Jump to content

blacking coming off by rubbing at the waterline?


IainW

Featured Posts

Is it normal that i can rub the hull at the waterline and get my hand very black? Is it the blacking paint coming off Or is it possibly oil on the hull? We're trying to get to the bottom of a slick that has been around our boats and trying to work out if it is one of our boats, i'm wondering if this is related???

Link to comment
Share on other sites

OK i'm getting worried about this slick now. When i waggle the tiller little bubbles of diesel seem to come up. Has anyone experienced this? Does that mean the diesel tank is leaking where the rudder is?? Help????

Link to comment
Share on other sites

OK i'm getting worried about this slick now. When i waggle the tiller little bubbles of diesel seem to come up. Has anyone experienced this? Does that mean the diesel tank is leaking where the rudder is?? Help????

 

That sounds a bit ominous!

It's not unknown for the rudder tube, which passes through the diesel tank, to become porous (i.e. corrode), as the inside of the tube can't be blacked.

 

How full is your tank? If there is a leak through the rudder tube, diesel will escape with a full tank, and water enter with an empty tank. Might be worth drawing off a bit from the bottom of the tank and checking for water.

 

If the top rudder bearing can be removed, or the rudder stock itself, it should be possible to check if there's diesel in the rudder tube.

 

Another strategy might be to move to a slick free area, and see if the slick follows you, or stays at the moorings.

Link to comment
Share on other sites

OK i'm getting worried about this slick now. When i waggle the tiller little bubbles of diesel seem to come up. Has anyone experienced this? Does that mean the diesel tank is leaking where the rudder is?? Help????

 

 

Yes, you probably should be worried, I fear.

 

As has been said, failure of the rudder tube where it passes through the diesel tank can occur.

 

Often builders use a tube here that is less thick than the hull sides, despite the fact it is actually an important part of the hull, and is also impossible to black, so more likely to corrode.

 

This happened to the boat we used to moor next to - exactly as you describe - if you wiggled the tiller, more diesel would seep out under the counter. I t took us a long while, (and a lot of polution), to convince the owner he had a problem - until he dipped the tank he had only just filled, and was now half empty.

 

I believe the same happened to RLWP's boat.

 

How old is yours, and what builder, please?

How full is your tank? If there is a leak through the rudder tube, diesel will escape with a full tank, and water enter with an empty tank.

 

Unless the bottom of the tank is well submerged, or the fuel has been run particularly low, it will normally be the case that the diesel level is well above canal level - so I think in "ninety something" percent of cases, diesel will flow out, rather than water flow in.

Edited by alan_fincher
Link to comment
Share on other sites

Probably not what you want to hear, but our shell when brand new had a tiny leak at the bottom of the rudder tube (porous weld). It had to be drydockd for a morning and have the weld re welded. It had similar symptoms when the rudder was "waggled."

Link to comment
Share on other sites

Rudder stock tubes passing through the diesel tank seems like a particularly bad design to me. I have the same thing on my boat. Maintenance is all but impossible, leakage and potential pollution is a very real possibility and if a new tube is required it means cutting into the tank. I'd love to meet the bloke who came up with the idea...

 

My engine hole is so wide they could have easily installed two tanks, one on each side of an exposed rudder stock tube, with a connecting tube between the tanks.

 

If the tube was exposed and it corroded through I suppose the drawback is that it could flood the engine hole and possibly sink the boat. Personally I wouldn't worry too much about that as my automatic bilge pump would deal with it until I saw it. Then I could just wrap some silicone repair tape around it until I could get the boat out of the water.

 

The other design I've seen is a semi-circular cutaway at the stern of the boat and the rudder stock actually sits outside the hull - there is no tube.

Edited by blackrose
Link to comment
Share on other sites

Thanks for all your replies. Alas I'm gutted to say I think you may all be right about a leaky rudder tube. We set up a sorbent boom around the back today and drained the diesel tank. Water and gunk in the bottom of it :-( At least no more diesel can get out until we get her into the dry dock. We pulled out 125l of diesel, mostly ok-looking and working back from how full she was pre-slick we haven't lost that much diesel. It's crazy how big a slick comes from a small leak. Gutted.

