Blacking A Narrow Boat – What’s All That About?
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Tue Jan 7, 2014 at 1:38pm

Why Do We Black The Hull?

The Basics – The hull is blacked to protect the bottom section of the boat, so specifically the area of the boat that is in the water and just above the water line. The “blacking” process protects the hull from rust, pitting, rubbing (through locks, other boats, banks etc) and generally extends the life of the hull.

Part and parcel of owning a narrow boat means that you need to carry out certain maintenance jobs and blacking is among one of those jobs.  Some maintenance work you will be able to do yourself, however blacking your narrow boat can be quite time consuming and something that you may not want to do yourself after reading this blog.

The boat will need to be out of the water for the blacking process to take place and there are three different ways that are actually used to get the boat out of the water. 

  • Dry dock, where the boat is floated into a chamber and then the water is removed.
  • Craning the boat out but this can be expensive. 
  • Slipway trailer, which is where the boat is put onto a trailer and a tractor pulls the boat out the water. This is the most cost effective and popular choice.

Types Of Coatings

There are two types of coatings that can be used to black the hull, Bituminous and Two Pack Epoxy. Epoxy paint is more expensive but it will last 5 – 6 years once applied and a Bitumen finished coating will last around 2 – 3 years.

If your boat is already coated with Bitumen you are unable to put Two Pack Epoxy over the top, you will need to get the hull “shot blasted” which means stripping everything back to the bare steel. This is a very expensive process and needs to be carried out by a specialised company.

A quick and easy way to check which coating is on the hull is to soak a cloth in white spirit and rub the paint, if the residue is transferred to the cloth it is more than likely to be Bitumen. Whoever undertakes the blacking process will check this for you before they quote and start the process.

The blacking process needs to be carried out on a dry day as the paint will not dry if applied in the wet and also will not stick if the temperature is too cold. Other than that the job can be done at any time.

Three Day Process Explained

Day One;
The Boat is pulled out of the water and pressure washed to remove the old blacking and debris like weeds, mud, and rust. This prepares the hull for the new application. You can also ask for a “scrubbler service” which is a machine used to pay extra attention to the water line area of the hull. Most companies will charge extra for this, so if required be prepared to pay the additional cost.

The boat is taken out of the water and the hull is pressure washed

Day Two
; The hull is now ready for painting and this has to be done manually with a small roller, the reason behind this slow manual process is the paint goes hard very quickly so it has to be applied in small sections.
The hull is ready for blacking

Day Three
; Repeat day two! The second coat gets applied and if required you can ask for an additional coat around the waterline (this may incur an additional cost). The boat is then left to dry before it is returned to the water.

The blacking is applied

Watch our You Tube videos for more information:

I think after you have watched the videos you will agree that blacking a narrow boat is not a DIY job.



