The Hole:  After removing all the wood trim, thus increasing the size of the hole to exactly the same size as the diameter of the original water heater; then removing a couple of valves attached to the old water heater, with it still deep inside this compartment, it narrowly fit out this opening (rubbing on all four sides).

Engine coolant flows through this heater to warm the water when without 115 vac, so the bilges were filled with coolant.  There's no way to catch all the coolant, but most of it can be removed through the engine before this process is begun.  Make sure the power is off, the water tanks are secured, and the fresh water pump is off before you start disconnecting stuff.  Don't even think about running the engine until the coolant has been replaced.

The Mounts: I decided to install a square water heater in the square hole, unlike the folks at Catalina who thought it would be cool to install a round one with valves and pipes sticking out of it.  The mounts here are made of PVC I bought at Lowe's Home Improvement.  It is actually used as a wood trim substitute.  It comes in 1x6 and 1x8 of various lengths.

They're held in place with a water proof version of liquid nail and stainless steel screws.  (don't stick screws through the bottom of your hull!!) I have confidence that these mounts will last damn near forever.

Bypass Manifold:  The new water heater has an aluminum heater core.  If you ever intend to use anything more harsh than water and coolant to flush your system you're going to need a bypass manifold to isolate the water heater.  In the event the water heater core develops a leak, it will allow you to run the engine without losing coolant into your water system too.  Here it is... All brass in this case.  I didn't see the need to go for bronze as it "should" never come in contact with salt water in any significant quantities for any length of time.

Mounted:  Notice, I mounted a piece of spare teak between the manifold and the PVC.  Engine coolant will be going through it and PVC starts getting soft at around 110 degrees Fahrenheit.  The wood will prevent the hot metal from contacting the PVC directly and provide a little insulation to prevent any melting.

Note:  Ran the engine for 6 hours going up the St. Johns River.  No problems, my theory has now been proven functional.

Plumbed and Wired:  This step is pretty straight forward.  Follow the directions that came with the water heater, hopefully you labeled the lines before you disconnected them or shortly there after, while you still remembered which is which.  If you didn't...  It's much easier to trace them to their source before you fill the hole with the heater.

Manifold?  Good thing you won't need to use this very often, it's in a pretty tight space.  I'd have mounted it higher, but the hoses would've interfered with the drawer directly above.  As with anything on a boat, it is a compromise.  This is the best compromise in my case.  Besides, it will give the next owner something to bitch about.

Now, with everything hooked up, is a good time to turn on the power, start the fresh water pump, fill the tank, bleed the air, check for leaks and wait for warm water.  Don't forget that engine coolant.  Fill it, start the engine and look for leaks.  If everything is good, you're awesome.  I had two leaks, that makes me just a notch below awesome, fortunately a simple hose clamp tightening in an easily accessible location fixed them both.

Done!  The wood is attached, the holes are filled, the water is warm.

The Final Tally:

Water heater:  $250.00

Brass Fittings: $30.00

PVC:  $40.00

Screws/Hose/Liquid Nail/etc...  $50.00

Grand Total:

$370.00, two bloody knuckles, and 2 days labor

A small price to pay for a warm shower.

Back to Projects