▁similar ▁to ▁the ▁diameter ▁of ▁the ▁prop eller , ▁with ▁the ▁ch ord ▁length ▁being ▁up ▁to ▁ 1 . 2 ▁× ▁prop eller ▁diameter . ▁If ▁extreme ▁man eu ver ability ▁is ▁not ▁required , ▁ch ord ▁length ▁can ▁be ▁reduced ▁to ▁a ▁minimum ▁of ▁ 0 . 5 5 ▁× ▁prop eller ▁diameter . ▁ ▁Ar ound ▁ 4 0 % ▁balance ▁should ▁be ▁provided , ▁a ka , ▁rud der ▁in ▁front ▁of ▁the ▁rud der ▁pivot . ▁ ▁The ▁distance ▁from ▁the ▁trailing ▁edge ▁of ▁the ▁prop eller ▁to ▁the ▁leading ▁of ▁the ▁rud der ▁should ▁be ▁a ▁minimum ▁of ▁ 0 . 2 ▁× ▁prop eller ▁diameter , ▁and ▁the ▁maximum ▁effective ▁angle ▁of ▁operation ▁for ▁a ▁single ▁rud der ▁is ▁ 2 * 7 0 ▁degrees . ▁ ▁No ▁information ▁as ▁to ▁the ▁layout ▁or ▁profile ▁design ▁of ▁a ▁tw in ▁rud der ▁system ▁is ▁contained ▁within ▁this ▁article . ▁ ▁Other ▁names ▁Rud ders ▁of ▁the ▁same ▁or ▁similar ▁profile ▁are ▁also ▁referred ▁to ▁as ▁the ▁Mac L ear - Th ist le ▁or ▁Myst ic ▁rud der . ▁ ▁Altern atives ▁Altern atives ▁to ▁the ▁Sh illing ▁rud der ▁concept ▁include ▁conventional ▁aer of o il ▁shapes , ▁i . e . ▁without ▁the ▁fla red ▁end , ▁f lap ▁rud ders , ▁K ort ▁no zz les ▁and ▁az im uth ▁thrust ers . ▁ ▁See ▁also ▁ ▁References ▁ ▁Category : W ater craft ▁components <0x0A> </s> ▁Two ▁explos ions ▁target ing ▁tour