I/O boat grounding/bonding

[MotorheadTed]

I recently bought a very clean 1992 Sportcraft 232 wac with a V/P 431b eng and DP-c drive that was a freshwater (Lake Erie) boat until two years ago when the p.o. brought it to florida, used it in saltwater a few times , then parked it. It still had the original volvo exh manifolds one it, and the engine is in remarkable condition, with the original carb still bearing its original paint on including the screw heads !! Low time boat for sure !
Problem is the out drive has an unusual amount and type of corrosion . The skeg has the worst corrosion which goes about a third of the way up, then stops at a definite line, as though it sat in the water with the drive up with the skeg partly in the water. The main body of the drive is fairly corrosion free, but the separate mounting/swivel piece is heavily corroded, especially around the mounting and trim ram pin holes.
I question the bonding of all this. Anybody have any experience/thoughts about how the drive should be bonded ?
TIA,
Ted

p.s. I'll try to post some pics later

 

[Thalasso]

Re: I/O boat grounding/bonding

I recently bought a very clean 1992 Sportcraft 232 wac with a V/P 431b eng and DP-c drive that was a freshwater (Lake Erie) boat until two years ago when the p.o. brought it to florida, used it in saltwater a few times , then parked it. It still had the original volvo exh manifolds one it, and the engine is in remarkable condition, with the original carb still bearing its original paint on including the screw heads !! Low time boat for sure !
Problem is the out drive has an unusual amount and type of corrosion . The skeg has the worst corrosion which goes about a third of the way up, then stops at a definite line, as though it sat in the water with the drive up with the skeg partly in the water. The main body of the drive is fairly corrosion free, but the separate mounting/swivel piece is heavily corroded, especially around the mounting and trim ram pin holes.
I question the bonding of all this. Anybody have any experience/thoughts about how the drive should be bonded ?
TIA,
Ted

p.s. I'll try to post some pics later

well what has happened is it was probably fitted with Magnesium anodes for fresh water, and never changed to zinc for salt water,hence the corrosion. Just my guess.

 

[MotorheadTed]

Re: I/O boat grounding/bonding

Thanks for the replies guys. The anodes showed no deterioration. Surfaces were coverd with a yellowish crust, like they had been exposed to the air too long, but that same crust covered most of the drive that would be normally submerged. Must have been something in the Lake Erie water, never saw anything like it down here.
I went to a big "garage" sale at Marine Surplus in Bradenton last month. They had John Grviskus(sp?) (the guy from "Shipshape TV")there, and I asked him how do I tell a zinc anode from a magnesium one ? He was stumped, as were others, so I bought a new circle zinc anode. When I got home I compared it to the one of the drive, they were the same weight. I would expect that if the old was mag, it would weigh much less. Also the "bar" anode on the transom plate is very heavy, I'll blast it clean before it goes into the water.
Still think there is a bonding problem between drive sections and the boat. Some parts are isolated by the plastic bushings for the movable parts. Boats in salt water are just one big science project!!!!!!!!!!!