Fresh water storage in sausage style tubes in ballast tank

[Flightfollowing]

I'm devising a fresh water storage system using long thin collapsible tubes to put into the water ballast tank throught the ballast valve. Quick math yielded 12 gallons per 12 foot long by 2.5 inch diameter tube. The water sausage would be tethered at the ballast valve end with a cord going to just inside of the valve for any subsequent retrieval, and the water line would lead out the vent tube under the v berth. The vent tube would need to run through a stopper so that it could still be used as a stopper for water ballast, and pulled partway out to provide venting for ballast. The sausages could be easily made using 3" diameter lay flat water discharge hose, with one end sewn and sealed closed and the other sealed to flexible 1/2" water hose, or else custom made similar to plastimo or lazillus collapsible tanks. One or two or three sausages in the ballast tank would yield 12 to 36 gal of water storage with no weight panalty when ballast is full. The stopper might need some pinhole vent to keep fresh water usage from sucking a vacuum with closed and full ballast. Installation would run fish tape from vent hole out ballast valve, and then pull the water line and attached tube right through the ballast valve, and then tying off a tether on the aft side of the sausage somewhere on the inside of the ballast valve. Am I forgetting anything with this concept?

[Jimmyt]

Cool idea! Depending on how much volume you shoot for, you might want to figure out a way to make up ballast as you use the potable water - to prevent partial ballast fill. Otherwise, sounds like a good solution. As you say, potable water storage with no weight penalty! You may want to verify the configuration of the M ballast tank, and confirm that sausages are the best shape, but some sort of bladder would surely work. Keep us posted on what you come up with. Most solutions I've seen (and thought of) put the water weight higher in the boat - which is not optimum for stability.

[seahouse]

I like it!

You could put a second hole right next to the ballast vent hole, so as to not interfere with it. And you could put a short stand pipe (connected to the sausage(s)) on that hole to prevent contamination of the fresh water with ballast water, and to provide you with some head pressure (say when pouring water into it with a funnel, not an issue with a hose fill) should you want to add fresh water with the ballast full. Desirable if you want to prevent burping and to keep air out of the sausage.

Whenever using or filling your fresh water, ensuring that the transom ballast valve is open would solve any water level or pressure issues, so no need for a separate vent.

Fire hose quality construction would eliminate fears of perforation from abrasion on the ballast walls.

Keeping some air in it when feeding it through (once past the transom opening) on initial installation would help prevent (volvulus-type) twisting. I believe the M transom gate valve is larger than on the X's, installing the larger one on an X would make the job easier.

- B.

[mastreb]

I like it. I would install a 3" water-tight access port near by the ballast tank vent to ensure that if something ever goes wrong you've got enough access to clear the problem. I also worry that full tubes in an empty tank may make it difficult to flood the tank with ballast. You may find you need to empty the tubes, flood the tank, and then fill the tubes with the tank open to expel extra water.

I think the best bet would be to install hoses through the access port to fill and drain the tubes, making them "semi-permanent". A simple capillary pump will work for extracting water while in the tank as long as they are bled of air.

You needn't worry about pulling a vacuum in the tank, just install a vent hose to the anchor locker or transom and keep the tank open to the atmosphere.

[Flightfollowing]

Thanks for the good suggestions. I hadn't thought to much on filling it while ballast full, but yes it would need the ballast valve opened at least partly during filling and might need a bit of water pressure to inflate fully, but maybe gravity filling would be adequate as well. And after significant water usage one would be safest to top off the ballast.
I have an aversion to cutting and drilling the hull in general, so I plan on the simplest minimally invasive approach to start. I also plan on inserting a stiff perforated 1/4" nylon tube into the length of the 3" hose, just in case during collapse of the hose the water flow through the partially collapsed hose was restricted, the little nylon tube will ensure flow throughout length of the hose.
I'm thinking the major risk might be blockage of the ballast valve during shifting, so I will make sure to anchor the hose at both ends with good clearance from the transom valve. I will plan to drill a small hole in the inside edge of the ballast valve for a tether line to both secure the aft end of the hose and to retrieve it.
I ordered 25ft of 3" lay flat discharge hose for $30, so I will give it a try. Does anyone know if the ballast tank has any baffles? 3" hose holds about 1.5 gallons per foot, I bet I can fit 15 to 18 feet of hose stretched along the tank, for a 23 to 27 gallon capacity.
I suppose the same concept could be used for fuel, although I have no plans to try this. One would need to run a long fuel line through the cabin in that case, but explosion hazard would be pretty nonexistent in a full ballast tank and even an empty one would have no ignition source. One would want to sniff the ballast tank once in awhile to confirm no leaks, although a fuel sheen in the water after de-ballasting would tip that off.

[raycarlson]

Not sure about an X But on an M its not one long ballast tank, its two seperate tanks connectected by two small channels that are only about 2 X 5 inches and 6-7 foot long. rear tank is 7 foot long at most and only about 4 inch thick.

[raycarlson]

And don't forget that all Mac fiberglass work is very crude to say the least, it's safe to say the inside of the tank will be equipped with long sharp shards of glass and resin spikes...

[Flightfollowing]

Ray,
Great info, this mod would be for an , so from what you describe, sounds like a 14ft long 3" tube would fit in an m ballast tank, but would probably partly obstruct one of the two water flow channels connecting the forward ballast tank from the aft ballast tank? If I understand this correctly, that sounds ok for this mod, although two of these tubes might obstruct both flow channels and might slow the transfer of ballast between tanks. I'll stick with 1 tube and see how things work.

