Re: Anode for a older O.B.
That is the normal place to attach it since it's flat there. Normally, it's placed on the top side of the anti-ventilation plate. Countersunk, flat head screws and nuts work out quite well for mounting hardware.
Since the anti-ventilation plates on these outboards are fully underwater when the boat is on plate, the anode will certainly increase drag. But it's not enough to cause handling problems and such since the speeds are not all that high.
Because of the higher drag, I chose to install mine on the side of the lower unit just above the anti-ventilation plate. This caused far more complication since the screw holes need to be tapped, the zinc needed to be relieved on it's back side to accommodate the curvature, and the screws had to be sealed to keep the exhaust from leaking out around them. I don't expect the threads I cut to last forever either.
I really think that if you can, tilt the engine out of the water when it's sitting. The corrosion seems to be beginning in the seam, and I don't think a zinc will help much with that. Keeping the paint up will afford better protection.
