Rust and water under floor boards

[KirstieH]

Hello friends.

 

We are very new to living aboard and are tackling dampness on the boat. We have looked down the sides of the floor boards and there seems to be glistening water / moisture on the hull of the boat round the edges near the walls. More in some places than others up to 2mm. The hull is rusty under there too. I know its not ideal but is it common? Can it really be condensation or is it a leak? It is very clear water but at the back of the boat it could be heating water / anti freeze as it smells sweet and the header tank has depleted. I was worried the dehumidifier was sucking it away!

 

All the best anc merry xmas

[Guest]

Hello friends.

 

We are very new to living aboard and are tackling dampness on the boat. We have looked down the sides of the floor boards and there seems to be glistening water / moisture on the hull of the boat round the edges near the walls. More in some places than others up to 2mm. The hull is rusty under there too. I know its not ideal but is it common? Can it really be condensation or is it a leak? It is very clear water but at the back of the boat it could be heating water / anti freeze as it smells sweet and the header tank has depleted. I was worried the dehumidifier was sucking it away!

 

All the best anc merry xmas

Given that there is a sweet smell, and the header tank is losing water, it sounds as though you do have a leak. The rust will likely be minimal and i wouldn't get too bothered about that. Can you get into the hull to dry it out then monitor the situation? Any obvious signs of leaks anywhere?

[KirstieH]

Given that there is a sweet smell, and the header tank is losing water, it sounds as though you do have a leak. The rust will likely be minimal and i wouldn't get too bothered about that. Can you get into the hull to dry it out then monitor the situation? Any obvious signs of leaks anywhere?

Hi thanks. No no obvious leaks. We are working through the boat bit by bit. I think deffo header tank but that isnt accounting for the clean water build up in the rest of the boat. Grrr its gonna be a long winter tracking this down! I think the previous owners had issues as the have taken all the kick boards / skirting off and cut some inspection hatches and a big chunk of floorboard under the bed. Makes it easy to check though lol. When asked they said they were not aware of any issues...mmmmm

[Guest]

Hi thanks. No no obvious leaks. We are working through the boat bit by bit. I think deffo header tank but that isnt accounting for the clean water build up in the rest of the boat. Grrr its gonna be a long winter tracking this down! I think the previous owners had issues as the have taken all the kick boards / skirting off and cut some inspection hatches and a big chunk of floorboard under the bed. Makes it easy to check though lol. When asked they said they were not aware of any issues...mmmmm

It is good to have inspection hatches, sadly lacking on many boats. If you can obtain a wet vac, you should be able to get most of the water out and then monitor it. Should give an idea if it (the freshwater) is condense or a more serious leak.

[Murflynn]

if the boat has a normal bow/stern trim you should check under the floor at the very back of the cabin where any leaking water will collect.

 

if there is no more water there than elsewhere then it may just be condensation clinging to the rusty steel hull.

[KirstieH]

Mmm totally dry at the front of the boat...57ft and woodburner keeping it dry maybe...still removing skirting lol

[Tony Brooks]

If the water pump stays silent for several hours at a time when turned on it is unlikely to be a domestic water leak. If you have central heating and the header tank stays at the same level that is unlikely to be leaking.

 

If its an all in one bilge (no bulkhead between rear outside and inside it might be water getting into the back of the boat outside. If you have a well deck below the water line it could be rain from there. Both these features tend to found on older boats. If the boat is like that it could also be a drip from the stern gland.

 

After some years windows tend to leak between the frames and hull so if it is worse after rain that or a roof fitting could be the source.

 

It could be condensation but that would be worse with cold outside and warm inside plus a lack of ventilation..

 

Take not of the other suggestions especially about looking under the floor at the back of the cabin. There may already be a trap there but if not I would advise cutting one. Mine is under the rear steps. Sometimes they are in the floor of a cupboard at the back.

 

If you do start to dry things out at the back note that it can take days for the water to work its way back past the ballast so it may take weeks of on and off sponging out so it can be a bit confusing.

 

One thing that is very unlikely on the vast majority of boats is a hull leak.

[Bee]

All you can do re. leaks in heating is to check all the joints and pipes everywhere. you might not even have antifreeze in the system unless you have put it there yourself. The header tank is also an expansion tank as well so don't overfill it or it will just overflow when it warms up. Many, many boats have some water under the floor, get it out if you can but don't panic. Condensation will settle in the bottom from thin patches of foam / polystyrene etc. Ventilation is what you need but it is difficult verging on the impossible to achieve in a boat but nice big cut outs in the floor under cupboards will help. Your woodburner will use a lot of air, if you can get it to take some of it from under the floor via some large dia. holes in front of it that could help. After years of living on I could tell when a boater stood next to me in the pub by the smell of mildew, just look forward to the summer!

[KirstieH]

Thanks everyone. Some brilliant tips here. Trial and error and working through seems to be the best solution. I love my boat even if it doesnt love me back! All the best to everone who commented

[Tony Brooks]

If the heating header tank is gradually loosing water then its a very good bet its a central heating leak BUT remember that if you fill to full and then turn the system on it will expand the water and blow it out of the tank so it is lower when it cools. Likewise it is normal to find the header tank is fuller when hot and the level goes down when it cools.

 

If your central heating has plastic pipes look very carefully at any joints/unions that use a compression fitting like the radiators and other valves might. I have found such fittings tend to leak, especially lever valves unless metal pipe inserts (not plastic) are used in the joint.

[KirstieH]

Thanks tony. Very clear advice. Will look today

[chubby]

My tuppence worth ,

 

When i had to look for where leaks originate i start by putting a sheet of kitchen roll under every join i can see & check later on to see uf there is evidence of the leak . If nothing else it allows one to then concentrate looking elsewhere

 

ETA . Im sure ive read in the past of folk adding food colouring to water tanks so that if pink water appears in the bilges then its a problem in the water system , Or blue food colouring in the central heating system , but if the bilge water remains clear then it may be leaky windows or condensation .

