I am searching out a new holding tank. I have searched through all of the pre-made manufacturers (Ronco, Kracor, etc.) and none of the existing molds meet my ideal needs. I am between paying for the rotational mold set up or having a custom welded tank built. What are the pros and cons of these two manufacturing methods? In either case, the wall thickness is a minimum 1/4". What are the different types of plastics used and which is best? Are there specific items to question when investigating a particular manufacturer? Thanks, Mike
- Status
- Not open for further replies.
P
Peggie Hall/Head Mistress
Among more than 400 shapes and sizes...
you couldn't find a tank? The best choice is a seamless rotomolded poly tank at least 3/8" thick. A welded poly tank is an acceptable choice, but a very distant second. Ronco tanks are the best in the industry. And with so many to choose from, it shouldn't necessary to pay extra for a custom tank. Let's talk a bit about what you consider to be your "ideal" needs...I betcha you and I can figure out how to meet 'em without costing you an arm and a leg. Tell me what you're trying to do--tank size, location, distance from the toilet, other available space, etc. Also your boat size...how many toilets, power resources...let's examine ALL your options before comitting to anything.
you couldn't find a tank? The best choice is a seamless rotomolded poly tank at least 3/8" thick. A welded poly tank is an acceptable choice, but a very distant second. Ronco tanks are the best in the industry. And with so many to choose from, it shouldn't necessary to pay extra for a custom tank. Let's talk a bit about what you consider to be your "ideal" needs...I betcha you and I can figure out how to meet 'em without costing you an arm and a leg. Tell me what you're trying to do--tank size, location, distance from the toilet, other available space, etc. Also your boat size...how many toilets, power resources...let's examine ALL your options before comitting to anything.
M
Mike Rose
Some more details
OK. . Here are some more details. This is the first holding tank being installed in a 1972 C&C 39. It is currently day-sailed and short cruised in Mass Bay. The head is located port side, just aft of the v-berth. This current discharge is overboard through a hose looped against the bulkhead, seperating the head and v-berth. All available lockers seem to be in the v-berth area. There are 2 on the outboard sides, approx volume 15 gal.each. (I wasn't crazy about having 2 tanks) The 3rd locker in the v-berth is the one I have been planning on using. It is not right on the bow and is on the bottom. So, I didn't think I would be carrying too much weight forward. I have an 4D house battery and a wind generator for power. Thanks for your help, Mike
OK. . Here are some more details. This is the first holding tank being installed in a 1972 C&C 39. It is currently day-sailed and short cruised in Mass Bay. The head is located port side, just aft of the v-berth. This current discharge is overboard through a hose looped against the bulkhead, seperating the head and v-berth. All available lockers seem to be in the v-berth area. There are 2 on the outboard sides, approx volume 15 gal.each. (I wasn't crazy about having 2 tanks) The 3rd locker in the v-berth is the one I have been planning on using. It is not right on the bow and is on the bottom. So, I didn't think I would be carrying too much weight forward. I have an 4D house battery and a wind generator for power. Thanks for your help, Mike
E
Ed Schenck
Mike, check earlier post.
A few posts earlier you will find one titled "Top Fitting Tail Pieces" or something like that. In the responses you will find one from me with a picture. That picture is my Ronco tank in the center v-berth locker. It is only 22 gallon but 35 would have fit. My problem was that my log and depth transducers are in there. I had to leave room to access them. And, as you can see, I had to cut the locker to get the tank in there. The beauty of Ronco besides the heavy duty material is they will put those connectors anywhere you want. And their price over the phone is better than advertised.
A few posts earlier you will find one titled "Top Fitting Tail Pieces" or something like that. In the responses you will find one from me with a picture. That picture is my Ronco tank in the center v-berth locker. It is only 22 gallon but 35 would have fit. My problem was that my log and depth transducers are in there. I had to leave room to access them. And, as you can see, I had to cut the locker to get the tank in there. The beauty of Ronco besides the heavy duty material is they will put those connectors anywhere you want. And their price over the phone is better than advertised.
M
Mike Rose
What model?
Ed, I had seen your earlier post and I would like to work with Ronco, but I searched their catalogue and can't find maximizes the space. What model 22 gal. did you use? Did you see a 35 gal. with v-berth shape? Mike
Ed, I had seen your earlier post and I would like to work with Ronco, but I searched their catalogue and can't find maximizes the space. What model 22 gal. did you use? Did you see a 35 gal. with v-berth shape? Mike
P
Peggie Hall/Head Mistress
V-berth is the best location on your boat
15 gallons is a bit marginal if you intend to rely only on a holding tank, but unless you're almost always in Buzzards Bay, Martha's Vineyard or Nantuckett, it would be adequate when combined with a Type I MSD 'cuz you'd only have to use the tank. when you do visit "no discharge" waters. Assuming that a tank IS the only option in your waters, you said there are two compartments on the port side in the v-berth...is the divider structural? I agree--you don't want two tanks, but if the divider isn't structural, consider removing it to create one larger locker that'll hold a decent size tank. Btw, Ed...his boat is a C & C...I thought yours is a Hunter. What works for one prob'ly won't work on the other.
