Hot water splattering and spitting from taps

Claremont490

help! i love my old van but am getting fed up of being soaked by the water spluttering out of the hot water tap (both kitchen sink and bathrokm) when i turn it on! it runs smoothly for a few seconds then does short very sharp blasts of water whether turned on slow or fully. any suggestions please? both taps are the combined one spout sort and the cold water runs smoothly.