Re: Are Tab Trims really needed??
Let me take a different tack of why you have a trim tab (sacrificial anode) ...<br /><br />Corrosion is a galvanic reaction... Your prop wants to produce electrons. There's stuff in the seawater that wants to absorb them...so (very slowly) your prop gets dissolved - or at least, converted into another form.<br /><br />Iron metal, for instance, will happily shed two electrons, and combining with oxygen to form rust. And salt water is almost as good a conductor as metal...so the electrons can happily sail off to be consumed by something else.<br /><br />A sacrificial anode interferes with this process. basically, it wants to produce electrons more than your prop does. It *really* wants to dissolve and produce electrons. So it does. <br /><br />We get a surplus of electrons around your sacrificial anode, which generally get conducted about the place. So the other half of our reaction, the bit that absorbs the electrons, suddenly has more than it's fair share so it no longer needs to suck electrons from your metal prop - because there's other, easier sources nearby. And if nothing is consuming the electrons from your prop, the reaction that produces them (corrosion) slowly grinds to a halt.<br /> <br />Of course, the ocean is pretty **** big, and the anode is only small. so, sooner or later, the sea water will win. The reason it doesn't win in the short term is simple enough - for an atom of a liquid (water) to react with a solid, it has to actually be touching it. As big as the ocean is, only so much of it can be in contact with your boat at any given time. And as long<br />as we can keep that tiny bit of the ocean fed with electrons, we can get away with it.
