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I am in the process of replacing my portapotty with a marine head. Triton106 does not currently have a holding tank. I have read a lot on the subject of holding tank and decided to go with a Vetus flexible holding tank to be located in the head area (between salon and V-berth) outboard of the the head itself. The reasons for choosing this location and flexible tank are as follows (I don't intend to start another debate on flexible vs. hard tank or the proper location for the holding tank - that is not the intent of this question because I have made the decision and bought the tank):
1. I have reached the conclusion that the holding tank will have odors no matter what (to more or less extent depending on installation and material). If it is going to smell I might as well limit it to the head area. Why contaminate the galley or the forepeak with unpleasant odors. I understand that this is an assumption on my part since I don't actually have any real experience with holding tanks and others seem to be happy with holding tanks under salon settee and under V berth.
2. Due to limited space behind (outboard) of the head I will maximize the space/capacity and minimize the effort by using a flexible tank instead of trying to custom build one like Tim (for Kayholee) and others have done. By cutting out the horizontal bulkhead between the bottom of the linen locker (the proper name escapes me) and the tiny wedge shapped area below that I can snugly fit a 14 gallon flexible holding tank perfectly. I can still use the upper shelf of the linen locker for, well, linen.
3. All plumbing will be all contained in the head area and runs are short. The weight will be fairly low (lower than most installations I have seen).
So here is my question, I know the inlet hose to the flexible holding tank will have to be near the top of the tank. Now since the odd shape of the area I chose to install it the holding tank will lay almost vertically (see drawing). Where should I install the outlet hose? Near the bottom on the inboard/top side or on the outboard/bottom side? My concern with the inboard/top side installation is that it will not be able to pump out all of the black water since the outlet is not at THE bottom. On the other hand the concen with the outboard/bottom side installation is that it will accumulate black water in the outlet hose and leading to odor problems down the road.
Your experiences and opinions (or if you still want to talk me out of flexible tank or the chosen location) will be much appreciated.
If you come out of the tank with 1 1/2" PVC pipe until you are above the tank then switch to hose to the deck outlet you should have no odor problem with that part. I also suspect that if you install a shutoff valve in the vent hose that you could pump it mostly dry from any location.
I fully read all of your cautions for replys but am going to add that I just finished re-plumbing the head on my Triton using all PVC except where hose was required to connect to hose only fixtures such as the Y-valve, discharge pump and deck outlet. I used a 6 gal plastic tank set just forward of the head. Had I known about the company in Maine, mentioned on this site, making custom plastic tanks at a reasonable price, I would have gone larger but in the same location (near to the center of the boat). I removed a Nauta flexible holding tank that was in the boat when I bought it. I spent hours scrubbing with straight bleach then primed with 2 coats of BIN and topcoated with Briteside. Until it sets closed up for some time I won't be sure that I have killed the odor. I understand that the Vetus tanks are better than the Nauta but the potential for odor exists. Whatever you do it is certainly your business and I wish you good luck with it.
Barry
Triton106 wrote:
1. I have reached the conclusion that the holding tank will have odors no matter what (to more or less extent depending on installation and material). If it is going to smell I might as well limit it to the head area. Why contaminate the galley or the forepeak with unpleasant odors. I understand that this is an assumption on my part since I don't actually have any real experience with holding tanks and others seem to be happy with holding tanks under salon settee and under V berth.
If you start with that assumption, then yes, your head will smell. I don't think it is a fair assumption to make at the outset, however. I've been on plenty of boats, my own included, where there is no hint of the smell of effluent. IMO your research should be focused on making the head odor-free-- first and foremost. There is nothing good about smelly head odors, regardless of where they are confined.
If you are dead-set on a flexible tank here are my suggestions:
1. Spend the money on the good Sea Land hose.
2. Use PVC for any long horizontal runs.
3. make sure the area you locate the bladder is free of chafe and any sharp corners-- preferably with a bed of foam... and then secure it from the top too.
4. Be prepared to replace the bladder once it starts to stink.
I also suspect that if you install a shutoff valve in the vent hose that you could pump it mostly dry from any location.
I suspected that also but have not read or heard anyone else confirm that.
Caesar wrote:
If you start with that assumption, then yes, your head will smell. I don't think it is a fair assumption to make at the outset, however. I've been on plenty of boats, my own included, where there is no hint of the smell of effluent.
That's encouraging to know that a head does not have to have odors. The limited number of boats I have been on I always detected some odor however minute (maybe my nose is too sensitive). I am sure it has not only to do with installation and material but also maintanence.
Rachel wrote
I wouldn't be so quick to throw in the towel on a mostly odorless installation.
I think I unintentionally left the impression that because I think the head will have odors I don't care about installation. I actually care about it alot which is why I want to contain it to the head area. It seems that there is a consensus out there that flexible tank will smell, many based on experience with PO's poor installation and maintanence. I have also read that from other experts (I am sure that is debatable too) insisting that flexible tanks will not smell or no worse than rigid tanks if installed correctly. Other than the Vetus flexible tank other material I am using are Sealand hose and Henderson sanitation pump.
I have also thought about what if the flexible tank does end up smelling more than what is acceptable despite all my efforts. I think I will have to make a custom tank but to fit in the current location.