[Flightfollowing]

I found what ray was talking about concerning ballast tank shape on the top of the second page in this forum thread:
http://macgregorsailors.com/phpBB/viewt ... 0&start=15
With good cross sections, But still looks doable. Might need to use super tough fire hose for the Fiberglas shards.

[Wayne nicol]

two questions:
1. what is that hose made from- what are the health considerations
2.does anybody know how the ballast tank is constructed-

if i were to build one- i would likely build two halves- over male moulds- join them together, and then laminate over the entire shape, making a homogenous unit with no join/seam lines. and then laminate it to the hull- once again encompassing it with a glass lay up adhereing it to the hull

[kmclemore]

I hate to be the only one to say so, but I think this is a bad and perhaps even dangerous idea.

The ballast on the Mac is meant to be absolutely full (i.e. no air) when in use, and absolutely empty when not in use. The reason is that if there is any air in the ballast chamber then the water, which is very heavy, can 'slosh' and cause sudden, violent changes in the balance of the boat, leading to loss of persons overboard or injuries from being tossed about, or, in the worst case, even potential foundering of the vessel.

Let's look at the two potential situations with these tubes installed...

If the ballast is empty and the tubes are installed the tubes themselves (which will be quite heavy) can shift inside the ballast tank, leading to that violent change in balance noted above. Not good.

If the ballast tank is full, and the tubes are installed, you're fine... just don't use any of the water. Once you begin to use water you will, as you noted, have to introduce air to prevent a vacuum, and there's your danger situation. As the amount of air increases, the danger of sudden weight shift increases dramatically.

It sounds like a great idea, but I believe it's a very dangerous one, given the design of the boat.

As a side note, if you have any air in the ballast it tends to make sleeping on the boat a rather noisy proposition... it constantly makes a 'sloshing' sound as the vessel rocks.

[Sumner]

I hate to be the only one to say so, but I think this is a bad and perhaps even dangerous idea. ...

I agree. For a ballast tank to function properly it has to be full. When the boat heels the weight of the water on the high side is what opposes the heeling moment. Reduce that water and its weight and let it move down will really effect the efficiency of what it is suppose to be doing. You don't want that weight moving around in a tank that isn't full. Would you want a fixed keel to be able to just move on its own?

There are other ways to store water on the boat. I carry over 40 gallons on the S without...



...a lot of trouble and I'm sure ways to store that much on an X or M can be found. Also it is nice to be able to clean and sanitize water storage and I think these tubes would be inconvenient when it comes to that. Just a thought,

Sumner

============================
1300 miles to the Bahamas and back -- 2015

The MacGregor 26-S

The Endeavour 37

Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[Lee Ward]

I think the idea is to replace the water as its consumed by ballasting down.

[seahouse]

I think the idea is to replace the water as its consumed by ballasting down.

Yes, your two (valid) concerns have been addressed above Kevin and Sum.

As Lee (and I above) points out the water used from the sausage would be replaced by water entering an opened ballast valve at the stern, so at no time would the ballast tank not be full. The tube would collapse as the water from it were used (no air need be involved in this) and at the same rate water would enter the ballast tank to replenish it. And, of course, it doesn't make any difference to the functioning of the water as ballast whether or not it is also contained within a tube.

Now, with the ballast tank empty the sausage as described above is secured at both ends, and contained in the middle by the narrow channels in the ballast tank. (Which might even be so narrow so as to prevent this whole thing from being viable in the first place, TBD). So sideways movement within the tank would be minimal and gravity would confine vertical movement to the profile of the hull. Fore and aft motion within the tube would be somewhat greater, of course, but its forces are far less effective in that direction because of the hull shape. Especially when compared to the effect of an adult person or two moving around in the boat, located much higher than the lowest point in the boat that the tube is located in.

So it is not any where near the same level of risk of instability that, say, a half empty ballast tank would present, IMHO.

I don't think that these tubes would present any more problems for sanitation than any other built-in water storage in any other boat would. (Plus using bottled water fro drinking). But not as convenient as your water set-up either, Sum.

[Russ]

I think the idea is to replace the water as its consumed by ballasting down.

Kevin is absolutely correct. Once full of ballast, you can't/shouldn't vent air into it at all. (no pinhole vents). Perhaps I missed the plan to replace the ballast water as it's consumed. That's what is needed.

I'm not sure keeping the gate valve open will solve this totally. On a starboard tack, won't this be lifted out of the water and allow air in? Not good. Maybe it's deep enough.

A water "vent" thru hull truly below the water line, centered in a place always below the water line would solve this. As fresh water is consumed, this "vent" would take water in to replace it with sea water thereby keeping the ballast full and air free.

Also, perhaps a check valve system on the v-berth vent to allow air out keeping the ballast full of water.

The question to be learned is if the tubes will block water from entering. I doubt it would. It might slow it down, but a watertight seal blocking sea water entry, I doubt.
This is exactly the idea I have thought about for years. I never had the guts to implement it. Some of the concerns mentioned I feel as well; keeping it sanitary and wear from friction on the sharp inside of the ballast tank. As long as you are prepared for contamination and don't use this for primary drinking, it might work. Please report your results.

Something like this for raw water intake might keep water from blasting in while under power.


--Russ