Once a tank is installed, it may be built-in or removable, you don’t want to have to do anything to it again other than general maintenance so it is very important to do the job right the first time.  Diesel fuel tanks can be built from stainless or mild steel, aluminium or fibreglass. Water tanks should be stainless steel, aluminium or fibreglass. Never use aluminium for holding tanks as there are chemicals in human waste that may corrode the aluminium. Both fuel and water tanks can be purchased, pre-made in rigid or flexible synthetic material.  I prefer to avoid the use of petrol or gasoline as a fuel for boat engines, or for any other use in a boat but in some situations this may be unavoidable so, be sure you seek professional advice on any such installation and what safety precautions to take. Over the years there have been some bad accidents with petrol/gasoline installations so you cannot be too careful with this fuel.

   In fibreglass boats, fuel and water tanks can be made of fibreglass, usually built in to the hull under the floor or furniture – special resins are available for this purpose and, in the case of water, are tasteless. Fibreglass tanks are not difficult to make and can save a lot of money – consult your fibreglass suppliers or boat designer for details.   Don’t forget to correctly vent all tanks.   The pipe for drawing off the liquid should enter through the top of the tank and not quite reach the bottom. In the case of fuel tanks, there should be a little reservoir around this pipe to stop the fuel sloshing around when the tank is low.   If a drain cock is fitted, it should be easily accessible and at the lowest point of the tank.   There should be access holes, large enough to allow cleaning of the tank interior, in every compartment.  The tops of these access holes should bolt in place and be fitted with a sealing grommet or compound.  Thoroughly test all tanks with up to 3 pounds of air pressure and post cure fibreglass tanks for at least 24 hours with a light bulb.