a boat.

 

[huntinfool]

Guess i better re-wire the grounds on my boat and on our other one too.

 

[ben2go]

Yep galvanic corrosion through electrolysis.Steel,copper,brass,iron,and zinc will cause really bad corrosion.Pressure treated wood has trace amounts of copper in it from the chemical treatment,it will dissolve aluminum fairly rapidly.Here is a description of what galvanic corrosion is. https://en.wikipedia.org/wiki/Galvanic_corrosion

 

[krisopp]

So what would be the ideal place to ground things to?

 

[ACarbone624]

The battery

 

[Bubba-Bear]

Rightt back to the neg terminal on the battery

 

[ben2go]

The battery

Rightt back to the neg terminal on the battery

Correct.Straight back to the battery.Try to isolate the cables/wires so they don't chafe and ground/short out on the hull.

 

[huntinfool]

Thanks everyone for the input. I've got it all tore apart and re wiring everything to a ground block that will be grounded directly to the battery instead of the hull. I'll have it done soon and be back on the water in no time.

 

[ben2go]

Make sure the block isn't grounding back to the hull.Some auto style blocks do this.Mount it on wood or the battery box.

 

[huntinfool]

It has a plastic back so it can't ground to the boat. I already checked to make sure about that.

 

[Hanr3]

The ground on the block is generally done with one or both of the screws/bolts holding the block in place. Kind of like an electrical outlet, the screw holding the outlet to the box grounds the outlet. Its an idiot proof method to ensure the outlet/block is grounded. Hence the recommendation to attach the block to a piece of wood and then mount the wood to teh boat. The wood acts like an insulator.

I used a pretty simple method to attache my battery, to everything, bolts and ring terminals. Much cheaper than terminal blocks that do the same thing.
https://www.tinboats.net/forum/download/file.php?id=5760&t=1

 

[huntinfool]

This is a marine grade application and could be used for ground or for power. So the mounting screws do NOT ground it to the boat...trust me I'm ok on this. I am however going to have to make one that I am mounting under my front deck for all of the lights up front.

 

[Hanr3]

Great!

I only posted becuase you said you looked at the back. The grounding isnt done on the back of the terminal block. Its done as part of the strip that connects all the terminals together, unless of coarse the whole strip is metal. If the screw holes were part of the terminal strip they would have metal around the top of the screw holes, not the bottom.

 

[huntinfool]

Nope. Mounting screws are seperate from the strip and lugs. Mounting screws go through the plastic backing and that only. It really is a great strip. I made my own for under the front deck and took two strips of plastic (starboard) and ran bolts through one and sunk the heads. Then placed the other piece over those to keep them from grounding out and then mounted it under my front deck to the wood. Now I can ground all of my lights up front, and pull power and just switch them from up front....at least when I have time to finish it up that is.