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Blacking over 2-pack


NBDensie

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We are due to be inspecting our hull next month for the first time since 2-pack was applied, 5 years ago.  It has been suggested that we black it with normal blacking over the 2-pack to provide extra protection.  It would also be a cosmetic improvement since the 2-pack has faded to battleship grey.

 

Any views as to whether this is a good or bad idea?

 

Many thanks.

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20 minutes ago, NBDensie said:

We are due to be inspecting our hull next month for the first time since 2-pack was applied, 5 years ago.  It has been suggested that we black it with normal blacking over the 2-pack to provide extra protection.  It would also be a cosmetic improvement since the 2-pack has faded to battleship grey.

 

Any views as to whether this is a good or bad idea?

 

Many thanks.

I put another coat of the same two pack above the waterline on my hull last autumn after collecting various scrapes from a summer of locks etc. It seems to have stuck with no issues…as it was in the water it had minimal prep…just a brush off of the dust etc. 

 

Bit of a faff to measure out the right amount of hardener vs coating but some paint measure pots from eBay and some maths saw the job done. 

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Are you thinking of the hull above the waterline?  My guess is that it will stick OK, If it is below the water I really would not. We Use epoxy below the water from new, last time I had it out of the water I used red epoxy below the water (red because it was a bit of a deal) then bitumastic paint above the waterline just to freshen the thing up. Its always had bitumastic above the water. The waterline was not terribly well done but the bitumastic really has not adhered to the epoxy where it strayed to the wet bit. It  is just coming away in big flakes, funnily enough the epoxy has adhered perfectly well to the old bitumastic so far as I can see. I would stick to epoxy below the water and some sort of black goo above. By the way, don't be tempted to use black gloss above the waterline. I did and it showed every contact with anything tougher than a thistle. Awful mess. 

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5 hours ago, NBDensie said:

We are due to be inspecting our hull next month for the first time since 2-pack was applied, 5 years ago.  It has been suggested that we black it with normal blacking over the 2-pack to provide extra protection.  It would also be a cosmetic improvement since the 2-pack has faded to battleship grey.

 

Any views as to whether this is a good or bad idea?

 

Many thanks.

Bad idea.

A properly prepped hull, originally can be corrosion for nigh on twenty years, as mine was.

Mine is still black two years after I applied jotamastic 90 with three coats In perfect conditions..

If it Grey's just clean , de grease, re coat.

Bitumen is from the seventeenth century

Edited by LadyG
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53 minutes ago, Bee said:

Are you thinking of the hull above the waterline?  My guess is that it will stick OK, If it is below the water I really would not. We Use epoxy below the water from new, last time I had it out of the water I used red epoxy below the water (red because it was a bit of a deal) then bitumastic paint above the waterline just to freshen the thing up. Its always had bitumastic above the water. The waterline was not terribly well done but the bitumastic really has not adhered to the epoxy where it strayed to the wet bit. It  is just coming away in big flakes, funnily enough the epoxy has adhered perfectly well to the old bitumastic so far as I can see. I would stick to epoxy below the water and some sort of black goo above. By the way, don't be tempted to use black gloss above the waterline. I did and it showed every contact with anything tougher than a thistle. Awful mess. 

Maybe you never left the epoxy long enough to dry as with the drying process it is still releasing vapours, maybe it wasn’t fully cured so the bitumin wouldn’t adhere.

Edited by PD1964
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Some epoxy’s don’t like the sun and go grey. Some don’t like water but love the sun. If you make sure you use the correct material then you can paint 2 pack over 2 pack, provided you prepare it correctly. 
if you go over the top with bitumen then you’ll not be able to revolt with 2 pack unless you go back to bare steel. 
There really is not a great deal of difference between 2 pack and bitumen when you take into account the cost of docking and effort preparing and painting. 

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5 hours ago, LadyG said:

Bad idea.

A properly prepped hull, originally can be corrosion for nigh on twenty years, as mine was.

Mine is still black two years after I applied jotamastic 90 with three coats In perfect conditions..

If it Grey's just clean , de grease, re coat.

Bitumen is from the seventeenth century

 

Jotamastic is subject to chalking from UV light which means it turns grey. It doesn't affect the paints other properties. I thought that was also the case with Jotamastic 90. If yours is still black after 2 years I'm not sure why. Perhaps you have Jotun Hardtop over the Jotamastic 90?

 

Actually, if you're re-coating any epoxy with itself after the maximum overcoating time has expired (typically a couple of months) then the existing coating will need thorough abrading, not just cleaning.

Edited by blackrose
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4 hours ago, Old Son said:

 There really is not a great deal of difference between 2 pack and bitumen when you take into account the cost of docking and effort preparing and painting. 

 

A properly prepped and epoxied hull should last 10 years. That's at least 3 dockings/bitumen applications. But the other factor which you might not have considered is hull condition. Bitumened hulls can deteriorate even if they are regularly blacked every 3 years. Diesel spills can take bitumen off around the waterline and UV deterioration starts straight away. 

 

In general I agree with you, if you regularly dock and black your boat it will be fine, but after 7 years in the water my 17 year old hull is still looking brand new and I didn't even need to come out this time. My epoxy would have lasted another 3 years 

Edited by blackrose
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My previous boat was blacked with 2-pack. The recommended interval for lifting the boat out the water and inspecting the underwater components was STILL the same, so there's no longevity saving there, since the main cost of blacking is lifting (or dry docking) and putting back into the water however you choose to do it. Also it is said to be more brittle than bitumen based blacking, so not quite as suitable for canal lock use. If the boat is mainly static/moored, then that aspect is weaker though. And finally, its more expensive. Its not really any more difficult to apply, mixing in the right proportion is simple.

