Electrolysis?

[allanb76]

I have kept my Silver Streak Challenger in the water at Poett Nook from May-Oct since buyng it new in early 2020. I did have it bottom painted (IP200E under Trilux II) when I purchased the boat. I normally pull it twice a season for maintenance/cleaning, but last year it was super busy every time I had the chance so I didn't. When I pulled it mid september I was surprised to see a bunch of my bottom paint flaking off, primarily on the pod. At the time I wasn't sure if it was bare aluminum I was seeing or the grey interprotect. I lightly pressure washed the area when I got home and a bunch more flaked off. I then sanded to see if it was aluminum....turns out it is. The cause of this is a bit puzzling to me. Bad surface prep? Electrolysis? It seems odd that a 2 year old boat made by a reputable company would have issues with electrolysis, but not impossible I suppose. The rest of the hull seems to be fine (aside from some flaking along keel weld) so surface prep must have been good.

My only observations so far:
1.) The first year I had it in the water, the hull anode seemed to be losing material aggressively at first. When I stepped in the boat on a Friday after being away all week, I could see a white cloud in the water coming from the anode. I did not notice this happening last year. In fact I noticed algae growth on it (should've been a red flag and I should've investigated further) The anode didn't look overly worn after the first season so i kept it on and wire brushed before use last year.
2.) There is also flaking near the trailer bunks. I discounted this being related as all of this damage occurred while it was off the trailer. It maybe unrelated to the issue at the stern, but I'm left wondering if Road Runner trailers use pressure treated lumber. I'm thinking I'll install the plastic slides to keep the boat off the carpet.
3.) Last spring I changed my trim tab anodes from zinc to aluminum. I noticed the zincs had no wear and was told by HC to keep them all the same. (hull and outboard are aluminum) Could this have caused something?
4.) I was in a different slip last year vs the first year. My new one is near the fuel dock.

I just had the paint fixed at Jenkins. I highly recommend them to anyone....definitely worth the drive from Nanaimo. At this point I will be digging out my multimeter and taking some measurements once its in the water again. I will certainly be putting a new anode on each season regardless of what it looks like.

 

[jim morrow]

I had a fibreglass boat with inboard outboard. I used that Trilux paint and it is not very tough, falls off easily. I used it only on the leg.
You can undercoat and paint the trim tabs, and rams, also.
Definitly change your zincs or whichever you use, every year/season. bolt tightly with stainless bolts and moly anti seize to keep the water out. keeps them electrically connected.

 

[allanb76]

I had a fibreglass boat with inboard outboard. I used that Trilux paint and it is not very tough, falls off easily. I used it only on the leg.
You can undercoat and paint the trim tabs, and rams, also.
Definitly change your zincs or whichever you use, every year/season. bolt tightly with stainless bolts and moly anti seize to keep the water out. keeps them electrically connected.

Thanks. I was wondering about painting the trim tabs. I thought there might be a reason the dealer didn't do it. I certainly get a fair amount of growth on them.

 

[wavetamer]

.i would be keeping a real close eye on that, Electrolysis occurs when you have current flow in he water and clearly you do ,the good news is YOUR ZINCS are working but something is going on . im assuming there is shore power on your dock ? are other alum boats also effected ? when you leave your boat battery switch off ? so the only powered up device is the bilge pump , these are known prob for alum boats have a real good look around the pump and make sure there is know positive leakage to ground . Check your motor neg and make sure you have good connections making sure the hull in not being used and the neg return path

 

[allanb76]

.i would be keeping a real close eye on that, Electrolysis occurs when you have current flow in he water and clearly you do ,the good news is YOUR ZINCS are working but something is going on . im assuming there is shore power on your dock ? are other alum boats also effected ? when you leave your boat battery switch off ? so the only powered up device is the bilge pump , these are known prob for alum boats have a real good look around the pump and make sure there is know positive leakage to ground . Check your motor neg and make sure you have good connections making sure the hull in not being used and the neg return path

I am definitely paranoid about it now. Good info...thanks. I will check the negatives on both motors. I do always turn my battery switch off. Both bilge pumps are the only things with power at that time. There is no power for boats to plug into, but they do have lighting and a fuel pump. The same slip I'm in now had an aluminum boat in it before. I haven't asked him about any issues but he is meticulous with his boat and I'm sure if he had issues he wouldn't have left it in the water.

