Saildrive Coating...do it right?

[Soulflyer1980]

Hey guys,

I have been forced to remove my saildrive and stripping it down to the bare aluminium. Now I have been researching this a bit and my best and long-lasting bet so far is to use epoxy resin to coat the saildrive (sanding the aluminum through the wet epoxy)before applying even copper based antifouling. Thanks to these guys:

Sail Drives

But now I am thinking to Powder coat the saildrive leg instead before antifouling it. Does anybody got some experience with that? Pros vs Cons or any thoughts?

Thanks a lot

Ferdinand

[Pete7]

You can't put copper antifoul paint on a drive leg or it will dissolve.

You need an etch primer paint first on the leg before applying the epoxy or it won't stick.

Powder coating could be an option, after all that's how they paint dive cylinders.

Pete

[Soulflyer1980]

Originally Posted by Pete7

You can't put copper antifoul paint on a drive leg or it will dissolve.

You need an etch primer paint first on the leg before applying the epoxy or it won't stick.

Powder coating could be an option, after all that's how they paint dive cylinders.

Pete

Thanks Pete, I am trying to create a physical barrier between the saildrive and the coppercoat. That way there shouldn't be any galvanic corrosion.

The idea is to use very slow curing epoxy resin (209 West System) and 'wet' sand (80 grit) the aluminium through the applied epoxy. That way I can get rid of the oxidation layer and making sure the epoxy will bond proper.

Powder coating sounded like an easier and less messy solution to me but I am afraid what happens if the Powder Coater gets it wrong...thats gona be a disaster if corrosion spreads under the coating since it only noticed once you remove the powder coat

I am just trying to find a better solution for the whole saildrive and prop debacle. All these 'special' products are way to expensive and so far haven't really served me well either

Ferdinad

[Captsteve53]

I would after cleaning off the old paint and back to bare Aluminium, treat for a short period with a acidic type Aluminium cleaner, then with a single pack self etch primer (this is a very thin coating which actually chemically binds to the Aluminium (You should still see the Aluminium after the coating is applied-again very thin!

Saying that times have moved on in the painting world and International paints are now stating that there inter-protect epoxy primer is suitable over fresh Aluminium,I would how ever cover with minimum three coats if you plan to over coat with a Copper coat of any variety

I would be cautious of over coating with laminating epoxies as correct epoxy paint will demonstrate better adhesion and with stand impacts and differing temperatures better than straight Epoxy type lay up over Aluminium(Hence why it;s hard to find any one recommending these Epoxies as primers)

[belizesailor]

A properly applied barrier coat will isolate the copper based antifouling from the SDs. Ive been using that on my SDs for 13 years now. No problems.

[YPSILANTI]

PLEASE DO NOT USE COPPER BASED ANTI-FOWLING on your sail drives. I've just renovated my sail drives and did much research. Yes, do prime them first. see https://www.burnsco.co.nz/a-complete...tifouling_1524.

[Soulflyer1980]

Originally Posted by belizesailor

A properly applied barrier coat will isolate the copper based antifouling from the SDs. Ive been using that on my SDs for 13 years now. No problems.

Thanks Belizesailor, that exaclty supports my thesis. I mean copper antifoul can only harm the saildrive with direct contact. With a proper barrier coat that is not the case and there should be no galvanic corrosion.

What barrier coat have you been using?

Ferdinand

[Soulflyer1980]

Originally Posted by YPSILANTI

PLEASE DO NOT USE COPPER BASED ANTI-FOWLING on your sail drives. I've just renovated my sail drives and did much research. Yes, do prime them first. see https://www.burnsco.co.nz/a-complete...tifouling_1524.

Thank you Ypsilanti, I know the normal procedurre to etch prime etc light Alloy but with the existing antifouling for saildrives I would have to lift it out every year or two just for the SD's while the rest of the boat (coppercoat) is in absolute good condition. I want to antifoul my Saildrives with coppercoat and the only way to do it, is to apply a barrier between Alloy and Copper. Wihout those two in contact there should be no problem for the saildriveor am I thinking wrong?

[Paul L]

Originally Posted by Soulflyer1980

Thanks Belizesailor, that exaclty supports my thesis. I mean copper antifoul can only harm the saildrive with direct contact. With a proper barrier coat that is not the case and there should be no galvanic corrosion.

What barrier coat have you been using?

Ferdinand

And what happens when you have a grounding and scratch the surface? It seems that copper is pretty close to the AL. I've seen a number of Coppercoat boats hauled to repair dings and flaking spots.
I've never owned a boat with saildrives, so just asking.

[YPSILANTI]

Why not just use the correct anti fowling that is designed for aluminum and not copper coat? I cant answer the technical aspects of the opposing electrical conductivity 1mm apart and the consequence's of scratches etc. but am of the opinion that you will definitely negate any risk of using the product best suited for the application and not one that is strongly discouraged. You'd be doing less harm by not coating with anything than applying copper coat. The disadvantages out way the desired benefit which will be negated. Applying the correct product will in no way disadvantage you in terms of timing, drying time, haul out time etc. Can be applied between tides secured to a slipway without the need to haul. see Repelling The Enemy - MySailing.com.au

[Paul L]

YPSILANTI
The OP wants to use Coppercoat, a 10 year copper-epoxy bottom coat system. So he doesn't want to be hauling to paint the sail drives annually

[Fore and Aft]

Regardless of what coating you put on the Saildrive you still need to inspect the anodes and change them when needed. If you get the coating wrong it's an expensive item to repair.
Cheers

[Paul L]

Originally Posted by Fore and Aft

Regardless of what coating you put on the Saildrive you still need to inspect the anodes and change them when needed. If you get the coating wrong it's an expensive item to repair.
Cheers

Anodes don't necessarily require hauling to replace.

[fstbttms]

Originally Posted by Paul L

Anodes don't necessarily require hauling to replace.

Anodes don't EVER require hauling to replace.

[Fore and Aft]

Paul L have you ever replaced a Saildrive anode? The ones I know of you have to remove the propeller then replace the anode once you have undone the two hex bolts that hold it in place. That all sounds easy but I have seen more than a few difficult anode replacements done on the hard stand.
That reminds me, if you are going to copper coat the Saildrive then how do you coat the inside of the raw water intake? Bukh is the only Saildrive manufacturer that I know of that does not use the leg for the raw water intake.
Out of curiosity who in this forum changes their Saildrive anode in the water?
Cheers