1990 SeaRay Express Cruiser - Draining Fresh Water Tank To Winterize

[Craig Lescombe]

Hello Folks - First time winterizing this boat as previous owners stored in an indoor heated facility. 70 gallon fresh water tank. Ran all outlets and drained to the 3" height mark, before outlets sputtering occurred, on a tank measuring L80" x W24" x H13". Doing the math leaves me with approximately 16 gallons in a 70 gallon tank. I have read all the previous info / posts info hand in hand with this topic and other than jumping through hoops to completely drain the tank, it is what it is.
The question being, can anyone approximate / recommend how may gallons of -50 degree celsius / - 60 degree fahrenheit anti-freeze I should add to prepare for maximum lowest winter temperatures of -10 degree celsius / + 14 degree fahrenheit? I ask because what I do pour in will get somewhat / considerably diluted by the freshwater left in the tank.

Thanks - Craig

 

[northern]

Our water tank empties to the point there is perhaps 1/2" water in it. At that point we do nothing with it. Sounds like you need to replace the suction hose on the tank. I once put Pink propylene glycol in the water tank and it took many flush to clean it. One boat forum an owner used vodka as winterizing fluid. In Anacortes you can get 1.75L of really cheap vodka on sale for $10 US. I had one drink of it and had a very bad headache next day clerk at store told me she uses it for cleaning.

 

[Craig Lescombe]

Completed the job this morning and here is what Thanks I did: I cut the hose from the tank 12" before the input into the pump and installed a t fitting whereas I switch one way to pull from the tank to utilize as normal and also drain the majority of the water from the tank when winterizing. Then I attached a separate 18" input hose to the other t portion where I can switch to pull directly from antifreeze jugs to winterize all the fresh water lines (galley, head and rear washdown tap), without having to pull from the tank. All done, utilizing less than 3 jugs. As to the water left in the tank, I will treat and flush the whole system in the spring several times to bring all up to potable / drinkable.