Courgette violation

I have five courgette plants in my veg plot. They're looking quite healthy but the fruit are not setting properly. They get to a few inches long then start to rot at the end. One possible cause for this is incomplete pollination so I have tried the old technique of giving nature a helping hand. Removing a male flower, taking off its petals and rubbing the stamen against the inside of the female flower. The female flowers are the ones with the stubby little fruit behind them, the male flowers are on longer, thinner stems. So, I've impregnated my first vegetable! I feel dirty...