15 gallons is a bit marginal if you intend to rely only on a holding tank, but unless you're almost always in Buzzards Bay, Martha's Vineyard or Nantuckett, it would be adequate when combined with a Type I MSD 'cuz you'd only have to use the tank. when you do visit "no discharge" waters. Assuming that a tank IS the only option in your waters, you said there are two compartments on the port side in the v-berth...is the divider structural? I agree--you don't want two tanks, but if the divider isn't structural, consider removing it to create one larger locker that'll hold a decent size tank. Btw, Ed...his boat is a C & C...I thought yours is a Hunter. What works for one prob'ly won't work on the other.
M
Mike Rose
molded vs. welded
Peggy, Thanks for the reply. One quick clarificaton, the two 15 gal. areas are port and starboard, not both port. Therefore, I plan to move forward on the center tank. I am inquiring with Ronco and Kracor to see if they have a model not listed. Is there a major difference between the 2? Are there others? If I go welded, are there considerations (material, gas used, etc.)? Thanks, Mike
Peggy, Thanks for the reply. One quick clarificaton, the two 15 gal. areas are port and starboard, not both port. Therefore, I plan to move forward on the center tank. I am inquiring with Ronco and Kracor to see if they have a model not listed. Is there a major difference between the 2? Are there others? If I go welded, are there considerations (material, gas used, etc.)? Thanks, Mike
Pros and Cons.
Mike: There are pros and cons with both types of tanks. The biggest dis-advantage of a roto molded tank is there is NO way to ensure that there is a consistent wall thickness of the tank. I personally know of people that have check these tanks and have found that the wall thickness is NOT consistent. Now I have also not heard any complaints from anyone that has owned one of these tanks either. The problem with a roto molded tanks is they have to make molds which cost a lot of money so you can only get what they have unless you want to pony up the bucks for a new mold. When you purchase a custom Poly tank you get a welded product that does have consistent wall thickness and they can be in almost any shape that you want. What you are dealing with here is the fact that each tank is custom welded which is much more labor intensive and you are depending on the company to ensure that you will have a tank that is properly built. If Poly is properly welded the seams should be as strong or stronger than the walls. So I suggest that if you go with a custom tank that you have your source checked out to be sure that you are getting what you pay for. This is going to be a premium price be 'should' be a premium product. I think you will find that the price is going to be between 2-3 times the price of a rotomolded product.
Mike: There are pros and cons with both types of tanks. The biggest dis-advantage of a roto molded tank is there is NO way to ensure that there is a consistent wall thickness of the tank. I personally know of people that have check these tanks and have found that the wall thickness is NOT consistent. Now I have also not heard any complaints from anyone that has owned one of these tanks either. The problem with a roto molded tanks is they have to make molds which cost a lot of money so you can only get what they have unless you want to pony up the bucks for a new mold. When you purchase a custom Poly tank you get a welded product that does have consistent wall thickness and they can be in almost any shape that you want. What you are dealing with here is the fact that each tank is custom welded which is much more labor intensive and you are depending on the company to ensure that you will have a tank that is properly built. If Poly is properly welded the seams should be as strong or stronger than the walls. So I suggest that if you go with a custom tank that you have your source checked out to be sure that you are getting what you pay for. This is going to be a premium price be 'should' be a premium product. I think you will find that the price is going to be between 2-3 times the price of a rotomolded product.
P
Peggie Hall/Head Mistress
Steve, how many different makes of rotomolded
have you measured? You "personally know people who've measured rotomolded tanks"...how many tanks from which mfrs have they measured? Have they only compared wall-thicknesses or matched the thinnest wall against the minimum specified wall thickness? If the thinnest wall meet that spec, is it a flaw if another wall is thicker? Mass produced cheap thin-walled tanks (the usual OEM quality) do indeed have inconsistant wall thicknesses--some walls thinnner than specified. Otoh, the best quality rotomolded tanks may vary SLIGHTLY, but if the mfr's specs call for a minimum wall thickness based on the size/shape of the tank, every wall is AT LEAST that thick. And all corners are reinforced...approximately 50% thicker than the walls of that tank. Welded tanks, otoh, are only as strong as the quality of the weld. As you said, they're labor intensive...subject to the attention span, skill--even whim--of the welder. They CAN be as strong as a seamless tank, but you take your chances. NO good quality rotomolded tank has ever split at a seam...the same cannot be said of welded tanks. I would not pay the premium for one unless there was NO other choice. As for limited selection, Ronco has 400+ to choose from...how many would you consider enough? Your condemnation of rotomolded tanksis simply not warranted.
have you measured? You "personally know people who've measured rotomolded tanks"...how many tanks from which mfrs have they measured? Have they only compared wall-thicknesses or matched the thinnest wall against the minimum specified wall thickness? If the thinnest wall meet that spec, is it a flaw if another wall is thicker? Mass produced cheap thin-walled tanks (the usual OEM quality) do indeed have inconsistant wall thicknesses--some walls thinnner than specified. Otoh, the best quality rotomolded tanks may vary SLIGHTLY, but if the mfr's specs call for a minimum wall thickness based on the size/shape of the tank, every wall is AT LEAST that thick. And all corners are reinforced...approximately 50% thicker than the walls of that tank. Welded tanks, otoh, are only as strong as the quality of the weld. As you said, they're labor intensive...subject to the attention span, skill--even whim--of the welder. They CAN be as strong as a seamless tank, but you take your chances. NO good quality rotomolded tank has ever split at a seam...the same cannot be said of welded tanks. I would not pay the premium for one unless there was NO other choice. As for limited selection, Ronco has 400+ to choose from...how many would you consider enough? Your condemnation of rotomolded tanksis simply not warranted.
