How often do you re-black your boat?

[bassplayer]

I'm sorry if this has been done before. Just wondered how often you re-black your boat and your reasoning behind the interval.

 

I've got a Les Allen which was re-blacked 3 years ago. The hull had a survey at that time and had negligible pitting or wear despite being 22 years old at the time. She's obviously been well looked after. I've heard a couple of people say it's a waste of time and money to do it at all, others prefer to have it done after 2 years.

 

My understanding is that there are factors which contribute to the degrading of the hull thickness and pitting. 1) Use of electric shore lines (I don't) 2) Amount of time stood still (we cruise a lot) 3) Type of paint used

 

...I'm sure there are other factors but is it true that the only bit which is at risk is the water line where the hull goes in and out of the water? Any thoughts gratefully received....

[Alf Roberts]

As often as you can afford.

[Wanted]

As Alf says.

 

I get to the point where the nagging in my head out weighs the cost. Dependant on boat use I aim for every two years, which normally ends up closer to three by the time I find the cash and booking etc.

[Geordie.narrowboat]

I do mine every 12-18 months, leave it in a marina on a hook up with an isolation transformer. My blacking is done for me at £450 for thee coats. As I work I get out every other weekend and school holidays. The more regular blacking is compensation for the limited time out and because I can.

[boots]

Was doing ours every two years (that's the most we could afford), but this year have had it two-packed and plan on leaving it 3~4 years before taking it out of the water again.

[Bloomsberry]

This depends on

1) How often it needs doing
2) How much money you have
3) How bothered you are to getting it done when it needs doing

I mentioned this in a recent thread but my experiances with bitumen are that blacking using this method , for me anyway , lasts for less then 6 months. So if I did it when it needed doing would be twice a year.

So next time I am planning on getting my boat 2 packed which is supposed to last for 10-20 years apparently.

Also Pitting can occur well below the water line and at an alarming rate too, a lot quicker than normal corrosion. I read an article about a 2 year old boat that had 2mm pitting well below the water line which represents a 3rd of the hull thickness penetrated in that short time. So taking the boat out of the water regularly for a visual check is very wise anyway.

[Paul's Nulife4-2]

Hi ya,

I've just done mine making it 3 times in 7 years, so should be good for another 18 months, I use international 16, Cruising Mainly Brackish and Salt water, & a CCr until this year, Regularly Drying out on the bottom of the Tide (sometimes on purpose !).

[Phil Ambrose]

My hull is cold galvanized and where bits of blacking have come off all you can see is grey metal so blacking isn't something I think about very often.

Phil

[AndyEd]

I think I'm right in saying that should you cruise through a diesel slick that this will attack the bitumen and fetch it off anyway.

[Keeping Up]

Breaking through ice will also remove the blacking from around the water line.

 

We have ours blacked every 2 years.

[Gordias]

These answers leave me wondering if blacking is a good way to protect narrow boats. It doesn't seem to work all that well; over time it's expensive; and it seems there are a lot of ways it can be removed through normal use.

 

How did it start? It there any reason to prefer it to the kind of paints used on salt-water boats?

 

Clearly canal boats are a lot more likely to bump into stonework and scrape the bottom than a marine boat, but it's hard to see paint as the ideal "sacrificial" solution to that.

Edited November 19, 2014 by Gordias

[Neil2]

I will never do it again, most folk use bitumen and there is so much diesel floating about in the cut these days it is just a waste of money. Those who say every three years might as well not do it at all.

 

Our boat is booked in for grit blasting and zinc coating next Spring.

[John V]

Morning All,

 

In 2007 I used Interzone 954......salt water environment drying out most of the time between tides, It has "chalked" but still in perfect condition apart from a little damaged area on rudder....hopefully will get another few years before needing re-doing. (But it's not a finish for the shiny boater brigade)

[Naughty Cal]

These answers leave me wondering if blacking is a good way to protect narrow boats. It doesn't seem to work all that well; over time it's expensive; and it seems there are a lot of ways it can be removed through normal use.

 

How did it start? It there any reason to prefer it to the kind of paints used on salt-water boats?

 

Clearly canal boats are a lot more likely to bump into stonework and scrape the bottom than a marine boat, but it's hard to see paint as the ideal "sacrificial" solution to that.

We use antifoul paint on our cruiser. We reapply it every year in March but we do high mileage.

 

Depending on the type you can get hard antifoul, semi hard or self eroding. The latter needs applying more often as it erodes off as the boat moves through the water.

 

We use a semi hard paint as the self eroding wasnt lasting us through a year. This year we could have probably gotten away with the self eroding as we have only been in the water for nine months

[Athy]

Those who say every three years might as well not do it at all.

 

 

What an extraordinary statement! Perhaps I should cease mowing my lawns weekly, as in a couple of days the grass will start growing taller again, so I may as well not do it at all.

 

I don't understand the thinking behind what you say.

[cuthound]

My hull is cold galvanized and where bits of blacking have come off all you can see is grey metal so blacking isn't something I think about very often.

Phil

My boat has blacking over "Zinga" cold galvanising. Last blacked in 2012, but looks fine (at least it did when surveyed at the end of May). I touch it up when a bit above the waterline gets scaped. I will next dock the boat in 2016.

