Vertical Center of Gravity...how low is it?

[er9]

Originally Posted by Benz

What has only been mentioned in passing is that not only is raising the weight undesirable, but moving it toward the ends is also undesirable. Ideally, the ends of the boat should be kept as light as possible. Having weight higher but closer to the middle is better than lower but closer to the ends. I think the two 20's idea is the best sounding.

Bernard Moitessier suggested the same in his book when he was rounding the cape. he seemed possessed with getting his bow and stern as light as possible. good reminder...thanks.

[kristjan]

Originally Posted by er9

then it seems having two smaller tanks on each side of the hull may be an advantage to one larger tank?

For maintenance and other reasons I prefer one central tank. You’d have to do the math in your case to see if there is much mathematical difference.

[Cheechako]

Another question is "how much fuel do you need"? I found on many of my boats that I had too much. It sits forever unused in a sailboat. I actually added two tanks to my cat before taking off and ended up abandoning those tanks when cruising. Of coarse if you are headed to the So Pac or Timbuktu etc then it's different.

[james247]

Originally Posted by er9

I know the math can get very complicated and not such an easy answer but generally speaking...is it possible to guess the approximate area where the center of gravity is on a monohull? for example would one estimate its just above the top of the keel, floorboard height, waterline height?



reason i ask is that adding gear , fixtures, tanks etc above this point affects stability so ideally we want to add heavier loads as low as possible. would adding 500lbs directly above this point drastically affect stability or marginally?



im considering moving my fuel tank a foot higher in the hull (40 gall tank) but dont want to make a drastic change to offshore stability. trying to guestimate the limits of what i should and should not do.



any insight would be appreciated.

The effect of additional load is directly proportionate to the size of your boat 500lbs is equal to the weight of three healthy blokes. In a 50 footer Wong notice the difference in a 20 footer if you put them on the same side you might be rail u dear. Additional weight needs to be as low as possible and as close the the middle of the boat. Weight in either the bow or stern can cause hobby horsing.
Get 3 mates and see the effect

[er9]

Originally Posted by Cheechako

Another question is "how much fuel do you need"? I found on many of my boats that I had too much. It sits forever unused in a sailboat. I actually added two tanks to my cat before taking off and ended up abandoning those tanks when cruising. Of coarse if you are headed to the So Pac or Timbuktu etc then it's different.

those destinations are on my list but a few years away so the 40 gallons total would probably be a good idea however...i'm planning on only installing a single tank for the time being because I run into the same issue currently as a coastal/weekend cruiser. at the moment my current 44 gal tank is only filled once a year at best.