Cleaning and painting the engine bilge

[Richard10002]

How about Craftmaster Bilge Paint:

https://craftmaster.myshopify.com/collections/other-paints-varnish/products/bilge-paint?variant=178689112

 

They also do a rust treatment

[Dr Bob]

8 minutes ago, dmr said:

I believe that most, possibly all, red oxide primers are Zinc based so naturally grey in colour but are died red only to please us older users who can remember just how good real lead oxide primers were.

............Dave

That's right Dave. Red lead was kicked out late 70's (or was it early 80's?). Zinc is ok but not nearly as good.

[dmr]

6 minutes ago, Richard10002 said:

How about Craftmaster Bilge Paint:

https://craftmaster.myshopify.com/collections/other-paints-varnish/products/bilge-paint?variant=178689112

 

They also do a rust treatment

Its hard to know. Craftmaster excel at brushing enamel, thats what the company was created to do. I suspect everything else was just added on to offer a wider range of related products. They have a top reputation to maintain so they are not likely to sell rubbish. Their varnish and engine enamels are certainly very good, in fact many consider the varnish to be the best available.  Danboline has been around for a long time and has a good reputation as International is much used in the lump water boaty market. Its probably a bit cheaper than Craftmaster. I suspect most paint factories all know and use the same chemistry set

...............Dave

 

[Dr Bob]

18 minutes ago, Richard10002 said:

How about Craftmaster Bilge Paint:

https://craftmaster.myshopify.com/collections/other-paints-varnish/products/bilge-paint?variant=178689112

 

They also do a rust treatment

The limited info on the link says it is a 'finish' paint, i.e. To be used over a primer. If used on its own it needs a good surface. For the application you need a rust and moisture tolerant primer and an oil and water resistant top coat......or a good 2 pack one coat coal tar epoxy.

Edited August 5, 2017 by Dr Bob

[Lily Rose]

Hmm.

It all sounds so damned complicated I'm starting to lean towards the "do nothing" option.

 

 

 

[dmr]

13 minutes ago, Dr Bob said:

The limited info on the link says it is a 'finish' paint, i.e. To be used over a primer. If used on its own it needs a good surface. For the application you need a rust and moisture tolerant primer and an oil and water resistant top coat......or a good 2 pack one coat coal tar epoxy.

If you follow the link it says best to prime and undercoat but can be used directly on bare metal. I think after all the effort of preparation I would use a primer. I personally would use bondaprimer on good steel or red Owatrol (CIP) if it was a bit rusty. I am tempted by Vactan, many forum members really like it, but I used some of the early rust converters on various old cars and was not impressed. I have used Hammerite Kurust a little bit recently but won't know if its any good for a few years yet (I hope)

.............Dave

5 minutes ago, MrBeethoven said:

Hmm.

It all sounds so damned complicated I'm starting to lean towards the "do nothing" option.

 

 

 

Who makes that one, is it International or Craftmaster ?

[Jak]

Now I'm confused. The only boat I've owned is my current 80s trad. The bilge is always wet. Either from rainwater or what I thought was 'normal' leakage from the stern gland when cruising (greaser seals it up fine when not running). 

Should I be aiming for a dry bilge somehow?  How??

 

[Froggy]

5 hours ago, WotEver said:

Vactan is made by Performance Chemicals:

http://performance-chemicals.net/vactan/

Yes, yes, and yes. Although it is in itself a primer so only requires an undercoat and topcoat. 

In my (and many others) opinion, yes absolutely. 

I found it on eBay on my first Google:

http://m.ebay.co.uk/itm/VACTAN-RUST-CONVERTER-AND-PRIMER-250ml-RUST-TREATMENT-/110979877654

Absolutely. Prep the surface as you would for any rust converter, slap it on, wait for it to dry, overpaint. 

Ok, many thanks for your input, you've convinced me, and the Fertan won't go to waste in the long term. There's a greenie headed your way when I get back on dry land, I cant seem to award any using the mobile site on my Windows phone.

[Froggy]

1 hour ago, Jak said:

Now I'm confused. The only boat I've owned is my current 80s trad. The bilge is always wet. Either from rainwater or what I thought was 'normal' leakage from the stern gland when cruising (greaser seals it up fine when not running). 