John Forbes | Sat May 3, 2014 at 6:28pm
I am not sure many people would agree with you that two-pack epoxy can be applied over blacking. It should always be applied over bare steel, and if done that way, should last a lot longer than 6 years.
Whilton Sales Team | Tue May 6, 2014 at 3:07pm
Thanks for spotting that one! It's a mistake on the blog and we will amend that now. Woops, proves we are human!
megan | Thu Jul 3, 2014 at 4:07pm
Will any standard hardware store bitumen paint do...sika or the likes... or is it a special type we need to look out for?
Whilton Marina | Wed Jul 9, 2014 at 3:59pm
Make sure that the bitumen is suitable for blacking a narrowboat hull, Whilton Marina Chandlery sell it. see their website
Andrew Porteous | Wed Jul 16, 2014 at 5:37pm
Thank you Really enjoyed it.
Camille | Tue Oct 6, 2015 at 2:10am
Does the base of the boat need to be blacked?
Whilton Marina | Mon Oct 26, 2015 at 1:06pm
Yes the base & sides of the boat hull need blacking to protect the hull from corrosion.
Juliet Markland | Thu Nov 26, 2015 at 12:48pm
Could you send me a list of prices for undertaking blacking a 54 foot narrow boat Regards, Juliet Markland
Steven Austin-Vautier | Sat Nov 28, 2015 at 9:43pm
A useful article. We are considering 2-pack but cannot find a boat year that does it owing to the health and safety requirements. Any advice would be appreciated.
John Langford | Thu Dec 10, 2015 at 9:13pm
Never owned a boat but seriously thinking about it. Just one question at the moment- exactly how thick is the hull of a narrowboat? and does it depend on when it was built?
Whilton Marina | Mon Dec 14, 2015 at 4:44pm
Hello John - the thickness of a modern narrowboat is usually 10mm, however some older boats such as Springer narrowboats were built with thinner hulls.
Whilton Marina | Tue Dec 15, 2015 at 3:34pm
In response to Steven Austin-Vautier's question above regarding health & safety in relation to Two Pack Epoxy narrowboat blacking above. We contacted Steven who clarified that "It was the issue of fumes and having to wear special gear which many boat yards can't be doing with because of a Health and Safety issue" We understand that there are H&S procedures to follow when applying 2 Pack Epoxy hull coatings which may sometimes be difficult for a boat yard to undertake especially if working indoors.
Whilton Marina | Tue Dec 15, 2015 at 3:42pm
Hello Julie Unfortunately we don’t have the capacity to undertake any narrowboat hull blackings unless you are a moorer with us. But for a guide - our price for blacking a 50ft narrowboat would be £720 and a 60ft boat £864 inc VAT.
Richard Weston | Fri Aug 5, 2016 at 3:47pm
Very helpful information exchanges thanks. My question is in two parts. How much more expensive is 2 Pack Epoxy coating. What is the lifespan of anodes?
Whilton Marina | Tue Aug 9, 2016 at 2:06pm
Hello Richard, Two pack Epoxy is twice the cost of bitumen, but lasts two to three times as long as bitumen coating.The life of annodes depends on usage, and depending on how much crusing the boat does. Anodes are used to help protect the hull in the case of galvanic corrosion caused by electrical current flowing between connections and between dissimilar metals. The theory is that by attaching a piece of metal to the hull that is more reactive than the hull itself then this piece of metal will corrode first.
Paul Roberts | Sat Jan 28, 2017 at 1:56am
I have often wondered if adding a fibre-glass or even kevlar mat to the two pack epoxy would be a way of extending the life of the blacking. Also sicking a soft polymer to the hull (like HDPE) has been proven to resist abrasion by particulate.
Paul Roberts | Sat Jan 28, 2017 at 1:58am
What are your views on zinc spraying a narrowboat hull please?
Whilton Marina | Mon Feb 20, 2017 at 3:07pm
Hello Paul,An interesting question, but to be truthful it's something that we have never come across before.
elspeth soutar | Tue Mar 21, 2017 at 5:54pm
Ive been reading about aluminium hulls and wonder if I need to black my hull after I have had it thoroughly pressure washed. Some seem to say that Aluminium hulls dont need blacking but the boat I am buying has been blacked before. Do I need to do it again this year if it was blacked 3 years ago on aluminium hull?
Whilton Marina | Tue Mar 28, 2017 at 11:42am
Hello Elspeth, Aluminium hulls do not need painting except below the waterline or where anything is touching the hull surface. Bare aluminium forms an aluminium oxide coating on its surface that creates a barrier and prevents the metal from corroding. If the boat has already been blacked, from a cosmetic point of view you may wish to black the hull again, especially as it will need blacking below the waterline.
Ahh Kid | Wed May 31, 2017 at 6:17pm
Hello, is it possible to get the blacking in a grey colour? due to I'm planning to have the top of my boat painted in battleship grey.
Helen Art | Mon Jun 5, 2017 at 8:05am
Does a fibreglass hull need Blackened? Is it basically a process to stop anything sticking to the boat from the water? What would be the best option if a fibreglass hull were to be Blackened? Thanks so much!
Whilton Marina | Mon Jun 5, 2017 at 2:37pm
Hello Ahh Kid, there may be a product on the market that is a colour other than black that could be used instead of blacking on a narrowboat, you would need to do your reseach about this as we are not aware.
Whilton Marina | Mon Jun 26, 2017 at 11:17am
