Corrosion

[sunnycoast62]

Would like some feed back on ways to stop corrosion. I have been told to unplug battery but have smart tech guages. Can I just turn the isolator switch to off or does this still cause corrosion to occur. BOAT IS ONLY 18 MTH'S OLD.... Any advise will help..

Cheers

Warren

[TheRealAndy]

Should be no corrosion at all. I would not be too concerned off the water, the biggest issue is when the boat is submersed.

[Jarrah Jack]

The main question is do you have a problem with corrosion now? I always have the isolation switch on off when not in use. Thats with the glass and alloy boat.

[nigelr]

Unless I'm using the boat the next day, in which case I use the isolator switch, I take both batteries out. Better safe than sorry I reckon.
Cheers.

[albey]

Would like some feed back on ways to stop corrosion. I have been told to unplug battery but have smart tech guages. Can I just turn the isolator switch to off or does this still cause corrosion to occur. BOAT IS ONLY 18 MTH'S OLD.... Any advise will help..

Cheers

Warren
I am assuming your boat is ally,but need to know where your corrosion is occuring.The biggest sin when wiring an ally boat is to use the hull as a negative return path,if this has happened then correct that immediately by disconnecting any cable that connects to the hull and replace it with tinned copper wire.The second possibility is anywhere that stainless steel is used and goes through the hull will set up an electrolysis possibility,in this case use "Tef Gel" to coat the screw or poprivet or the face of a rod holder for example and that will stop the problem.Tef Gel is avail from Bias,Whitworths,Leisure Marine in fact any good chandler.
There is no need to disconnect the batteries if the boat is wired correctly,however definately turn off the iso switch ,this will save the battery which will still be running any inherant hidden memories in todays complicated electronics.
But need more detail.

[PADDLES]

hi waz, do you actually have a corrosion problem? corrosion needs moisture, let your boat dry out as best you can and store it under cover if you can. for sure, check your electrics for any rubs or scuffs that may connect your hull to the electrical system, but i wouldn't be worried to the stage of removing your batteries.

[Mr__Bean]

Like 95% of the other corrosion in painted aluminium boats, it is most likely to be galvanic corrision and not electrolysis.

Google galvanic corrosion and you will get a wealth of information from those that have had the same disappointment that you are feeling now.

Doesn't matter a hoot what you do with your electricals if the problem is being caused by 2 dissimilar metals being in contact with salt water providing the electrolyte to set up a local little electrical cell that is working its way further and further under your precious paint work.

Here is a good read for a start: http://www.skippersschool.com.au/docs/boat%20tips-04.pdf

Good luck.

- Darren

[TheRealAndy]

Like 95% of the other corrosion in painted aluminium boats, it is most likely to be galvanic corrision and not electrolysis.

Google galvanic corrosion and you will get a wealth of information from those that have had the same disappointment that you are feeling now.

Doesn't matter a hoot what you do with your electricals if the problem is being caused by 2 dissimilar metals being in contact with salt water providing the electrolyte to set up a local little electrical cell that is working its way further and further under your precious paint work.

Here is a good read for a start: http://www.skippersschool.com.au/docs/boat%20tips-04.pdf

Good luck.

- Darren

Nice link. Might I add, you dont need dissimilar metals to get galvanic corrosion either. Just need one section that is more positive (electrically) than another section. Great place for this is where metal exposed to oxygen is then starved of it, like the edge of a pint line of a small paint chip!

[oldboot]

The biggest thing you can do to prevent corrosion, after you take the boat out of the water is to get it properly clean and dry as soon as possible..

lots of boats have carpet and enclosed cabs..the carpet can hold moisture for a long time so some forced ventilation..like a cheap box fan, will help circulate the air and dry everything out.

Sand leaves and other carp in the bilge and in all the knooks and crannies will accelerate corrosion.

the second thing is to treat every single nut, bolt, screw or other fastener ona metal boat or the trailer as it is applied with whatever is appropriate.

If it is a permanent fastener fixing an accessory "Duralac" or some similar under the fastener will go a long way... but almost any thing that will keep moisture from between surfaces or in crevices is better than nothing.

Google "crevice corrosion"

on working fasteners on your motor or the bolts on your trailer, a good quality marine grease.....castrol APXT or as it is now called LMX or similar "blue grease"is a good start.

So many trailers as you get them will not have a spot of grease on them appart from the bearings.....you have a choice.....pull your trailer appart and grease every nut bolt and screw and do your next maintenance with a spanner..or do nothing and do it with a grinder.

This disconnect the electrics......it probaly wont make much difference to the hull......but it may make a difference to the electrical connections, particularly the multipin connectors connecting your electronics.

a little lanolin spray or even better one of the electronic water protection sprays on your electrical joints and connectors will help....... but don't go overboard as it will make the glue on insulation take go gummy and fail.

but nothing clean and dry ever corroded.

cheers

[albey]

The biggest thing you can do to prevent corrosion, after you take the boat out of the water is to get it properly clean and dry as soon as possible..

lots of boats have carpet and enclosed cabs..the carpet can hold moisture for a long time so some forced ventilation..like a cheap box fan, will help circulate the air and dry everything out.

