water ballast in a CS

[Hirilonde]

Some of the prototype Mini 6.5s use water ballast.  They have as many as 4 fixed tanks (usually just 2).  Each tank has a scoop in the hull that works like an Anderson bailer in reverse to fill the tank.  Then each tank has a built in manual bilge pump and hard plumbing with a Y valve that allows you to pump the water to the tank on the opposite side or overboard to empty it.  This may be a bit more complex than most people are looking for, but for those who really want to push the envelope it is a very viable system that requires only manual power to operate.

Acadia specs briefly describes one such system and includes a video (though not very clear) of the layout.

Next thing people will want Graham to design is canting centerboards with balllast  

[paul_stewart]

I wouldn't be interested in water ballast on our CS20.  However,  I could mention one advantage of water as a material for ballast:  it is neutrally buoyant when submerged in water 

--Paul   

[wkisting]

No worries sitearch... I didn't take offense at your response/tone. I also hope I wasn't one of the folks who sounded like I was scolding anyone. I'm a constant fiddler/thinker about this stuff, so that's how I came up with the shifting ballast design I was suggesting to you as a possibility. I decided it isn't something I would actually use or desire for my own purposes becuase I find that I'm always happier with the CS if I focus on keeping things simple. But I wouldn't laugh or criticize at all if you decide to put ballast on your boat, and actually, I would love to see someone try my idea just because I'm curious about how it will work.

If you want my candid views about water ballast, this is the little I know... The water ballast idea has always interested me because it sounds clever and workable, but I have never heard a consistent view about its effectiveness. For every person who I've heard say it is a proven method, I have also heard folks who own (or claim to have owned) supposedly-proven water ballast designs say that they think it is "gimmicky" or fraught with problems that make it "less than ideal" compared to the simpler, more traditional solution of just weighting the keel/centerboard/etc. So, having never own a water ballast design myself, I've always regarded it with some suspicion simply because there doesn't seem to be a clear consensus about how well it works. I also think that if it works, it probably works best for designs that were originally designed with the water ballast in mind.

The reason I personally would prefer a sliding hard weight is because, once attached to the boat, it would operate simply on a principle I know works very well... having a person shift from one side to another to make a significant difference in heeling and the force the sails can stand up to. Also, as a solid weight, it could be very small in size compared to the volume needed for an equaivalent amount of water, and as I said earlier, could aslo be shifted further to windward to make the weight more effective than a low-mounted tank. The only downside would be the presence of the weight while trailering, but to my mind, it would be a small issue and a preferable tradeoff to the extra build complexity and setup involved with building ballast tanks (which also may become a problematic site for rot) or filling/emptying plastic jugs or containers, or however else one might add water ballast.

To show you that I am a kindred spirit with crazy ideas of my own, I have also imagined ways to build my sliding ballast/weight contraption so that the weight could also be shifted fore and aft to adjust boat trim to ideally suit the sailing conditions. But for my own purposes, I don't need such a system and don't think it would be truly practical. So now I'm trying to sell you on the idea so that you will build one and then send me pictures of how cool it is. 

Either way, I look forward to seeing how you implement a solution for ballast, if you decide to do so. Some of the old sharpies would put stones or bricks low in the hull for ballast... you might want to try that first to see if and how signficantly the weight affects the performance--whether for better or worse. It would also tell you where (location wise) the ballast proves most effective and least intrusive. Personally, I'd probably use sand bags to experiment, since they won't shift around while heeling and won't scratch the interior paint.

[Ray Frechette Jr]

I don't have any negative feelings toward water ballast.

Personally I have never felt the need for ballast on my CS 20 at all.    And I have a hard time conceiving of a benefit with it.  But that is a personal opinion not to be confused with known fact or law.

That being said I probably would not purposefully go out single handed in anything more than 20 knts windspeed.

