Don’t Landlord Special Your Boat

If you're new to boat renovation and restoration and intend to spend long periods on your boat you may be wondering what paint to use on the inside of your hull.  Well, the answer is simple - none.  Believe it or not, this is an incredibly common question on technical groups and forums.  We can all agree that bilge and locker paints are incredibly useful below floor level, out of site and in engine rooms. They are relatively easy to clean and can now be sourced in big quantities making them ideal for restoration.  A freshly painted bilge can even help locate leaks from hull fittings as well as inboard oil leaks, a faulty water waste system etc,  only if a contrasting colour is used.  Generally speaking modern bilge paints are a great choice for below the waterline internally.

Just don't fall into the trap of slapping bilge paints over your cabin roof.

Mouldy - Anchor Locker- Seamaster 950

It worked for me!

Painting bare fibreglass internally has been the go-to for many years and you can see why.

If you're racing boats the chances are you don't care too much about the shade of Smaragdine green above your halfberth. It needs to be functional lightweight and good enough. If you're a weekend cruiser or hobby fisherman you probably only care about keeping the beer cold and bringing an extra sleeping bag liner.

'Arrrr your just a soft land lubber'

If it works for you the chances are you don't spend long periods on your boat in cold climates. Boats that aren't insulated are too hot in the summer and too cold in the winter.  If you don't belive us try putting a laser thermometer on your deck in the peak of the summer.  The end result is having a boat you can't spend much time on, which is not suitable for everyone.

You can’t landlord special a boat.

Everyone knows that landlords are notoriously bad for whitewashing houses in the cheapest paint known to mankind to cover dampness, mould and imperfections. Oddly enough the secondhand GRP boat market actually draws a lot of similarities here. Let us consider that your typical rookie boat owner may not have lived or spent time onboard.  The first thing they see is a mouldy failing, painted hull coating,  oh the horror!

The easiest option here is to give the hull a good prep and paint right? Most new boat owners will have done some research. Now they know enough to know boats are special? Unlike a house, they will need to buy a specialist marine quality paint. 

Unfortunately, they are not considering why the paint failed in the first place and it's that issue that needs addressing.

Don’t Paint The InsIde Of Your Hull

With certainty, dampness and mould caused by humid conditions onboard fibreglass boats is the main cause for paint coatings failure.  Even with adequate ventilation and a heat source, your fighting a loosing battle when in comes to a non-insulated surface.

There are however other causes of paint failure.

Notably, Second to that you have heat and temperature fluctuations, passive UV from windows and lastly structural defaults.

If you poked your head into almost any boat yard you'd find a project boat with a ramshackle interior. The chances are it's been abandoned as it looks like a troll's cave with stalactites of Sandtex masonry paint oozing from the ceiling because some guy at the yacht club told them it was a great idea to paint away the dirt.

It's not a great idea.  It's incredibly dumb, but don't worry we've all done it, myself included.

Good reasons to not paint over your hull

  • You're painting over a failed paint substrate because it looks bad with something that is going to look even worse down the line.
  • You're using expensive 750ml tins of marine quality paint that that will need to be painfully scraped off in the future if you want to insulate effectively.
  • There is no magic paint that stops damp unless you're spraying a inch of rubber from a standard transit lorry.
  • Bare GRP is often rough and has a poor finish, so painting it will only mask its imperfections.
  • Water is going to pool above head and drip in humid conditions or cold nights.
  • Your not adding value to a boat.
  • Simply put, YOU NEED TO INSULATE.

Painting a interior hull makes renovating boats incredibly difficult as before you can insulate you need to deal with mechanicaly removing failing paint coatings. This is often above head and in cramped spaces. Grab adhesives are best bonded to bare GRP or non waxed Gelcoat -Topcoat, they will adhere to a well bonded paint but there's always a relative risk that they will fail sooner.

Boat Hull- Westerley

Electric isn’t cheap anymore

The days of free electricity on moorings are coming to an end. Electricity prices are skyrocketing and unlike in the 80's people can't afford to keep electric radiators, continuously running onboard to prevent damp build-up on non insualted surfaces. For many years it would be commonplace to have a Dimplex heater onboard - 500 watts in a small non insulated boat would be enough to keep the damp from rotting an interior.

If you're a liveaboard who's living and cooking inside then your boat it has to be well insulated and ventilated. Simply painting a hull will not stop damp ingress. If your hull is only painted you'd expect to run a 1-2kw heater all day through the winter to try keep water from pooling on your hull. If your boat is old and typically has a few leaks on fittings and windows then essentially all your doing is forcing the water in your bilge to condensate on your roof and walls by heating the room.

What’s the Solution?

The bottom line is, you need to insulate. Your budget and time constraints are going to dictate what is possible here.  It could be as simple as carpeting, or as complex as creating custom-fitted sandwich insulation panels.

Foam backed adhesive vinyls are your friend in this situation especially if you're in a hurry.  Patterns can be quickly crafted, unlike having to cut closed-sell foam and aluminium bubbles which is more labour-intensive. If you want to live or spend time on a boat you need to nail that insulation and forget the expensive paint coatings.

3 thoughts on “Don’t Landlord Special Your Boat”

  1. Yup, gloss paint over glass is horrendous, also bloody carpet….WHY??? My boat has both of those things going on….

  2. Its a total nightmare isn’t it. I hate it and I can see I’m going to have to soda blast my boat inside to fix it. If they were going to paint the bloody thing why didn’t they fair first…

  3. Thanks for sharing brp! You would not believe how much time we wasted on our Dawncraft cabin cruiser stripping out the old paint layers. what makes things even worse the hubby found the leftover tin of paint onboard in a locker. it can only be a few years old!!

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