my %shipToActBins = ();
foreach my $ship (@shipsInCombat) {
    # Add ship to initiative hash
    if (not exists $shipToActBins{$ship->{thruster}}) {
        $shipToActBins{$ship->{thruster}} = [];
    }
    push @{$shipToActBins{$ship->{thruster}}}, $ship;
}
my %weights = ();
for (keys %shipToActBins) {
    $weights{$_} = 2 * $_ + 1;
}
SHIP: for (0 .. $#shipsInCombat) {
    my $ship;
    my $sum = 0;
    my @bounds = ();

    for (sort keys %shipToActBins) {
        if (@{$shipToActBins{$_}} == 0) {
            delete ($shipToActBins{$_});
        } else {
            $sum += $weights{$_}*@{$shipToActBins{$_}};
            push @bounds, $sum;
        }
    }
    my $roll = int(rand($sum));

    CHOOSE: for (sort keys %shipToActBins) {
        if ($bounds[0] >= $roll) {
            $roll = int(($bounds[0] - $roll - 1)/$weights{$_});
            $ship = splice(@{$shipToActBins{$_}},$roll,1);
            last CHOOSE;
        } else {
            shift @bounds;
        }
    }
    #...
    #Simulated mayhem
    #...
}