Trojan Boat Forum

I posted some questions a month ago about the type of MSD system I have on my 1985 10 Meter Express and received a lot of responses and I thank you all. To a lot of peoples disbelief it winds up I have a Mansfield vacuum flush toilet with a model TDX-S treat and discharge system not plumbed to the built in holding tank, overboard discharge only. Holding tank is not plumbed at all nor is there a deck pump-out fitting. I know it's odd but that's the set up. I know where the tank is located and its untouched. Living in NJ there is a no discharge law statewide on inland waterways so this system is not an option plus the control module is shot. This weekend I plan on eliminating the system and converting to the holding tank and installing a deck pump-out fitting. I'm keeping the toilet system though.

I've searched this forum for anyone who has done this but have not found one. I'm sure it's in here somewhere but I cant seem to locate it.

My questions are as follows:

1. Has anyone else done this.
2. How thick is the holding tank lid.
3. Will standard 1.5 inch 90 degree threaded elbow fittings for the fill and pump out be sufficient diameter. Is a broader sweep needed on the fill fitting to eliminate back up from the force of the vacuum flush at the bend or should I install straight fittings and run the fill hose straight in from above (my choice). Where can I pick up these fittings, can't seem to find them locally in Monmouth/Ocean County even at West Marine. Internet search was deceptive regarding use in a holding tank. Livewell fitting abound but are they ok for this type of use.
4. Will 2 vent lines be needed for the force of the vacuum toilet or will one 1" suffice.
5. Is there another type of fitting available that doesn't need an inspection port to get to the nuts on the threaded portion of the elbows in the tank such as a flanged fitting I can screw onto the tank top without needing a nut on the inside.
6. How was the pick up inside the tank set up for the pump out elbow.
7. Is anything else needed for this install besides a fluid level indicator and what problems should I expect to encounter.

Thanks for any help.

Last year we replaced our system piping and I noticed that sealand has what appears to be a very convenient install....a tank that has all the works with it on top that you need,had I not of had all the other stuff already (vac pump,vac tank etc), I would have gone with that....check it out ,if your current tank is removable maybe that might be the way to go, maybe save a lot of trouble ....

I just changed my lines too and one thing I liked with new systems is the holding tank input and output come through the top of the tank only.
More importantly is the output. Rather than have the output at the bottom of the tank it should come down vertically with a pick up tube from the top of the tank. If it's in the bottom, the liquids will sit in the pipe up to the equilibrium level of the holding tank. This will generally cause odor permeation faster since the pipe will continuously have liquids in it. When you say your tank is "untouched" I would recommend having both input and output in the top of the tank only.

The tank is part of the boat. It's built into it between the stringers on the centerline and bulkheaded in fore and aft between the engines. There's a fiberglass lid on top sealed and screwed down. The inside of the hull bottom is the base of the tank. It has to be plumbed from the top, no other option. I was wondering about the fittings but thanks and I agree that the top of the tank in any install is the smart way.

Check out uniseal fittings. They are a large rubber grommet type fitting that allows you to hole saw the tank top and push pvc pipe or pvc pipe fittings through to make a water tight seal. I used one of these to fix the broken vent fitting on my ten meter express holding tank last year. The company I work for manufactures toilets and plumbing systems for superyachts and we use these all the time.

I suppose if it were me, I'd be very tempted to pop the top off the unused holding tank and if possible, insert a Sealand HTS system right inside that cavity.

I believe these HTS systems include everything you need. (The vacuum generator replaces the cylindrical vacuum tank)

I believe Sealand manufactures these HTS systems in three sizes - a small (almost useless) ten gallon unit, an eighteen gallon model plus one that holds forty-two gallons.

Vertical height required for the smaller ten gallon tank system is 16 1/2 inches, the eighteen gallon tank requires twenty-two 1/8 inches. Finally, the forty-two gallon unit needs vertical clearance of twenty-five inches.

When I had two Sealand vacuflush units installed in my former TriCabin, I thought seriously about an HTS system. Due to dimensional issues, I ended up going with custom fibreglass holding tanks connected to a pair of vacuum generators and thus avoided the need for the cylindrical vacuum tank.

Failing all of the above, I would install a custom tank with dimensions most favourable for the space available. Then I would install a vacuum pump and tank nearby.

Those are just my ideas. For whatever reason, I don't favor going with a holding tank system that uses the boat's hull as active participant.

Good luck with whatever you decide to do.

Rick

If you do in fact have the original 10 Meter Express with the built in holding tank between the stringers, it holds 40 gallons.

I am one of the few who has removed this lid, and can help you with plumbing details.

My lid had to be removed and re-set due to the overuse of formaldehyde chemicals softening the factory RTV sealant.

Removal of this lid was no easy task. Do not do this unless it is deemed absolutely necessary.

RWS

Here's a shot of the top of the tank, plumbed.

This pix was taken during the diesel re-fit in 2005

The vent goes to the port side.

I added the bung for inspection purposes, and to aid when I need to do a "clean out"

I replaced the macerator with a second vacuum pump.

Hope this helps,

RWS

For those who are curious, here's a couple of photos of the inside of the tank with the baffled lid removed:



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Well I spent about 8 or 9 hours yesterday taking care of this. I removed the old system and kept the toilet system like I planned. It winds up that the built in tank lid is fiberglass on both sides with 1 inch thick plywood sandwiched in between and a total thickness of about an inch and a half or more. The threads on the fittings I bought were not deep enough so I used a larger hole saw and went through the outer fiberglass and the plywood and stopped there so I could get the fitting on the interior tank fiberglass which allowed me to get the nuts on. The small void where the plywood was exposed was filled with 5200. It worked out fine . I put three inch and a half straight fittings in and fed hoses from the top straight down with no bends other than in the hoses. The pump out fitting has a short piece of hose connected to it touching the bottom of the with the end cut on an angle. I am going to use a one inch reducer for the vent line. All I have left is to secure the access plate, secure the deck pump out fitting and install the vent hose.
We'll see how it works out and I will post that. As far as putting a tank or other system in the hole it will never fit if the dimensions you stated are needed. It's only about 12 inches deep about 30 wide but it tapers with the shape of the hull. I also like having this area flat and accessible to work on the front of the engines so any system protruding above what is now the top of the lid will be in my way.
Thanks to everyone for their input.

Blueflu - You're absolutely correct, after seeing the photos sent by RWS, I understand the situation better. I had the wrong impression about where this holding tank was located. Looks like you have things well in hand. Good luck with the final work on the install.

RWS You did a really great job on that holding tank.

By the way, (RWS) did you happen to receive those photos of my 370 express that I emailed you last fall? My subsequent emails to you have refused to leave my outbox.

Rick