Water Ballast Pros/ Cons

[DAVA390]

Ok. everyone we have time for one more pot stirring before everyone goes sailing. As a rookie who is currently learning on a trailer boat, I would like to know good/bad of W/B boats. I know the basic theory I think,and i like the looks of the C250,H240,H260. Please Discuss. Thanks, David

 

[Paul Brinkley]

Hi, David. Maybe the document below will help you. I ran across it during a discussion of water ballast a couple of years ago. By the way, I have a water ballast boat and love it. You may run across someone who will tell you that water ballast can't possibly work; if so, you may be assured that 1) they have little or no knowledge of physics:naughty:, and 2) they are wrong. There are some small drawbacks to water ballast, but for me and a lot of others, it works just fine. -Paul
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Water Ballast​

There is a lot of misunderstanding and misinformation about water ballast boats. These boats have a reputation for being "tender". How "tender" a boat is depends on many factors, such as hull and keel design, displacement, length, beam, and sail plan. In general, long, narrow boats with deep ballast will be more "stiff" than wider, shorter boats with a higher center of gravity. However, it is possible to design a boat with water ballast that has performance equivalent to similar sized boats.
Here's a discussion about water ballast boats that might help set the record straight:

​

Technically Speaking—How Water Ballast Works​

By; Ramblin’ Rod Brandon
rodney.brandon@sympatico.ca

First Published in Clipper Snips the magazine of the Trailer/Sailors Association Fall 2007 Pg 10​

I remember as a young child, my father posing the question, "What weighs more, a pound of feathers or a pound of lead?" Of course the answer is, that they both weigh exactly the same. This is a critical premise to understanding how water ballast works.
Some people believe that because water has neutral buoyancy in water, that water ballast would have to be lifted above the waterline, to have any effect on righting moment. This isn’t true. To understand why, one needs to know how righting moment is generated.

(see illustration wb01.jpg)

Every vessel has a centre of gravity (CG) and a centre of buoyancy (CB). The centre of gravity is the axis on which the boat will tend to roll when heeled. The centre of buoyancy is the relative volumetric centre of the water displaced by the vessel.
As the boat heels, CG remains stationary, whereas CB shifts laterally. The lateral distance between CG and CB is proportional to the righting moment GZ. The greater this distance, the stiffer the boat will be.
Dense ballast such as lead has the benefit of lowering CG which helps extend GZ. Since water ballast must be carried higher in the vessel, raising the CG, more weight in water ballast is required to create the same GZ as lead.

(see illustration wb02.jpg)

Note how in Illustration 4, the water in the ballast tank is not raised above the waterline outside of the vessel, and yet contributes significantly to righting moment. Without the water ballast, the CG would be much higher still, resulting in less GZ. This is why a water ballasted boat is so much more "tipsy" (technical term totally unrelated to beer or rum ballast), before the water ballast is loaded.
Water ballast must be raised above the water line to be effective? Myth busted!

Water Ballast Q & A​

Water ballast has been used for many years in many types and sizes of boats. In addition to trailerables, ocean going maxi-racers use water ballast since it can be pumped to the windward side to reduce heeling. These questions and answers only apply to the trailerable water ballast boats manufactured by Hunter, Catalina and Macgregor. These vessels are safe when operated within design parameters. Comments are welcome at: george@kobernus.com.
1. Q: What is the biggest difference between a trailerable water ballast boat and a trailerable conventional fixed or swing
keel boat?

A: The biggest difference is that the water ballast can be removed while the ballast in a conventional boat remains
the boat at all times. As a result, a smaller vehicle is needed to tow a water ballast boat and/or a larger water ballast
boat can be towed by the same vehicle.
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2. Q: How do you get the water into the tank?

A: Water ballast boats are designed to be self-filling without overflowing the vent hole. If the water intake valve and
vent hole are open when the boat is launched it will automatically fill. Once the tank is full and all vents and valves
are sealed no further action is needed. See these pictures for more information.
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3 . Q: Does the water "slosh" around in the tanks of a water ballast boat?

A: If the water intake valve is opened completely, the tank will fill to the top, replacing the air in the ballast tank.
There is no movement of water & air in the tank; as result there is no "sloshing". It is important to remember to
close the valve and plug the vent hole after it is full.
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4 . Q: Can you sail the boat with the ballast tanks empty?

A: NO! These boats should never be under sail with the tank empty. The McGregor is designed to operate much
like a traditional powerboat with the tank empty under power but should never be sailed with an empty tank. Some
water ballast models have lead ballast in addition to water ballast, but both types of ballast are needed to ensure
boat stability under sail. There is one famous case of a overloaded McGregor 26 that capsized with an empty ballast
tank; however, the boat was not under sail, the operator exceeded the designed passenger limit of the boat, and
alcohol was involved. For more on this incident go to this link. For more on this subject go to this link.
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5. Q: Can the water in the tank leak into the interior of the boat?

