Cooling Systems
General
The following features are necessary in the cooling system.
An intake thru-hull strainer (seacock cover) must be screened to prevent entry of foreign objects and must not be aligned (in relation to direction of travel) with the propulsion engine intake. See Figure 6-11. The recommended thru-hull strainer should be flush mounted. Strainers with slotted holes must be installed with their slots parallel to the direction of vessel movement. The area of the strainer opening(s) must be equal to or greater than the inside diameter of the waterline hose to the seawater pump.
An intake thru-hull strainer must not be of the scoop or cup design. This style can cause a ramming effect and force water upward, past the seawater pump, and into the engine cylinders when the vessel is moving and the generator set is shut down. Hull designs incorporating sea chests are also not suitable for intake thru-hull strainers. A sea chest is a concave molded-in-the-hull chamber that is also aligned to the direction of travel. A sea chest configuration applies a positive pressure similar to a scoop-type thru-hull strainer.
A seacock is to be mounted to hull, assembled onto the intake and accessible for operation. Figure 6-12 shows a typical installation. Install the canvas on the outside of the hull, and the canvas or rubber packing on the inside of the hull.
If caulking is used to seal the seacock, be sure not to apply an excessive amount. Excess caulk can cause improper water flow and in some cases develop a barrier which can force water upward, past the seawater pump, and into the engine cylinders when the vessel is moving and generator set is shut down.
