"Roger Long" wrote in message
...
JimB wrote:

1. Damp the boat's bobbing - make the forward pitch a different
stiffness from the rearward pitch.

I used to be a great believer in asymmetry until sailing my present boat
which is fairly symmetrical and has a surprising full entrance for a
1970's design. She has a cruising weight mast, a large anchor hung out
over the bow, water tank under the V berth, batteries and lots of gear
aft, everything that urban legend says should promote wicked pitching. She
has about the nicest motion I've encountered in a sailboat.

It used to be thought that spreading weight out into the ends made for a
more comfortable boat. This was back when boats tended to be more
symmetrical. Now, everyone "knows" that moving weight from the ends to the
middle reduces pitching. The shape of the typical boat has changed but so
may have the conventional wisdom to some extent. Does the boat really
become more comfortable after you have spent a long, hot, afternoon moving
all that heavy stuff from the ends to under the midship berths? Send three
people up to the bow sometime when beating and compare the results
immediately.

The physics of pitching are pretty much the same as rolling, a subject
I've pondered enough to have produced some powerboats that are considered
remarkable for their comfort. Like props, it's a complex subject and the
common rules of thumb, 3 blades better, move weight to the middle, are
often correct for a narrow range of typical boats but wrong as general
principles.


--
Roger Long


I've sailed a Yamaha 30 for a number of years. One of the things that's
interesting about this boat is the old one-lung diesel and fuel tank are
under the v-berth. I don't find it to hobby much at all compared with
similar size boats.

--
"j" ganz @@
www.sailnow.com