A: With some designs it is possible to experience water spilling out of the tank vent hole if the hole is not plugged
when heeling . Also, since the water tank top is usually the floor of the cabin, drilling holes in the floor is a bad idea
(don't laugh, this has happened).
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6. Q: Can the water in the tank "leak" out of the boat into the surrounding water?

A: You can't really "leak" ballast. Water in the tank will always maintain the level of the surrounding water. There
is a gasket on the valve that helps seal the tank when closed. However, I would guess that 99 percent of all hunter
water ballast boats have "leaky" gaskets. A "leaking" ballast valve will not significantly effect the righting moment
of your boat. Think about it - the ballast tank level will never drop below the surrounding water; even if the gasket
leaks, the amount that leaks out out when you heel will just leak back in when you level off. The next time you pull
the boat, keep the valve closed and see how much water leaks from the tank. If the amount of leakage concerns you,
try cleaning the valve surface and the gasket. If still not satisfied, replace the gasket.
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7. Q: How do I get the water out of the tank?

A: It is a very bad idea to remove water from the tank while the boat is in the water as this affects the righting moment
of the boat. See question # 4. When the boat is pulled from the water and the intake valve opened, the water will
drain out. Some owners have rigged up a pump to remove the water but this is a bad idea as this converts the boat
into a very large canoe! The McGregor is an exception to this rule as it can be emptied while operating under power,
just as any small powerboat can. In addition, installing an access hole to install a pump could violate the integrity of
the tank.
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8 . Q: How much water does the ballast tank hold?

A: The water amount varies depending on the boat manufacturer and model. Water weighs about 8.3 lbs per gallon.
The Hunter 260 ballast tank contains about 238 gallons or about 2000lbs of ballast. Some boats such as the
McGregor series have both water and conventional ballast.
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9. Q: Are there baffles in the tank?

A: No, there is no need for baffles since the tank is designed to be full at all times and this could increase the time
required to fill or drain the tank.
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10. Q: Does the ballast have to be raised up above the waterline to effect the righting moment of the boat?

A: No, this myth is debunked in the above article by Rod Brandon.
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11 . Q: Will a water ballast boat capsize easier than a conventional ballast boat?

A: Compared to what boat? Any boat can capsize under the right conditions. Trailerable water ballast boats are Class
C vessels only certified for inland and coastal waters and are no more liable to capsize than similar trailerable
conventional ballasted boats. Many water ballast boats have successfully weathered severe weather and have
completed long open water voyages. One Hunter 260 owner recently completed a 5800 mile Great Loop trip, and
more than one H260 has done the Miami-Nassau run, but this is not a blue water boat by any stretch of the
imagination.
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12 . Q: I've heard that water ballast boats are "tender".

A: It is possible to partially quantify how "tender" a boat is using conventional engineering data. Go to this link to look
at the data of similar boats. The Hunter 260 has a displacement of 5000lbs and carries 2000lbs of water ballast. The
two foot shorter Dana 24 has a displacement of over 8000 lbs with 3200 lbs of conventional ballast. In this case the
fact that the Dana is less tender than the H260 has more to do with the displacement and design of the keel than the
type of ballast. With water ballast boats you'll notice it feels more like a powerboat when sitting at the dock or
motoring with the sails down; but it's rock solid once it heels more than 5 degrees.
After all, the H260 is still a 26ft boat with a displacement of 5000 + lbs and 320 sq. ft of sail. This gives it a SAD of
18.8. The hunter has a significant roach in the main so it is a good light wind sailor but it can become easily
overpowered when the wind pipes up and will round up if you are not paying attention. As a result, you can't just
lock-up the mainsheet and throw away the key like you can with larger boats. Tending the main and reefing the sails
early are the keys to safe, comfortable sailing.
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13 . Q: Will a water ballast boat heel more than a conventional keeled boat?

A: No. Because the center of gravity of a water ballast boat is higher than a conventional ballast boat, the initial
righting moment provided by water ballast is not as pronounced for about the first 5 degrees of heel, then the weight
of the ballast begins to take effect. Beyond that initial point, there is no significant difference between the
"tenderness" of water ballast and conventional boats given similar size, ballast weight and displacement. The ballast
does not have to raise above the water line before it begins to resist heeling. See this diagram.
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14. Q: Where is the water ballast. Is mechanism complicated or easy to break?
A: Think of the water ballast as a long shallow flat keel attached to the bottom of the boat. It is a little more complicated
than a lead fin keel that just sits there, but more complicated than a heavy swing keel that has to be lowered and
raised.
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15 . Q: Does the water have to be replaced periodically?

