CROWLEY’S TIP #12: Continuity is key to corrosion protection.

Performing a continuity test ensures that the anti-corrosion devices on the engine package are functioning properly. It also uncovers any breaks in the protection of your engine. A digital multimeter is all you need.

Continuity test
This test can be done with or without Mercathode System installed. To conduct this test, take your digital multimeter and set it for continuity, which is the ohms setting. You need to test for good continuity between all of the major metal parts on the engine and drive unit, especially the sacrificial anodes. Your readings should be no higher than 150 milliohms, 1.5 kiloohms, or .15 ohms. If you find no continuity between any of the external metal parts that you’ve tested, you’ll need to search for the cause of the poor electrical connection. It could be a broken continuity circuit wire. Once you’ve located and fixed the problem, the continuity test should be repeated to ensure you’ve fixed the problem.

Using Stainless Steel Propellers
Stainless steel is a very strong metal that resists corrosion. But stainless steel propellers can corrode if not protected. Deep pits in the propeller blade are signs of loss of continuity between the propeller and the drive unit. This can happen when a continuity washer is not installed. Late-model propellers now have a different type of sleeve inside that keeps good continuity between the propeller and drive unit. The prop should be removed and inspected on a regular basis to make sure it is making good electrical contact with the drive unit. During your inspection, lubricate the prop shaft for further corrosion protection. Never allow fishing line to maintain contact with stainless steel components because eliminating oxygen from the surface of stainless steel allows corrosion to occur.

To wrap up our series on corrosion, following are some basic tips we’ve covered:

· The best defense against corrosion is regular preventative maintenance, like replacing wasted anodes and keeping a complete coat of paint on vulnerable surfaces
· Inspect anodes regularly
· Regularly prime and paint nicks and scratches
· Do not paint sacrificial anodes
· Other corrosion inhibitors are Mercathode systems, galvanic isolators and continuity devices
· Corrosion testing is an important part of your protection plan