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Frequently Asked Questions About Narrow Boat Hulls Answered.

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Tue Jan 26, 2016 at 10:22am

At Whilton Marina we frequently get asked questions about steel narrowboat hulls. So in this article we will share these popular questions and give you the answers.

How Do I Know What Condition a Narrowboat Hull is in?

Generally speaking we don't know what the hull is like on the used boats we have for sale, unless the boat has had a recent hull survey carried out. This is why as a company we always recommend a prospective used narrow boat purchaser to commission a survey to be carried out on the boat before proceeding with the sale. 

How Thick Should the Steel be on The Hull?

For insurance purposes the minimum hull thickness must be 4mm.

The majority of modern narrowboats are built using 10/6/4mm plating or steel thickness specification, 10mm is the steel thickness on the hull base, 6mm the sides and 4mm the roof.

Why Do You Black The Hull?

Blacking the hull is a way of maintaining the condition of the boat and protecting it from rusting and should be carried out every 2-3 years. If Two Pack Epoxy paint is used then you are able to go 5-6 years before reapplying.

Can I do the Blacking Job Myself?

Yes if you want, but once you realise the time and effort that is required to complete the task you will appreciate that paying for this service is well worth every penny!

How is The Boat Taken Out the Water to Work on The Hull?

There are three different ways for getting the boat out of the water so that the whole hull can be inspected and treated if necessary.

  • Dry dock: where the boat is floated into a chamber and then the water is removed.
  • Cranin: but this can be an expensive option.
  • Slipway trailer: the boat is floated onto a trailer in the water and a tractor pulls the boat out. This is the most cost effective and popular choice.

What is used to black the hull?

There are two types of coatings which can be used to protect 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.

When opting to use Epoxy the boat has to be grit-blasted to produce a perfectly clean surface before it is applied, this is why it is a more expensive option. However it will save you money in the future saving on the amount of dry docks needed.  

NOTE: You cannot apply two pack to a boat that has been blacked with bitumen previously. All east west narrowboats were blacked with two pack from new.

How Long Does It Take To Black a Hull?

It’s basically a long, messy and hard three day process.

Day 1; The boat is taken out of the water and pressure washed to remove muck and grime, the old blacking and debris like weeds, mud, and rust. The hull is now ready for the new application of paint. If the water line needs more attention, a machine can be used to work on this area. This machine is called a “scrubbler” if it is used during the blacking process it will usually incur an additional charge.

Day 2; Now the hull is cleaned it is ready for painting. The application has to be done manually with a small roller. The paint has a similar consistency as tar so has to be applied in small sections as the paint goes hard very quickly, therefore no machines are used and it is a timely messy job.

Day 3; Repeat day 2! 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 for 48 hours to dry before it is returned to the water.

How Much Does It Cost to Black a Hull?

We have supplied some estimated price examples using Bituminous paint on 3 different sized boats, each marina or contractor will have their own individual prices so please only use these costs as a rough guide;

Bituminous paint;
57 foot - £820
70 foot - £1000

Epoxy paint;
57 foot - £1,130
70 foot - £ 1,400

What Should I Do to Keep the Hull Well Maintained?

Unless you suspect a problem with your hull, or if you've just had a recent hull survey, then your boat does not need to be taken out of the water every year, but it should be preferably be taken out every two to three years.

Careful cruising will go a long way in protecting your hull! Crashing through ice will damage the paint protecting the hull, as will crashing into banks and locks, so responsible cruising will lessen the chances of the hull being damaged.

When the narrow boat is out of the water you can get the hull pressure washed to enable you to check the hull and stern gear. It is important to check for rust or pitting, particularly round the waterline.

The sacrificial anodes should never be painted over when painting the lower part of the hull as this would prevent them from working.

What Are Anodes?

The correct name for these important lumps of metal is a ‘Sacrificial Anode’ and they form a key part in the boat’s battle against corrosion. Put simply, they have a higher electrochemical value than steel, which means they corrode away faster. They are basically blocks of magnesium which are bolted to the hull at the bow or stern.

Why are the Anodes on a Steel Hulled Narrowboat Important?

