Hi Newbie,
Thanks for posting the link to the Bilge-Keels and Rolling Chocks article. I just finished reading it and it now makes sense to me why the Bilge-Keels are not considered stabilizers. Although it is probably convenient to call them Passive Stabilizers in relation to Active Stabilizers, they apparently do not stabilize the boat per the definition of making a hull more stable. Stable meaning seaworthy. I suppose reducing roll does not make a boat more seaworthy by reducing an uncomfortable characteristic. They (bilge-keels) just make the boat more comfortable. Where active stabilizers make a boat more seaworthy by "reacting" to forces that make a boat less seaworthy. But don't the Bilge-Keels do the same thing just to a less degree? Doesn't reducing roll make a boat more seaworthy to that degree?
Does that leave anyone else wondering the same thing or did I misunderstand the article?
I'd also like to point out that the article refers to the size of the Bilge-Keels and the type of hull that they are used on having a significant effect on the expediency of the system. The article states that Bilge-Keels of up to 18" wide are typically only installed on vessels that are 60' and longer. My Bilge-Keels are 18" wide and quite long maybe as long as the chine. My boat is 46' and has hard chines. The article talks about hulls with hard chines not working well with Bilge-Keels because of the turbulence that the chine creates interfering with the effectiveness of the Bilge-Keels. I believe that the fellow who builds and installs them up in Canada puts them right at the chine, (see picture). Maybe he does it because of this issue. I also had them installed hollow because the boat was sitting too low in the back. The Bilge-Keels raised the back of the boat about 3" and it's still a bit low! The Bilge-Keels can also be built solid if desired by the client.
So far they seem to work very well on my boat. They are likely sensitive to the location of placement so I would recommend using someone who specializes in installing them.
Looking at the picture I was concerned about the keel hitting the dock. After having them installed I can attest that they do not hit the dock even when tied tight to the dock. As long as fenders are used. I haven't tried tying to a dock without fenders nor do I intend to. We had a North Pacific 44 and 45 rafted together with fenders at the Seattle boat show and during high winds the Keels did bump. Adjusting the fenders took care of it for the rest of the show.
Someone asked about added drag and fuel consumption. Unfortunately I can't answer that question. The savings from not buying an active fin or gyro system was at least $40k. That's a lot of fuel. Maybe there is a naval architect out there that can give me the coefficient of drag per square foot? With that I suppose we could calculate the additional wetted surface area and figure it out from there? Then again maybe not.
I highly recommend the Bilge-Keels. I've only had them for about 220 miles of use but the difference in how the boat handled was significant. The captain that delivered the boat before and after Bilge-Keels was sufficiently impressed to want to put them on his boat. The difference in cost from a typical active fin system is about $40k. I was told that if I wasn't satisfied with the Bilge-Keels that I could add an active system with the Keels. So far I have no intention of doing that.
Good Luck!