Might take some flushing out though after experimenting!!

Definately create a hatch as far back in the boat as poss as mentioned above

cheers

Edited December 24, 2016 by chubby

[Tom Richmond]

+1 to the toilet roll idea...

[Bloomsberry]

I don't understand why it is important to have the baseplate bottom blacked but it's deemed ok to have water on top of the baseplate

[Scholar Gypsy]

I don't understand why it is important to have the baseplate bottom blacked but it's deemed ok to have water on top of the baseplate

 

I'd say it is the other way around. The baseplate on my boat is not blacked, there is little oxygen there and you need that for steel to rust.

 

In the bilges there is plenty of oxygen which is why your bilges need to be painted when built, and water presence minimized...

 

PS if you have any holes in the roof (eg for radio aerials - I have a couple) then check those too, and apply mastic liberally. If you have a window leak (I did!) then the water will appear inside the boat somewhere completely different.

[Guest]

 

I'd say it is the other way around. The baseplate on my boat is not blacked, there is little oxygen there and you need that for steel to rust.

 

In the bilges there is plenty of oxygen which is why your bilges need to be painted when built, and water presence minimized...

 

PS if you have any holes in the roof (eg for radio aerials - I have a couple) then check those too, and apply mastic liberally. If you have a window leak (I did!) then the water will appear inside the boat somewhere completely different.

 

 

I'd say it is the other way around. The baseplate on my boat is not blacked, there is little oxygen there and you need that for steel to rust.

 

In the bilges there is plenty of oxygen which is why your bilges need to be painted when built, and water presence minimized...

 

PS if you have any holes in the roof (eg for radio aerials - I have a couple) then check those too, and apply mastic liberally. If you have a window leak (I did!) then the water will appear inside the boat somewhere completely different.

Yes any holes in roof are suspect. Sealant can break down under vents etc.

Said it many times, but on a future boat, I would have no holes in the roof, ever (other than stove flue.)

Edited December 27, 2016 by Guest

[Morningmist]

Still in the bilge, My hull builder has cut a 4" hole in my base plate in the engine compartment! he says this is a sump for a bilge pump. Is this a good idea? I am concerned that as this sump projects out below my base plate by some 3" that it will catch on any junk in the canal and given the boat momentum and weight if I hit something really solid that the whole thing could be ripped off leaving a very large hole in the boat bottom!!

[Murflynn]

don't you have a steel skeg which extends from the base plate under the engine to the lower rudder bearing?

 

if you do, it would protect the projecting sump.

[Morningmist]

Apparently the skeg will run from behind the sump, but even if a skeg did start before the sump, I still feel that's its vulnerable to damage and is a sump really a useful item to have, I understand a bucket and sponge is all that it needed. This is my first boat so I have no experience and any advise would be most welcome.

[Scholar Gypsy]

Can you say more about how your bilges are organised? For example, I have three sections in my boat, isolated from each other:

• under the cabin floor, which you can pump out at the rear (which is lower), and then use a sponge
• under the engine, which (as it will contain a mix of oil, diesel and antfreeze) should not be pumped anywhere, but can be cleaned using sponges etc (and various other techniques). Here's a photo that shows how you can get it dry
• under the stern gland, where I have a plastic tray to catch the drips (you can see it on the left of the photo) and which also contains a bilge pump (you can see the hose, just below the prop shaft) that I run for a few seconds each day to pump any water out.

Is yours like this, or something different (for example some boats have drains from the foredeck into the bilges).

 

I can't really see how a sump would be much use in practice, quite apart from the risk of damage that you refer to.

 

Edited December 27, 2016 by Scholar Gypsy

[Morningmist]

The hull is being built as a trad with a small tug deck and a mid engine room. I have a sealed bulk head just aft of the bowthruster, then nothing until just before the stern gland where I shall presumably catch the drips. The engine will sit on its own self contained engine bed. Any water will presumably be able to drain from the front of the vessel right to the back, presuming the usual aft trim and no lean to either port or starboard.

[Murflynn]

in order to ensure there is little opportunity for water to be trapped you should ensure there are adequate limber holes (cut-outs for drainage) in the bottom cross-stiffeners, and ideally the ballast should be bricks or blocks placed on short lengths of thick electrical cable to allow water to migrate and to allow air circulation to evaporate any water that may get trapped.

[Morningmist]

There are no limber holes in the frames I assumed the bilge water ran under the un-welded part of the frames, but I would prefer to have dedicated limber holes, thank you Murflynn for your advise, and I agree with Scholar Gypsy that the sump is an unnecessary inconvenience.

[Neil Smith]

You don't need a sump so get him to weld a plate over the hole after removing the sump. and get him to put drain holes at both ends of the floor bearers at hull/bottom joint at least 1/2" dia.

 

Neil

[Murflynn]

There are no limber holes in the frames I assumed the bilge water ran under the un-welded part of the frames, but I would prefer to have dedicated limber holes, thank you Murflynn for your advise, and I agree with Scholar Gypsy that the sump is an unnecessary inconvenience.

water will be blocked by the frames as soon as a bit of muck or rust builds up, or if the bottom is painted.

 

limber holes are normally provided at each end where the framing is truncated to allow the inside of the side/bottom seam to be welded continuously.

 

just make sure the ends are kept clear of muck; mine got blocked by sawdust, spray-foam cuttings and the like and needed a good clean up before the cabin linings were fixed, after which they become inaccessible.

 

I would prefer a good limber hole say 100mm long and 15mm deep in the centre of each bottom frame stiffener as well