Northern Spy
Guru
- Joined
- Feb 5, 2012
- Messages
- 4,075
- Location
- Canada
- Vessel Name
- Northern Spy
- Vessel Make
- Nordic Tug 26
When I get home I'll take a look at my GM calculations. Mine was pretty snappy when relaunched and empty after repowering. After a few years of re provisioning (placing useless crap back in the lockers) her roll is more gentle.
That is 180 degrees opposite of intact stability. A "too stable" vessel has a large GM and will roll quickly. Adding weight will lower G and unless there is a large change in draft, the GM will only increase and the boat will roll (snap)even faster.
I had also thought about putting some lead in the bilge (keel box) but I think she'd just get snappy again with the hard chines on my boat.
That is the way it works. Adding weight down low increases static stability but increases roll rate. If you want a slower roll, take weight out of the bilges or add it higher.
You're absolutely right, it was more likely the removal of railroad track down low and adding the weight back up high (kayaks on pilothouse roof, restepping the mast, building an overhead console) rather than the minor increase in draft that raised G, lowered GM, and lessened the righting arm.