The “sacrificial anodes” corrode in place of the metal of the hull and prop, thereby giving protection. So it is important to check the anodes, as their purpose is to prevent electolytic corrosion of the steel plate and the bronze stern gear. If the anodes are half wasted it is vital to replace them to prevent pitting and corrosion of the steel hull. If you do not do this then it can be a very costly mistake.

If the hull is corroded because the anodes are not doing their job properly it can be one of the most expensive things to put right, as it may mean that some re-plating needs to be done to the hull.

What is over plating/re-plating?

Over plating and re-plating are actually the same thing and a boats hull may need a full over plate, side plating, bottom plating or just patching. Quotes for over plating work can vary enormously due to the various degrees of work that may need to be carried out. Watch our video for more information...

Who Decides a Narrowboat Needs Over-plating/Re-plating?

A qualified marine surveyor is the ONLY person that can survey a boat AND then issue it with passed certificates.

Does the Condition of The Hull Affect my Insurance?

Yes! As mentioned above the hull should meet the minimum thickness of 4mm plating or steel thickness specification.

You will need to have a hull survey carried out by a qualified marine surveyor. During the survey the surveyor will inspect the hull (and other areas of the boat if you have a full survey) he will measure the thickness of the steel and check for damage and pitting.

If any overplating work needs doing to meet the 4mm minimum requirement he will recommend this in his report. Once the work has been completed the surveyor will return, check the work and if he agrees it meets the correct standards he will present you with a certificate.

We hope we have answered all your questions regarding narrowboat hulls but if there is anything we have missed, please give us a call or leave us a comment below and we will get back to you!  

 

