New Holding tank questions

[Blitz]

Hello all,

I've been looking to replace my holding tank for some time. This was delayed due to thinking hard about installing a Electra Scan and smaller holding tank but the costs, electrical and space limitations on that has evolved to just putting in the largest tank I can fit without major modifications.

I'm able to fit a 25 gallon tank under my v berth without cutting it up. I built a mock up and the tank is something like 20" w x 30"l x 10" tall and will fit well. I'm going to go with all tank penetrations on the top of the tank since the 10" height will allow for this.

In deciding on the vent I'll go with a 3/4" dia vent mounted on the center line of the new tank. The vent thru hull to replace the one I have (which is the original 1/2" screened fuel vent style) will be a groco 3/4" SS model mounted near the bow. Is there any issues with using SS or would marelon on or plastic be better? Not sure if one might be corrosive with gasses.

The new tank will need at least two 1-1/2 connections, one coming for the head discharge (manual Raritan PHC in my case), and one dip tube style for the pump out. I'm also thinking about a third dip tube style outlet for a macerator discharge for when I'm allowed to (or maybe manual pump since it won't be that often). Should I peruse this?

My y valve after the head allows for direct discharge or to the holding tank. I'll remount this y valve closer to the head for easy adjusting without digging under the v berth to change the discharge. I'm thinking of a Bosworth flush mounted valve assessable near the head or in a locker.

I'm thinking of a 4" inspection port in the tank to allow for cleaning.

My tank will be about 8" above the discharge thru hull. I'll try to eliminate any low spots in the hoses to avoid odors.

I'm posting this just to see if anyone has any thoughts or concerns in what I've laid out. What did I miss?

 

[WayneH]

I am replacing my tank this year. What the Admiral and I decided on was to remove the Y valve entirely and route the head to the tank directly.

Then off the dip tube connection we are putting a T with one leg going up to the deck pump out and the other leg going to a manual overboard pump out. Which relieves the worries about which way the Y valve is set at when boarded by the CG. Because the manual pump out and its through hull are sealed until usable.

I actually got the idea from a friend's boat. His tank had a bottom outlet and immediately T-eed to the macerator and the deck pump out. He thought he had to run the macerator to pump out his tank. But he left the macerator through hull closed. Hmmm?

My original tank had a second 3/4" attachment for a wash out line. The bad part was all four ports were on the end of the tank. The new tank has them all on the top.

YMMV.

 

[All U Get]

Loop

Hello all,

In deciding on the vent I'll go with a 3/4" dia vent mounted on the center line of the new tank. The vent thru hull to replace the one I have (which is the original 1/2" screened fuel vent style) will be a groco 3/4" SS model mounted near the bow. Is there any issues with using SS or would marelon on or plastic be better? Not sure if one might be corrosive with gasses.

QUOTE]

My vent hose has a loop at the thru hull to keep out the seawater when the bow dips into the waves. I also set the tank on some neoprene to cushion it against the frame and hull.

All U Get

 

[dparilla]

I personally used a 1 inch marelon through hull for a vent, having seen corrosion build up on metal ports.

 

[Blitz]

Then off the dip tube connection we are putting a T with one leg going up to the deck pump out and the other leg going to a manual overboard pump out. Which relieves the worries about which way the Y valve is set at when boarded by the CG. Because the manual pump out and its through hull are sealed until usable.
YMMV.

Thanks - that is a good idea. I would like the keep the option open for direct discharge for coastal cruising though.

Attached is a picture of my bow with the current 1-1/8" SS Thru-Hull for my anchor locker drain and above that the current corroded Perko type holding tank vent which I hope to replace with a 3/4" SS Thru-Hull.

 

[Bill1565]

Just a thought . If you have two dip tubes you will not need a Y valve.

 

[Blitz]

Dip Tubes (1 or 2)

Just a thought . If you have two dip tubes you will not need a Y valve.

True, if I went only from the head directly to the tank and removed the option of directly from the head to the thru hull for direct discharge overboard (outside NDZ limits) or for misc rinsing.

Putting the two dip tubes in now would give me options.

 

[BioAndy]

Another thread in this forum that may be useful:
http://forums.sbo.sailboatowners.com/showthread.php?p=1044723&highlight=

 

[Blitz]

Threaded outlet in holding tank - dip tube fabrication

I'm looking at ordering the tank as soon as possible.

My remaining questions that comes up are on the fittings to install a dip tube. Should I be ordering a tank with the 1.5" outlets installed or cutting them myself and installing a Sealand Dip tube. I'd rather have the tank fittings already installed and threaded but I don't see a dip tube kit for this - The Sealand dip tube are for cutting my own holes into the tank.

Maybe could fabricate something with PVC? Like an all thread pipe through the tank fitting to attach inside the tank to a tube and outside the tank by a female elbow to hose connection. The problem being finding a 1.5" PVC all thread...

How is everyone installing dip tubes for already threaded outlets in your holding tanks?

Thanks again

 

[BioAndy]

How is everyone installing dip tubes for already threaded outlets in your holding tanks?

Thanks again[/quote]

I'm not an expert, but I didn't see any options for a threaded dip-tube installation when I replaced my waste holding tank. I did go with the Sealand Dip-Tube kits, which only requires a hole saw of the proper size to bore the hole in the plastic tank to accept the rubber grommet which the dip-tube slides thru.

I was a little apprehensive about this sealing arrangement, but after an entire season of use, I can report no leaks (or smells) originating from the new holding tank intallation.

Andy