In actuality the ship's hull is not that well connected to the water. There are a number of issues such as the paint used on the hull to prevent corrosion in salt water and the fact that the ship's screws are generally made of brass and galvanic corrosion is a problem. Which is why US Navy ships have large sacrificial anode of lead on the bottom of the hull. Ships can also become magnetized and often must pass through a degaussing range on return to port. As for RF ground with respect to sea water, one might argue that the paint is so thin that is the effective capacitance negates any insulating value at frequency. However naval radio and radar systems are very high powered and I don't believe they rely on that alone.
Best, Doug On Mon, Jul 8, 2019 at 1:48 PM Richard Nute <[email protected]> wrote: > > Hi Peter: > > Sea water is a very good conductor, better than soil. Fresh water is an > okay conductor. Pure water is a poor conductor. > > The hull of a steel ship is well grounded in the ocean, and reasonably > well grounded in fresh water due to the large contact area with the water. > > If the hull is not steel, there usually are enough fittings that the ship > is reasonably well-connected to the water. The propeller and drive shaft > also provide a connection to the water. > > I've heard of ship-board hams who will tow a large brass plate for a good > ground for their transmitter. > > Commercial AM transmitters try to locate their antennas near a body of > salt water like San Francisco Bay or the Great Salt Lake. > > I would guess that a ground pin of a shipboard outlet would be connected > to the hull metal. This gives the same protection from electric shock as > land-based outlets. > > See also: > > > http://electrotechnical-officer.com/primary-methods-of-grounding-and-bonding-on-ship/ > > > Best regards, > Rich > > On 7/8/2019 11:19 AM, [email protected] wrote: > > Hello group, > > Is there a real ground in a ship? i.e if a Class I product is used on the > board of a ship, does the ground pin actually doing anything? The ship is > floating in the ocean and I cannot understand if there is a real ground > there or not? Can you guys educate me please? > > Thank you > Peter > > > - > ---------------------------------------------------------------- > > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to < > [email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > -- Douglas E Powell [email protected] http://www.linkedin.com/in/dougp01 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
