Horizontal shelf in bath

[msmsm]

Hi,

I hvae just moved into a new house and noticed that, when using the shower, a small leak occurs around a tiled shelf at the end of the bath.

Upon inspection the grouting was badly cracked on the shelf and this was allowing water onto the boarding behind and also into the plastic edging tubing, which was then dripping onto the floor.

Looking at the boarding forming the shelf it does not look it particularly damaged and I have raked out the old grout (which was exceptionally wet) and replaced with some designed for power showers and wet rooms. However, the shelf is horizontal, which means water invariably pools on it. I have read the waterproof grout is not actually waterproof and so is there anything I can coat the shelf in (it is 1 tile deep and about 6 wide) to stop the water ingress in future. Would putting sealant along the grout lines work, or it there something better? I do not fancy the idea of using epoxy grout as I am not good at DIY!

Matt