Rust at waterline

[Phil1884]

Hi there,

 

I'm aware this is a common issue given the constant exposure to air and moisture, however, I was a little surprised to see this happening in a few areas around the waterline given that my boat is only 16 months old. There could be many reasons, electrolytic corrosion, mill scale flaking off from underneath, abrasion etc, however, the anodes seem OK and I'm rarely on the shore line, in any case, I have a galvanic isolator.

 

My plan was always to get it re-blacked at two years so has anyone got any recommendations on what to do in the mean time? I've heared about using Fertan whilst others have simply suggested coating with some more bitumastic.

 

I've attached some photos

 

Thanks

 

Phil

[alan_fincher]

It is often hard to tell from photos, but I would say that if your boat is only 16 months old from new, it rather looks as if your builder may have scrimped considerably on blacking it in the first place.

 

However, unless you can get it out of water, or have some clever ruse for beaching or tilting the boat to bring the exposed part much above waterline, I can see very little you can do about it until it is next pulled out for a proper blacking.

 

Edited to add:

 

The fact that you appear to have rust running down from the bottom of a "guard", (often called "strakes"), would also seem to indicate they are not continuously welded at the bottom edge. That is not hugely unusual, but is a way builders cut down on build costs. When it is blacked you would do well to try and brush it well into obvious gaps.

Edited October 5, 2015 by alan_fincher

[Guest]

It is often hard to tell from photos, but I would say that if your boat is only 16 months old from new, it rather looks as if your builder may have scrimped considerably on blacking it in the first place.

 

However, unless you can get it out of water, or have some clever ruse for beaching or tilting the boat to bring the exposed part much above waterline, I can see very little you can do about it until it is next pulled out for a proper blacking.

Happened on my boat. We hauled it and re-blacked it. The original blacking was very thin.

[BEngo]

The cut these days has so much diesel floating on the surface that no bitumen blacking is going to last very long. Yours looks typical ( wot Alan said too) and like all rust is worse than it looks. Either careen the boat (tilt it so the waterline is clear of the water, using a rope from the top ring or other handy roof fitting) or bring your next out-of water experience forward. In either case attack the waterline rust with an angle grinder and wire brush, then re-black.

 

 

Trouble is it's really the wrong time of year for blacking and it will be slow to set, even on a dry day.

 

Long term grit blast and epoxy pitch or chlorinated rubber is the way to go. The grit blasting pays for itself because you save on docking cycles- every four-five years instead of every two. Epoxy/CR is not much if any dearer than the fancy modified bitumens.

 

N

[Guest]

The cut these days has so much diesel floating on the surface that no bitumen blacking is going to last very long. Yours looks typical ( wot Alan said too) and like all rust is worse than it looks. Either careen the boat (tilt it so the waterline is clear of the water, using a rope from the top ring or other handy roof fitting) or bring your next out-of water experience forward. In either case attack the waterline rust with an angle grinder and wire brush, then re-black.

 

 

Trouble is it's really the wrong time of year for blacking and it will be slow to set, even on a dry day.

 

Long term grit blast and epoxy pitch or chlorinated rubber is the way to go. The grit blasting pays for itself because you save on docking cycles- every four-five years instead of every two. Epoxy/CR is not much if any dearer than the fancy modified bitumens.

 

N

That is what we did when the boat was ten years old. No regrets. Epoxy is so much more hard wearing.

[Phil1884]

I wouldn't be surprised if a very thin coat had been used. I'm seriously considering going for the two pack epoxy next time, shame everything has to be removed first!

 

I think I'll attack it and remove what I can then treat with bitumin, and aim to get it re-blacked eraly next year, just too busy with work to take time off to cruise it for 5 hours to the nearest yard that'll do it. It's only very recently that I have noticed the rust (I don't get down to visit it very often these days)!

[Guest]

I wouldn't be surprised if a very thin coat had been used. I'm seriously considering going for the two pack epoxy next time, shame everything has to be removed first!

