Remove pineapple core; remove fruit and cut into 3/4-inch pieces.
In small saucepan,
over medium heat, heat pineapple pieces and water to boiling. Cover; simmer 5 minutes.
Drain well. In top of double boiler, combine 1/2 cup sugar, flour and salt. Stir
in 1 whole egg and 3 egg yolks. Stir in milk. Cook, uncovered, over boiling water,
stirring constantly until thickened.
Remove from heat; stir in coconut and rum extract. Spread about 1/4 cup custard
on bottom of a 1 1/2-quart casserole; cover with layer of wafers. Top with 1/3 of
pineapple. Pour about 1/3 of remaining custard over pineapple. Continue to layer
wafers, pineapple and custard to make 3 layers of each, ending with custard.
Beat remaining 3 egg whites until stiff but not dry.
Gradually add remaining
1/4 cup sugar, beating until stiff peaks form. Spread over custard, sealing well
Bake at 425 degrees F for 5 minutes or until delicately browned.