E
Ed Schenck
Mike from Ed.
I may have exaggerated a little Mike. I think the tank I really wanted to use was #3 of the 30 gallon size(using the Ronco "Tank Search"). Instead I chose #2 of the 22 gal. size. I can easily get in front of and below the tank in case I have to access the transducers. And there is still a lot of storage space. Actually I find that 22 gallons is quite adequate with our Cricket head. I instruct people to only use three of four pumps, just enough to clear the bowl. In the evening before lights out I flush with a gallon of fresh water. With the Sealand hoses I don't worry about "stuff" lying in the hoses during the day. With the First Mate and I sailing a couple times a week and grandkids on weekends we can go without a pumpout for three or four weeks.
I may have exaggerated a little Mike. I think the tank I really wanted to use was #3 of the 30 gallon size(using the Ronco "Tank Search"). Instead I chose #2 of the 22 gal. size. I can easily get in front of and below the tank in case I have to access the transducers. And there is still a lot of storage space. Actually I find that 22 gallons is quite adequate with our Cricket head. I instruct people to only use three of four pumps, just enough to clear the bowl. In the evening before lights out I flush with a gallon of fresh water. With the Sealand hoses I don't worry about "stuff" lying in the hoses during the day. With the First Mate and I sailing a couple times a week and grandkids on weekends we can go without a pumpout for three or four weeks.
M
Mike
Fiberglass built-in?
Peggy, I have talked to Ronco and Kracor, neither can come close without loosing half the volume and their custom stuff is $700+ I am interviewing poly welders currently, but they may be $400+. It has been suggested to glass in the area and gelcoat. Thoughts? Mike
Peggy, I have talked to Ronco and Kracor, neither can come close without loosing half the volume and their custom stuff is $700+ I am interviewing poly welders currently, but they may be $400+. It has been suggested to glass in the area and gelcoat. Thoughts? Mike
P
Peggie Hall/Head Mistress
Let's look for another tank location
Glassing in a tank just limits future options for the space. Over the years I've found space for a lot of owners. E-mail me...I'm in the owners directory.
Glassing in a tank just limits future options for the space. Over the years I've found space for a lot of owners. E-mail me...I'm in the owners directory.
M
Mark Sanford
plywood & epoxy
Have you considered a home made tank of Plywood and epoxy construction? This allows the flexibility of custom sizes and low cost. However the trade off is the time required to construct the tank and the effort required to convince your partner that this is an acceptable approach to tank construction. There are a number of articles on the web from epoxy manufacturers on this topic.
Have you considered a home made tank of Plywood and epoxy construction? This allows the flexibility of custom sizes and low cost. However the trade off is the time required to construct the tank and the effort required to convince your partner that this is an acceptable approach to tank construction. There are a number of articles on the web from epoxy manufacturers on this topic.
M
Mike
Stainless?
Peggy, I was just about to pull the trigger on a welded poly tank, when a friend mentioned getting it made in stainless for less money. I haven't received the written quote yet, but if it is less money, is it viable? I know you are not a fan of aluminum, but stainless steel? Thanks, Mike
Peggy, I was just about to pull the trigger on a welded poly tank, when a friend mentioned getting it made in stainless for less money. I haven't received the written quote yet, but if it is less money, is it viable? I know you are not a fan of aluminum, but stainless steel? Thanks, Mike
P
Peggie Hall/HeadMistress
Stainless is no better than aluminum
Urine will eat through the weld at a seam or a fitting in a stainless tank in about the same amount of time as it will in an aluminum tank...you MIGHT gain year, but not much longer. Same is true of the sheet metal..urine will even eat through 316 stainless within 10 years. Otoh, a good quality thick-walled (at least 3/8") seamless plastic tank will still be in excellent shape 20 years from now. Whether the same can be said of a welded plastic tank will depend only on the quality of the welds. As much as you've agonized over this, now is not the time to try to save a buck.
Urine will eat through the weld at a seam or a fitting in a stainless tank in about the same amount of time as it will in an aluminum tank...you MIGHT gain year, but not much longer. Same is true of the sheet metal..urine will even eat through 316 stainless within 10 years. Otoh, a good quality thick-walled (at least 3/8") seamless plastic tank will still be in excellent shape 20 years from now. Whether the same can be said of a welded plastic tank will depend only on the quality of the welds. As much as you've agonized over this, now is not the time to try to save a buck.
- Status
- Not open for further replies.