SailNet Community - View Single Post - Full or fin keel?
View Single Post
Old 03-30-2012
skygazer's Avatar
skygazer skygazer is offline
Senior Member
Join Date: Sep 2011
Location: western Maine
Posts: 392
Thanks: 2
Thanked 4 Times in 4 Posts
Rep Power: 4
skygazer is on a distinguished road
Re: Full or fin keel?

Originally Posted by PCP View Post
In a static situation without waves I don't know but recent tank testing showed that in a dynamic situation with waves the mast will help the boat to right itself up faster. Yes I know, it looks odd, but I read the paper and against facts there are no arguments...just the need to understand why


Faster righting from inverted (turtle) position with rigging and mast, than without, that is not very intuitive.

In science I learned that one can usually devise an experiment to get the results desired.

Here is a possibility. A beamy shallow hull, compared to a deep V hull, is very stable upside down, and will resist righting. Thus the fascinating tilting keel in the video in this thread, to change the dynamics of the beamy hull.

A mast will hang down deep, well below the wave action, in deep still water. So if beam on, the waves could carry the hull along while the mast stays behind, thus in effect starting the roll towards righting.

But generally a mast and rigging stabilize the rolling of the hull, so generally it would greatly slow the rolling back from an inverted position. If the boat was not beam on to the waves, I would think it would have to wait until (and if) wave action slewed it around to beam on. A rogue wave may not have another behind it strong enough to push the hull beyond the mast. If wind capsized the boat, the waves might not be strong enough, and lacking the leverage of the mast, the wind will slide over the hull.

As an extreme example, a flat (beamy) board will resist rolling, but a round log will roll very easily. When I fell a tree it tips over very slowly, like the mast and rigging. Once on the ground, I can roll the log easily, like a dismasted boat.

This has remained an incredibly interesting thread, thank you to all who provide their insights, thoughts, and experiences.
Reply With Quote Share with Facebook