Cleaning the outdrive?

[ss2016]

My boat was lifted today. Before the boat was jetwashed the outdrive was horrendous. The tabs also. See the picture. Worse than previous years, presumably the result of only 50 hrs use rather than the 100 previously.



After jetwashing there are still plenty of baby limpets mussels and tubeworms clinging on. I want to coat it in Hempel Ecopower and see if that leaves it looking better next year. My question is what can I clean it with? Presumably brick cleaner is a no-no because much of the drive I presume is aluminium. I can of course just abraid it but that will damage the existing VP grey paint. What is the 'normal' process.

PS Thinking about it perhaps the reason for the abundant growth is the water temp. being considerably higher than previous years.

 

[Momac]

 

[Fantasie 19]

View attachment 167433

Oxalic acid based.. looks like a good choice for hull cleaning but it says not recommended for painted surfaces??

 

[oldgit]

Bad year for fouling in many places.
Boat in a Medway marina.
Somewhere under there is a trim tab.

 

[Momac]

Oxalic acid based.. looks like a good choice for hull cleaning but it says not recommended for painted surfaces??

I have used Bar Keepers Friend Power Spray several times for cleaning the outdrives. Including very recently as the boat is ashore at the moment I would say that makes it the 4th or 5th occasion since I have owned the boat as it is lifted approx every 2 years and the first time out was in 2015.
The product is very effective in softening limescale which can then be scrubbed /wiped or lightly scraped off. The paint does not seem to be adversely affected. The paint is not perfect as new but not bad for a 20 year old boat. I do of course wash off with water but leaving the product on overnight doesn't seem to do any harm.

 

[BruceK]

elbow grease and plastic scraper


whats the world come to?

 

[ss2016]

View attachment 167433

MartynG, thanks for that. Looking at the picture you certainly keep them looking good. I think I will give it a try. I will test a bit of paint first. I am not certain what make of drives you have but they look as though they have rather less nooks and crannies than VP DPI.
I have been surprised that not more offered their solutions since it must be a common problem.

On a different subject I was cleaning the S/S props today and surprised how well I was doing with just soap and water. Last year I used a mild acid. What was strange was the low pressure face was much easier to clean than the high pressure face. I would have expected the high pressure face to be cleaner and easier to clean.

 

[Momac]

not certain what make of drives you have

Volvo Penta dp-e

 

[Momac]

On the stainless steel trim tabs and around the waterline where there was some stubborn limescale I used Spirits of salt diluted by adding it into water

This is very powerful stuff. Wear gloves and safety spectacles etc. The work gloves I used with this stuff a few weeks ago have holes in them now!

 

[Fantasie 19]

On the stainless steel trim tabs and around the waterline where there was some stubborn limescale I used Spirits of salt diluted by adding it into water
View attachment 167481
This is very powerful stuff. Wear gloves and safety spectacles etc. The work gloves I used with this stuff a few weeks ago have holes in them now!

25% hydrochloric acid...

 

[Momac]

25% hydrochloric acid...

What's the concern?

 

[Fantasie 19]

What's the concern?

None.. just surprised..

 

[jon and michie]

On the stainless steel trim tabs and around the waterline where there was some stubborn limescale I used Spirits of salt diluted by adding it into water
View attachment 167481
This is very powerful stuff. Wear gloves and safety spectacles etc. The work gloves I used with this stuff a few weeks ago have holes in them now!

@MartynG - I take it a lot of fresh water to rinse it off would be a wise move ?(asking just out of curiosity)

 

[Momac]

Yes I have rinsed with plenty of water .

 

[Momac]

And to be 100% clear I am not suggesting diluted hydrochloric acid is used on clean stainless steel trim tabs. I have used the diluted acid to help remove limescale. So the acid is largely neutralised by the limescale. Scraping of the partially dissolved and softened limescale was still required but that process was eased by the use of the acid . But in any case the trim tabs were well rinsed with water once down to bare metal.
I don't use antifoul paint on the trim tabs.

 

[oldgit]

An extremely powerful jet wash on our club drying blocks would remove anything and everything on my outdrives including any less than well attached paint, water jet also very good in blasting fouling out of difficult to reach nooks and crannies.
Always resulted in having to apply primer here or there before applying new A/F paint.
The toy jetwashers sold in your local DIY shop are useless for this job.
Do not forget the little gap at the transom to prevent the A/F coming into contact with the outdrive assembly. ?

 

[GrahamHR]

An extremely powerful jet wash on our club drying blocks would remove anything and everything on my outdrives including any less than well attached paint, water jet also very good in blasting fouling out of difficult to reach nooks and crannies.
Always resulted in having to apply primer here or there before applying new A/F paint.
The toy jetwashers sold in your local DIY shop are useless for this job.
Do not forget the little gap at the transom to prevent the A/F coming into contact with the outdrive assembly. ?

The drive is painted, so concentrated HCL won't harm the aluminium below the paint. Aluminium props, there is no exposed alumimium; just a protective rather inert aluminium oxide layer.

 

[Momac]

Do not forget the little gap at the transom to prevent the A/F coming into contact with the outdrive assembly. ?

I often see no gap.
Not sure exactly the preferred dimension of the gap

 

[oldgit]

Supposed to have be around 20mm ? but it would appear that nobody bothers any more ?
My Volvo Penta outdrives never appeared to suffer from any corrosion issues.
On a previous boat fitted with Mercruiser outdrives , the hydraulic rams seemed to take on the job of anodes ,dissolving on a regular basis.
Main corrosion was on the threaded joint between the cylinder tube and the end cap with the piston seal.
Unfortunately no repair possible....and there was 4 of the perishing things.

 

[Momac]

Supposed to have be around 20mm ? but it would appear that nobody bothers any more ?

I would say 20mm is about right
The white exposed GRP strip does become fouled but cleaning it up is not a great challenge