Should I be aiming for a dry bilge somehow?  How??

 

Take the boards up while the engine is running warm and check some of that water isn't coming from leaking pipes and header tanks because that's what I found.

Edited August 6, 2017 by Froggy

[rusty69]

5 hours ago, Jak said:

Should I be aiming for a dry bilge somehow?  How?

Yes put a tub beneath the leaking gland with a bilge pump in, or a separate pump/pipe.

 

If Its Rainwater, find the leak and fix it. 

Edited August 6, 2017 by rusty69

[blackrose]

20 hours ago, Froggy said:

Well, this job is overdue. We bought the boat in November with standing water in the engine bay, and although for some of this time it's been dry, with one application of Fertan applied, we now want to get the job over and done with. So, would i be correct in assuming that these are the requisite steps:

1. hoover out any loose debris

2. apply degreaser

3. remove degreaser with warm soapy water

4. liberally apply Fertan and allow to dry

5. hoover out any loose debris

6. one coat of primer

7. two coats of bilge paint with rust inhibitor additive

I've been advised to 'remove loose rust' by one boatyard. I'm reluctant to start chipping away at rust. Would i be doing the right thing to interpret this literally and just remove rust that is literally loose, i.e. flakes that have come away from the steel and can be brushed/hoovered out?

Why are you reluctant to chip away the rust? Rust is oxidised metal - it's not a sound substrate to paint on. You should be wire brushing and yes chipping away at rust scale that won't come off with the wire brush. The easiest way is to use wire wheels on an angle grinder but make sure you have eye protection, ear defenders and a dust mask. Leather work gloves are a good idea too. There is really very little point painting rust converter or paint over rust scale, you need to get it back to sound steel and convert the minor bits of rust that won't come out of any pitting with Vactan.

Cover your engine with a dust sheet. You should be using the angle grinder with a side handle and keep the grinder mains cable well away from the wire wheel. Sounds obvious but when you're in a confined space the two can often be in close proximity and come together!

Edited August 6, 2017 by blackrose

[blackrose]

On the other hand, if you're reluctant to chip away at rust because you think the sound metal is so thin that you'll go through it, then you need it over-plated or replated, not painted! I don't know your boat but you're probably worrying unnecessarily.

[rusty69]

2 minutes ago, blackrose said:

On the other hand, if you're reluctant to chip away at rust because you think the sound metal is so thin that you'll go through it, then you need it over-plated or replated, not painted! I don't know your boat but you're probably worrying unnecessarily.

Not sure i agree with that. If he's reluctant to scrape because he believes its thin or is worried to find out, then its best to have it surveyed or left alone til out of the water 

[blackrose]

34 minutes ago, rusty69 said:

Not sure i agree with that. If he's reluctant to scrape because he believes its thin or is worried to find out, then its best to have it surveyed or left alone til out of the water 

Well, yes surveyed first, but my point was simply that if it's too thin to get the rust off then there's not much point painting it.

I've ground, scraped and chipped the rust out of a coupe of 110 year old rivetted steel hulls and they were fine. We only went through in a couple of places! 

Edited August 6, 2017 by blackrose

[rusty69]

Just now, blackrose said:

Well, yes surveyed first, but my point was simply that if it's too thin to chip and scrape the rust off then there's not much point painting it.

That is true, but potentially risky, and of course they may not know how thin it is. I thought I did with ours, but now im not so sure. 

[blackrose]

5 minutes ago, rusty69 said:

That is true, but potentially risky, and of course they may not know how thin it is. I thought I did with ours, but now im not so sure. 

Risky not painting it? How so?

Edit: If the boat is sitting on a wafer thin sheet of steel then why are we even thinking about painting it? It doesn't make any sense to me.

Edited August 6, 2017 by blackrose

[rusty69]

11 minutes ago, blackrose said:

Risky not painting it? How so?

Riskier sinking. 

 

See my "sinking" thread if you are interested. I am currently Sat under a crane after scraping my engine room a few weeks back. 

 

 

Edit. Nobody said it is, he may be worried that it might be(maybe not) 

Edited August 6, 2017 by rusty69

[blackrose]

27 minutes ago, rusty69 said:

Riskier sinking. 