22 Comments

Brian Hutchins | Thu Feb 18, 2016 at 2:46am
Is polyurea a viable hull coating for narrowboats? What sort of cost might this coating incur?
Whilton Marina | Wed Feb 24, 2016 at 3:31pm
Hello Brian, We have never come across a steel hulled narrowboat that has been coated with Polyurea. We believe the challenge with covering the steel in this product is that all rot, rust and corrosion must be removed and fixed before applying, such as it would with Epoxy coatings. The best thing to do would be to speak to a manufacturer or supplier of Polyurea who may be able to help you with this query.
Claire | Sat Dec 17, 2016 at 10:38am
Shell of narrow boat need metal thickness survey ? Approx cost please
Vic Hall | Sun Jan 1, 2017 at 1:11pm
Hiya and Happy New Year!Can you help me with a simple query? I am repainting my boat this Spring. Do I take the blacking onto the cheeks at the front (the parts that project from the hull that come into contact with lock walls etc)? At present the previous owner painted it with the standard gloss colour of the boat and stopped the blacking under the cheek. It seems to me to be easier to maintain the cheek in good condition if it is blacked. I intend to use Multiforte down the length of the boat to meet the blacking so it is only the front that I am concerned about.Thanks very much Vic
Whilton Marina | Wed Jan 4, 2017 at 12:28pm
Hello ClaireA hull survey costs between £400 and £500 depending on which surveyor you use. There is a list of surveyors local to our marina on our website in the Buyers info section, or copy and paste this link into a web browser to find our page on narrow boat surveys and surveyors: https://www.whiltonmarina.co.uk/Buying-a-narrowboat/Surveys-and-Surveyors.aspx
Whilton Marina | Wed Jan 4, 2017 at 12:44pm
Hello Vic, I think you mean the rubbing strakes, (which are a steel reinforcing strip welded along the side of a narrowboat or canal boat’s hull, usually from one end to the other, to protect the sides of the boat from knocks and scrapes when mooring and in locks)We wouldn't normally black the rubbing strakes on a narrowboat, but obviously it is down to personal preference and is up to you if you wish to black them. Narrowboats are normally only blacked below the waterline for aesthetic reasons.
Mary | Thu Feb 16, 2017 at 6:50pm
Would appreciate a ball park figure to over plate 42 ft narrow boat including weed hatch, bitumen and anodes. Timeslots available for this year would be appreciated. Boat built 1989 by brummagem
Whilton Marina | Mon Feb 20, 2017 at 3:13pm
Hello MaryUnfortunately due to the amount of narrowboats we sell, we do not have the capacity to take on any overplating work on other boats.
David Obrien | Mon Apr 3, 2017 at 5:27pm
Can you take a wide beam boat on the open water
Whilton Marina | Tue Apr 4, 2017 at 3:34pm
In general, narrowboats and widebeams have been designed for inland use, i.e. on canals and river navigations.Most can also handle estuaries and lakes, provided the waters are reasonably protected and care is taken about tides and other currents. The engine may not be powerful enough to make headway against fast flowing water.However, it is possible to take one across the English Channel, or for a short coastal journey. But (very important!) only with careful preparation, appropriately skilled crew, the correct equipment, and the right weather. You should also check your insurance policy as it may not be valid.
Joseph | Wed Apr 5, 2017 at 12:27pm
Is there are minimum number of times a boat can be overplated? Does this affect the chance of getting insurance?
Pat Craven | Fri Apr 14, 2017 at 3:39pm
I am looking to buy a canal boat and am very interested in one that the owners do not know who the builder was. Should this be a problem?
Whilton Marina | Tue Apr 18, 2017 at 1:17pm
Hello Pat, Narrowboats usually have a plate somewhere on the boat with the builders name. However if you can't find a plate and don't know the builder it should not be a problem, and does often happen with older boats.
Whilton Marina | Tue Apr 18, 2017 at 1:31pm
Hello JosephI think you mean maximum, and not minimum, when you asked the question "is there a minimum number of times a boat can be overplated and does it affect the insurance"A narrowboat can be overplated for a second time. The first lot of plating would be removed and re plated once again. However if the first lot of re plating, once removed showed excess wear on the original hull, it could mean that the boat may not be able to be replated again and would mean the end of the boats life.For insurance purposes any re plating work should be checked and signed off by a suitably qualified marine surveyor, the insurance company would want to see written evidence that the work had been done to a satisfactory standard.
Dave | Tue Apr 18, 2017 at 9:30pm
Hi are all hulls built as one space or are they separated into sections? So if I have a leak into the front (e.g.from fresh water tank) will the water flow to the back of the boat as it is lower and where I can inspect it from a hatch?
Whilton Marina | Mon Apr 24, 2017 at 11:58am
Hello DaveNarrowboat hulls are built in sections which are called bulkheads, however potentially any water leak could fill the whole of the hull. There are inspection hatches to enable sight of inside the hull to check for water.
Hannah | Wed Jun 28, 2017 at 6:23pm
Is it okay to purchase a second hand boat that has been entirely over plated? The one in question has been surveyed and is in good condition, but will this effect the re-sale value in, say, 5 years?
Whilton Marina | Mon Jul 17, 2017 at 2:48pm
Hi Hannah, We would always advise to have an independent hull survey done when buying a used narrowboat, this especially applies to ones that have been over plated. If the overplating has been done correctly and was signed off by a surveyor at the time the work was done, and a current hull survey was undertaken with a satisfactory outcome, there is no reason not to buy a narrowboat that has been over plated. The re-sale value in five years time will obviously depend on the condition of the boat and the market at that time.
phil | Wed Jul 19, 2017 at 5:47pm
Hi I have a new widebeam boat brought from New 2years ago. The fresh water tank filler under rear deck has cracked & broke away we had no way of telling this so over time the hull filled with water when we did find this out we pumped out over 100gallons of water. We got back to company we brought from they will deal with water tank & hopefully any damage to wood panelling inside. Could you tell if there will be long term damage in future to the hull. As the company assures there won't be. Will I need marine surveyors report to say there will be no corrosion from this leak in the future. It's peace of mind for me incase I have to go legal against the company as the boat cost over £100000. THANKYOU.
Tony | Fri Jul 21, 2017 at 1:38pm
Does the hull have to be 4mm think to get 3rd party insurance ?
Whilton Marina | Tue Jul 25, 2017 at 11:18am
Hello Phil, If you are worried that there could be long term damage to the inside of your widebeam hull, we would advise you to talk to a qualified marine surveyor who will give you independent advise about this.
Whilton Marina | Tue Jul 25, 2017 at 11:33am
Hello Phil,Yes that is correct the minimum thickness of a narrowboat hull is 4mm to get third party insurance.

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