How do you feel about water ballast?

Discussion in 'Sailboats' started by ryanluskin, Sep 15, 2015.

  1. ryanluskin
    Joined: Sep 2015
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    ryanluskin Pa'a

    How do you feel about water ballast: Mac 25 Vs 26 S,D or other Alternative

    I would appreciate your thoughts. I’m looking to buy a trailer sailor on Maui Hawaii, for my family of four, where I’ve sailed for twenty years. I want to tow it with a 6 cylinder 4 wd. truck, rated to tow 5,000 lbs. With that towing capacity, I can either get a boat like a 22 foot Catalina, O’day, etc. Or, I could buy a 25 or 26 foot, more lightly built, Macregor…and have 4 ft. more comfort. What do you think?

    I believe it is the magician, not the wand. I am debating between the water ballasted Macgregor 26s, or the 25 with a swing keel (625 lb.) I would like to hear your thoughts on the water ballast, or other boat options. While purists often don’t seem to love Macregors, I’ve found numerous stories of people cruising them over 1,000 miles, and both boats have positive floatation.

    My original assumption was that the weighted keel of the 25 would give me a more seaworthy boat. However, I’ve read that while the water ballasted 26 is initially tender, it becomes more stable and stiff as it heals, because the water is kept high and broad. The capsize ratio for the 26 D is 2.24, while the 25 is 2.45. A lower number is better. Next, the motion comfort for the 26 is 11.43, while the 25 is 8.8. The higher the number, the greater the comfort. I watched the sales video for the 26, and they were out in 25 kts of wind, in some sea, and she was handling. So, if the weighted keel of the 25 does not necessarily make her more seaworthy, I don’t see any benefits of the 25. The 26 is a foot longer, lighter to trailer, has a second double berth, a better layout, and I wouldn't have to maintain the swing keel. What do you think? Am I missing something?
    Last edited: Sep 18, 2015
  2. Petros
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    Petros Senior Member

    sounds like you have made up your mind.

    water ballast is a great innovation for a trailer sailor, but the inboard volume it takes up is very large as compared to steel, lead or even a concrete filled keel. So for the size I suspect you get noticeably less internal volume for any given size hull. Of course you can see that for your self when you inspect the boat, you do not even have to sail it to determine this.

    Usually, for performance, the heavier/more dense the ballast, the lower, the better. Water ballast lose against all others in these areas. However if comfort is your goal, rather than performance, that large volume of water relatively high on the hull, might be what you actually want.
  3. jehardiman
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    jehardiman Senior Member

    1 person likes this.
  4. gggGuest
    Joined: Feb 2005
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    gggGuest ...

    I'm curious. If I have a 45 gallon drum of water inside the boat as movable ballast, how does it know when its been lifted above the waterline?
  5. whitepointer23

    whitepointer23 Previous Member

    Was thinking that myself. 200 kg is 200kg. Don't matter what it is made of.
  6. Skyak
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    Skyak Senior Member

    The 26D is a few hundred pounds lighter on the trailer, the 25 is a few hundred pounds lighter on the water. The 26D looses internal volume to the water, but the 25 has an irregular floor and a couple inch bilge. The 26D has the 'comfort number' but it lacks righting force at low angles where you need it for sail power on all headings but downwind. The 26D will be 'rolly', the 25 will out sail it. I think the capsize ratio of the 26D benefits from higher topsides and significantly greater weight. I think that most commentators here would chose the 25 for performance (boats in new condition) and the pleasure of sailing. If the 25 does not fit you or your trailer puller, the 26D is a good boat.
  7. sharpii2
    Joined: May 2004
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    sharpii2 Senior Member

    Water ballast does two things that can be usefull on a sailboat:

    1.) it adds weight which acts as heft, which helps it split waves better and gives it a more comfortable motion.

    2.) it improves ultimate stability, helping the boat right itself from a knock down.

    That's it.

    It does not add to sail carrying ability because it lowers the Vertical Center of Buoyancy (VCB) almost exactly as much as it lowers the Vertical Center of Gravity (VCG).