 

See my "sinking" thread if you are interested. I am currently Sat under a crane after scraping my engine room a few weeks back. 

Riskier sinking? Do you mean a greater risk of sinking if the steel is or isn't scraped and painted? I did see the start of your other thread but didn't read the 100+ posts. I guess you mean that at least you found out your steel was thin because you were scraping and went through, so you were able to do something about it because you were there. On the other hand, imagine if you had not gone through the steel and painted over a wafer thin section - that arguably that would have comprised a greater risk because the problem would have remained hidden for longer. But thin steel is thin steel, so the risk is there and if nothing is done about it then one way or the other the boat may sink, so eventually it will have to be over-plated or replated.

Anyway, all I'm saying is that if one is worried about thin steel then painting over it doesn't make any sense because you have bigger problems than cosmetic/protective treatment of rusty bilges! I can only give advice on how to prep steel properly from my professional experience of working on boats - much of it doing this specific job. After that it's up to others to make their own minds up about how best to do it on their own boats. 

Edited August 6, 2017 by blackrose

[rusty69]

10 minutes ago, blackrose said:

Riskier sinking? Do you mean a greater risk of sinking if the steel is or isn't scraped and painted?

Yes, it must be a greater risk of sinking if you go through the bottom. You will likely sink anyway if you just paint it, but perhaps the time it buys you, you will have found out there is a problem at the next lift out. 

Obviously if you think you have a problem, that should be sooner rather than later. 

[Richard10002]

Could a surveyor measure the thickness of the steel from the inside, while the boat is in the water? - after all, it's accessible enough in the engine compartment.

[blackrose]

 

3 hours ago, rusty69 said:

Yes, it must be a greater risk of sinking if you go through the bottom. You will likely sink anyway if you just paint it, but perhaps the time it buys you, you will have found out there is a problem at the next lift out. 

Obviously if you think you have a problem, that should be sooner rather than later. 

Yes, obviously!  If you go through the bottom then sinking is a greater risk. 

How does a few coats of paint buy you time? It doesn't. Painting over unsound steel just hides the problem. If the idea is to seal any impending holes with paint then by that logic it would be better to smear mastic all over the steel rather than paint (they are both bad ideas by the way!) 

Edited August 6, 2017 by blackrose

[blackrose]

34 minutes ago, Richard10002 said:

Could a surveyor measure the thickness of the steel from the inside, while the boat is in the water? - after all, it's accessible enough in the engine compartment.

Yes, that is possible, I know someone who got a surveyor in to do it, but it's not going to be as easy or accurate as taking measurements with the boat out of the water because you don't know what is encrusted on the outside of the hull and this may affect the measurements. But it's worth a try. You might also be able to hire an ultrasonic thickness tester and take some measurements yourself.

http://www.dmv-uk.com/ultrasonic-thickness-gauge-hire-andamp16350-per-week/p361

 

[rusty69]

Did that myself. Not convinced about the results, hence sat under crane. 

[rusty69]

36 minutes ago, blackrose said:

 

Yes, obviously!  If you go through the bottom then sinking is a greater risk. 

How does a few coats of paint buy you time? It doesn't. Painting over unsound steel just hides the problem. If the idea is to seal any impending holes with paint then by that logic it would be better to smear mastic all over the steel rather than paint (they are both bad ideas by the way!) 

The paint won't add to the time, the lack of scraping might. 

[Froggy]

Thanks for all the input guys. I'm currently on the cut with almost no remaining data allowance until the middle of the month, will reply in greater detail when I can, I might possibly be on dry land again in a few days time. One query I have though: why hack away at rust scale that isn't easily removable rather than neutralise the rust then paint over it? As long as you don't fracture the paint layer there's no more water ingress and hence no further advancement of rust. Obviously the relatively unsound substrate is at greater risk of fracturing if you walk on it, but certainly on our boat we can do most minor tasks in the engine bay without stepping on the baseplate anyway and then it's just a case of monitoring the paintwork and doing localised repairs if necessary. The chances are our 20 year old boat still has a sound baseolate, but finding out it hasn't while the boat is in the water isn't something that fills me with relish. On the other hand, leaving things as they are and applying no rust converter and paint merely leads to further degradation of the plate.

Edited August 6, 2017 by Froggy