[Hirilonde]

I don't think there is any question about whether water ballast works or not.  It most certainly does.  If you are spending a quarter million dollars or more to campaign a racing machine against the top sailors in the world you do anything and everything you can to gain an edge.  If you own a 20 foot semi-racing daysailor it becomes very questionable whether such a system has any place at all regardless of how well it works.  I would certainly not want to give up the room the tanks require, never mind the time, expense and energy installing it would cost me.  If I really wanted to solo a CS 20 in stiff winds I would reef the sails.  Even though extra ballast to weather helps a lot the inverse applies as well.  Should something go wrong, and it does tend to happen more in tough conditions, ending up with ballast to leeward can be catastrophic.

[Peter HK]

Bob said

Graham was kind enough to put up with me and a few months ago I finally asked  him to design a powersailor for me when he gets time from designing all of the motorboats he is involved with nowdays. A powersailor--you know a boat that both sails and motors well with a cabin etc

At one stage I decided to try a powersailer and ended up with a Mach28 (an Australian designed and built powersailer loosely based on the Mac 26 but built to a much higher standard). This was water ballasted with about 1.2 tonnes in the tank under the floor and powered with a 90 hp ETEC.

[wkisting]

I don't think there is any question about whether water ballast works or not.  It most certainly does.

Dave, are there particular water ballast designs that people are consistently pleased with? I'm not doubting what you say... just curious which designs people are consistently pleased with. It certainly seems workable, but...

Years ago, when I was interested in the water ballast concept, I chatted with a lot of folks who had experience with water-ballasted designs. Many definitely reported that water ballast "works," but it seemed like an awful lot (majority?) of those folks still were reluctant to describe it as an "ideal," "highly effective," or "totally satisfying" solution. More than a few told me they didn't like the space consumed by ballast tanks, etc. (in at least a few cases, this was because they felt it robbed them of precious seat storage or cabin interior space). A few of those said they would definitely prefer to have a weighted keel in retrospect. Others told me they only went the water-ballast route because of trailer-weight considerations. Some seemed happy with how quickly and easily the ballast tanks could fill, but some said their ballast tanks were problematic because the tanks were hard to get completely full and that sloshing water inside the tanks would occasionally cause instability rather than cure it (I'm assuming that was a design flaw, but it was so long ago I have no recollection of whether they were talking about a home-built design or a professionally-built design). Those who had built their own ballast tanks warned about the importance of having large inspection hatches to inspect for rot, but they also seemed to complain often that it was hard to keep these inspection hatches watertight (usually, this was an issue with home builders using Bomar hatches or some similar variant). Several argued that the main "problem" with water ballast is that it isn't very effective until the hull heels far enough to raise most of the water ballast tank above the waterline, which doesn't do much/enough to help some designs sail flat if that was the goal. Some claimed it was difficult to fully evacuate the water from their tanks, raising concerns (not necessarily actually problems) about rot. Anyway, the list of complaints, concerns, or semi-minor gripes seemed to go on and on, even among folks who claimed to like the water ballast concept. I finally decided it was a can of worms I didn't want to open in my own search for a good trailerable sailing design.

To this day, I have no idea how accurate any of those concerns/complaints were, but that's what has always made me suspicious about water ballast... just the lack of a steady line of folks who are happy to report "I love it," rather than a much more mixed message. Anyway, since I always like to learn more about this stuff, I'm just wondering if there are particular water ballast designs you (or anyone) might point me toward as good proof of the concept. I certainly have no definite prejudices against the concept.... just a lot of questions.

[Mike Vacanti]

I've read all the replies to this thread and it seems to me that there are 2 different ballasting schemes being discussed. The type most common to trailerable sailboats places all the ballast low and in the middle of the hull. I've sailed on 2 different boats (Catalina 250 and Mac 26X) that used this design and neither sailed very well to weather. Both boats heeled fairly easy but at least the owners of these boats could pull the boat with a reasonable sized vehicle. This seems like the only advantage of this style of water ballast.

The other type of water ballast system has tanks as far from the centerline as possible and the water must be transferred when the boat tacks. I've never sailed on this type of boat, from what I observe this is used on high performance racing boats and is very effective but a lot more hassle. Pumping water on every tack when daysailing seems too much like work to me.

