Glad that Mike opened up the sailboat door--since that is the world I come from. The latest racing large sailboats use very concentrated metal ballast at the bottom of very narrow canting keels--two of these failed in the most recent Sydney to Hobart race and the boats capsized. Some of the most uncomfortable boats I have been on had a 50% or more ballast to displacment ratio. If a sailboat looses its mast generally the motion is very snappy and uncomfortable. Many long passagemaking sailboats have lower ballast ratios, with the ballast distributed over a larger area of the full keel. Movable liquid ballast is also used both in sail boats and in power boats. In sailboats, it is used in tank, with rapid transfer pumps to place water ballast on the windard side of the boat. Roll damping water ballast systems have been used. Georgs noted in his round the world boat that he would utalize water ballast as fuel was utalized. I think of ballast to give righting moment and improve ultimate stablity in a passagemaker. However one cannot divorce hull shape and design from ballast in looking at stablity and sea keeping ability. A narrow and deep boat will have little intial stablity and high reserve stablity adding ballast will improve intital stablity. A beamy shoal boat will have high initial stability and poor reserve stability. Adding ballast to the shoal beamy boat will add little if any to her reserve stability or initial stablity. It seems that many boats designed for passagemaking tend to have low placed ballast. Nordhavn 46 has about 4000 lbs of ballast in iron glassed into the keel. The Nordhavn 62 has 7000 lbs. Not a huge amount compared to a sailboat, but significant. In reviewing the newer Nordhavn boats they do not appear to be designed with metal ballast. The Willards and Krogens have ballast. Many of George Buehler and Michael Kasten's designs have ballast of some form A good marine architect will design appropate ballast to improve ultimate stablity and decrease motion. Just adding ballast may actully make a boat less seaworthy. Mike pointed out that boats behave much better with light ends--yet many voyaging boats do put heavy chain and anchors in the bow, which will increase the pitching moment and decrease the bouyance foreward. Trimming ballast is effective in all boats to allow the boat to lie on its lines and avoid lists. Steve Dashew addresses stablity (and if you read the entire web site on the FPB drogues and paranchors are addressed) http://www.setsail.com/dashew/dashew215.html Here the ultimate stability of hull form is paramount. Michael Kasten addresses these issues at: http://www.kastenmarine.com/beam_vs_ballast.htm In summary: There are good sea boats with ballast and good sea boats without traditional ballast which depend on hull shape for stability and seakeeping comfort. Bob Austin

At 10:48 PM 1/9/05 -0600, you wrote: >and anchors in the bow, which will increase the pitching moment and >decrease the bouyance foreward. Trimming ballast is effective in all >boats to allow the boat to lie on its lines and avoid lists. I forgot to mention that use. Good point. Mike Capt. Mike Maurice Tualatin(Portland), Oregon

At 10:48 PM 1/9/05 -0600, you wrote: >from ballast in looking at stablity and sea keeping ability. A narrow and >deep boat will have little intial stablity and high reserve stablity >adding ballast will improve intital stablity. A beamy shoal boat will >have high initial stability and poor reserve stability. Adding ballast to >the shoal beamy boat will add little if any to her reserve stability or >initial stablity. Take the following sample boat, a passagemaker with a fairly heavy dinghy located some distance above the CG. If it is not placed evenly from side to side you may need ballast to trim the boat out. And if you want to counteract the moment of inertia caused by it's being above the CG then the only way I know to compensate is to add an equal weight exactly opposite to it an equal distance away from the CG. This is not the most desirable state of affairs but at least the moments of inertia can be cancelled out. Of course the boat will now have twice the weight of the dinghy as "ballast" aboard. The weight distributed both above and below the CG , but at least the tendency to roll/rollover will have been balanced out. >Adding ballast to the shoal beamy boat will add little if any to her >reserve stability or initial stablity. The statement above is correct, but ballast will add to to side to side inertial stability if the weight is distributed around the side to side location of the CG. In other words, every bit of weight has some effect, which can be compensated for by the addition of more weight placed somewhere else. But, it also follows that the boat is getting HEAVIER. Carried to extremes, the boat would have a waterline somewhere above the deck. Not desirable at all. If there is one habit that seems to be ingrained in the present buying public, it is the tendency to put on weight. Both the personal and the nautical. Both have their undesirable results. We have met the enemy... This business of overloading is obvious in such things as Granite counter tops in galleys and heads and also shower walls. The moment you see this in a small craft, you know the builder and the buyer are way over their eyebrows. Run, don't walk for the exit. Mike Capt. Mike Maurice Tualatin(Portland), Oregon