 

[Gham]

Those stainless trim tabs are like 2 big battery terminals connecting your aluminum hull to the saltwater. Might be worth pulling them off to make sure they are bedded with something like sikaflex to isolate them from the hull. Priming and painting them will help as well.

 

[wavetamer]

I am definitely paranoid about it now. Good info...thanks. I will check the negatives on both motors. I do always turn my battery switch off. Both bilge pumps are the only things with power at that time. There is no power for boats to plug into, but they do have lighting and a fuel pump. The same slip I'm in now had an aluminum boat in it before. I haven't asked him about any issues but he is meticulous with his boat and I'm sure if he had issues he wouldn't have left it in the water.

if you can i would talk with him , how fast were his zincs sacrificing, did he notice any thing abnormal occurring with his boat. have a really good look at you wiring, look for corrosion or wire chaffing, correct bottom paint for alum boat ? is there a difference ?

 

[allanb76]

Those stainless trim tabs are like 2 big battery terminals connecting your aluminum hull to the saltwater. Might be worth pulling them off to make sure they are bedded with something like sikaflex to isolate them from the hull. Priming and painting them will help as well.

I thought the same thing so I tried to check that. The first 2 screws I tried broke so I decided against going further. With a multimeter I checked continuity and they are definitely not isolated. Knowing that I asked around a bit. Jenkins and others told me it’s common practice not to isolate them. That doesn’t make sense to me knowing what I know about dissimilar metals. I’d love to isolate them, but it seems like it will involve cutting the mounting plates off And having new ones welded on the boat.

 

[trophywife]

i added zincs just fore of midship on my kingfisher, added them to the trim tabs and had extra welded on zincs with the aluminium tabs every season just under the pod.
usually changed the anodes on the leg every 2 seasons. If your boat sits on carpets, that is not great either, even more so if you have pressure treated bunks under the carpet. i put some cheap plastic covers over the carpet to prevent any corrosion this way also.

 

[allanb76]

Another interesting thing I discovered today. I disconnected the negatives from both motors one by one and checked continuity to the hull. The main motor is not bonded to the hull but the kicker is. Why the main isn't is a mystery to me. Thick Paint on mounting bracket maybe. Now I'm left wondering if it's best to have the hull isolated from the common. I seem to be finding conflicting information on this topic. I could easily do this by putting something under the kicker clamp bolts. I suspect that's why it's a better bond than the main. The electrician in me thinks the hull should be bonded to the negative, but it is a pretty small wire on the 9.9 that connects to the block.

 

[sir-vivor]

A bud of mine has a 20 ft. Striper and was moored beside a guy at China Creek for 3 season, he pulled is boat out and his 2 thru hulls on the bottom of the boat were eaten so bad all he did was push on them and they just fell into the hull . You gotta be checking if your mooring your boat , even seasonal, that electrolysis is nasty nasty

 

[Tom Mac]

I'm not a electchicken but I have been told that sometimes its not your boat that has the problem but is a diffrent boat close by that is giving off stray currants. I have replaced lots of sq feet of hull damaged by electrolysis because of a "hot" marina. Might be somthing to check next time its moored.

 

[Derby]

Since you have started fishing this boat how has your fish catching ability.. have you notice it better or perhaps not as good..
?

 

[allanb76]

Since you have started fishing this boat how has your fish catching ability.. have you notice it better or perhaps not as good..
?

I’ve done very well from day 1 with this boat.

 

[Offshore]

In the past when I was in a ”hot” marina I would use a grouper zink. It has an alligator clip to the negative on the battery and the zink hangs in the water from a cleat.

 

[allanb76]

In the past when I was in a ”hot” marina I would use a grouper zink. It has an alligator clip to the negative on the battery and the zink hangs in the water from a cleat.

I was looking at those and thinking it might be a good idea. I think I'll also purchase a silver electrode to accurately measure the hull potential from time to time.

 

[bryce]

In the past when I was in a ”hot” marina I would use a grouper zink. It has an alligator clip to the negative on the battery and the zink hangs in the water from a cleat.

I’ve seen one of these in a marina but I believe it was clamped onto the cleat is that not proper?

 

[Gong Show]

Was your boat plugged into shore power?

 

[allanb76]

Was your boat plugged into shore power?

No, I have no AC systems on my boat.

 

[allanb76]

I’ve seen one of these in a marina but I believe it was clamped onto the cleat is that not proper?

Clamped on to the motor mounting bolts and hung from the cleat is what the manufacturers suggest. They say right on the directions not to clamp to negative battery terminal.