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Our boat biult by Big Fish is just 4 years old and we have just started to have two leaks under the port side gunnell.one leak is at bow about 15 foot back the other is 12 foot from stern please do you have any thoughts on sourcing the route of problem

Asked by: Bayliss Brown  | 10.36am, Thursday 13 January

WW says:

There are three possibilities that come to mind:
The first thing I would rule out is that it is not condensation running from the cabinside, and pooling behind the lining (often in the metal supports for the cabin linings), and then running out, where it is noticeable. This can often be rust-coloured, as it picks up iron oxide as it passes through, though not always!
Even with the best insulation, it is possible for moisture from the cabin to consense on any cold surface behind the lining, rather than being a leak per se.
The second I would check, is that there isn't either a leak, or significant pooling of water from a window/door, that is causing the problem. The seals around portholes and doors are often difficult to seal, and if they have moved, due to corrosion or extremem heat/cold, they can leak.
The third one, which is much more difficult, if that a weld might be leaking- however, this is usually the least likely option. One way to trace this, would be to remove the cabin side linings, if possible, and to paint a solution of sodium fluoroscein, (which is a green highly water-soluble dye- about 0.5g per litre water maximum needed!) along the welds, and then to detect any ingress inside the shell, using a cheap UV (ultra violet) handlamp, which would indicate if water was coming through.
The same technique could be used to trace window leaks as well. You might need to apply plenty of solution- don't worry if it goes into the canal, as it is harmless (you can drink it quite safely) and is used in hydraulic studies of water flow in canals and rivers anyway.
If you need any more specific advice, then please ask- but I would think that would be the best starting points.

Mark Langley  | 11.56AM, Thursday 13 January

Readers say:

We have a Big Fish boat - Funky Fish - been living on it for 4 years. We too had the same problem - and fixed it. Its poor welding (we have found a couple of other bits of poor welding which we have sorted). Along the roof on each side there places where you can tie a fender. It looks as though there is a long metal rod going the length of the boat on each side of the roof with a couple of gaps to tie things. At one of these gaps the weld underneath was not perfect and leaked a small bit of water when it rained. It got quite bad - discovered it when we had just bought the boat secondhand. covered the area in silicon rubber to sort it and its still ok. Hope this helps.

Colin Clayton  | 9.33PM, Sunday 6 March

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