Plumbing

"That which makes life easier"

Perhaps I should have discussed this topic earlier because plumbing, for the most part, is installed in the hull. Therefore, much of it should be installed before the cabin deck is laid in place. Anyhow, better late than never. I will split the subject into two parts. The first will be about 'fresh water' systems and the second will cover 'waste water'.

The fresh water system, on most vessels, consists of a storage tank, a hot-water tank, a pump system and a distribution system or piping.

Storage of fresh water is done in, either, a single large tank or a series of smaller tanks that are connected or 'manifolded' together so that they are filled and emptied as one. Either way, the tank or tanks, should be located as near as possible to the center of buoyancy of the hull. Positioning the tank or tanks at the center of buoyancy means that the trim of the vessel will not change as water is used thus the paddlewheel depth does not change.

If a single large tank is used, it should be positioned fore-to-aft and also be fitted with baffles to slow the movement of water from end to end. Positioning a tank side-to-side in the hull is usually easier, however, if a few people stand to one side on the boat, the water will also flow to that side, is spite of the baffles, and increase the vessels' list dramatically. The positioning of smaller tanks side-to-side, usually, does not cause this problem for it takes a much longer time for the water to shift.

The safest way to distribute the water is through galvanized pipe, however, I feel that most of you will want to use plastic or PVC and that works pretty well too. I do suggest that you spend the little extra money and buy schedule 40 PVC. 'Schedule' refers to the thickness of the pipe and schedule 40 will handle the shock and vibrations encountered in a boat better than schedule 20. I must also add that pipe carrying hot water must be listed as 'CPVC' for regular PVC will not handle hot water.

Filling of the tank is usually accomplished with two lines that enter the top of the tank. One is the fill line and the other is an overflow. They should be placed close together and in a convenient location, close to the deck, for easy access. I generally install screw-on covers for both these lines to prevent insects from building nests inside. If you do this, a third line should be installed from the top of the tank to a position high on the cabin wall for a vent. Fit this then, with a protective screen cover.

I recommend installing a good filter on the discharge line from the tank just past the main shutoff valve. For those who intend to do a lot of traveling, a filter placed on the fill line of the tank could also prevent a lot of problems.

Next comes the pump and accumulator. The pumps are 12 volt and are sized in gallons per minute to accommodate the number of outlets that you might be supplying at any one time. The accumulator tank is to provide an air cushion so as to reduce the cycling of the pump. The larger the accumulator, the longer the time between pump cycles, but it also increases the running time of the pump when it does come on.

There is another way to develop pressure and that is to pressurize the entire system including the tank. This pressure is supplied from a compressor either mounted on the main engine or powered by a 110 volt motor or, sometimes, both. Of course, with this system, there is no vent and both the fill and overflow lines must be fitted with valves. The tank or tanks must also be able to withstand the pressure with a safety factor. I suggest a safety factor of 2 or 3 times the operating pressure. There should also be a safety valve in the air supply line set to relieve just a few pounds more than the operating pressure. This is an excellent system especially if both compressors and an adequate air storage tank is installed. However, a couple words of caution. First, resist the temptation of using an 'automotive air-conditioning' compressor on the main engine. Most of these allow oil to be introduced into the system and this will ruin a good cup of coffee. Been there, done that. Also, be sure to install a valve in the line between the air tank and the water tank so that the system can be blown down and refilled without emptying the entire air storage tank.

Routing of the distribution lines should be as high in the hull as possible. This allows the system to be easier drained for winterizing and makes the lines less susceptible to damage when you are moving about in the hull. Also, when penetrating a bulkhead, do so with a packing gland. This is a 3 or 4 inch long piece of steel pipe with an internal diameter ½ to ¾ of an inch larger than the outside diameter of your distribution piping. This gland is welded in the bulkhead, your piping passes through it and packing is forced in and around the pipe to make a water-tight seal. With this, you maintain bulkhead integrity and the piping is not stressed as the hull twists and flexes.