 

I think I'll attack it and remove what I can then treat with bitumin, and aim to get it re-blacked eraly next year, just too busy with work to take time off to cruise it for 5 hours to the nearest yard that'll do it. It's only very recently that I have noticed the rust (I don't get down to visit it very often these days)!

As has been said, it normally looks far worse than it is.

The beauty of blasting is it really cleans everything up and takes off the millscale. I regret not expoxying the boat from being new.

[craftycarper]

I wouldn't be surprised if a very thin coat had been used. I'm seriously considering going for the two pack epoxy next time, shame everything has to be removed first!

 

I think I'll attack it and remove what I can then treat with bitumin, and aim to get it re-blacked eraly next year, just too busy with work to take time off to cruise it for 5 hours to the nearest yard that'll do it. It's only very recently that I have noticed the rust (I don't get down to visit it very often these days)!

put a ratchet strap over the boat and tie it to a strong fixing, ie ring, mushroom or something simular, as you pull it tight it will tilt your boat over clean it and re bitumin it then turn it around and do the other side, a dinghy is ideal if you have one

[ditchcrawler]

 

 

I think I'll attack it and remove what I can then treat with bitumin, and aim to get it re-blacked eraly next year, just too busy with work to take time off to cruise it for 5 hours to the nearest yard that'll do it. It's only very recently that I have noticed the rust (I don't get down to visit it very often these days)!

In that case I wouldn't worry about it, a few months will make very little difference especially as you are unlikely to get the steel fully dry and the paint dry while the boat is in the water this time of the year.

[blackrose]

I always say when you start to see rust on the waterline you've got another year to get it out of the water.

[peterboat]

i think i would have a word with the builder 16 months should last longer

[blackrose]

I'm not sure why anyone having a boat built would have it blacked with bitumen? No criticism implied - I did it myself! It's more a criticism of builders doing things on the cheap.

[Bloomsberry]

The rust lines are parallel to the waterline so think it is safe to suggest that diesel on the water surface is the culprit with bitumen the original blacking. Is it kept in a marina ?

 

I've had my boat blacked 3 times since ownership, twice by boatyards and once myself and each time it has had rust at the waterline within a year.

 

It's expoxy for me next time.

[PeterG]

I agree diesel and bitumen do not like each other at all, you can see the bitumen disolve before your eyes.

[nicknorman]

The original blacking on our new boat didn't last very long. It hadn't been blasted and so I suspect the mill scale didn't help, plus there was paint primer under the bitumen which I don't think was a good idea. We had it blasted and 2-pac epoxied at around 18 months old and it is still good after another 2.5 years of hard use. Yes the epoxy on the strakes gets scraped off a bit in locks etc but it is much more hard wearing than bitumen and well attached. There is no rust at all around the water line, the coating there is good as new.

 

It was a bit expensive, but in the context of a new boat, well worth it.

Edited October 6, 2015 by nicknorman

[cuthound]

The original blacking on our new boat didn't last very long. It hadn't been blasted and so I suspect the mill scale didn't help, plus there was paint primer under the bitumen which I don't think was a good idea. We had it blasted and 2-pac epoxied at around 18 months old and it is still good after another 2.5 years of hard use. Yes the epoxy on the strakes gets scraped off a bit in locks etc but it is much more hard wearing than bitumen and well attached. There is no rust at all around the water line, the coating there is good as new.It was a bit expensive, but in the context of a new boat, well worth it.

Who did the shot blasting and 2 packing Nick?

[Bee]

Can't disagree with much that's been said but it looks like old fashioned rust and not electrolytic stuff. Nothing to panic about but builders really should not be using bitumen in this day and age.

[nicknorman]

Who did the shot blasting and 2 packing Nick?

Aqueduct Marina on the Middlewich branch. They are pretty expensive but have good facilities and did a good job, although of course we then picked it up and did the Llangollen which is perhaps not the best way to treat brand new expensive blacking!

