Debdale Wharf Molten Zinc Hull Spraying

[jddevel]

Anyone have personal experience of Molten Zinc Hull Spraying by Debdale Wharf. Is it really worth it please. Although booked in I`m now having reservations regarding its value. I anticipate keeping the boat for probably no more than another 5/6 years. It was a new hull 2016.

[mrsmelly]

9 minutes ago, jddevel said:

Anyone have personal experience of Molten Zinc Hull Spraying by Debdale Wharf. Is it really worth it please. Although booked in I`m now having reservations regarding its value. I anticipate keeping the boat for probably no more than another 5/6 years. It was a new hull 2016.

My hull, a colecraft is now eleven years old. When it was out and blacked at a forum members boatyard this year he remarked at how good the condition of the hull is. Its virtualy " As new " no sign of pitting etc etc. Make of that what you will. Edited to add that its just had the usual basic bitumastic stuff over the years.

Edited December 16, 2018 by mrsmelly

[Robbo]

20 minutes ago, jddevel said:

I anticipate keeping the boat for probably no more than another 5/6 years

I think you’ve already given yourself the answer.

[Alan de Enfield]

29 minutes ago, jddevel said:

Anyone have personal experience of Molten Zinc Hull Spraying by Debdale Wharf. Is it really worth it please. Although booked in I`m now having reservations regarding its value. I anticipate keeping the boat for probably no more than another 5/6 years. It was a new hull 2016.

I am yet to be convinced as to the usefulness of Zinc coating as a rust-protector on boat hulls.

 

My thinking :

 

Zinc is used as an Anode on salt-water boats as it erodes whilst giving Cathodic protection. Whilst we normally use Magnesium anodes on Fresh-Water boats, Zinc will still 'perform' the anodic function but at a slower rate than Magnesium.

 

So, why cover you boat in something that is going to erode, when what you actually want is for it to give maximum coverage for rust prevention ?

 

Alternative views and explanations welcomed.

[jddevel]

My problem is/was that obviously with such a big investment I`m naturally looking to protect it as much as possible. It`s a conundrum - try and retain its value as much as possible or just accept that it`s going to de-value what ever one does just possibly make it easier to sell against those without that preparation. I must confess that if one reviews the property and say collector car market people pay ridiculous prices for things requiring "total renovation" spending more than the finished article is worth. 

[OldGoat]

 In my humble (not) and most likely untutored opinion, the only useful zinc process is electroplating.  Hot dip and painting is not particularly effective long term. You need a chemical  bond.

[rusty69]

2 minutes ago, Alan de Enfield said:

 

Zinc is used as an Anode on salt-water boats as it erodes whilst giving Cathodic protection

I notice they are trying to push Aluminium anodes as a more cost effective alternative these days.

[Alan de Enfield]

11 minutes ago, rusty69 said:

I notice they are trying to push Aluminium anodes as a more cost effective alternative these days.

Aluminium Alloys have always been recommended for 'brackish' water as the 'best of both worlds' but when you look at the table pure Aluminium is not as effective as either Zinc or Magnesium.

 

The theory is that you need the greatest possible 'distance' between your metals so the 'best protection' would be Gold with Magnesium anodes., one of 'worst' protections would be (example) a Mild steel boat hull with Aluminium anodes. as they are next to each other on the scale.

 

 

Edited December 16, 2018 by Alan de Enfield

[MtB]

12 minutes ago, jddevel said:

My problem is/was that obviously with such a big investment I`m naturally looking to protect it as much as possible.

 

Point of Order.....

 

A boat is not an investment in the dictionary sense of the word. An investment is an asset used to protect and grow the value of your money. A boat is the opposite, a money pit which will sorely disappoint you.

 

If you want to protect the value of your money buy some shares or property, I suggest. 

[Phil.]

49 minutes ago, jddevel said:

Anyone have personal experience of Molten Zinc Hull Spraying by Debdale Wharf. Is it really worth it please. Although booked in I`m now having reservations regarding its value. I anticipate keeping the boat for probably no more than another 5/6 years. It was a new hull 2016.

We had it done three years ago and our hull is as clean as a whistle. Bear in mind that if you are keeping the boat another six years, then you have at least two, possibly three blacking sessions ahead, so deduct the cost of those from your overall cost. It won't add value, but when you sell, it will probably mean your less likely to get huge chunks shaved off the asking price. You also don't know what the future holds, in six years, you may decide to keep boat a little longer, in which case it will definitely be worth it.

