Change blue background values!
1. Enter needs in mA/mē (20 mA/mē in coastal sea water for steel - 10 times less for aluminium - Less in fresh water)
2. Enter waterlength and sum (width + draft) in m.
3. Enter surface coefficient 1.0 for a motor-boat or similar, 0.8 for a sailing-boat with wide keel and 0.6 for a sailing-boat with narrow keel
4. Enter duration of needed protection in hours (1 year = 8760 h.)
5. Clic anywhere in the table to have calculation done...
Cathodic protection must be checked following installation (particularly with aluminium and magnesium).
Safe ranges of potential measurements (from... to...) |
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| Wooden hull | -600 mV | -550 mV | |
| Polyester hull with IB | -1000 mV | -750 mV | |
| Polyester hull with OB or Z-drive | -1050 mV | -900 mV | |
| Aluminium hull | -1100 mV | -900 mV | |
| Steel hull | -1050 mV | -800 mV | |
Values refers to Ag/AgCl electrode immersed in sea water - Informations delivered with all proper reserves - Check regularly your anodes! - (c) 2011 by www.galvatest.com |
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1. On wooden and polyester hulls, measurements refers to metallic immersed outfits vs electrode (shaft...)
2. Lower values readings (towards -) indicates over-protection, higher values readings (towards +) under-protection
3. Same protective values should be reached in fresh water
4. However, due to poor salinity, +120 mV maximum must be added to readings made in fresh water (see picture below)
5. Potential measurements are common use in naval industry and figure corrosion monitoring best practices, as recommended by NPL (UK National Physical Laboratory) and ABYC (American Boat and Yacht Council)