2008 350 4 stroke noob question

[jamievan]

Hello all, I have a pair of 350 four strokes, and my mechanic has told me that when not in use that I need to leave my legs fully in the water or electrolysis will eat my engines. After six weeks away from the boat the legs are covered with growth. My question to all of you is, do I need to keep them down. When they are in the full up position they still touch by a couple of inches. Thanks for your help.

[greasyshaft]

I can't really see why he would say that, all the boats down here in NZ have them tilted up & I can only only imagine what the growth does to the water intake etc.
You shouldn't have a problem with electrolysis, if there is get him to sort that problem first. Galvanic corrosion is your enemy here.
Just anti-foul the area of the gear case that is in the water when titled up.

[rodbolt17]

they make special antifouling paints for AL.
make sure the bracket anode is clean and bonded.

make sure you have the rotor changed every 300 hours.

[jamievan]

Thank you both for your responses. The boat was new to me last year with about 300hrs, and I had put around 30 hrs on it when one of the engines blew, and while that engine was in on warranty the Yamaha mechanic found that the leg was corroded badly enough to need to be rebuilt. He also said that if I had kept the leg in the water while not in use that the corrosion would likely not have occurred. Rodbolt, seeing as how you are a Yamaha Master Mechanic, would you agree that by keeping the legs up while at dock could have created the corrosion problem...in only one leg? Or is it more likely that the previous owner neglected his zincs to the point of causing the corrosion? Also specifically would you recommend keeping the legs in the water while not in use?

Thank you for your assistance,
Jamie