Galvanic Action

[striped bass]

There is some surface galvanic action on the back vertical surface of my engine Gill bracket (see photo) where the engine mounts onto the bracket. The marine yard here says that this is a common issue with Grady brackets and that the galvanic action on the surface is not a serious issue. They suggested backing out one or two of the bolts to check for any damage but thats about it. I would appreciate any opinions from any one out there in Grady White land with knowledge or experience on this issue.
Thanks.

 

[jimmy's marine service]

this could get ugly....

it's like this...if you,or the marina who paints the bottom,has been using a copper based antifouling paint,you've created this mess...the aluminum will sacrifice itself,just like a zinc...it's common,due to the fact people can't understand that aluminum parts require a tin based antifouling paint...do a search of my posts,you will see the correct way to paint the bottom...follow the text as well..it explains it all...

where's the pictures ?????????

 

[BobP]

The photo didn't post.

Galvanic corrosion activity must to arrested as soon as possible. otherwise expect big bills down the road.

The bottom paint is probably the wrong type, must use the type for aluminum, non-copper based like Trilux, and the zinc anode must be serviced on the drive.

Have the bottom paint stripped off and repaint with Trilux or equal.

How does the anode look? Any such damage on the engine brackets? Any other galvanic corrosion damage on the thruhulls, FF sensor bracket, trim tabs? What does the anodes look like on the engie brackets by end of season? Has the anodes erroded faster lately ?


Are you a DIYer?

 

[striped bass]

Thanks for your helpful insights. Here is more information. The boat has never had any bottom paint. No other galvanic action appears anywhere. Everything else is clean and ship shape. The anode on the engine was replaced this winter (needed replacing). The boat will receive its first ever barrier coat and bottom paint this spring. I'll make sure the yard follows your directions. The photo is coming. Jeff (site administrator) is posting the photo to my entry (may take until this evening to get posted). In the mean time if you want to send me your email address I'll send the photo now. charlesmiller6@cox.net

 

[BobP]

I take it you have someone doing the work?

The marinas replace the anodes, irrespective of condition, as a policy usually.

Do you keep the boat connected to shore power when you leave the dock, or any other connections like cable tv, phone, etc, if the marina has it ? Is your DC ground system in the boat intact, all negative connections good like engine neg connections, or other neg connections. Using a galvanic isolator for shore power?

You have two issues, how bad is the damage and arresting any further damage to occur.
My advise is aimed at maintaining the existing drive indefinetely, as it was designed. I would need more info in order to see what is going on.

If you don't have bottom paint on the drive, then galvanic corrosion can be also attacking other underwater metals, the engine is made of the same alloy as your drive.

The Drive's anode (or any other anode) must never be depleted during the season, get more zinc weight on the drive until it is found out the source of the stray current leaving the boat and mitigated.

 

[striped bass]

Thanks again for your helpful comments. Yes, the boat is yard maintained and do all the work. The photo will show extent of surface damage when posted this evening by Jeff unless you want me to send photo now to your email. This is a GW Tournament 225 (1998) so there are no extra electronics like cable tv, telephone or shore power outlet. The surface damage in not extensive so keeping this original OEM bracket is very doable. All connections are in tact but I'll have the yard electrician check them all again. The boat has been dry stored on a trailer by the former owner when not in use and is not left at a dock. Starting this coming season the boat will hang off a mooring. I just took delivery on this 225 in November and had it shipped to CT from SC.

 

[BobP]

I'll take a look at the photo when it comes through, may be limited what we can see.

Since your marina is charged with taking care of your boat, if they are unsure of teh drives condition, there are things to do. I would run up there myself if I was not so far away. Perhaps another member closer can assist.

I know there is a Grady dealer in CT, contact him and say you were advised to seek his opinion on Great Grady.com !!, see if he can send a technician (get marina approval). What else are they doing this time of the year ?? It's up to you if you need such advise.