Hello Helen,Fibreglass boats are not blacked, they are firstly primed with a special primer that is suitable for an antifouling coating to be applied. This effectively stops weed growth from attaching itself to the hull. Antifoul is normally applied every couple of years.
Phil B | Sun Aug 6, 2017 at 8:18am
I have a permanent mooring, and in 6 months, have only done 8 hours of cruising. If this is similar at the end of the first 2-3 years, will I definitely have to have it blacked then, or can I wait a bit longer ?
Whilton Marina | Mon Aug 21, 2017 at 4:16pm
Hello Phil BThree years is the recommended time for narrowboats to be blacked regardless of how much they are used. This is because the boat is sitting in water. Which causes rusting on the waterline.
Keith Yeandel | Thu Sep 21, 2017 at 1:28pm
Can International Intertuf be applied over a 2-pack epoxy above the waterline?
Whilton Marina | Mon Sep 25, 2017 at 1:12pm
Hello Keith, We recommend that you speak to the manufacturers of International Intertuf to ask them if it can be applied over a 2 pock apoxy coating on a narrowboat hull.
Ayesha walker | Tue Feb 13, 2018 at 11:31am
If you only have your boat drydocked when blacking how are you able to black the base , as you would not be able to get under the boat in a dry dock? Many thanks
ANDY H | Wed Apr 18, 2018 at 4:19pm
Hello, I am buying a secondhand steel narrow boat in May.The dry dock and surveyor are booked.The boat comes out of the water on the Saturday and i will pressure wash it straight away to stop mud ,weeds etc drying on.However the surveyor is not coming until Monday and doesn't want any blacking put on until he has finished.Should i apply anything to the bare metal to stop rust forming over the weekend,such as a rust converter?
Whilton Marina | Mon Apr 23, 2018 at 4:11pm
Hello Andy, You don't need to apply anything to the metal once the boat hull has been pressure washed. The boat will be fine until the surveyor has finished his survey and at that stage you can apply the blacking.
Alan Vickery | Wed May 23, 2018 at 12:20am
Hi, is there any need to anti foul over the black 2 pock paint, my barge will be lifted into a saltwater river for a few weeks before going into a fresh water canal? Thanks
rosie | Sun May 27, 2018 at 2:38pm
Hi I had my boat blacked last June and I noticed in April that an extensive amount of rust was appearing on the waterline. Can anyone advise me on this?Rosie
Whilton Marina | Tue May 29, 2018 at 4:36pm
Hello Alan, we have checked with a local surveyor who confirmed that is the boat is only going to be in saltwater for only a short period of time, no harm will come to it.
Whilton Marina | Tue May 29, 2018 at 4:39pm
Hello Rosie, (two comments above) Did you cruise the canals during icy periods? as this can strip back the blacking on the waterline. We suggest if you are worried get the boat out of the water to get the hull checked.
Cheryl | Fri Jul 20, 2018 at 12:04pm
Is blacking a boat the same thing as anti fouling or do both things need doing.
Whilton Marina | Tue Jul 24, 2018 at 3:35pm
Hi Cheryl, Narrowboat hulls require pressure washing and blacking approximately every five years.Antifouling is used on fibreglass and seagoing boats to protect from erosion and to slow the growth and/or facilitate detachment of subaquatic organisms that attach to it. Antifouling is not usually used on narrowboats.
whilton Marina | Wed Jul 25, 2018 at 11:05am
Hi Cheryl, the above answer to your question should have said Narrowboat hulls require pressure washing and blacking approximately every 2-3 years using Bitumen and 5-6 years if using Two Pack Epoxy.
Victor Vectrix | Mon Aug 27, 2018 at 12:54pm
I have discovered that permanently keeping my narrowboat out of the water prevents rust. I recommend readers try this as it saves a lot of money on blacking.
Whilton Marina | Tue Sep 11, 2018 at 12:53pm
Hello Victor.. that's a novel way of thinking about narrowboat blacking! However it's not an option if you want to actually use the boat for cruising the waterways which you won't be able to do with it out on the bank.
Ivan | Tue Mar 5, 2019 at 7:18am
I'm getting the blacking done this summer, as it will be 3 years since it was last done (it was blacked and overplated just before I bought it). There's a fair bit of exposed rusted metal just above the waterline, not sure why. Would you recommend getting a survey and how much time do you think it will add to the whole process? Thanks
Whilton Marina | Tue Mar 5, 2019 at 1:59pm
Hello Ivan, It is always a good idea to commission a hull survey while the boat is out of the water for blacking, especially if the boat has already been overplated some years previously. We would recommend booking your surveyor so that the boat can be pressure washed and surveyed whilst out of the water. The extra time added to the process would depend on the findings of the surveyor and whether or not any hull repairs are needed before blacking.
Kate somerfiekd | Sun Jun 16, 2019 at 11:32am
Hi,If a narrowboat is grit blasted and 2 pack epoxy used on the bare steel, when the hull is needing re-blacking, can epoxy be put straight on to the existing epoxy or does it require blasting again?
Whilton Marina | Mon Jun 17, 2019 at 12:25pm
Hello Kate, If a narrowboat already has two pack epoxy on the hull you don't need to get it shot blasted back to bare steel again, you can just pressure wash the hull, allow to fully dry before applying two coats of epoxy over the top. However if a boat's hull already has epoxy and you want to use bitumen when re-blacking, you are able to apply bitumen over the top of expoxy.