 

I used some ecover detergent in the area but after some googling it was dubious whether it is a good idea to use washing up liquid or not. Unfortunately it is meant to be very still the next few days so I don't think it will dissipate so quick.

Link to comment
Share on other sites

Probably not what you want to hear, but our shell when brand new had a tiny leak at the bottom of the rudder tube (porous weld). It had to be drydockd for a morning and have the weld re welded. It had similar symptoms when the rudder was "waggled."

And that was supposedly pressure tested to comply with the BSS

Link to comment
Share on other sites

that's interesting. Our best guess is that we've lost 10-20l of diesel and the slick covered a 2 mile long stretch of canal at about 20ft wide. It certainly took a long time to spread dispersant along the area. The wind and rain are picking up tomorrow so i'm hoping that will get rid of any remnants. Not a nice episode of our canal lives at all...

Link to comment
Share on other sites

that's interesting. Our best guess is that we've lost 10-20l of diesel and the slick covered a 2 mile long stretch of canal at about 20ft wide. It certainly took a long time to spread dispersant along the area. The wind and rain are picking up tomorrow so i'm hoping that will get rid of any remnants. Not a nice episode of our canal lives at all...

To put things in perspective, a similar sized spillage resulted in a temporary ban on all Warships fuelling even small amounts in the dockyard at Plymouth and senior officer being summoned to the Environment Agency to avoid it becoming a permanent ban.

Link to comment
Share on other sites

And that was supposedly pressure tested to comply with the BSS

I think you may mean RCD.

 

only requirement in BSS is :

 

2.5.3 Are fuel tanks, including seams and openings, in good condition and free of signs of leaks?
Check the condition of all fuel tank surfaces, seams and openings which can be seen and reached.
Fuel tanks including seams and openings must be free of signs of leaks, heavy corrosion, deep pitting or any other signs of material failure.
All inspection and cleaning access closing plates must be secured in place and free of signs of leaks.
Applicability – the fuel tank must be accessible enough to allow a general assessment of condition. Tanks not accessible to assess condition must be recorded as ‘not verified’ on your checklist, and it must be considered that the check has not been completed until such time as their general condition has been verified.
Applicability – where accessible, pay particular attention to areas under dipsticks/sounding pipes for evidence of damage from dipstick ‘bounce’.
Edited by Murflynn
Link to comment
Share on other sites

that's interesting. Our best guess is that we've lost 10-20l of diesel and the slick covered a 2 mile long stretch of canal at about 20ft wide. It certainly took a long time to spread dispersant along the area. The wind and rain are picking up tomorrow so i'm hoping that will get rid of any remnants. Not a nice episode of our canal lives at all...

 

My understanding is that it spreads out one molecule thick, so a little goes a VERY long way.

Link to comment
Share on other sites

 

I think you may mean RCD.

 

only requirement in BSS is :

 

2.5.3 Are fuel tanks, including seams and openings, in good condition and free of signs of leaks?
Check the condition of all fuel tank surfaces, seams and openings which can be seen and reached.
Fuel tanks including seams and openings must be free of signs of leaks, heavy corrosion, deep pitting or any other signs of material failure.
All inspection and cleaning access closing plates must be secured in place and free of signs of leaks.
Applicability – the fuel tank must be accessible enough to allow a general assessment of condition. Tanks not accessible to assess condition must be recorded as ‘not verified’ on your checklist, and it must be considered that the check has not been completed until such time as their general condition has been verified.
Applicability – where accessible, pay particular attention to areas under dipsticks/sounding pipes for evidence of damage from dipstick ‘bounce’.

 

You are right, I was thinking back about 18 years when we fitted our boat.

Link to comment
Share on other sites

You are right, I was thinking back about 18 years when we fitted our boat.

Yes it should have been tested to comply with RCD. It was very quickly tested following remedial work which I witnessed! I agree with Mike/Blackrose that it is stupid passing the tube throguh the tank. My previous boat was done differently and far better IMHO. Another item on my list of "IF I had my time again...."

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.