Annoying designs.

There are just too many of them.

Some products are faulty by design (Davis weather stations).

Yet others are just in need of a little help (VSDControl for class A AIS units).

There are even nice products which are just a bit lacking in the documentation department (Airmar H2183 / Si-Tex HDK-11 heading sensor).

Products from certain equipment vendors seem to require expensive add-ons for very simple tasks (Standard Horizon HX300 marine VHF radio).