A: There is no need to replace the water under normal conditions. Some people assert that the water gets "stale" and
smells. This is should not be a problem if you keep the vent hole plugged. Few if any organisms can survive for long
in a sealed tank without light and depleted oxygen. In tropical climates where the boat remains in the water all year,
some owners have been known to treat the ballast with bleach, water bed solution or other chemicals. Despite this,
in virtually all situations discharging chemicals into open water is against the law and heavy fines are possible.
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16 . Q: What should be done to prepare a water ballast boat for winter. Is there a possibility that the water will freeze?

A: Yes, the water can freeze and the tank can be damaged. Some people suggest putting anti-freeze or water softener in
the tank. You'd need a lot of chemical, and this could result in a large fine for polluting the surrounding water. The
whole idea of a trailerable boat is that it is easily retrieved. Pulling the boat and draining the tank is the best option
when temperatures drop below freezing. Level the boat and ensure the ballast drain valve is open. This will insure
all the water will drain from the tank.
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1. Q: I'm confused. My friend has a water ballast boat and he says he has a keel that sticks down in the water about 6 feet.

Is that where the water ballast is?
A: No. Most water ballast boats typically have a centerboard that weigh less than 100 lbs. The purpose of a centerboard
is to resist sideways motion of the boat when sailing. See this picture.
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18. Q: does a water ballast boat point as high as a similar boat with a conventional or swing keel?"

A: Again, you have to ask "Compared to What boat?" The great majority of the sailing manners of a boat depend on
factors other than the ballast. Design of the Keel/centerboard, rigging, sail plan, length, width, and displacement
result in a whole greater than its parts. Many observers agree that some water ballast boats don't point as high as
some conventional keeled boats; however, others believe that gaff-rigged boats also don't point as well as some
conventional keeled boats or water ballast boats for that matter.

 

[r.oril]

Thank you Paul. I will copy this info and add it to my MacGregor 26D Binder.
Bottom line is that I feel very safe when sailing my boat.

 

[mspiers]

Ive had two water ballasted boats, a macgregor 26D and a hunter 19... and i just purchased a C250 water ballast that will be ready to be picked up next friday..

My experience is if you are a trailor sailor who trailers to sail for a weekend 95% of the time then you cant beat water ballast. The lower your boat sits on a trailer the happier you will be.

I have really high hopes for this c250, but Ive never sailed a swing keel, centerboard, or shoal keel that compares to a full keel, but getting craned into the water every sail is expensive and time consuming. Even a wing keel is a pain generally. I have also hit very hard aground in a swing keel and simply quickly cranked her up to get free. A centerboard water ballast would also give you that degree of oh crap but were ok.

Ive seen WB's in the permanent slip and kinda cringed... I mean they have bottom coating, but the whole inside is full of water, so i dont understand why someone would slip one for more than a vacation. I personally am not even going to bottom coat my c250 at all because when i come home so shall she.

 

[Bob 04 H260]

I have owned two water ballasted boats and been very happy with both of them. Easy to trailer and launch.

I have taken a number of sailors out in them sailing who expressed surprise they did not feel much different than the small keel boat they owned.

Often when comments are made a about water ballasted boats being very tender it is being made by someone that has never sailed on one.

I keep my boat in a wet sliped in a club with over 500 boats when not trailering it. We sail on a river with two other large clubs near by, it can get quite congested at times. It gives me the chance to sail near many other boats of all sizes and makes. I can see a gust of wind coming down river as the boats ahead of me heel over. What surprised me at first was that many keel boats heel more than I do, I suspect they are designed to do that to increase the waterline.

As far as marine growth in the water tank is concerned I suppose it depends on the water the boat is in. I have never had a problem or concern but have heard of sailors adding a bit of bleach to the water tank to prevent any growth over a summer.

Bob

 

[Quoddy]

H260/270&Cat250/250wb

Good Q&A and attachments on water ballast. We own a H260, great boat.

I believe a boat that carries its ballast in the hull (all other factors being equal) will not resist heel as much as one with lower ballast. As you lower the CG the GZ get wider for an equal amount of heel, therefore the resistance to heel increases with a lower ballast. So if you have two boats with equal ballast and similar design, one with ballast in the keel and one with ballast in the hull, the hull ballast will be less resistant to heel.

One of the advantages, motion wise, of ballast in the hull is an easier motion and less hobbyhorse effect. Another is neutral buoyancy of the ballast. The boat is less likely to sink if flooded.