Sand leaves and other carp in the bilge and in all the knooks and crannies will accelerate corrosion.

the second thing is to treat every single nut, bolt, screw or other fastener ona metal boat or the trailer as it is applied with whatever is appropriate.

If it is a permanent fastener fixing an accessory "Duralac" or some similar under the fastener will go a long way... but almost any thing that will keep moisture from between surfaces or in crevices is better than nothing.

Google "crevice corrosion"

on working fasteners on your motor or the bolts on your trailer, a good quality marine grease.....castrol APXT or as it is now called LMX or similar "blue grease"is a good start.

So many trailers as you get them will not have a spot of grease on them appart from the bearings.....you have a choice.....pull your trailer appart and grease every nut bolt and screw and do your next maintenance with a spanner..or do nothing and do it with a grinder.

This disconnect the electrics......it probaly wont make much difference to the hull......but it may make a difference to the electrical connections, particularly the multipin connectors connecting your electronics.

a little lanolin spray or even better one of the electronic water protection sprays on your electrical joints and connectors will help....... but don't go overboard as it will make the glue on insulation take go gummy and fail.

but nothing clean and dry ever corroded.

cheers
Not strictly true regarding nothing clean and dry ever corroded.There are two types of corrosion,Electrolysis which requires two dissimilar metals,not necessarily in contact with each other and an electrolyte such as salt water.Happens a lot in ally boats when sinkers are left in the bilge for lengthy periods and shows up as pitting or even pin holes due to the aluminium being moved to the other metal(The same process as electroplating).
The most common however is galvanic corrosion which again requires two dissimilar metals but ARE in contact with each other and DO NOT require moisture only temperature(such as with a thermocouple,which when heated produces electricity),however any moisture present makes matters worse.Generally shows up as blisters under the paint work in areas in close proximity to a stainless steel attachment such as bimini saddles and rod holders and the like
This is the one that is avoided during installations by the use of "Tef Gel" or the older "Duralac",and even works on self tappers being screwed into ally-magic stuff and worth its weight in gold considering the value of what it is protecting.
If this is your corrosion then the ONLY way to beat it is remove the offending item and remount it after treating all contact surfaces with the gell mentioned previously,Drill out the pop rivets which use an aluminium which is not for marine use,(only use monel or SS rivets), but they will still require gell treatment.
If this is your corrosion then keeping the boat dry will not help,using lanolin will only waste money and do nothing,and using heaters in the garage will make matters worse.
Dont hesitate to contact me if you rquire further assistance.
Albey
Marine leccy(Rtired)

[TheRealAndy]

Not strictly true regarding nothing clean and dry ever corroded.There are two types of corrosion,Electrolysis which requires two dissimilar metals,not necessarily in contact with each other and an electrolyte such as salt water.Happens a lot in ally boats when sinkers are left in the bilge for lengthy periods and shows up as pitting or even pin holes due to the aluminium being moved to the other metal(The same process as electroplating).
The most common however is galvanic corrosion which again requires two dissimilar metals but ARE in contact with each other and DO NOT require moisture only temperature(such as with a thermocouple,which when heated produces electricity),however any moisture present makes matters worse.Generally shows up as blisters under the paint work in areas in close proximity to a stainless steel attachment such as bimini saddles and rod holders and the like
This is the one that is avoided during installations by the use of "Tef Gel" or the older "Duralac",and even works on self tappers being screwed into ally-magic stuff and worth its weight in gold considering the value of what it is protecting.
If this is your corrosion then the ONLY way to beat it is remove the offending item and remount it after treating all contact surfaces with the gell mentioned previously,Drill out the pop rivets which use an aluminium which is not for marine use,(only use monel or SS rivets), but they will still require gell treatment.
If this is your corrosion then keeping the boat dry will not help,using lanolin will only waste money and do nothing,and using heaters in the garage will make matters worse.
Dont hesitate to contact me if you rquire further assistance.
Albey
Marine leccy(Rtired)

Have to disagree with you there Albey. Galvanic corrosion DOES require an electrolyte.

[albey]

Have to disagree with you there Albey. Galvanic corrosion DOES require an electrolyte.
My schooling,and books I've read agree with you,however experience tells me otherwise.
Had two runabouts come into our shed at different times,but built under similar circumstances,one by a bloke who bought a hull and outfitted it in his industrial shed,then he died and it sat in the back of the shed for two years,never saw salt or fresh water,obviously humidity was present,the second one was a hull assembled in another industrial shed but this time he assembled the hull as well rivetting all the overlaps(like the Dehav Trojan)-what a job-but then lost interest and again she stood for a couple of years,again no water.We saw both of these boats for repair,and they were a mess,it looked like galvanic corrosion to us,but called in an electrical marine engineer for a report,and that is what he confirmed,and explained as per my previous post.Both boats were repaired and are still fishing the bay to my knowledge,in fact the first one we repowered around 5yrs ago.The rivetted hull I'm not sure about.
Have also experienced similar corrosion internally in dry areas of large cruisers in areas where amateurs have fitted attachments.
But I reiterate, moisture will exacerbate the problem.
We do however agree on the solution which is what is important to this poor bugger.