On Sun, 30 Dec 2007 18:01:09 -0500, "Roger Long"
wrote:

Any suggestions for a starting point?

Yes, start by deciding whether you are willing to invest a lot in
construction and additional weight with it's attendant increase in fuel
consumption to make things just a little better. If it's worth it just to
reduce motion by 10 - 15 percent, you can probably do something.

Thanks, some interesting points there. Weight could largely turn out
to be a non-issue if used only at anchor or as a backup to the dynamic
stabilizer system (Naiads). It would be easy enough to pump some salt
water up into the tanks when I wanted to use them, and drain it back
out afterwards.

I was thinking of buying a couple of fiberglass dock boxes from West
Marine and cross connecting them with PVC pipes. The system could be
tuned by restricting flow or adding additional pipes. I have no idea
how to calculate optimal starting pipe size(s) however.

Just for the sake of argument, lets assume 400 total gallons and a
natural roll period of about 3 seconds. Given a 5 degree roll, most
of that water would have to flow to the downhill tank in about 1.5
seconds if I'm conceptualizing this correctly.

On Sun, 30 Dec 2007 20:28:13 -0500, Wayne.B
wrote:


I was thinking of buying a couple of fiberglass dock boxes from West
Marine and cross connecting them with PVC pipes. The system could be
tuned by restricting flow or adding additional pipes. I have no idea
how to calculate optimal starting pipe size(s) however.

Just for the sake of argument, lets assume 400 total gallons and a
natural roll period of about 3 seconds. Given a 5 degree roll, most
of that water would have to flow to the downhill tank in about 1.5
seconds if I'm conceptualizing this correctly.

My first shot, off the top: two 30 in diam smooth pipes

Brian W

On Sun, 30 Dec 2007 20:53:17 -0600, Brian Whatcott
wrote:

Just for the sake of argument, lets assume 400 total gallons and a
natural roll period of about 3 seconds. Given a 5 degree roll, most
of that water would have to flow to the downhill tank in about 1.5
seconds if I'm conceptualizing this correctly.



My first shot, off the top: two 30 in diam smooth pipes


That's much too big of course. Can you take us through your
calculations? It would take a large rectangular tunnel to achieve
that much cross sectional flow area without creating an unworkable
obstruction on the flybridge.

On Sun, 30 Dec 2007 23:53:18 -0500, Wayne.B
wrote:

On Sun, 30 Dec 2007 20:53:17 -0600, Brian Whatcott
wrote:

Just for the sake of argument, lets assume 400 total gallons and a
natural roll period of about 3 seconds. Given a 5 degree roll, most
of that water would have to flow to the downhill tank in about 1.5
seconds if I'm conceptualizing this correctly.



My first shot, off the top: two 30 in diam smooth pipes


That's much too big of course. Can you take us through your
calculations? It would take a large rectangular tunnel to achieve
that much cross sectional flow area without creating an unworkable
obstruction on the flybridge.

I looked up a table of flow rates for smooth pipes of various
diameters on Google and scaled to a flow rate of 12000 gal/min

Brian W