Four water inlet holes, I mean mounting holes, not difficult?
Only if you have the equipment, knowledge and the confidence.
A) dont have the right knowledge
B) know which equipment, never mind have the equipment I need to drill through GRP/Wood/MDF/? As back to A I don't even know what the internal part of my transom is made of and as a result
C) most importantly, due to A and B, don't have the confidence to make water inlet holes below the waterline, just to save a few hundred pounds if i had just spent somewhere between £5k and £10k on a boat!