MATERIALS

Water Tanks can be manufactured from either stainless steel, aluminium, polyethylene or flexible fabric. All these materials are quite suitable but do have their own advantages and disadvantages. Modern mass produced boats such as Jeanneau and Beneteau will have almost certainly have rotationally moulded polyethylene water tanks that can be black, blue or white(natural) in colour.
Boat builders manufacturing boats in smaller quantities may not have invested in expensive tooling to produce moulded tanks so will be having them fabricated individually by specialised companies such as Tek-Tanks who fabricate polyethylene tanks from flat sheet or The Tank Company in Poole who specialise in stainless steel or aluminium water tanks.

TANK CONSTRUCTION

Water tanks normally contain baffles which help prevent excessive movement of the water inside, the spacing of which will vary with the type of material used. A Tek-Tank polyethylene water tank will have a baffle spacing between 250mm and 350mm with each baffle having a hole in the middle so adjacent compartments can be accessed for cleaning and inspection. A stainless steel water tank will generally have less baffles with a spacing of about 500mm.

TANK POSITION

Water tanks can be situated anywhere on a boat but are commonly found either situated centrally, or, one each side of the boat to keep it balanced. When they are mounted each side of the boat they are normally joined together with a balance pipe of about 1″ in diameter which keeps both tanks at the same level. If the balance pipe is too small it can take a long time to fill because the water is unable to transfer quickly enough from one tank to the other. The feed is often teed off this balance pipe. A balanced system also only requires one level indicator assuming the two tanks are at the same height in the boat.

TANK FITTINGS

The filler is normally 1 ½” in diameter but on larger tanks can be 2″. The hose used to connect the fill point on the tank to the deck filler can be a clear braided hose or a green tinted delivery hose. It is important that all hoses used in a water tank installation are of good food grade quality otherwise a “taste” may develop from the hose itself.

The feed and vent pipe is usually ½” in diameter to suit available pumps and deck fittings. Other sizes can be used but it is worth checking with the pump manufacturer first.

The actual fittings that connect to the hoses are called hosetails and are barbed so as the pipe cannot easily come off. The hose is simply pushed onto the hosetail and tightened with a jubilee clip.
1. Fuel tanks
2. Water tanks
3. Grey water tanks
4. Waste tanks