Winterizing season is here. Winterizing a boat.

[BB marine]

The use of RV antifreeze needs to be selected based on its use. I recommend using a quality Propylene Glycol non toxic antifreeze. The -50 straight out of the bottle has a slush point of +15. This is were it starts to freeze. This is 100% pure with no water mixed. The bottle says -50 is the burst point. If you are winterizing a fresh water system it is best to make sure that there is little to no water left in the system or use a couple extra gallons of -50 to flush the system to make sure the concentration is straight Anti-freeze. Most parts of the country will not see temperatures much below zero. So most winterizing with a small amount of water mix in the -50 will keep the burst point protected to -5 to -10. Probably ok. When I do fresh water system winterizing I drain the water tank and hot water tank completely. I do not put antifreeze in the water tank. I make up a hose connector that attaches to the water pump suction side to suck the antifreeze out of the bottle. After draining the hot water tank, I disconnect the cold water line into tank and Hot water line out of tank. I made up a jumper line to attach the two lines together. This by-passes the water heater tank. I then turn the fresh water pump on flushing the water system with straight -50 poly propylene antifreeze. I open each faucet one at a time cold first then hot, waiting until I see a full concentration of pink antifreeze. I then check the overboard drain to confirm antifreeze has made its way through the drain and filled any low spots with pure -50 antifreeze. I will use a refractometer to check that I have a straight concentration of antifreeze coming out of the faucet.

For winterizing the marine air, raw water wash down, head, and raw water cooling of the engine and generator I use -100 Propylene glycol. This product has a freeze point of -30 based on my testing with a refractometer. Using -100 is more forgiving when there is a possibility of mixing the antifreeze with water. If there is some dilution the bursts point should still be -30F or lower. When it comes to expensive equipment an few extra dollars for better protection anti-freeze is worth the peace of mind!

I will do the engine first then generator. Start the engine and let it run so it is not running on a cold start when you suck the anti-freeze into the raw water cooling. If you are winterizing in salt water application this is a good time to run the engine on fresh water flushing before exchanging the water with anti-freeze. Close the seacock, remove the stainer lid and basket drain the water out of the strainer, reinstall the strainer drain plug. Fill the strainer with anti-freeze, pour 3 to 4 gallons of antifreeze in a container that gives me the ability to pour the antifreeze fast. ( trying to pour out of the bottle is to slow!) The seawater pump will pump about 5 gallons a minute at idle. This is not going to take long. After 3 to 4 gallons has run through the raw water cooling, shut the engine down. Pull the muffler lift can drain plug and confirm a good concentration of anti-freeze is present. I use a refractometer for this. I drain a small amount of antifreeze so I can inspect the concentration and install the plug quickly. (less mess) Repeat the process with the generator.

Head, Marine air and raw water wash down: Close the seacocks. If there is a strainer remove the lid and basket.If the boat is used in salt water this is the time to flush with fresh water before adding anti-freeze. Run each component long enough to get a good fresh water flush. After flushing, drain the strainer and pour straight -100 in the strainer. If there is no strainer. Remove the hose from the seacock and place it in a bucket for flushing and antifreeze. Flush the head until a straight concentration of anti-freeze is present in the bowl. Once you see a straight concentration in the bowl you will know the suction side of the system is protected. Now pour a half gallon of antifreeze into the bowl. Flush that until the bowl is empty. This is filling the black water side lines with antifreeze. I then pour enough antifreeze in the bowl to make a water seal so that waste gases don't exhaust out of the head bowl (water trap).
Marine air, I use the water pump to do the work, fill the strainer with antifreeze and have a method of adding the anti-freeze quickly, It does not take long to flush antifreeze through the system. Once you see a good concentration of anti-freeze exhausting out the the hull fitting you are done

The raw water wash down use the same procedure. if you have a refractometer test after each system for peace of mind.

After completing the winterize procedure reinstall hoses removed, check all clamps and fittings to confirm they are tight and ready for spring summarize. Place a tag on the engine start button, sink faucet or water pump breaker, hot water tank breaker, and raw water wash down pump breaker. The tag should read winterized, drained, seacocks closed do not operate.I also place clear plastic wrap over the head seat with a tag Do not use.

This is a complete boat winterize procedure that I used for years. This procedure was used when I winterized customers boats and my own. It needed to be bullet proof. I did not want any issues when summarize season started. I can honestly say I have never experienced freeze damage to any boat that I winterized. Over kill maybe but piece of mind!

I had several other procedures added to my winterize program that were preventative maintenance, yearly or hourly maintenance items. I thought the freeze damage portion is redundant to all inboard applications and outboard models with the exception of the engine winterize.

 

[Horigan]

Good stuff. One clarification. A solution of water and antifreeze/coolant has a lower freezing point and higher boiling point than either in the pure form. That’s the interesting thing about solutions. Similar with dissolving salt in water.

Edit: In practice though, it’s difficult to get all the water out of some systems, so adding pure antifreeze results in a low freeze point solution. This obviously works given the experience above.