I'm preparing to help my brother solve a problem with his boat.It's a'97 Lund Pro-V 1775,'97 Evinrude 115,no kicker.Apparently some sort of electrical leak is burning tiny holes in the transom.I'm assuming I'll be looking for bad grounds or bare wires near metal.No new accessories have installed.The steering helm was replaced was spring.Some connections at the fuse box were cleaned as the running lites weren't working.Other then that everything is original.As far as I know everything is working and there is no problem with the battery going dead.Is there a common problem with the wiring or switches in this hull or outboard?Is the location of the holes mean the problem is near the transom?Any help finding the needle in this haystack would be greatly appreciated.

Sounds like w wire is rubbing bare and touching the hull somewhere. Seems it would have to be fairly high current, not a graph for instance. What's around there, bilge? Live well pump? Have you looked over the main motor leads?

I would get a VOM and set it to read current. I would make sure everything is electrically turned off. I would then disconnect the negative lead off the battery and connect the VOM in series from the disconnected cable and the negative battery terminal and measure how much current is being drawn off the battery. If you're drawing current, I would then start disconnecting things one at a time to determine which accessory is causing the drain. As far as the pin holes.....sounds very strange. Where are you seeing them exactly? Are there any wires close by?

If it were me - the first place I would look would be right where the holes are. Chances you have wires shorting to ground right at those locations. It could be from bare wires, pinched wires, etc.

Is everything working?...a square 9 (or 16 ?) wire harness/plug runs thru the bilge below the waterline right near the drain plug on my '95 Pro V 1775. I have not replaced the entire plug,just individual wires that corroded out.

That's the first place I'd look.

Sounds like w wire is rubbing bare and touching the hull somewhere. Seems it would have to be fairly high current, not a graph for instance. What's around there, bilge? Live well pump? Have you looked over the main motor leads?

MUNSHAW hit the nail on the head here. Other possibility is that an accessory has been directly grounded to the hull rather than grounded direct to the battery.

Thanks for the help and ideas,guys.I haven't actually seen the boat.My bro's been talking to me about the problem and I've been instructing him as to what to look for. He's found nothing but I don't know how hard he looked.Yesterday he told me the first appeared about three years ago high on the starboard side of the transom opposite of some sort of master battery switch.I'll start there.Last summer 6-10 new ones appeared across the transom.The boat comes out of storage this weekend so I'll get on it next week.I'll post any findings.I'm not looking forward to this job!

OOC,
1. Make sure that you have a good ground between the power head of your motor and the lower unit. Normally there is a braided strap between the two to guarentee a good ground connection.

2. Make sure that the sacrificial anode on your engine is in good shape. There can be electrolisis going on, but the sacrificial anode should be taking the brunt of the corrosion.

3. Go to your motor and battery. Remove the wires from both ends of the wiring harness -i.e. motor and battery. Go over the entire lengths of the line to insure that the insulation is in good shape, that there are no shorts, and that the connections at each end are very clean, and tight. It is not a bad idea to put a layer of grease on these connections, before tightning them down, and then put another layer of grease over the top of the connections. This will insure that the connection is completely encased in grease and prevents any oxygen or moisture to get to the connection and cause a corroded connection.

4. Double check, but many aluminum boats also have a separate ground between the transom and the hull of the boat. If so, make sure that this conneciton is intact and secure.

Good luck
REW

It could be possible that rectifier from stator is malfunction and releasing the current through ground wires near cdi packs or rectifier regulator. I would first check grounds clean up metal underneath if needed. How many volts are you getting at battery while motor is running. I would also look for a cut wire on hull. Any sparks at battery while hooking up, is power leaking to hull somehow. Be sure you have proper fuses at connections including the trolling motor. You could hook everything up check that wires are not hot.

Another point of interest, is the boat under discussion normally kept in the water for the season?

Or is the boat, just put in the water during use, and then taken back out and stored on a trailer.

Most issues with this sort of corrosion problem are those boats that are kept in the water during long season use.

REW

You might want to check out this thread. Something about the chemicals in the wood causing corrosion on the transom.

http://www.walleyecentral.com/forums/showthread.php?t=164237