I believe there is some 'spoil ground' in Portsmouth harbour (just North of the naval area). If you go past at low water you'll see great big old anchors sticking out the ground, bug metal bars sticking up, etc. Best to be avoided.
Spoil Ground refers to the spoil or material collected when clearing, cleaning or dredging, the material is taken out and dumped in an area that is marked on your chart to warn you the bottom could be anything from mud to pure rock and steel.
A good place to stay well clear of, normally located well off the shipping lanes and local destination lines.
Avagoodweekend Old Salt Oz /forums/images/icons/cool.gif