Some of you may wish to install a secondary water system which draws water from the river for flushing heads and/or washing down decks. This is okay if you use the right method for water pick-up. However, DO NOT install 'through-the-hull' pick-ups BELOW THE WATERLINE! Anyone who has been around boats for very long will know of one or more vessels that have been sent to the bottom because of failure of this type of fitting or some related component. A good location for this pick-up is through the splash bulkhead just above the engine room deck. Install the pipe with a 90 degree ell turned down and attach to this a length of rigid rubber hose fitted with a foot valve. Of course, place the foot valve deep enough so that turbulence around the paddlewheel doesn’t cause it to become exposed. The 'rigid hose' will flex out of the way if a piece of drift or debris comes through, but will spring back in place without breaking off. The pump and tank can be placed in the engine room with the rest of the equipment.

This brings us to the subject of waste water. Waste water falls into two classes. One is 'gray water' and the other is 'black water'. Gray water is that which is discharged from sinks, showers, lavatories and bathtubs. Black water, of course, is that discharged from the heads.

Some water-ways do not allow over-board discharge of any water. Some will permit gray water but no black water. On most rivers, overboard discharge is not permitted, however, to date, the only vessels forced to follow the rule have been commercial ones. It’s probably just a matter of time before all of us will have to comply, but for now, we can still discharge overboard. I have no problem with the discharge of gray water overboard. And, most of the time, I don’t have a problem with discharging black water. However, when attending a regatta and staying tied beside several boats with continuous overboard discharge, in a few days, there tends to be a mess around the boats. For this reason alone, I suggest that you install a holding tank for black water. This tank can be emptied after leaving the regatta with, I feel, no detrimental effect on the environment. Of course, this tank can be also be pumped out with a 'Honey wagon' at your dock or most marinas.

Now, let’s look at the three basic types of heads. First is the household type. Most of these now flush on about 1 to 1 and ½ gallons of water. Older models used over 3 gallons. Thus, either of these must be supplied with river water and they must discharge overboard. Marine heads come in two basic types. One is equipped with a pump which is operated by hand, foot pedal or a 12 volt electric motor. The electric models are usually equipped with a macerator which grinds all contents while pumping them. The other type is the direct dump model. These gravity dump straight out the bottom. The pump models can be mounted most anywhere because they force the discharge either into a holding tank or overboard. The direct dumps must either empty straight down into a holding tank or into a very short tube directed overboard.

Either type marine head works well and are my choice over the house type. However, both do have shortcomings. The direct dumps do not have a 'trap' so, if black water is left in the tank for a few days, an odor can permeate the boat. Of course, daily treatment of the tank contents with deodorizing chemicals will prevent this. Nevertheless, don't leave the vessel docked for several days without first dumping the tank. The first flush after coming back on board will probably bring tears to your eyes. The pump models, although they don't allow odors to escape, can be easily jammed by foreign objects and are difficult and messy to clean out.

The discharge lines for either gray water or black water should be installed as high in the hull as practical and under NO circumstances should they discharge BELOW THE WATERLINE! You may ask, how do you install a holding tank that discharges above the waterline? There are two ways. One is to use a pump that pumps the contents overboard. The second, and my choice, is to mount the tank directly against the underside of the deck. By using larger lateral dimensions and a low height dimension, the bottom of the tank can usually be held above the vessels waterline. The discharge line from the tank should be kept as short as possible and be fitted with a 'dump valve'. There needs to be only a couple inches of drop in this line. Therefore, if your vessel has a freeboard of, say, 18 inches, the height of the tank can be 14 to 15 inches. Then, with lateral dimensions of, say, 36 by 48 inches, you can easily have a tank with a capacity of over a hundred gallons. This, used with a marine head, can take care of your needs for several days.

There's one last item I feel needs to be addressed and that's 'habits'. Since you're on a vessel with a limited water supply, I suggest you develop 'water conservation' habits and make your guests aware that you're not hooked up to city water. Learn to take short showers preferably with a shower head that can be turned on and off. Don't flush the heads for any longer than is absolutely necessary and don't leave the water running while you're brushing your teeth or shaving. I'm confident you'll even learn of other ways to conserve water after running out a few times.

Well, that's it for plumbing. As always, if you have any question, please get in touch.

 

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P.S. I've just written an article for the American Sternwheel Association's magazine, the 'Sternwheeler' and have included it below. I hope it helps.

 

A Fresh Water System

by

Captain Gary Morton

 There are many ways of installing a fresh water system on a boat.  Although I’ve used several over the years, this is my favorite.  I’ve even recently installed it in the Gambler, on which  Marilyn and I are now living full time.  I know it works well and it has many advantages over others I’ve tried.

