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earth to ground...

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tbosch
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163 Posts

Initially Posted - 05/04/2010 : 08:42:34

I'm installing a below decks gas tank in my 1980 Catalina 25. The project is going well but I need some advice on hooking up the "earth-to-ground" that is meant to dissipate static electricity build-up. I thought I would check here for possible solutions.

The tank's installation instructions say to connect an earth-to-ground wire from the tank's fill neck and lead it to a grounded object, "such as the engine". Well I've got an outboard. Does it make sense to just lead the wire out the back and attach it to my outboard?

I saw a thread on another forum where someone suggested connecting the wire to the grounding bus of the electrical system (12v). Does that make sense? I will already have a connection to the grounding bus when I wire the tank's sender to a fuel gauge. Is that sufficient for eliminating static electricity build-up and make the earth-to-ground wire unnecessary?

On a related note, should I also connect an earth-to-ground wire to my stainless steel deck fill? Can static build up there as well?

I looked at a past member's project description for installing a below deck fuel tank similar to mine but he doesn't mention the earth-to-ground. Any advice or recommendations you have would be appreciated!

The 12 gallon tank will be mounted to a platform at the forward end of the "dumpster" under the electrical panel. I'll be installing a cover over the electrical panel. I'm not sure if that is necessary but it will make me feel better. I'll also be adding a blower to the existing vent hose. The tank itself will be vented out the back of the boat. In case anyone is interested...

Thanks!

Todd
1980 C25 SR/FK "Dora"

Edited by - tbosch on 05/04/2010 08:42:55

Stinkpotter
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Djibouti
9075 Posts

Response Posted - 05/04/2010 : 08:56:49

You're correct to suspect "ground" in your 12V system is not really ground--it's just a common return to the negative side of your battery. And the "engine" they're talking about is an inboard connected to a prop-shaft... However, I'd say your cast iron fin keel is your best actual ground (assuming it's not perfectly encapsulated, as most iron keels aren't). Maybe you could wrap the ground wire a few turns around one of the keel-bolts. I won't offer an opinion on the deck-fill.

Edited by - Stinkpotter on 05/04/2010 09:06:02

tbosch
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Response Posted - 05/04/2010 : 10:34:19

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 ... I'd say your cast iron fin keel is your best actual ground (assuming it's not perfectly encapsulated, as most iron keels aren't). Maybe you could wrap the ground wire a few turns around one of the keel-bolts. I won't offer an opinion on the deck-fill.
<hr height="1" noshade id="quote"></blockquote id="quote">

Dave,

I like that suggestion. Ironically I just finished sealing my rusty keel bolts with a rust encapsulator and water barrier last weekend. I could grind a bit of that away and make the connection you suggest. The bottom of my fin keel has not been maintained and I'm sure will be in good contact with the water. I just posted in the cat 25 forum about maintaining the bottom of the keel but I'm leaning towards leaving it bare.

Does your "stinkpotter" have it's deck fill connected to a ground? Is that easy to check? Just curious.

Thanks

Edited by - on

Happy D
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Response Posted - 05/04/2010 : 14:31:42

There are requirements for installing a gasoline fuel tank inside a boat.
You can read all about it here. http://www.uscgboating.org/regulations/boat_builders_handbook_and_regulations.aspx
Make sure you read the section on ventilation and electrical also. Electrical stuff can't even occupy the same space unless it is SAE J1171 ignition protected. Your electrical panel is not.
When I read the regulations, it says, “ To comply with the law...” That means to me that they can arrest you for violating the regulations. You make the call.
Don't take this lightly. Your insurance company won't take it lightly.

Edited by - on

tbosch
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Response Posted - 05/04/2010 : 14:36:41

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Happy D
 There are requirements for installing a gasoline fuel tank inside a boat.
You can read all about it here. http://www.uscgboating.org/regulations/boat_builders_handbook_and_regulations.aspx
Make sure you read the section on ventilation and electrical also. Electrical stuff can't even occupy the same space unless it is SAE J1171 ignition protected. Your electrical panel is not.
When I read the regulations, it says, “ To comply with the law...” That means to me that they can arrest you for violating the regulations. You make the call.
Don't take this lightly. Your insurance company won't take it lightly.

<hr height="1" noshade id="quote"></blockquote id="quote">

Great advise. I will give this a thorough read.

Todd

Edited by - on

Stinkpotter
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Djibouti
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Response Posted - 05/04/2010 : 19:44:39

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by tbosch
 [quote]Originally posted by Stinkpotter
 Dave, ...Does your "stinkpotter" have it's deck fill connected to a ground?<hr height="1" noshade id="quote"></blockquote id="quote">I'll try to figure that out tomorrow.

Edited by - on

tbosch
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Response Posted - 05/04/2010 : 20:11:21

I've been reading through the USCG requirements documents that "Happy D" pointed out. There is a lot of interesting info there. I'll come back to those documents for future reference.

Regarding the earth-to-ground question on the tank install I found that the metal deck fill will definitely need to be grounded. Metal tanks also need to be grounded but since mine is poly it does not need to have a grounding wire attached. I plan to ground the deck fill to my cast iron fin keel, as suggested by Dave.

The electrical panel needs separation from the gas tank via a bulkhead OR isolation. It looks like isolation can be accomplished in the form of a box that covers the back of the panel. Being above the fuel tank it is not required to be air tight but I plan to install a panel cover with a gasket anyway.