It would be good to hear from people who have experience sailing both types of boats, especially the H260/270 and Cat 250 and 250wb. Same boats different ballast.

 

[soling42]

We owned the 240 wb and have now owned a 2004 H260wb for over 5yrs and I must say that the 260 is quite a bit stiffer than the 240 even with the 260s' large roachy main(which is predominately a light air sail).

That said I recently added a 300sq' gennaker on a bow sprit and the boat handles it very well, especially off the wind up to 12kts. Our boat's on a dock for 7mths and then I trailer it home each broiling season(summer to you northerners). It trailers like a breeze and without the added height of a keel it fits into my shop like a silk glove.

The water in the tank won't go bad if there's no light or air. Just dump it at the ramp and loudly proclaim that you didn't realize your holding tank was so full from all that beer your crew drank. Bottom paint is not evil it works and with minimal effort keeps your hull happy too.

WB naysayers are generally uninformed or are biased to their favorite brand of ride but aren't we all.
Mike

 

[mspiers]

Ive never heard anything mentioned on the subject, but seeing a wb in a slip for a long period of time (even with bottom coating) makes me concerned about blistering on the inside of the water ballast tank, damaging and adding unneccesary weight where you cant even reach to repair it.

Like I said, Ive never seen anything mentioned on the subject, but how can this not be an issue on a slipped wb boat?

 

[monkeybars]

insides of WB tanks are not gelcoated.no gelcoat no blisters.

 

[mspiers]

Oh ok, I didnt realize you needed the gelcoat for the process. I purchased and hauled a boat years ago, back when I was basically a used sailboat dealer of sorts, and she came out with a bad case of chicken pox. I had to sand every two hundred or so of those 2 inch across lumps until the water bubble burst, then sand the "dead skin" if you will, off and then i let her hang and dry out a few weeks before coming back in with the repair.

Now the "dead skin" I referred to Was fiberglass cloth, so the damage was well past the first layer of cloth, but that was definitely under the original gelcoat layer.

 

[DAVA390]

Thanks all for your replies and information. This helps me out a lot.

 

[watercolors II]

Compromise

Compromise, compromise and compromise.

Every sailboat ever built is a compromise, each model was and still is designed and constructed for a specific market. Generally one could say every boat built in the 70’s and 80’s was built with sailing capabilities being close to the top of the list and boat design in the 90’s and 10’s family oriented is closer to the top. This would be one of the major over all compromises in the last 40 years.

A furling head sail over a hanked on sail there is a compromise, wheel steering over tiller steering is also a compromise, learning to sail a boat is really the easiest part of sailing, all of the compromises one has to make is the hard part.

Now, comparing boats; the article says "Compared to What boat?", about as close to apples to apples I can get is a Catalina 22 swingkeel, Catalina 250 finkeel and a Catalina 25 swingkeel. Two of my best sailing friends have these two boats. My wife has not been on my 22 since 1994, the 250 his wife sails with him twice a year and the 25 his wife misses about 40 percent of his outings. All 3 of us are mostly sailing single-handed so, we often go together on one boat for the camaraderie and of course the beer. During one summer I may have sailed on the other two models maybe 10 times each, and have been on trips to larger waters on both boats.

I really do not feel that much difference between my 22 and the 250 under sail or motor. All 3 have larger cockpits than the average, the 250 loses room because of the wheel steering but it makes this up with the seats mounted on the stern railings. The cabin height on the 250 is close to my 22 because of the water tank in the floor. Rigging the 250 when trailering is about the same as the 22 as far as the weight of the mast but, the rigging times is twice as much as the 22 because of handling the furler. 3 fellows on the 25 and 250 with furler or with 2 people using a ginpole setup. On trips or overnighting the 250 and 25 with the extra storage and room is a big plus. I’ve sailed on a Macgregor 26x and it is very similar to my 22 in handling.

I would say the 22 and 250 are twin brothers except for the cabin room. The 250 and the older 25 are more like sister and brother, they walk, talk and physically are very different.

Hunter 27, 1989, 9.0 wide, 3.5 foot wingkeel draft and 10 hp yannar inboard is very trailerable. Spent so much time on one at the lake and on the Chesapeake Bay that we’ve ruined 3 sails. Have not tried the H260 for comparison.

I would say the smaller the boat the less of a difference would be between the ballast issue, the larger the boat the greater the difference.

If I was trailersailing I would go with the water ballast, if I only moved the boat to it’s mooring and back where trailering is not the issue I would go with the weighted keel in same boat size.