Christine haylett | Thu Jul 4, 2019 at 8:27pm
Does cruiser boats need blacking? , I heard because they are fiberglass they don't need blacking? .
Whilton Marina | Mon Jul 8, 2019 at 12:50pm
Hello Christine, Fibreglass boats are not blacked, they are firstly primed with a special primer that is suitable for an antifouling coating to be applied. This effectively stops weed growth from attaching itself to the hull. Antifoul is normally applied every couple of years.
Simon Wilkes | Wed Jul 24, 2019 at 2:59pm
My boat is currently coated with 2 pack do I just paint more 2 pack over the top
whilton Marina | Mon Jul 29, 2019 at 12:34pm
Hello Simon, You need to pressure wash the hull, allow to fully dry, before applying two coats of epoxy over the top of the existing 2 pack epoxy.
Gail evans | Wed Aug 14, 2019 at 12:19pm
This probably sounds a stupid question,but while we are having our narrow boat blacked where do we stay? I mean do we have to leave during the day when it's being done?
Whilton Marina | Mon Aug 19, 2019 at 11:00am
Hello Gail, As the boat will need to be taken out of the water to be pressure washed and blacked, it may not be possible to stay onboard for the duration of the work, in which case you would need to find alternative accommodation.
Dawn Cowley | Mon Oct 14, 2019 at 12:13pm
Hi I am looking at purchasing a springer 1979, it has had epoxy resin applied last year, but I am concerned about the thickness of the hull. The seller said that it had to have a survey before the epoxy resin could be applied, is this normal practice?I have requested a copy of the survey.Thanks
Whilton Marina | Mon Oct 14, 2019 at 1:20pm
Hello Dawn, We would always recommend having at least a hull survey before purchasing a second hand narrowboat, especially one of that age. Springer narrowboat hulls were produced using thinner steel than newer boats ; with modern narrowboats nowadays usually built to a specification of 10/6/4mm (the first figure is the hull thickness ) Although Springers were built in a V shape to create a stronger structure. Their Water Bugs were built using a 3mm steel hull and the larger boats were usually built with 5mm steel hulls.
Ali Hills | Wed Oct 16, 2019 at 9:16pm
Re: Blacking the bottom. As a former painter & decorator I have no problem with tackling the blacking to the sides but as a previous poster asked - how do you get to the base and ensure adequate coverage? I have seen boats up on wooden blocks only around 6-10 inches high. I don't fancy repeatedly putting my arm under several tonnes of narrowboat and definitely not my head! Even with a slightly bigger block I don't think you could get enough leverage for good coverage with a long roller? - Also, do you then have to get the trailer in to move the blocks so you can do those bits? - what about the 48 hour drying time? Thanks, Ali.
Whilton Marina | Fri Nov 22, 2019 at 4:30pm
Hi Ali, it is generally believed that the base plate of the hull does not require blacking as the coating would quickly be worn off under normal use, and is normally not possible due to the restrictions placed in the dry dock. We apply two coats of blacking over the course of three days.
Vary | Sun May 10, 2020 at 11:19pm
HiHow much would it cost to take a 35ft springer out of the water and blacked?Thanks
Whilton Marina | Sun May 17, 2020 at 9:31pm
Hello Vary, cost for Whilton Marina to black a narrowboat up to 50ft length £768.00 inc VAT for normal blacking, or £900 inc VAT for using Two Pack.
isabel | Sun Sep 20, 2020 at 12:54pm
Hello, could you please help me with the following question: On tins it usually says bitumen paint is toxic to aquatic life. Does that only apply when its wet? And is it safe once it is dry and has cured? Thank you in advance for any advice.
Whilton Marina | Mon Oct 19, 2020 at 4:42pm
Hello Isabel, Yes once it’s dry bitumen paint will not cause harm to wildlife. It is not however recommended for potable water tanks etc. We would advise that when blacking a boat you protect skin and eyes and apply in well ventilated areas outdoors, do not inhale. Do not apply near open flames, sparks, heat or hot surfaces. sources. Dispose of any waste responsibly as it is toxic to wildlife. And obviously Do not swallow.
D Simpson | Wed Nov 11, 2020 at 2:36pm
Is there a need for a shared ownership boat to be blacked every year?
Whilton Marina | Tue Nov 17, 2020 at 10:13am
Hello, you wouldn't need to black a boat every year, typically bitumen blacking is every 2-3 years and two pack blacking every 5-6 years. This will depend on usage of the boat and if it is spending most of the time out on the canal or in a marina. Two pack blacking does cost more however you do have greater longevity.
Mick | Sun Feb 21, 2021 at 11:32am
Hi, once the hull has been jet washed do you treat rust spots with a rust inhibitor or do you just black over them please?
Whilton Marina | Mon Feb 22, 2021 at 4:50pm
Hi Mick, Depending on how deep the rust spots are you can just black straight over them. If they are deep the hull will require pitting work.
Dave | Sat Feb 12, 2022 at 1:50pm
What happens if you leave it longer between blacking than 2-3 years, does the paint come off, what would the boat be like in 10 years, a pile of rust?
Whilton Marina | Tue Feb 15, 2022 at 12:48pm
Hi Dave, Blacking the hull helps protect the boat from rust, if the boat is left for 10 years there will be rust on the hull yes.

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