Water In The Cabin Bilge

We often get calls and emails regarding water in the cabin bilge at the Floating Boatyard. The aim of this post is to make you aware of the causes of water under the boat floors and how to prevent it from happening.  We will show how we solve this problem and why you should not ignore the water on the inside of your boat. You should deal with water in the cabin bilge and water under the boat’s floor as soon as possible.  Left untreated, water under the boat’s floor will rot the base plate from the inside out.

If you have any further questions about water under the boat floors or would like to book work with The Floating Boatyard, ring 07886 388 689 or use the contact form on this website.

Water In The Cabin Bilge - Albert bathroom rust - the Floating Boatyard. Water under boat floors - Bow water tank rust - the Floating Boatyard

Some examples of the damage caused by water in the cabin bilge

Water in the Cabin Bilge is Not Always Obvious

All canal boats should have an inspection hatch inside the cabin towards the stern. You need to check this regularly to see if there is any water under the boat floors. This hatch may be hidden under furniture – under steps and beds are common places for them. If you have hunted high and low, but still can’t find an inspection hatch, we recommend having one installed.

One of the symptoms of water under the boat floors is an increase in the damp in your boat. This is mainly visible through a lot more condensation on your windows. In severe cases, the floorboards will begin to warp and you may get a smell of mildew. If your water pump goes off by itself intermittently, then there may be a leak in the fresh water system.

Water in the Cabin Bilge – Preventative Measures and Routine Checks

At the Floating Boatyard, we check our personal boats for water in the cabin bilges every time we fill up the water tank. This makes it part of the routine, and less easy to forget. We also check for signs of water around our water tanks and water pumps, as these are common failure points. Shower rooms and bathrooms are another usual suspect. Keep an eye on your tiling and bathroom sealant and make repairs as soon as they are needed. Any small cracks will allow water to slowly seep through and into the hull of your narrowboat. This water will get trapped under the ballast and won’t dry up.

During the winter, when the canal is icy cold, you will often find a small amount of condensation on the base plate. This is normal and not to be confused with problematic water under the boat’s floor. We recommend keeping your boat well heated. Keep the bilge ventilated and leave the inspection hatch open if it is not a danger to do so.  As with so many boat repairs, get to know your boat and if something feels weird, check into it.

Water In The Cabin Bilge - Cutting the first hatch - The Floating Boatyard.

Cutting an inspection hatch – this boat only had a small inspection hatch in the bathroom, this is what we discovered in the main living area.

Damage Caused by Water Under the Boat’s Floor

Let’s say you look into your inspection hatch and find 1 cm of water in the cabin bilge which wasn’t there the last time you checked – where do you go from here? Firstly, turn your water pump off. Report the leak to your insurance company if you are fully comp insured, as soon as possible. Check obvious failure points for signs of leaks such as water tanks, pumps, pipework connections. Don’t despair if you can’t find it immediately. The leak may come from a drainage, hidden pipe work or skin fitting which you can’t access. Using a wet/dry vac or a pump, remove as much of the water as you can. The Floating Boatyard can help you with all of these steps. We have the equipment and necessary experience to act fast and limit the damage to your boat.

We will help you track down the cause of the leak if it’s still an unknown, and get it fixed. Our team will then take a look in the hatch to get a rough estimate onto the extent of the damage. This is not an exact science, it is difficult to gauge the condition of a 60ft x 6ft 10 piece of steel by only looking a 1ft x 1ft  section of it.

If the water in the cabin bilge has been sat for some time on an untreated steel hull, the hull will corrode from the inside out and you face the task of repairing the hull. If you do not have a recent survey and have no idea how long the water under the boat floors has been in the hull, we will not begin any work before getting a marine surveyor to assess the thickness of the hull.

Water In The Cabin Bilge - Bluebelle Ballast Close Up - the Floating Boatyard

Starting to cut the floor out – the baseplate is not immediately visible even when the floor is up.

Treating the Damage Caused by Water Under the Boat Floors – Getting to the Hull

Most narrowboats are built and trimmed in a way which, in theory, allows any water in the cabin bilge to slowly run to the stern. In practice, we often find blocked limber holes, bad ballast choices such as gravel and iron, and unsuitable linings used.

We need to get access to the base plate itself in order to fully dry and remove any rust, and then paint the bilge to protect it from any future water leaks. This means lifting up the flooring in most cases. We have two options here, depending on the construction of the hull and how the flooring was laid originally.. Most flat-bottomed canal boats will not need the whole flooring to come up in order to lift out the ballast and treat the steel below.

We usually cut a channel through the centre of the boat’s floor and work around any built-in furniture. We can then reach under the floor boards to remove the ballast. This is time-consuming but faster than refitting the entire boat. If you have a v-bottomed hull, we may get away with cutting a series of inspection hatches in a channel through the cabin. We can lift the floors either all in one go or in sections. Doing the entire boat at once will be faster, but you will find it extremely difficult to live on during this time.


Water In The Cabin Bilge - Waterbug hatches - The Floating Boatyard.

Hatches cut into the floor of a v-bottomed Springer Waterbug

Treating the Damage Caused by Water Under the Boat Floors – Treating the Hull

Once we have access to the cabin bilge, we will remove all ballast to air dry. Most boats we come across have concrete slabs as ballast. This is relatively easy to remove and dry out. We have come across boats with gravel as ballast. This collects water, is difficult to lift and has a nasty habit of sticking to bad corrosion. We also see the use of heavy steel such as railway tracks and stage weights being used. This causes problems inside the cabin bilge. There is no way of telling what corrosion comes from the steel ballast and what from the hull.

Once the ballast is out, we can start to attack the rust. This is the point where we can fully see the extent of the corrosion. Up until now we will have only been able to make a rough guess as to the damage caused. We use a variety of tools for removing all of the loose corrosion, such and wire brushes and scrapers. This stage of works can generate some dust in your boat. We cannot avoid this entirely.

Once the loose rust is removed, it can be treated chemically with a rust converter. We also recommend that we apply bilge paint to the bilge. Applying primer and bilge paint will help protect your hull from any future water under the boat floors. This means that if you have this same disaster again in the future, you will incur less expense and less hassle to make it right. After the bilge has been painted, we repalce the ballast and refit the floors.

Water In The Cabin Bilge - Albert Cleaned - the Floating Boatyard

Cleaned up flooring – note how we have cut the flooring away around the furniture

Water under the boat floors- Albert vactan in progress - The Floating Boatyard.

Rust Convertor in Action

Water Cabin Bilge - Albert Bathroom Vactan done - the Floating Boatyard.

Dryed Rust Converter

Water in the Cabin Bilge - Waterbug hatches painted - the Floating Boatyard Water under the boat floors - Bluebelle Bow tank after painting - the Floating Boatyard

Freshly painted bilges – these should resist corrosion for many years to come

If you have any further questions about Water under the boat floors or would like to book work with The Floating Boatyard, ring 07886 388 689 or use the contact form on this website.




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