Help! I think my engine wants to experiment with Seawater!

You've done your best for engine; nurtured it through sickness, given it sustenance and nice things, and a steady home. Its almost ready to go out into the world on its own however, and you're worried it may be lead astray.  You know other engines in the area are ingesting copious amounts of seawater almost every weekend, and stories of ruin and self-destruction are rife. You're worried, as anyone would be!

Ultimately the cost of depriving your beloved motor the "salty" (one of seawater's many streetnames) may cause greater damage than it trying it (and recovering afterwards) with you present. By being responsible and setting boundaries early, you can make its seawater habit far less dangerous and prevent your loved one's slide into ruin.

 Sorry about that, I assure you the substance abuse analogy is now over. Its implication cannot be overstated however, seawater is horrible stuff and you need to protect your motor from it!

Here's a very simple way that I used on my boat. The main 1" seawater line has a T-piece going to a barbed 1/2" hose fitting, with a tap mounted above that. A garden hose can thus be connected after a voyage and used to flush out the horrible, evil, marriage-destroying, demonic, pernicious, insidious... SALT WATER that hides in every pore of your cooling system. The elbow (on the far right) is around 1" higher than the inlet, so that that length of hose will have plenty of water in it, and therefore the pump in the engine won't run dry. NOTE: If the hose tap is left open when you next launch, the pump WILL run dry (or at least suck in lots of air and become very sad), so exercise caution if you implement a similar system.

The hole in the hull was drilled with a spade bit, and then the thru-hull was fitted with both an opposing nut and large amounts of thickish epoxy glue. The epoxy should bolster the mechanical strength as well as provide a watertight seal, and once the excess was wiped off the fitting looked very neat. A large ball valve was fitted immediately after the hull fitting, so that if a hose splits upstream the water inrush can be stopped easily.

These connections (particularly below the waterline where they are under positive pressure) should have two stainless steel hoseclamps per join, and eventually they will. This is definitely not the place to use crappy, zinc-plated $5-for-a-10-pack clamps, as their failure could overheat the engine and/or sink the boat if they fail under certain conditions.

So, that takes care of the saltwater (urgh!) and freshwater flushing (YAY!) systems. Remember: You can't stop your engine engorging itself on the 'salty' when its out and about, but you can slow the effects of salt abuse when the boat's living under your roof. Rad!