I presently have a Thetford port a potty on my 28' sailboat, the holding tank capacity is about 6 gallons. The capacity is not enough for the extended (?) cruising I hope to be doing after my wife retires. Dumping that thing is not my favorite task either. Thetford makes a pump out device for it, which I think replaces the dump tube. Could I fit the pump out adaptor to the port a potty, and pump into a separate (larger)holding tank, or should I bite the bullet and go with a regular marine head with all the related problems I hear of?
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Gordon, Sometime back this sort of a question came
up and I suggested that a couple of tanks for his portapot might help. That way you can make the switch before the active tank is full (therefore lighter)and dump that at the convenient opportunity. It would also double your holding capacity at smaller cost.
up and I suggested that a couple of tanks for his portapot might help. That way you can make the switch before the active tank is full (therefore lighter)and dump that at the convenient opportunity. It would also double your holding capacity at smaller cost.
Several things you can do...
A 6 gal portapotty holds 50-60 flushes, which should be about 5-6 days for a cruising couple. So you may not actually need more capacity. But if you do, you can take Ross' suggestion and buy a spare tank...but I wouldn't be any more thrilled than you are at having to haul TWO tanks that weigh 30-50 lbs apiece off the boat to empty 'em. Or you can swap out the one you have for a model designed to be permanently installed and fitted for pumpout. Just replacing the "dump tube" with a pumpout hose won't work...the tank also has to be vented. But a pumpout hose and vent line are all the plumbing an "MSD" version needs...all the advantages of a toilet and remote tank with none of the downsides. If you opt to do that, you have a couple of choices: 1. put a y-valve in the pumpout line...one side to a deck pumpout fitting, the other side to a manual or electric pump and on to an overboard discharge thru-hull. 2. you can add a second larger tank--that will also have to be vented--and, instead of a y-valve the portapotty tank discharge line, just go straight through the pump and into the larger tank. The downsides to this one are a) the tank will occupy storage space you prob'ly need for other things for extended cruising...b) a lot of additional plumbing etc that will also not only occupy storage space, but require maintenance...and c) you'll have to put a y-valve pump in that tank's discharge line if you want to be able pump it out or dump it at sea. I'd stick with option 1, if I were you. I would NOT recommend replacing the sefl contained system with marine toilet and holding tank...a marine toilet uses a lot more flush water, which means you'd need a 25-30 gal to hold the same number of flushes as your portapotty...50 gallons to gain any real advantage over it. You'd also be trading in a system that requires almost -0- maintenance for on that requires quite a bit...and then there's all that plumbing and space lost to a tank.
A 6 gal portapotty holds 50-60 flushes, which should be about 5-6 days for a cruising couple. So you may not actually need more capacity. But if you do, you can take Ross' suggestion and buy a spare tank...but I wouldn't be any more thrilled than you are at having to haul TWO tanks that weigh 30-50 lbs apiece off the boat to empty 'em. Or you can swap out the one you have for a model designed to be permanently installed and fitted for pumpout. Just replacing the "dump tube" with a pumpout hose won't work...the tank also has to be vented. But a pumpout hose and vent line are all the plumbing an "MSD" version needs...all the advantages of a toilet and remote tank with none of the downsides. If you opt to do that, you have a couple of choices: 1. put a y-valve in the pumpout line...one side to a deck pumpout fitting, the other side to a manual or electric pump and on to an overboard discharge thru-hull. 2. you can add a second larger tank--that will also have to be vented--and, instead of a y-valve the portapotty tank discharge line, just go straight through the pump and into the larger tank. The downsides to this one are a) the tank will occupy storage space you prob'ly need for other things for extended cruising...b) a lot of additional plumbing etc that will also not only occupy storage space, but require maintenance...and c) you'll have to put a y-valve pump in that tank's discharge line if you want to be able pump it out or dump it at sea. I'd stick with option 1, if I were you. I would NOT recommend replacing the sefl contained system with marine toilet and holding tank...a marine toilet uses a lot more flush water, which means you'd need a 25-30 gal to hold the same number of flushes as your portapotty...50 gallons to gain any real advantage over it. You'd also be trading in a system that requires almost -0- maintenance for on that requires quite a bit...and then there's all that plumbing and space lost to a tank.
Thanks a bunch for the reply.
I've ruled out #3, that was easy. Looks like it will be #1 or #2. #2 was what I had in mind. I need to see what model of Thetford I have, and just how much storage space I use. It's not made real clear on the Thetford web site, but it looks like the MSD models can have any of 3 discharge pipes. 2 for deck pumpout, and one manual dump. It's not made real clear. Option #1 would save having to lug that tank unit through the boat, up the ladder, and down the dock. Would not resolve the capicity issue however, we will see. Thanks again Gordon
I've ruled out #3, that was easy. Looks like it will be #1 or #2. #2 was what I had in mind. I need to see what model of Thetford I have, and just how much storage space I use. It's not made real clear on the Thetford web site, but it looks like the MSD models can have any of 3 discharge pipes. 2 for deck pumpout, and one manual dump. It's not made real clear. Option #1 would save having to lug that tank unit through the boat, up the ladder, and down the dock. Would not resolve the capicity issue however, we will see. Thanks again Gordon
A couple of things to consider...
Your 6 gal system should last 5-6 days--a week if you use the lee rail whenever practical. It's unlikely that you can stay out longer than that on a 28' boat before you have to come in for fresh water, ice, provisions and maybe fuel too (not to mention a REAL shower with plenty of hot water for a change)...but even if you don't HAVE to come in, surely you don't plan to cruise to various places without ever getting off the boat to explore 'em...you'll WANT to come ashore at least once a week...all of which also gives you a chance to pump out. If you plan to do any coastal cruising, you'll only have to be 3 miles offshore to dump the tank. You're likely to need a lot more storage space for the things you'll want with you when you move aboard for weeks or even months at a time than you're using just for weekends and the occasional week aboard. But if you still insist on adding a second tank, the size should be a multiple of 6 gallons because that's how much your portapotty holds. Any size that isn't a multiple of 6 would risk overflowing it or wasted capacity to make sure you don't overflow it when you dump the portapotty into it.
Your 6 gal system should last 5-6 days--a week if you use the lee rail whenever practical. It's unlikely that you can stay out longer than that on a 28' boat before you have to come in for fresh water, ice, provisions and maybe fuel too (not to mention a REAL shower with plenty of hot water for a change)...but even if you don't HAVE to come in, surely you don't plan to cruise to various places without ever getting off the boat to explore 'em...you'll WANT to come ashore at least once a week...all of which also gives you a chance to pump out. If you plan to do any coastal cruising, you'll only have to be 3 miles offshore to dump the tank. You're likely to need a lot more storage space for the things you'll want with you when you move aboard for weeks or even months at a time than you're using just for weekends and the occasional week aboard. But if you still insist on adding a second tank, the size should be a multiple of 6 gallons because that's how much your portapotty holds. Any size that isn't a multiple of 6 would risk overflowing it or wasted capacity to make sure you don't overflow it when you dump the portapotty into it.
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