These are my take-aways from reading these documents. Anyone doing a similar project should read them for themselves and not take my word for it. If you have looked at them and don't agree with what I've interpreted it would be good to get your feedback.

The part of my plan that is NOT according to the requirements is the placement of the deck fill. There just isn't much room on the side decks below the coaming/cabin for a deck fill unless you put it where it would have to route through the galley (1980 cat 25). My plan was to mount it on top of the cockpit coaming between the winch and cleat. While very convenient, it does not meet requirements. The requirements consider a self bailing cockpit to be "inside the boat" and no splashes or spills from filling the tank are allowed inside the boat. There is a slight outboard slant to the cockpit coaming but not enough to satisfy the requirement. I only plan to fill my tank one or 2 times per season so I may fudge on this one... But the grounding and the panel isolation definitely NOT!

Thanks again for the link to the requirements.

Edited by - on

redeye
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Response Posted - 05/05/2010 : 04:33:54

Gotta say it. I would not put electrical and gas in the same compartment. No. Not ever. Nada. And good luck with that insurance.

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Stinkpotter
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Djibouti
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Response Posted - 05/05/2010 : 05:49:35

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by redeye
 Gotta say it. I would not put electrical and gas in the same compartment. No. Not ever. Nada. And good luck with that insurance.
<hr height="1" noshade id="quote"></blockquote id="quote">Ray, every C-25 built before about 1983 (?) was designed to have a tank in the same compartment as the completely exposed panel, so the tank vents into the compartment and liquid gasoline can spill into the bilge (out of an open vent or whatever) to evaporate there. Catalina tried to mitigate this by adding passive air circulation through the compartment--a coaming vent pointed forward and another pointed aft. I'm glad I didn't have that whole arrangement, but I haven't heard of any C-25s blowing up.

Todd is proposing to install a closed system in that space, with a filler on deck, a vent through the hull, and the a line to the engine--all sealed within the locker. On top of that, he proposes to add fan-forced ventilation--possibly an unnecessary redundancy. This setup seems far superior to the factory one (pre-'83).

The deck plate ground, where fumes are exposed to a potential static charge, is probably the more serious issue. If he gets that right, I'd say he has a safer system than he had before (and many people have now). And I don't see how his insurer can complain if it meets the industry requirements.

Edited by - Stinkpotter on 05/05/2010 05:51:02

redeye
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Response Posted - 05/05/2010 : 08:10:16

Thanks for explaining it. I did get it and understand his setup, I just personally don't like it, but I'm looking for a solution that is not there.
My power boat has 70 gallons onboard and they always make me skiddish, like when a smoker walks up to my boat after trailering and stands next to the gas vents with a cigarette, and you don't notice at first.

It is difficult to iron out the details, such as the ground.

Sorry about being negative.

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tbosch
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Response Posted - 05/05/2010 : 08:43:46

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by redeye
 
Sorry about being negative.
<hr height="1" noshade id="quote"></blockquote id="quote">

Not a problem. I post questions here to get feedback. Positive, negative or indifferent it helps me think a project through and, hopefully, avoid mistakes. If I was afraid of someone disagreeing with me I wouldn't post. It's all good!

This whole discussion has been really helpful to me and I've made changes to my original plan based on the feedback and resources that were offered by the group.

Edited by - on

Happy D
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Response Posted - 05/05/2010 : 08:46:47

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Ray, every C-25 built before about 1983 (?) was designed to have a tank in the same compartment as the completely exposed panel, so the tank vents into the compartment and liquid gasoline can spill into the bilge (out of an open vent or whatever) to evaporate there. Catalina tried to mitigate this by adding passive air circulation through the compartment--a coaming vent pointed forward and another pointed aft. I'm glad I didn't have that whole arrangement, but I haven't heard of any C-25s blowing up.<hr height="1" noshade id="quote"></blockquote id="quote">

That doesn't make it right. There have been many many boats that have blown up causing death. That is the reason for the regs. I always get flamed for posting this information. I'd rather be flamed here than on my boat.
Asbestos used to be OK too.

Edited by - Happy D on 05/05/2010 08:47:23

farrison
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USA
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Response Posted - 05/05/2010 : 09:11:23

Todd;

I have worked in the chemical industry for years, and we pour chemicals or flamable solvents from one container to another. The safety requirement is to ground the two containers together with a ground strap, such as when pouring solvent from a 55 gallon drum to a 5 gallon work container. There can be a static build-up created by the flowing liquid an the ground strap equalizes any charge between the two containers. If ther is no ground strap, when the two containers are disconnected a spark could jump vbetween the two and ignite the solvent fumes. So in the case of filling the tank with gas, I would think that a ground strap between the on-shore gas tank hose/neck and the filler neck of your boat would be more important than the tank to keel/water as suggested.

Paul

Edited by - on

Stinkpotter
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Djibouti
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Response Posted - 05/05/2010 : 18:25:05

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by tbosch
 [quote]Originally posted by Stinkpotter
 Dave, ...Does your "stinkpotter" have it's deck fill connected to a ground?<hr height="1" noshade id="quote"></blockquote id="quote">I'll try to figure that out tomorrow.<hr height="1" noshade id="quote"></blockquote id="quote">It does indeed. Not sure where the wire goes--it probably ends up at the engine, the bracket for which is always in the water. If the pump handle is also grounded, then it and the deck filler fitting should be equalized. No explosions so far...

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