Since you say the boat will be moored, the boat painter can't paint the drive with the same bottom paint as the hull. Depending on how they respond to such comments: they may know this already, or not care what you say and paint it as they would have if you never said anything.

When the drive is bottom painted correctly, all that has to be done is brush over the drive paint onto the hull where the drive meets the hull with plenty of overlap, , then have the regular bottom coat continue from there on, no need to use masking tape, both paints are compatible so they can overlap eachother, just keep the boat paint away from the drive.

When the anodes are replaced, have to be sure there is continuity between drive, engine case, and ground. A simple multimeter "continuity" (ringer) test will cover it.

The anode may never have been serviced properly, hence the damage.
Now you know what to do in the future.

 

[jimmy's marine service]

There is some surface galvanic action on the back vertical surface of my engine Gill bracket (see photo) where the engine mounts onto the bracket. The marine yard here says that this is a common issue with Grady brackets and that the galvanic action on the surface is not a serious issue. They suggested backing out one or two of the bolts to check for any damage but thats about it. I would appreciate any opinions from any one out there in Grady White land with knowledge or experience on this issue.
Thanks.

i got your email concerning this...i emailed you back...take a look...

 

[striped bass]

BobP:
Good idea about contacting a Grady dealer. I contacted the Grady dealer in Niantic and sent them the photo. They stated that this is a common issue with older Grady Gill brackets and is not a structural probllem. Their advice was to scrape off just the affected area and apply etched primer and paint over the exposed aluminum.

 

[Seafarer228G]

Here is the pic Charles center me.

 

[BobP]

Glad it is working out for you.

The coating is peeling off, as all coatings will do eventually, regardless of claims by vendors. It's because moisture eventually breaks through at some point, and gets behind it and moves along.

Can't tell if it's galvanic damage from the photo, have to scrap off the coating (look for pits) to see what's behind it. If no pits and just white dust, then any restoration serves for cosmetic purposes only, not structural ones. So it depends on your needs. Eventually, if you keep the boat long enough, all the coating will be doing the same.

I don't think it's galnavic damage since it looks the same above the waterline as below.

You didn't say if any water was found inside, and if so, how much. There are mini sumps at the bottom that need to be drained from season to season, and measure the amount of water to see if it increases. Some water is ok. Just place a 5 gallon bucket under the plug(s), and let the water drain, then pour into say a soda bottle to get approx. amount.

I see something esle, normally the engine mount bolt heads are in the inside of the drive, this appears to have been done opposite, with heads facing rearward. To me it would be easier to seal the lower drive holes (to keep water out) if the bolt heads were on the inside, that's just me. Nothing to panic about, perhaps others have seen it this way, I never have. As long as the lower holes especially are sealed, it doesn't matter.

 

[gw204]

That bracket is different than your's Bob. The lower engine bolts thread into nuts welded (I think) to the inside of the bracket. You just have to put some sealant on the bolts when you install the motor.

 

[BobP]

I didn't know that.

I have looked at the new bracketed boats at Spellmens, as well as all the others they line up outside, I always see double nuts on the outside.

Being anal, I wonder how they welded the steel nuts to the Almag.

How about the top holes? Same?

 

[striped bass]

Thanks for your helpful insights. Yes, I did check the bracket for water. It was dry as a bone on the inside. To keep any further corrosion at bay I am having the boat bottom and bracket painted now that the boat will be moored all season in R.I. The Niantic dealer and Jimmy were careful to specify the correct procedure for painting the boat bottom and the bracket neither of which have ever been painted. The main point is to keep the boat bottom antifouing paint away from the bracket drive as it will cause galvanic action. The good news I'm told is there is a new clear antifouling spray paint for drives that has just hit the market; it's called Trilux Prop & Drive paint by Interlux. It's brand new, and boat dealers are going to be using it this year and look forward to the results. Being that it is clear supposedly you can just spray on and coat everything without it looking messy. I'll let you know the results.