    As a consequence, water ballasted boats need a lot of form stability and tend to have boxy hull sections, so may not perform as well in light winds as their couzens with more dense ballast.

    Think of it as having a very streamlined tank of water attached to the bottom. As the boat heels over, more and more of that tank is lifted out of the water. When the boat is on its side, at least half the tank is out of the water. Then it is definitely adding righting moment, as water is much heavier than air.
  8. rcnesneg
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    rcnesneg Senior Member

    If you're talking about the old Macgregor 25 swing keel, I would NOT get one. They sail incredibly slow. It looks like it's standing still all the time, even when at top speed. I've seen the 26 do 30 mph under motor with no sails, but under sails they seem rather slow, but maybe not as bad as the 25 swing keel, I don't know. I would be more inclined to get something smaller with a fin keel or long keel, like a Cape Dory 25 (4000 lb displacement). I would stay away from water ballast, especially in the ocean.
  9. whitepointer23

    whitepointer23 Previous Member

    So how is that different to any other internal ballast
  10. minno
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    minno Junior Member

    I'm not a rocket scientist, ( or a naval architect ) but water below the water line displaces the exact same weight of water as the water in the ballast so it might as well not be there until it is lifted above the water line while denser ballast will still have a righting effect while submerged equal to the weight of the ballast less the weight of the water it displaces.

    I'm guessing that having your ballast higher on the boat lessens the snap of righting and so gives a slower roll and a smoother ride?

    I'm not sure if it's appropriate to ask here, but I had a question on water ballast in a catamaran, I was playing with the Idea of building the hulls around a piece of sewer pipe and filling them (the sewer pipes) with water when I'm short on crew, but it sort of seems like any gain in weight to the windward hull would be canceled by the equal loss of flotation on the leeward hull?

  11. jehardiman
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    jehardiman Senior Member

    gggGuest and whitepointer, minno and sharprii2 have it right. Water ballast is just a waste of space on a small boat. Better to change the hull form and save the weight.
  12. Squidly-Diddly
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    Squidly-Diddly Senior Member

    I think Water Ballast is a great opportunity to include several other niffy features.

    1)Transferable ballast for greater sailing performance, especially on long tacks.

    2)Storage of extra fuel or fresh water in bladders within the ballast tanks.

    3)Combo ballast/flume tanks.

    4)Emergency buoyancy tanks.

    5)Double hull.
  13. whitepointer23

    whitepointer23 Previous Member

    The mac 26 is one of the highest selling production boats around, i can't believe they have got it wrong. Water ballast can be dumped for power boat operation. There is nothing else they can use in a mono. I would not like to bounce over chop at 20 knts with a weighted swing keel bouncing in the center case. Imagine how long that would last.
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The Mac 26 is a high seller for the same reason that the Ford Mustang is. The Mustang is kind of sporty, but not really compared to a real sports car, it's kind of a small family car, but not really compared to a real one. Simply put it's a secretary's car in it's lowest trim level and fully dressed up is just loud. Both the car and boat's real sales appeal are their low price.

    Brendan, most swing keels don't bounce in their cases, because they're locked down. Water ballast can have some advantages, if you're racing against a set of rules, but in small craft it's really just a volume robbing marketing gimmick. Water is simply just way to light to be particularly effective as ballast. Hell, heavily reinforced concrete is about 3 times heavier and it's only about 160 pounds a cubic foot, which is still way too light to be useful in small craft, when you can use lead at 700 pounds a cubic foot. Maybe a set of tanks to hold lead shot and a really heavy duty pump that can move the bird shot from one side to the other. You save about 90% of the internal volume with the lead, but you'd probably get pretty annoyed with the little lead shot balls rattling around in a beam sea.

  15. whitepointer23

    whitepointer23 Previous Member

    Ok . But the mac is able to dump water to make a lighter planing hull. Even a locked swing keel is still going to create stress at planing speeds in rough water. I have never been onboard a mac but i like the idea. Maybe a cat would work better in the same role.
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