[blackrose]

41 minutes ago, mrsmelly said:

My hull, a colecraft is now eleven years old. When it was out and blacked at a forum members boatyard this year he remarked at how good the condition of the hull is. Its virtualy " As new " no sign of pitting etc etc. Make of that what you will. Edited to add that its just had the usual basic bitumastic stuff over the years.

 

I don't think anyone's ever said that ordinary bitumen doesn't do the job, it's just that it has to be done regularly and frequently compared to more advanced paint systems.

 

My Liverpool boat is was last lifted out at Evesham 3 years ago when it was 12 years old and the guys in the yard all commented on how good the hull looked. Up until a year earlier I'd only used bitumen based paint, but decided to get that all blasted off and I repainted with 4 coats of epoxy because I wanted to extend the time between painting. That was 3 years ago and I'm not expecting to have to do it again for another 5 or 6. 

[blackrose]

29 minutes ago, Alan de Enfield said:

I am yet to be convinced as to the usefulness of Zinc coating as a rust-protector on boat hulls.

 

My thinking :

 

Zinc is used as an Anode on salt-water boats as it erodes whilst giving Cathodic protection. Whilst we normally use Magnesium anodes on Fresh-Water boats, Zinc will still 'perform' the anodic function but at a slower rate than Magnesium.

 

So, why cover you boat in something that is going to erode, when what you actually want is for it to give maximum coverage for rust prevention ?

 

Alternative views and explanations welcomed.

 

I've always wondered about that too when people talk about Zinga, but I've never managed to get a satisfactory answer.

[MtB]

5 minutes ago, blackrose said:

 

I've always wondered about that too when people talk about Zinga, but I've never managed to get a satisfactory answer.

 

I suspect the answer is that coating steel in zinc, known as galvanising, is a recognised and very standard method of surface protection for steel. Farm gates, fencing wire, steel components in the building industry are routinely galvanised for rust protection because it works. Why not do it to a boat too? 

[Captain Pegg]

There is an important distinction between hot dip galvanising and hot spray which is routinely overlooked in these discussions.

 

Hot dip galvanising is done at a temperature in excess of twice the melting point of zinc and provides a chemical bond between the parent metal and the protective layer. Obviously it's a process that is limited to smaller components.

 

Hot spray is heated sufficiently so it can be sprayed but it gives a mechanical bond and the highly zinc rich nature of the paint means it lacks some of the binding properties of a more conventional paint. For that reason hot sprayed coatings have limitations in industrial use as the benefits aren't always worth the price.

 

Personally if I wanted to protect a hull for 5/6 years in one go I think a two-pack epoxy is probably the safest bet from a cost versus performance point of view.

 

JP

Edited December 16, 2018 by Captain Pegg

[blackrose]

20 minutes ago, Mike the Boilerman said:

 

I suspect the answer is that coating steel in zinc, known as galvanising, is a recognised and very standard method of surface protection for steel. Farm gates, fencing wire, steel components in the building industry are routinely galvanised for rust protection because it works. Why not do it to a boat too? 

 

Because unlike the items you mentioned a boat is immersed in water where galvanic action occurs between dissimilar metals and zinc is routinely used for its anodic properties.

 

As Alan asked in post 4.   "why cover your boat in something that is going to erode"?

 

Also, judging by the post above I'm not sure we're talking about galvanising here?

Edited December 16, 2018 by blackrose

[Mike Adams]

I had my whoe hull blasted to shiny steel, zinc sprayed and 2 pack coated at debdale 3 years ago. The results were excellent even if you scrape a bit of paint off the zinc stops it rusting. My hull is 85 years old so I am hoping it will last a bit longer! Although it is expensive, nothing reduces the value more than a bad hull and you save time and money in the long run. I can recommend Debdale- a real proffesional job.

[Captain Pegg]

27 minutes ago, blackrose said:

 

Because unlike the items you mentioned a boat is immersed in water where galvanic action occurs between dissimilar metals and zinc is routinely used for its anodic properties.

 

As Alan asked in post 4.   "why cover your boat in something that is going to erode"?

Because it prevents the thing you are protecting from eroding. All coatings have a shelf life. Not a massively relevant question.

 

JP

Edited December 16, 2018 by Captain Pegg

[blackrose]

4 minutes ago, Captain Pegg said:

Because it prevents the thing you are protecting from eroding. All coatings have a shelf life. Not a massive relevant question.

