English to Croatian Other Ships, Sailing, Maritime yacht

Skin fittings - refers to the fittings used to maintain any hole through the Hull of a Boat, to allow seawater in (ie. for engine cooling) or waste water out.
Skin Fittings below the Waterline must be fitted with a valve (sea cock) so that they can be closed.

https://www.chsmith.com.au/Wiki/Skin-Fitting.html

The following skin fittings are fitted in the hull of the craft.
Manual valve on skin fitting and diaphragm punp on head
Galley sink drains (2 sinks to 1 skin fitting)