 

Having said that, the hull was in exceedingly good condition with almost no corrosion for a 20 year old boat, so it had obviously done something to help this.

 

So its kinda dependent on how you (plan to) use the boat. Lots of use and cruising - bitumen based and yearly blackings. Little/no use except moored - 2 pack and maybe stretch out the dockings/liftings to make it pay.

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9 hours ago, Paul C said:

My previous boat was blacked with 2-pack. The recommended interval for lifting the boat out the water and inspecting the underwater components was STILL the same, so there's no longevity saving there, since the main cost of blacking is lifting (or dry docking) and putting back into the water however you choose to do it. Also it is said to be more brittle than bitumen based blacking, so not quite as suitable for canal lock use. If the boat is mainly static/moored, then that aspect is weaker though. And finally, its more expensive. Its not really any more difficult to apply, mixing in the right proportion is simple.

 

Having said that, the hull was in exceedingly good condition with almost no corrosion for a 20 year old boat, so it had obviously done something to help this.

 

So its kinda dependent on how you (plan to) use the boat. Lots of use and cruising - bitumen based and yearly blackings. Little/no use except moored - 2 pack and maybe stretch out the dockings/liftings to make it pay.

I disagree. We use our boat a lot for cruising and locks. We had it 2-packed in 2011. We took it out of the water in 2016 for a look, having cleaned it off you couldn’t see where the waterline was and there was no significant corrosion. Obviously the rubbing strakes get a bit of wear but corrosion was minimal. We gave it one recoat of 2pack. That’s the last time we took it out of the water, there is still no significant rust anywhere, and certainly nothing at the waterline. We were on the Thames recently and could see the absence of rust below the waterline. It’s probably due out again if only to check the anodes.

 

So I would say it is vastly superior to bitumen regardless of whether you use the boat or not, and of course one of the many issues with bitumen is that it can be adhered rather badly and retain water behind it. Whereas epoxy is properly bonded to the hull and doesn’t do that. So many bitumen blacked boats have exfoliating rust at the waterline, why would you do that?

  • Greenie 1
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The days of bitumen really should be over - at least for beneath the waterline, its a sort of marine version of creosote and is banned in most of Europe because of its toxicity, I still use it above the waterline but that is mainly because of habit and I still have some tins left. If you were responsible for an oil rig, a tanker or any sort of massively expensive steel structure in fresh or salt water or even out of water such as the recently repainted Iron bridge just down the road from us you would not even consider using bitumen for protecting it. For years narrowboats got off to a really bad start in life by having one very thin coat of 'blacking' sprayed on by the builder - and probably nothing at all underneath, some of the poor condition of relatively young boats can probably be traced back to the first day in the water. 

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51 minutes ago, nicknorman said:

It’s probably due out again if only to check the anodes.

 

Book into Liverpool - the water is so clear you can do a hull inspection from the jetties either side.  It's also brackish so tends to kill off any weed growth.

 

The fact the run through the docks is one of my favourite journeys on the inland waterways doesn't hurt either.

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22 minutes ago, TheBiscuits said:

 

Book into Liverpool - the water is so clear you can do a hull inspection from the jetties either side.  It's also brackish so tends to kill off any weed growth.

 

The fact the run through the docks is one of my favourite journeys on the inland waterways doesn't hurt either.

I'm not sure if I can get through to Liverpool, I'm on the Calder and Hebble, and finding these locks pretty tough, Im beginning to think it's part of CRT strategy, to get rid of the old gits who have nothing better to do than moan about the state of the locks, the grass cutting, and more. Leave the boating to young, fit and well heeled boaters who keep their boats in marinas and venture out a few weeks in summer.

Edited by LadyG
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I don't think there's ever been a neat and tidy solution for boaters who physically can't operate locks, etc especially if single handing. It is, by its nature, a manual task that requires a level of strength and agility, what with the structures being historic and not adaptable to the less able.

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4 minutes ago, Paul C said:

I don't think there's ever been a neat and tidy solution for boaters who physically can't operate locks, etc especially if single handing. It is, by its nature, a manual task that requires a level of strength and agility, what with the structures being historic and not adaptable to the less able.


You can help yourself though by using your freedom to venture to easier canals to navigate.

 

The Coventry, Ashby, north Oxford area is an obvious case in point but I’ve previously directly suggested to @LadyG that she would likely find the narrow canals of the Midlands a lot easier than she apparently finds the northern canals.

 

She may have reasons for wanting to be further north and that’s her business.

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Yes I m heading S, but I have family up here, and I still need to operate locks as I transit, of course.

Also stayed on the L and L for a while as it is so scenic, plus some local attractions, museums, art galleries etc.

I can get though the locks, it takes time and there is not much enjoyment. I don't have any problem with some of the smaller locks. I know some people like locking thru at a rate of knots, but I don't really see any reason to do dozens of locks in a day, what's the point? If I wanted speed I'd go by car. I did find narrowboating frustratingly slow and boring at first, which, compared to sailing it is, but I've settled in to the slowness of it all.

Last year,'s summer cruise was to Lincoln, I really enjoyed it, Boston , not so much.

So this year's cruise to Hebden Bridge has been stopped in its tracks. By the time I get to Sowerby Bridge, it might be my winter excursion!

Edited by LadyG
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