 

Does anyone know if Zinga can be over coated with 2 pack, or if not, whether it would still be worth removing the Zinga and replacing with 2 pack?

[Kwacker]

Our boat was freshly blacked when we bought her, reblacked (properly) 5 months later when she was lifted out for a repair, then again a year later as routine, and yet again when she was taken out for a repaint, so that's 4 blackings in 5 years ...... hull should be in good nick I reckon.

Next time she is out though, I'll be looking to use something better than bitumen, as even though most of the blackings were only a year apart, I was not impressed with it's lastability at the waterline as per Neil2 and think 3 years is too long between reblackings

Edited November 19, 2014 by Kwacker

[Neil2]

What an extraordinary statement! Perhaps I should cease mowing my lawns weekly, as in a couple of days the grass will start growing taller again, so I may as well not do it at all.

 

I don't understand the thinking behind what you say.

That's a very strange analogy.

 

Blacking with bitumen probably goes back hundreds of years and I suspect it was conceived originally as a good way of protecting a wooden boat hull. And when most boats worked for a living I reckon they saw the "fragile" nature of bitumen as a distinct advantage, the fact that it can be easily removed, for repairs etc. In my view it was never meant to be a "permanent" coating eg good for three years without attention but I've read so called experts saying it's ok to black the hull every five years.

 

So it's like keeping on top of painting your outside woodwork at home, if you don't do it regularly there's no point as the rot will have already set in.

 

There are plenty of rusty/overplated boats on the network to illustrate this.

[Athy]

That's a very strange analogy.

 

 

I would preferred "original" or "imaginative", but O.K.

When you have blacked the boat the coating is effective for a few months, but then begins to wear off. That id preferable to not blacking at all, in which case the coating will not be effective for a few months, because there won't be one,

 

Better?

Edited November 19, 2014 by Athy

[The Lockie]

I do wonder if all this "2 pack lasts 10years "ect is relevant for canal use. Yes it may last that long, yes it might offer better resistance to diesel. However its still going to get scraped off by that thoughtfully placed supermarket trolley or some other detritus and once that's happened its just like cheap bitumen!! It ain't there anymore and the hull is unprotected. But the owner has the false sense of security that it will last 10 years!!!

 

Ours was out of the water every 2 years, I wanted to see what the hull condition was in that timescale so that potential areas of corrosion could be nipped in the bud.

[Machpoint005]

Every two to three years in our case, but a lot depends on the water you are afloat in -- clean water, no floating diesel, blacking lasts a lot longer.

And the Lockie has it right IMO

[SamKingfisher]

Every two years. Ice completely fecks it, including passing boats, so really it should be done after an icy winter regardless unless the ice remained unbroken and there is no sign of damage.

[Gordias]

Are there any other "defensive" options than blacking, paint, or otherwise treating the surface of the metal? The methods described so far seem remarkably poorly suited to the task of protecting the surface of a narrow boat hull from "kinetic interactions".

Edited November 19, 2014 by Gordias

[cuthound]

Are there any other "defensive" options than blacking, paint, or otherwise treating the surface of the metal? The methods described so far seem remarkably poorly suited to the task of protecting the surface of a narrow boat hull from "kinetic interactions".

Galvanising, either " hot dipped" (a bit impractical for a narrow boat) or "cold painted" offer protection by zinc becoming a sacrificial anode to protect the steel. However the zinc coating is easily damaged in a canal boating environment, hence my question of covering it with a 2 pack epoxy paint (which is much tougher than other types of paint, so should last provided the rubbing strips do their job). Note that most corrosion occurs close to the waterline, due to the high oyxgen levels found there. Usually wear away rather than corrode (at least from the outside in).

 

ETA the missing comma.

Edited November 19, 2014 by cuthound

[Jim Batty]

I do wonder if all this "2 pack lasts 10years "ect is relevant for canal use. Yes it may last that long, yes it might offer better resistance to diesel. However its still going to get scraped off by that thoughtfully placed supermarket trolley or some other detritus and once that's happened its just like cheap bitumen!! It ain't there anymore and the hull is unprotected. But the owner has the false sense of security that it will last 10 years!!!

 

Ours was out of the water every 2 years, I wanted to see what the hull condition was in that timescale so that potential areas of corrosion could be nipped in the bud.

 

Our boat was 2-pack epoxied (Dacrylate) when new. It was five years old when we bought it and the out-of-water and ultrasonic hull survey showed it to be in almost pristine condition.

 

The boat is now coming up to 10 years old. I keep telling myself the 2-pack should be re-done. But every summer, when the water is clear (Thames) and the sun is high I keep looking closely all along and below the waterline ... and I have a couple of places where I have removed any scum/growth from waterline to bottom plate and monitor that ... and have yet to see any sign of corrosion or pitting. (And I know what this looks like because I saw a lot of it when looking around for a boat!) Even the original sacrificial anodes are 2/3 intact.

 

My understanding is (and I am no expert in this area) that the initial 2-pack epoxy application chemically bonds to the shot-blasted steel of the hull. And the second application chemically bonds to the first.

 

Anyway, all will be revealed soon as I hope to have it out of the water next year for 2-packing. The main challenges seems to be 1) finding someone with the proper facilities who is confident/capable of doing the work and, so far impossible down south here, 2) finding someone who has experience with Dacrylate -- as I take it it is important to keep to the same regimen.