Changes

Bilge keels are a type of fin attached to the chines of the hull. They serve as passive roll stabilizers, by offering resistance to the water when the trawler boat rolls. They should be located as far aft as possible, to reduce roll and improve stability.<ref>Cape Horn Yachts, http://capehornyachts.com/</ref> Long low-aspect keels can reduce rolling by 35-55%.<ref>Marine Technology, see http://www.kastenmarine.com/roll_attenuation.htm/</ref> (Aspect ratio is the ratio of width to height, e.g., 4:3 is 4 units wide by 3 units high.)

Bilge keels can be tied into the structure and made strong enough to support the hull and keep the boat upright when it is accidentally or deliberately grounded. To support grounding, both the keel and bilge keels are engineered three to four times stronger than ABC requires. Failing to engineer the keels adequately can cause bilge plates to crack.<ref>Ship Construction, D. J. Eyres, Butterworth-Heinemann, ISBN 07506807092007</ref> Such keels will offer some protection to accessories attached to the main keel. Bilge keels can also be designed as short angled fins.

The downside of bilge keels is that they increase drag slightly. Hopefully the extra drag will be offset by the performance of a [[BulbousBowGeneral|bulbous bow]].