The move follows the arrival last September of former Credit Suisse First Boston MD and international prime brokerage head Rod Barker.
He joined RAB as director of business development and distribution.
Tulchan is believed to have pitched against two other firms.
Consultants David Trenchard and Celia Gordon Shute report to Barker and former Grandfield MD Marc Popiolek.
Popiolek has been heading RAB's communications on an interim basis since Bell Pottinger's merger with Grandfield last year (PRWeek, 8 April 2005).
Barker is said to have been given a remit to shake up RAB's marketing and communications.
Barker's compliance and risk management experience as a prime broker is also likely to come in handy as the increase in institutional capital into RAB's funds attracts regulatory attention.
Hedge funds are hoping to recover this year, having last October suffered their worst month in nearly five years.
RAB made a pre-tax profit of more than £5bn for the six months to 30 June 2005, up from £2.1bn for the same period in the previous year.