Thursday, October 11, 2012

Easier Winterizing

rev. 11-30-2012

I'm not clear why a boat made in Canada came without the most basic provisions for winterizing.


The Head

Since I stay in the water all winter, I need to be able to winterize every hose. During the coldest weeks I flush with a weak glycol solution, so the down stream portions are no concern. I pump-out before it gets too cold for the stations to close and generally make it until they thaw. However, the suction side presents a problem. Additionally, I've had occasional trouble with sea grass fouling the intake valve on the head pump. Two years ago I installed a simple Y-strainer, which solved the clogging problem, but it was very difficult to clean; the lid would stick and the location and leverage were terrible. About a year ago I replaced the intake hose, upgraded the strainer (also a freebe) and moved it to a more convenient location in the holding tank compartment, and added a glycol addition fitting. No more clogs and 5-minute winterizing. Yes, the fittings are light-duty (SCH 40 PVC), but this is 30 inches above the waterline in a bulkheaded compartment. Corrosion resistance and scaling resistance seemed more important.

To winterize the sea cock side:
  1. Place the head pump in the locked position.
  2. Clean the strainer, if you think it's due.
  3. Open the sea cock.
  4. Open the blue valve and add ~ 1 quart of glycol from a jug on deck (it also has a drain valve).
  5. Close the sea cock.
To winterize head side:
  1. Open the blue valve.
  2. Unlock the head pump and pump until you see red.
  3. Close the blue valve.
Why red instead of pink? I use ethylene glycol (EG) antifreeze on the head system:
  • I get it for free (we make it).
  • The affect on the sewage plant is less than for propylene glycol (pink non-toxic, AKA PG) because less is needed (PG is less effective, on a percent basis) and they biodegrade at the same rate.
  • Ethylene glycol is NOT more toxic to fish or the environment. It is only more toxic to mammals. Don't take my word for it--read the MSDSs.  
  • The head side is most certainly not potable!
  • EG is less harmful to the hoses and joker valve than PG. Just a little, but that is one of the reasons propylene glycol is not favored by automotive OEMs. On going testing also suggests that PG is tough on the neoprene joker valves common in Jabsco heads. Raritan and Groco use nitrile joker valves, which are more resistant. Since these valves are interchangable (identical dimensions) you could always use a Raritan joker valve in your Jabsco head.
The Pressure System

Adding just a few valves made this into an easy one-gallon job. 15 minutes, tops.
  1. Pump the tank empty. Remove what remains by bailing with a cup or with a shop vac. No glycol in the tank.
  2. Close the valve to the left of the strainer. 
  3. Open the valve to the right of the strainer and place the hose in a jug.
  4. Open every tap on the boat, both hot and cold, and let run until glycol comes out. Have a jug handy to catch any extra.
  5. Once the jug runs empty (most likely before you are finished), let it blow air through the pipes for just a few minutes. Open every tap you have winterized and catch what comes out. It will be enough for the rest of the boat. Don't forget the transom shower.
  6. Close the glycol valve.
  7. Remove the strainer, clean, and put a little glycol in it. Yeah, I could just leave it off, but I know I'll forget in the spring and get a slight flood.
Only non-toxic propylene glycol on the potable side, obviously.

After reading Mike's link, I figured I should add these. I've also posted winterizing stuff here.

Shower Drain

I guess I might as well mention this, while on the topic. Pour about a quart in the drain and pump.


They're all hose and drain anyway. Skip it.


They drain if raised.


 The previous owner blew out lines and disconnected lines. I spent a season chasing leaks in connections that had been opened too many times and replacing cracked fittings on the water heater that didn't quite drain. This is MUCH better. The only thing lazier would be wintering in Grenada....


  1. Nothing really to add since I'm wintering in Grenada except that I read and enjoy your blog for some time - really great work :-)

  2. Hey, don't knock the Grenada thing until you try it!

    Did you ever see this post?