 

JP

But why wouldn't you just use a hard-wearing coating that doesn't erode itself? All coatings have a shelf-life but some are longer than others so surely it is relevant.

 

Anyway, personally I don't think I want a sacrifical coating on my hull.

Edited December 16, 2018 by blackrose

[matty40s]

7 minutes ago, blackrose said:

But why wouldn't you just use a hard-wearing coating that doesn't erode itself?

They do, they tend to 2 pack over the zinc.

[Captain Pegg]

9 minutes ago, blackrose said:

But why wouldn't you just use a hard-wearing coating that doesn't erode itself? All coatings have a shelf-life but some are longer than others so surely it is relevant.

 

Anyway, personally I don't think I want a sacrifical coating on my hull.

All coatings are sacrificial, just by different mechanisms. That's why they all have a shelf life. It's a personal choice as to what method and unless we want to apply some science above primary school level we will never know for certain which is best.

 

I already answered your question above in my first response to the original question. That coating will still degrade though.

 

JP

[dmr]

1 hour ago, OldGoat said:

 In my humble (not) and most likely untutored opinion, the only useful zinc process is electroplating.  Hot dip and painting is not particularly effective long term. You need a chemical  bond.

 

Surely hot dip and hot spraying do give some chemical bonding, or at least a local alloy, whilst electroplating is just very good painting, and Zinga and Galvafroid etc are just ordinary painting?.   There are a couple of good technical articles on the www, that suggest the alloy at the zinc-steel interface after hot dip galvanising is harder then the steel itself.

 

I am quite tempted by the hot spraying, especially as the boat is approaching middle age, but its a bit costly. I know a lot will get scraped off but what remains should provide some protection. I have seen some hot dip galvanising where the zinc comes off in sheets leaving trapped water behind it, but that's probably not an issue underwater, and should not happen if done well?

 

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

[Alan de Enfield]

40 minutes ago, Mike the Boilerman said:

 

I suspect the answer is that coating steel in zinc, known as galvanising, is a recognised and very standard method of surface protection for steel. Farm gates, fencing wire, steel components in the building industry are routinely galvanised for rust protection because it works. Why not do it to a boat too? 

Galvanised gates and construction items are rarely submerged and have loads of 'loose electrical worms floating around them' - Galvanising on gates is not for cathodic protection simply 'rust' protection from casual 'wettings' in the rain.

 

When I used to supply stainless steel components to the oil industry (for cable fixing) there were huge problems (particularly in hot, dry desert countries) with galvanised cable tray just falling into dust. In the North Sea the biggest problem with Galvanised cable tray was in the Splash Zone.

Edited December 16, 2018 by Alan de Enfield

[Tacet]

1 hour ago, Alan de Enfield said:

So, why cover you boat in something that is going to erode, when what you actually want is for it to give maximum coverage for rust prevention ?

 

Because it is the boat you wish to protect and not the covering.  Same as wearing a hat, even though it will get wet because its raining.

 

With a sacrificial anode, such as galvanising, it does not need to be completely intact to do its job, unlike a paint.  Whether spraying hot zinc (or sort of zinc) on to a cold steel surface offers a similar electrical bonding to an electro-plating or hot-dip, I don't know.  But hot-dip is more frequently used for appropriately sized objects.......

[Alan de Enfield]

2 minutes ago, Tacet said:

Because it is the boat you wish to protect and not the covering.  Same as wearing a hat, even though it will get wet because its raining.

If folks tell me that they are using the Zinc coating as an eroding anode, I can live with that (but in Fresh water a mag coating would be more effective)

But - that is not what they are saying - they use it as an alternative to paint to stop corrosion/rusting of the hull

[MtB]

2 minutes ago, Tacet said:

Because it is the boat you wish to protect and not the covering.  Same as wearing a hat, even though it will get wet because its raining.

 

With a sacrificial anode, such as galvanising, it does not need to be completely intact to do its job, unlike a paint.  Whether spraying hot zinc (or sort of zinc) on to a cold steel surface offers a similar electrical bonding to an electro-plating or hot-dip, I don't know.  But hot-dip is more frequently used for appropriately sized objects.......

 

I don't presume to speak for Alan but I think you have missed a point. Using your hat analogy if the hat gets worn out from getting wet you just get another hat. Same with sacrificial anodes. With zinc coating on a boat, if the coating gets sacrificially eroded you are stuffed and back to blacking or another high cost coating. Daft when the coating is a electrically less noble metal we KNOW is gonna erode.