Thursday, 26 January 2012

Should the bottom of a narrowboat be painted?

I have stumbled across a question that I didn't even know was an issue.  Should the bottom of a narrowboat be painted?  I've been doing some reading about this and it does seem there are (surprise, surprise) two opposing camps on the matter.

It seems many aren't painted.  It is believed that as the base plate of a narrowboat never sees the light of day, it won't rust.  There isn't sufficient oxygen in the water for rust to form - according to the "no need to paint the bottom" camp.  There are comments of people with 20+ year old boats with bottoms as good as new, so they claim. 

Then there is the other side of the story - those that are determined you should paint the bottom of the boat.

I do recall reading something a couple of years ago that said boats in marinas are more prone to pitting of the hull than those on inline moorings or cruising.

Would like to hear your thoughts.

4 comments:

nb Epiphany said...

Within minutes of leaving the yard we would be scraping the bottom, so would not have much left pretty soon!

Tom and Jan said...

Well I'm not blacking the bottom of Waiouru. I can't get down that low and my arm isn't long enough.

I'm working on the principle that any rust will be rubbed off when we (frequently) run aground! :-)

Paul and Elaine said...

My take on this is that there is no point in anti fouling the bottom plate as is often scrapes along the canal bed removing any growth. Re pitting on marinas Boats connected to improperly grounded shore supply systems should employ a galvanic isolator to isolate from any stray currents in the marina (either from the shore mains or neighbouring boats). Without the isolator, a galvanic corrosion path may be created damaging metal equipment below the waterline pitting the hull etc. Anodes may help, to prevent this, but often prove insufficient when the boat stays in the marina for extended periods.

Paul,

Dave said...

Can someone explain the following: what part sunlight has to play in the rusting process? What depth is the point where oxygen is sufficiently depleted so no rusting will happen and why canals don't act like other fluids? Has anyone told the fish not to go below 2'9"?
On the other points when I've scraped the bottom of my boat it's normally been when mooring up against the bank of a silted up canal (silt not particularly abrasive) and the stern on the bank most side hitting the bottom. I have heard that nasty scrape of gravel against the bottom normally when I've lost concentration and veered from the channel on a shallow section but this has only happened a couple of times in 3 years and I'd expect the damage to be limited to a sub section of one edge rather than a full clean hull.
I'm about to do my own baseplate, am I mad?