 

[CaptDon01]

Re: Compromise

We have friends with a C-250 WB, and I must say, I was impressed with the stability of the boat. Yes, the headroom is reduced, but it's still HUGH inside! And the enclosed head with a door is a real plus! The C-250 WB and WK both share the same spars and sails. Only real rigging difference between the two is the WB uses a fixed mainsheet location, vs the WK has a short traveler. The C-250 WB has about 4" additional headroom in the cabin over our C-22 MK-II, and is only slightly heavier to tow than our C-22 MK-II. I was always dead against the thought of a WB'ed boat until I actually got on the C-250. Sure changed my attitude, and now, that's our "retirement" boat down the road.

We also have friends with a Hunter 260 WB. That's another boat that sure changed my opinions....Hugh interior also, actually more headroom in the Hunter, but I'm just a Catalina guy stuck in my ways.....

Don

 

[mspiers]

I purchased a c-250 wb last friday and have sailed her one weekend only so far and in 20-30 mph winds and 4 ft waves....

Much tougher boat than i was expecting.. I had heard they heel really fast and will catch you offguard.. I had heard you really had to reef early and be careful....

I started out with an unreefed main and no furler... no issues... i ran a main on second reef with half the furler out... Then pulled the main down and ran all furler... I then went back to the unreefed main with partial furler out... i was running more sail than most anyone else out there because i wanted to see what she could do... water never got past the rubrail. i never got much spray at all.. as a matter of fact only time i did was under aux power. She would try to turn up to weather in really strong gusts but id just ease the main. Mph reading was anywhere from 6.5mph all the way up to 8.4 mph. I was impressed, and Ive owned around 20 plus boats and sailed i dont know how many.
Didnt even scare the wife that much, and she can be a little nervy...lol

 

[Hawk4661]

great post....good read for me as a novice sailor.

 

[DJN51]

Check out youtube video[ huntercapsize02].I sail the hunter 23.5 these guys are trying to bring over.My son and I tried,same result,my boat just heads up every time.I sail Lake Michigan mostly solo,it can be a little tender,but once you know your boat you compensate.Love my 23.5.

 

[Roger Long]

Water ballast is interesting. If the following two boats have the same dry weight and center of gravity they will also have the same initial stability or sail carrying power. In other words, they will heel the same amount when with the same sail plan and trim in the same wind or when passengers move from centerline to side. The water ballasted boat will feel heavier, hit the dock harder, and pound less in a seaway but you could say, from the stability standpoint, that the water ballast isn't doing anything. It will take more power to push the boat on the right through the water which is why sailboat hulls have increasingly gotten so wide and shallow over the years.

However, the boat on the right will have more initial stability when there is water in the tank than when it is dry.

 

[soling42]

No one could say that "water ballast isn't doing anything" for stability on any number of WB vessels from the basic WB system of the much maligned and arguably under-ballasted Macgregor sailboat to more complex designs in freighters, submarines and the open 60's.

Captive weight on a vessel is all it amounts to whether it's lead, rocks, cargo, sand or water. Captive ballast has added stability for centuries, water is just more readily available on a boat and works fine(when captive) on sailboats too.

For sailors, movable stabilizing ballast(rail meat or WB) creates an even faster ride than lead in a fixed keel. The ballast tanks on modern Open 60s' are the perfect example and invaluable to their performance but the comment by a noted designer sums it up for nearly every WB application:
"Water ballast can be taken on when you need it, you don't have to feed it, it doesn't talk back to you, and you can dump it when its usefulness has expired."

Found here: http://www.vgyd.com/Waterballast.html
A good rule of thumb is to never dump your crew for the sake of speed so I just leave 2000lbs of captive ballast(in my case water) at the ramp.

Thanks for your effort on the website.
Mike

 

[Thomas Dynneson]

I have a Hunter 23.5 with water ballast tanks and find them easy to fill and empty. My boat had been in dry storage for some time and when we came to clean her up I found some mildew in the aft of the back cabin under the rear cushions. I pulled the cushions to clear it up the mildew and found some one inch bubbles in the jell coat surface, not many but some. I quickly learned that the dealer from whom I had purchased the boat had cut a hatch in the stern floor to create an additional storage locker. The hatch evidently leaked when it rained and I found water in the area below near the bilge area. I dried this up and I am going to insulate the installed aft hatch to make it water proof. Question: What should I do with the several (8 to 10) blisters under the rear cushions. Do they need to be sanded opened, cleaned, and resealed? If so, how should I proceed?

 

[dscribner]

Thom,

Pick up the quintiscential Don Casey book on sailboat hull and dec repair. I got a copy for about $15 including shipping. If Don doesn't know it, you don't need to! Hey, it's all in the name!

Don

Biddeford, Maine