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Correcting a list

Our 55 foot narrow boat has a slight list to the starboard side - probably about 1.5°. Various 56lb and 20kg are already deployed on the uxtor plate and front locker. My guess, from getting people to stand on the gunnel is that I need about 200kg of additional ballast. It has been suggested I could put some steel ballast on the base plate on the bilge which wouldn't be a corrosion hazard because of the grease in the bilge. Any thoughts? Should I consider lead ballast?

Asked by: Clive Dutson  | 5.33pm, Monday 8 September


WW says:

It does indeed sound as though your boat is incorrectly ballasted. If you have an accessible section of floor on the port side it will be best to investigate the type of ballast fitted on the base plate. Most narrowboats are ballasted with concrete slabs fitted between the floor bearers. If you find that the area uncovered is already full of slabs your only alternative is to remove them and replace with a higher density material such as steel or lead ingots. Lead is the highest density material that is readily obtainable in sheet form for roofing, and will not need any protection; whereas steel slabs should be painted to resist corrosion, and positioned on pieces of rubber mat to prevent movement that can lead to annoying rattles whilst under way.
Another option is to remove ballast from the starboard side, which is worth considering as adding more ballast will cause the boat to sit deeper in the water; or a combination of removing ballast on one side and adding to the other.
It is much better to have the ballast evenly distributed along the boat rather than at the ends; sorting out the problem properly will release storage space in lockers. The gas locker especially should not be filled with items that could block the drain holes.

Rupert Smedley  | 1.03PM, Tuesday 9 September

Galvanised chain will react in the presence of stainless steel, and you may find both pitting on the stainless (depending on the type of alloy) and that, eventually, the glavanised coating will react away, leading to corrosion of the chains directly. Galvanised chain in itself loses the zinc coating without other metals being present- plus contact with the hull brings in a three-metal system (plus your anodes) which might not be a good idea for galvanic corrosion.
You would also need a prohibitively expensive amount of chain, and it would potentially cause some issue of clattering!

Mark Langley  | 4.19PM, Tuesday 9 September

A section of floor can be cut to make an access hatch. It is always a good idea to be able to get to the bilge to check that everything is OK. So often it is completely sealed with no ventilation.

Rupert Smedley  | 4.46PM, Tuesday 9 September

Plastic coated lead sounds good.
A section of concrete slab 1m x 0.5m x 50mm will weigh about 60kg, and an equivalent amount of lead will weigh 284kg. Therefore if you can remove that amount of concrete ballast and replace it with lead you can easily achieve your estimated 200kg of extra ballast.

Rupert Smedley  | 5.12PM, Wednesday 10 September


Readers say:

The ballast is indeed concrete slabs but their is no access to adjust it. I think I'll just have to go for the lead option. Another suggestion is to put chain in space between the stainless steel water tank and the hull on the starboard side. Am I right in assuming galvanized chain would not cause a corrosion problem?

Clive Dutson  | 4.14PM, Tuesday 9 September

I can't see that cutting out a section of floor would enable me to make the amount of adjustment needed. Standard chain would be no better presumably? Any issues with plastic coated lead ballast other than the price?

Clive Dutson  | 7.45PM, Tuesday 9 September

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