 First, and most importantly, I should point out that all liquid holding tanks should be placed as close as possible to the ‘Center of Buoyancy’.  This is that point in the hull along its length, where there is an equal amount of buoyancy forward and aft.  The reason for selecting this point is that the ‘trim’ of the vessel is not affected by the use of, or the addition to, these liquids.  On most ‘scow bow’ hulls, this point is usually very close to the actual center of the hull.  On ‘model bow’ hulls, this point is sometimes slightly forward of the actual center. 

 This system consists of using multiple small tanks and ‘manifolding’ them together so that they fill and discharge as one.  The use of small tanks allows them to be installed and or replaced after construction of the hull or during the re-fitting of an older one.  Also, smaller tanks can be more easily located in the limited spaces usually found in most hulls without cutting decks or frames.   An added advantage is the inability of water in small tanks to add to a vessels list.  A single large tank is usually installed side to side in a hull such that it fits between frames.  Even though it may be fitted with baffles to reduce ‘slosh’, one or more persons standing on the side of a boat can cause the water in a half filled tank, to quickly run to the same side.  This adds to the list.  For instance, a two hundred and fifty gallon tank half full, holds about a thousand pounds of water.  On most vessels, one person standing on a walkway will heal the craft over enough to allow the water in the tank to run to the same side.  Now, you have the equivalent of about six people standing in the same location greatly adding to the list.  One more advantage of small tanks if they are properly connected, is the ability to ‘valve out’ a leaky tank and continue to use the system until a replacement is installed.

 The amount of fresh water required on any vessel has always been a concern for designers and boat builders.  The designers of United States Navy vessels have settled on six gallons per day per crewman.  They use this for determining storage and production requirements for new vessels.  If you carry a lot of water, this adds significantly to a vessels tonnage thus reducing its speed and performance.  Too little creates a major inconvenience.  Marilyn and I have measured our consumption over several months and have found that we use an average of five gallons per day each.  This goes to drinking, washing dishes, taking showers (navy style, not Hollywood), doing our ‘chores’ and flushing the head which is a low volume RV type.  We don’t skimp on water nor do we waste it.  I have installed six, thirty-five gallon plastic tanks for a total of two-hundred and ten gallons.  Therefore, we can go about three weeks between fill-ups.

 The plastic tanks I chose were safe for potable water, had a sort of ‘base’ molded in and incorporated a ‘fill opening’ on top.  This opening is about six inches in diameter and is fitted with a screw on cap.  The cap has a gasket for sealing.  I cut three holes in the tanks to mount ‘bulkhead fittings’.  One was down low for discharge and two were on top for the vent and fill.  The original fill opening was large enough to allow me to reach inside to install the nuts on the bulkhead fittings.  The openings in the bulkhead fittings contained female pipe threads.  For the discharge and fill, I selected one-half inch pipe.  For the vent, I selected three-quarter inch pipe.  The reason for the larger vent was extra insurance that no pressure would build in the tank as it was being filled.

 I tested each tank before installation by plugging the discharge and hooking a garden hose to the fill.  Another piece of hose was connect to the vent.  I quickly found that the gasket around the original large fill opening leaked.  Nothing that I, or the tank supplier, did  would stop the leak.  The supplier then suggested that he ‘weld’ the opening closed and this he did.  He cut a disc the size of the fill opening, from a one-quarter inch thick piece of the same plastic the tanks were made.  Then, with what looked like a ‘wire feed welder’ except it fed plastic instead of wire and used hot air instead of an electric arc, he welded the disc in place.  No more leaks.

 I placed the tanks in the hull putting three on each side.  They fit well through a twenty-two inch square hatch opening.  Unfortunately, I had to place them slightly forward, about two feet, of the center of buoyancy.  This resulted in about a one inch change in trim from full to empty on a forty-five foot hull.  I can live with it but I’d rather not have the change. 

