The holes on a boat can serve different purposes. They can be scuppers, if their function is to drain excess water. They can be hawseholes (anchor or mooring lines pass through), or limber holes, to drain water from bilges.
Or, they can be ventilation holes and portholes.
During a pre-purchase survey, it is necessary whether the boat is made of fiberglass, steel, aluminum, or wood to assess the condition of this holes.
Oted above the waterline and obviously not all; some drains such as toilet drains are for reasons of decorum below the waterline.
It will be essential in the first place to ask the seller if there have been any replacements in the life of the boat because we know or rather by convention it is established that some materials beyond a certain age still need prior replacement even if the exterior appearance is not that bad.
The most common materials in use are as follows: brass, CR brass, bronze, stainless steel and plastic materials. These are matched to boats for different needs such as the construction quality of the systems or the hull material.
But let’s get more specific about the materials :
Brass: the most widely used from the 1980s to the present has proven and that is why it is not possible to mount it on new boats, its ability to corrosion and therefore rapid deterioration;
CR Brass and Bronze vice versa guarantee other standards of durability and reliability;
Stainless might seem the best. However, from my experience, I can say that if not produced in first quality stainless steel the result compared to the expectation can be poor;
Those made of plastic-like composite material if of prime production can be an excellent alternative both for performance hulls so need to reduce weight, and for metal hulls, vice versa I have rated poorly some plastic fittings widespread in the nautical market that appeared more for agricultural than marine use.
How do you judge the body of a sea socket? The outward appearance first i.e., the obvious presence or absence of corrosion or scale, the lever actuation must always be efficient and for brass the change of the outer color to red which will indicate the end of the anticorrosive coating.
The nautical surveyor must check the condition of hoses and hose clamps DOUBLE!
I have experience working in one of the best shipyards in Italy that often the deteriorated part is the hose holder that is the graft of the pipe which then will not be visible after disassembly of the pipe itself, an operation that cannot be carried out during an appraisal; so when in doubt replace the sea intakes but above all have it done by specialized shipyards, the risk with the DIY – in case of incorrect tightening – is having to wing the boat again with high costs.