Originally Posted by hannah2
Sorry I never bothered to ask about the stability curve I'm not an NA. For me understanding how the boat sails in seas where stability math comes into play was what was important.
The Boreal does have a keel lower than the hull, within that keel is the lead. The centerboard I believe weighs about 284 Kilo water neutral. Also remember that the Boreal has 100 meters of anchor chain centered just forward of the mast giving the boat more center of balance.
You don't need to be a NA to know how to read a stability curve and to see its good and bad points. Just need to have the knowledge for that and it is a lot less than the one needed to be a NA.
If you look at the photo of the Boreal and Drawing of the Allures 45 you can see that they are very similar and have not any significant space for ballast outside the hull. About 300Kg is also what weights Allures 45 centerboard, that like the one of the Boreal is made of solid aluminum. No lead ballast there.
Besides the type of boats like the Allures and the Boreal, there are boats that have all the the ballast inside a box outside the hull, some that have part of the weight inside and part outside in the keel (like the Southerlies), others that have all the ballast on a keel that can be swigged up, like the Pogo or the Opium and even others that have a bulbed keel that can be pulled vertically up.
I guess this covers all the types of variable draft boats that I know.