Ultrasonic Surveys

Galvanic Surveys

Corrosion ranks with fatigue as the most common cause of material failure

- Handbook of Marine Surveying - Thomas Ask

Corrosion is the nemesis of all mariners, one of natures phenomena is the fact that two different connected metals immersed in electrolyte (in our case sea water or polluted fresh water) develop electrical voltage and current, the result of which is the loss of the most active metal – your propeller, rudder, “P” or “A” brackets or other under water items.

It seems that everything touching seawater quickly weakens due to the unstoppable effects of corrosion. “Corrosion ranks with fatigue as the most common cause of material failure” however they often work together, what corrosion starts fatigue will finish.

galvanic surveysAnodes are fitted and bonded onto your boat because they are designed to readily give up their loosely attached electrons to other materials, thus protecting your other immersed items.

With anodes undertaking such a vital role can you be certain that your anode is protecting your very expensive pair of propellers?

The answer is yes, there are several ways. One is to constantly lift your boat to check the anodes are being eroded at the correct rate.

However, this still leaves you with the uncertainty as to whether the anode is over protecting, under protecting or is just right for your cathodes (propellers, shafts, rudder etc).

ultrasonic surveysAnother option would be hiring a diver to check the anodes, but that would only tell you their present state, giving you no indication to their actual lifespan.

Both of these options are costly and time consuming and still do not give you the full picture on the status of your anodes.

REA ASSOCIATES Ltd can carry out a full Galvanic Survey. This would detail a report assessing the following information:

  • How well each under water item is bonded and how effectively the anodes are protecting important equipment.
  • Highlight any stray AC or DC current problem from the dock or boats own system
  • Make recommendations on galvanic systems on board and any improvements that can be made to any part of it.
 
This Survey is suitable for boats of all types and construction and can be carried out while the boat is in the water.