[wkisting]

Mike, thanks for the useful clarification. I should say that the first kind of ballast you described is the kind that elicited the range of comments I was summarizing above. I was always talking to folks about trailerable designs (usually shallow draft, though I think a couple were "hybrid" designs that used both a moderately weighted partial keel and ballast tanks).

I don't think I've ever encountered someone who had experience with the second type of water ballast (side tanks that pump the weight back and forth to either side), but that sounds like it would definitely offer higher performance since the weight would be further to each side and therefore more effective.

[P.S. -- Sukie, I overlooked your question about my downhaul above. You can see it on my webpage about the tweaks/upgrades we've made to our CS20, located here: www.roguepaddler.com/cs20u.htm ]

[Ray Frechette Jr]

[ Several argued that the main "problem" with water ballast is that it isn't very effective until the hull heels far enough to raise most of the water ballast tank above the waterline, which doesn't do much/enough to help some designs sail flat if that was the goal.

This is a complaint given often about water ballast.  Esenytially it is intuitive that water ballast provides no weight untill it is hauled above waterline form heeling.  That below it the weight dissapears.

Bogus claptrap is all that is.  Not that I am opinionated or curmudgeonly.  I am just stating absolute verifiable fact there.

Not to say that having dense ballast is not better in this respect.  The vertical center of gravity can be lower with dense ballast. Just saying that the idea that water ballast provides no benefit untill it is lifted out of the water is bogus.

There are good water ballast designs and awfull ones.

And yes it is a series of compromises.  Pro of water ballast is that it is left on the ramp when you go home so you don't have to haul it around.

Yep , that is pretty  much the biggest pro.  Oh Yeah,  If boat is capsized then once water gets into hull etc then the wieght of the ballast ceases to exert an effect.  Once it is completely surrounded and supported by water it will only sdisplace and euqual weight of water...  But water in a ballst tank stillweighsbetween 62 and 64 lbs per cubic foot wheter that tank is below waterline in the boat or above it.

Try this experiment.

Go on a submarine.  Dive below water.  Weigh a 12 0z can of soda.

Surface and re weigh it up on deck outside the boat.  It will weigh pretty darn near the same in both places.

[wkisting]

That's my sense of it too, Ray. I remember that exact issue setting off a heated debate about water ballast and principles of physics. If I recall, those folks finally agreed with what you're saying: that water ballast does work even before heeled above the waterline, but with the caveat that it still is not as efficient as other forms of weight because (due to the volume of water needed to get enough weight), water ballast can never be carried as low and close to the hull as an equal-weighted dense solid, such as lead. The lower the weight sits in the hull, the better. Makes sense.

[Hirilonde]

Ray is absolutely correct.  The location of any ballast, water, lead or feathers is only significant in relation to the center of gravity of the boat.  It doesn't know or care where the water line is or whether it is above or below it.  That is, if it is inside the hull of the boat.  It is not adding any volume, only weight.  

Personally I don't think water ballast is practical at all.  As I said in my previous post it is effective, not convenient.  On a Mini you fill it in strong winds and very likely sail on that tack for many hours and possibly days.  You are racing from France to Brazil.  You don't care that it takes a lot of effort to pump it out or across to the other tank.   Well, ok, you care, but since winning is a strong drive you do what ever you have to to gain speed.  Your opponents are working hard at anything as well, so you have to.  And when the wind dies down you empty it to reduce weight and wetted surface.  Solid ballast can not be taken on and later disposed of at will.  Only water can.  On a Mini you move all of your gear around, hourly if necessary to balance your boat.  You sleep on top of your gear on the weather side in spite of the fact that sleeping to leeward is much more comfortable.  If you can even call the 15 minute naps between scanning the horizon, checking on sail trim and such sleeping.  Convenience, practicality, ease of use, comfort all have absolutely nothing to do with your decisions.  Water ballast is an ocean racing option for those crazy people who will torture themselves for days on end in and effort to get to the finish line before their opponents.

I would never bother to put one in any boat other than a serious racing machine.  No matter how effective it is the space lost to storage isn't worth a little bit a speed that you don't really need any way.  And even with an effective scoop to fill the tanks and a properly plumbed pumping system, moving water about while day sailing can hardly be considered worth the effort.  You would be totally exhausted after a couple of tacks.  

