Subject: [harryproa] bow down trim |
From: "bjarthur123" <bjarthur123@yahoo.com> |
Date: 7/16/2011, 11:43 AM |
To: harryproa@yahoogroups.com.au |
Reply-to: harryproa@yahoogroups.com.au |
rick,
i've been going back and re-reading all the old msgs on the bow down issue. more than anything i think bow down trim enforces a speed limit due to the possibility of pitchpoling.
what i'm curious about is whether this trim attitude occurs at speed on "normal" boats, or whether this is a consequence of fore-aft symmetry. does having a "bow" sticking way back aft push the front bow down? do the typical square transoms of tackers alleviate this issue?
ben
> There is advantage in a slight flare in the sides - say 5 degrees -
> for improving performance in waves. Take the flare all the way to
> the ends so the longitudinal righting moment goes up as the ends
> bury. But keep the deck line at the ends low so there is not a large
> volume to push through waves or a buoyant trailing end to lift that
> end when running off a wave. Increasing waterplane area as the bow
> initially dips will help avoid burying the bow when in waves. You
> also want a deck shape at the ends to lift easily through green water
> rather than resisting the lift from the bottom and sides of the hull.