Next, I fabricated a ‘manifold’ for the fill system.  This was made of one-half inch PVC pipe, five tees and two ells.  The overall length was about four feet.  From the center tee, I ran one-half inch ‘beverage tubing’ to a fill port on the outside of the boat to which a garden hose can be attached.  But, between the tubing and the fill port, I installed a pressure regulator set at thirty-five pounds and a ball valve to close the system.  Beverage tubing is clear vinyl with fabric molded in for strength.  To the other four tees and both ells, I mounted PVC ball valves to control the incoming flow to each tank.  Adjusting these valves allows for filling each tank at the same rate so you don’t have to wait on some tanks to fill while others are wasting water out the vent lines.  I then ran one-half inch tubing to the top bulkhead fitting in each tank that was for one-half inch pipe.  Of course, I had to install pipe to tubing fittings in all of the bulkhead fittings and the PVC ball valves.  I also had to heat the ends of the tubing and apply soap to the barbed fittings in order get the tubing onto the fittings adequately .  As an extra precaution, I also installed hose clamps on each fitting.

 Next came the vent manifold.  This was made exactly like the fill manifold except it was made from three-quarter inch PVC with corresponding size valves and hose.  The hose from the center of the manifold was routed to a fitting on the outside of the boat to which a short piece of garden hose can be attached.  This allows the overflow discharge to go overboard instead of on the deck.  Also, there are no valves or other restrictions in this line thus removing the possibility of pressurizing the tanks.  I then ran three-quarter inch tubing from the ball valves to the remaining bulkhead fittings on the top of each tank.

 Next came the discharge manifold.  This one is like the fill manifold with one exception.  All five tees and both ells are fit with one-half inch PVC ball valves.  The outboard tees and ells of course, were connected to the lower bulkhead fittings in the tanks.  The center tee connects to the fresh water pump.  This extra valve will allow me to remove the pump for repair without first emptying the tanks.  I’ve found that either a 2.8 or a 3.2 gpm (gallon per minute) pump is adequate for our use.  I have been pleased with the performance of the Shurflo direct drive pumps but I’ve been disappointed with the Jabsco belt driven ones.  From the discharge side of the pump, I ran more one-half inch tubing to another ball valve then to a two gallon ‘accumulator tank’.  This tank is a ‘diaphragm type’ and was pre-pressurized but fit with a valve so I can re-pressure if needed.  This tank allows us to draw about a quart or more of water before the pump kicks on.  This means the pump runs longer when it comes on but it comes on less frequently.  The valve preceding it allows for pump removal without all of the water in the lines of the boat draining back into the hull.  More one-half inch tubing runs from the accumulator tank to a ‘whole house’ or perhaps I should say, ‘whole boat’ filter canister with replaceable filters.  The outlet of the filter is connected to the rest of the plumbing in the boat.  I should point out that even though I used PVC pipe for all of the manifolds, I used a pipe labeled CPVC for the rest of the plumbing.  PVC is not suitable for hot water where as the CPVC is.

 To fill the system, I connect a water supply to the inlet on the outside of the boat.  This is the one with a pressure regulator set to thirty-five pounds and a valve.  I connect a short piece of garden hose to the vent connection and route it over the side.  Next, I turn on the water, open the valve and let the water flow until all tanks are full and water discharges out through the vent.  For the first three or four fills, I monitored the rate of fill in the tanks and adjusted the valves on the fill manifold so that all tanks filled at the same rate.  Once this was accomplished, subsequent fills require me to observe only when the first sign of water is discharged from the vent.  I then close the inlet valve, shut off the water and un-hook the hoses.  The job is done and with my present water supply, the whole job takes about thirty minutes.

 The astute reader will wonder, “why all of the extra valves”?  Well, by placing valves in all lines to and from the tanks, any tank that may develop a leak can be completely valved out of the system.  This allows continued use of the system until the problem tank is repaired or replaced.  

I should also point out that I installed this system not to do a lot of work and spend money but to replace our old system which developed a malady.  Our previous system consisted of a single one-hundred and fifty gallon tank made of 304 stainless steel.  This tank was filled as described above but of course, without the manifolds. I used air pressure on the tank instead of a pump, to supply the water pressure.  However, after about sixteen years of use, the tank developed several ‘pin hole leaks’.  These leaks were not in weld joints but in the steel itself.  I have not a clue why fresh water that we used for bathing and drinking would eat holes in stainless steel but it did.  Some people I’ve talked to suggested that chlorine can work on stainless steel but I’ve not been able to verify this.  Anyhow, it was a bit frightening and I’m glad we now have a good source of well water at our landing.

 One last point.  I’m not claiming this is the best fresh water system you can have.  I’m merely stating that it is the one we use and it’s good for us.  Perhaps it would be good for you.

  

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