 

I struggled to find somewhere more local, Streethay would only do it with a needle gun (didn't like the sound of that) and CTS at Norton Canes had a long waiting list. The boatyard at the A5 aqueduct at the bottom of the Shroppie (can't remember the name) were approached and would have been much cheaper but they were not good at communicating and in the end I went with Aqueduct who run a slick (but expensive) operation.

[cuthound]

Aqueduct Marina on the Middlewich branch. They are pretty expensive but have good facilities and did a good job, although of course we then picked it up and did the Llangollen which is perhaps not the best way to treat brand new expensive blacking!I struggled to find somewhere more local, Streethay would only do it with a needle gun (didn't like the sound of that) and CTS at Norton Canes had a long waiting list. The boatyard at the A5 aqueduct at the bottom of the Shroppie (can't remember the name) were approached and would have been much cheaper but they were not good at communicating and in the end I went with Aqueduct who run a slick (but expensive) operation.

Thanks Nick,

 

Hopefully Norton Canes waiting lists may shorten now they have a presence at Glascote Basin as well as NC.

[nicknorman]

Thanks Nick,

 

Hopefully Norton Canes waiting lists may shorten now they have a presence at Glascote Basin as well as NC.

It was CTS (Canal Transport Services) which, as I understand it, is not the same as Norton Canes Boatbuilders although they are adjacent. Steve was unable to do blasting at Glascote - he tried it once but apparently there were a lot of complaints about the dust and it got closed down by the council.

[cuthound]

It was CTS (Canal Transport Services) which, as I understand it, is not the same as Norton Canes Boatbuilders although they are adjacent. Steve was unable to do blasting at Glascote - he tried it once but apparently there were a lot of complaints about the dust and it got closed down by the council.

On well, looks like I'll have to look further afield when DQ needs reblacking. It is comastic over 2 pack over Zinga, so maybe the domestic can be pressure washed off, the 2 pack abraded and more 2 pack (black, not grey this time) applied.

 

Doesn't need doing yet, but probably will in the next couple of years, so I will have time to look around.

[Phil1884]

Hello!

 

Thanks for the replies, I only get to look at them on my lunch and after work. I'm not sure if my photos make it look worse as this is only on one side and the section is probably 3 feet in total.

 

So I'm looking at the two-pack epoxy option but this will mean getting it shot-blasted. I'm on the Kenent&Avon by saltford, I'm aware of a few yards but if anyone knows anywhere on that stretch that will undertake shot blasting then I'd be grateful to hear.

 

I'm familiar with the costs of getting a standard coat of bitumin but how much would the shot blasting involve bearing in mind we're only talking about a 25 ft narrowboat here?

 

Thanks again

 

Phil

[Bloomsberry]

The nearest boatyard to me that does shotblasting is a fair cruise away so I'm going to have a crack at diy epoxy.

 

As the area compromised is the waterline, I'm going to clear the area with a terco blaster (which is supposed to be as good as shotblasting apparently) then expoxy over. If there are any suspect areas below the waterline then I'll probably do the same to them. If I have time I may even do the welding seams to be on the safe side.

 

i'll take the boat out of the water in 2 years time to check on the progress and report my findings.

 

BTW I have no interest in colour matching, as long as it stops the hull corroding I'll be happy,

[alan_fincher]

Steve was unable to do blasting at Glascote - he tried it once but apparently there were a lot of complaints about the dust and it got closed down by the council.

 

It's good the "rivets" can withstand this treatment. I have visions of near bystanders being showered by rusty washers with bits of weld attached.

 

(Sorry!, I've been good for months, and months, and months, but couldn't resist this time - and you did have a major go about unreliable 1930s crappy old diesels with near zero oil pressure the other day, didn't you!!!...........................)

[Dalslandia]

If you used Jotun Jotamastic from start it would not happen, not in 10-20 years. How do I know?