When I said water ballast was effective, I meant that the weight to weather was effective in balancing a sailboat in strong winds.  And it is.  But it sure as heck isn't practical.

[PAR]

The problem with water ballast is it's weight. It just doesn't weigh much for it's volume. Second is the amount of weight we're generally talking about for a Core Sound. Lets take an arbitrary amount, say 400 pounds. which is probably more then most would want in their boat. This is roughly the size of a 50 gal fish tank in your boat. Any of you that have 50 and 55 gallon fish tanks at home, know how big this really is. Okay, clearly too much for one location, so divide it into two 25 gallon tanks, one on each side of the centerline, right? Okay, now we're talking about two big coolers (size wise) that you can't use, in the middle of the boat.

Now if you used lead, a strip about 3" tall x 3" wide, the length of the centerboard case, laying directly on top of the keel, would be about what you'd need to have the same weight. It would be centered on the keel, it's CG would be considerably lower and you wouldn't have to sacrifice any noticeable interior volume. You could divide this hunk of metal into manageable littler hunks, maybe with built in handles so you could load or off load them as desired. I have a 40' yacht with 220 little hunks of lead, used as trimming ballast. I remove them every so often to clean things. It takes about a half hour to gather all the little lead bricks up and toss them into a wheel barrow on the dock. This is over a ton of lead now.

Okay, lead is expensive so use iron, copper, bronze, brass or steel, covered in several coats of epoxy so it doesn't rust or oxidize. Make your casting 3.5" wide by 3.5" tall and the same length (centerboard case) and bingo, a cheap metal ballast, that doesn't take up any room and you can actually carry two big coolers, but this time filled with beer. Again small, manageable hunks so you can off load as needed.

Then there's the issue of off loading the weight. Do you really need to remove 400 pounds from your trailer boat? Is your tow vehicle so anemic that 400 more pounds will kill it?

Water ballast was a racing fad that didn't last too long. It was tried, attempts to develop it into a more viable system tried and ultimately it has been abandoned. Naturally, when something hits the racing circuit, it quickly trickles down to production boating. It's just as bad in this venue, but the tooling isn't paid for, so they continue to produce these "bastards" until they can justify removing the ridiculousness from their products. Water ballast just takes up too much room for it's weight.

Lastly, driving a boat hard doesn't necessarily mean she's going faster. I sail in heavy air fairly frequently in the summer. Reefing down doesn't mean going slow, in fact I was doing 18 knots the other day with a 90% jib and a reefed main, instead off the 130% jib and full main I had up 15 minute earlier. With the gusts, I don't think I could have kept her upright with the 130 and full main, but if I was able to, she'd have been going slower, burying her rail and threatening to take the rig with each lift.

All boats have a "groove" that they want to live in. The CS series has a fairly big groove, so find it and learn what it feels like. If you're out of this groove, no matter what the reason, you're not driving the boat harder or faster, you're just making more work for yourself and the gear you have aboard. A three man crew can claw into a 20 knot head wind pretty well and keep the boat on her feet and in the groove. A solo sail, under a single reef in both sails will keep her on her feet and remain in the groove in the exact same wind strength. So tell me what's the difference and why again do you need ballast?

[Ray Frechette Jr]

Okay, lead is expensive...

Fifty cents a pound is expensive??

I can deal with 200 dollars for 400 lbs of ballast myself.

Shoot , plumbing and tanks wouldn't be a whole lot cheaper esp once all fittings and such.

[sitearch]

Thanks to all. I have learned a lot. Maybe I am persuaded not to try to add any additional weight to my CS. I will just sail with a more lean sail.

And thanks to Peter HK for the Mach28 reference. I have looked at the Mac26 and it may work for me in the future here in Alaska. In fact when I ask Graham to design me a boat to sail and motor his response was positive not negative.

Anyway thanks to all for the good advice.

Happy sailing.

Bob

in Alaska

Here is a picture of the Bayraider by Swallow Boats in Europe. It has water ballast and a motor well.