View Full Version : 35' Kingscraft water tankage- strange issue

03-13-2015, 03:54 PM
I recently installed a new pressurized water pump and redid some of the plumbing in our new-to-us Kingscraft 35. We hadn't been using the old system at all. When things seemed ready, we filled the tank for the first time since we've had her. It all seemed to go well. We filled until water came out the vent (and a little slopped out of the fill fitting and onto our deck too, heh).

I then flipped on the pressurized water, and again, everything seemed just fine. Yay, water at the sink finally! I pumped it dry... with the idea of putting in several fills and emptying them. As I was doing this, I started timing how long it took to pump the water out of the tank. Based on our pumps rated max flow, it seemed like we were pumping the water out faster than we should. So I did a little more rigorous testing, and I've discovered that we can only pump out about 61-62 gallons out of our tank.

So here's the issue. All the specs for this boat I can find say we should have a 125 gallon tank. The tank is built in to the boat, in the keel. There is no inspection port... there are just 3 welded-into-place pipe nipples sticking up out of the top of the tank. 1 for the fill, 1 for the vent, and 1 for the pump intake.

So I see three possibilities. The pump intake could have a hole in it about halfway up inside the tank. The tank has a *whole lot* of buildup. Or for some reason our tank was made with only half the rated volume. Anyone know anything about these boats? I'm thinking about cutting an inspection port into the top of the tank, but it's not a job I really want to do if I don't have to.


03-13-2015, 04:24 PM
Get a 5 gallon bucket and time fill it to see if your calculations are valid.

03-14-2015, 09:15 AM
Maybe the tank was changed out in prior ownership.

Every year a fresh water tank should be (I forgot the word Miss Peggy would use) cleaned / sterilized . Meaning I would pour a quart of bleach in the tank, fill it, pump it down, and repeat several times. Then on the last fill add a quart of lemon juice to fill the beach smell.

03-14-2015, 09:33 AM

The fresh water tank on a KC is the sealed keel.

03-15-2015, 07:11 AM
Get a 5 gallon bucket and time fill it to see if your calculations are valid.

Yep, that's the exact thing I did when I did my "more rigorous testing". Total time from full tank til sucking air with the pump, divided by the time to fill a bucket, times the volume of the bucket. :)


03-15-2015, 07:55 AM
Great minds tend to go down the same path:)

03-15-2015, 01:27 PM
Thanks. :) I wish I knew what the heck was going on with my tank... maybe I'll just put in plastic tanks in the bilge and be done with it.

03-15-2015, 04:53 PM
65 gallons is a lot of water. Try it the way it is first. Over 500 pounds.

03-21-2015, 08:51 PM
Couple of things... first, I'm mostly worried about the tank being half full and not being able to be fully emptied. It would cause problems for say, cleaning the tank with bleach. A lot more cycles to get enough of the bleach out to make it safe.

The other thing is... while this houseboat is new-ish to us, we've actually been living on boats for 3 years, year-round (also off-and-on for the prior 5 years). 65 is a lot of water when we have easy access to fill the tanks... but if you have to ration it out to last a couple of weeks, that's tough. We had 230 in our previous houseboat (it started with 120 and I added another 110). That was great... about right for me, my wife, and our three dogs when we had to go up to 17 days at times between refills. We tend to do our dishes, rather than use throw-away plates and cups. It goes quicker than most people realize.

I have an aluminum welder coming out Monday to see what it would take to install an inspection port into the tank. :)

Miller Tyme
08-15-2016, 08:33 AM
See if you can snake a smaller diameter pipe down you pickup line and try pumping from it. If uou pickup nipple is 3/4 " a 1/2" copper pipe should fit down inside. Might be the simplest solution to your problem.

10-22-2016, 09:10 AM
I have owned 3 Kingscrafts and just simply love them. The water tanks are part of the keel as you mentioned. I would not bet all my $ on it being 125 gallons since they welded these boats and it all varies, or the pick-up tube actually reaching the bottom. Cutting an inspection hole should be easy enough. Just make a plate with 4 holes and tap the water tank top to mount. Personally on our current 55' Kings, I shut off the keel tank and mounted 4, 25 gallon plastic tanks in series. 100 gallons is plenty for us, and it has no metallic taste. Also have to watch these original keel tanks for corroding through. Then you will have an eternal supply of water, albeit, not so fresh.

10-24-2016, 04:24 AM
I wouldn't use a copper pipe in an aluminum tank. Consider CPVC, it's the same size.

You can get plastic inspection ports or deck plates from any marine supply, seal in the rim with silicone or 5200. You can cut the hole with a jig saw.

When I lived aboard I installed a seawater system, used it for washing dishes (rinsed with fresh) among other things. It definitely saved on potable usage.