If you are worried about remembering how to tie knots then you need to buy a 6' piece of line
and tie knots while watching TV. One of the things that is important on a sailboat is that there typically is a right way to do things, not doing it right can lead to a tragedy of errors that leads to broken bits.
Halyard knots are fine, but they are really oly used for, well halyards. The knot you really need to know, blind folded, wet, miserable, in the rain, cold, blindfolded, and drunk is how to tie a bowline. Everything else comes with time. But a bowline is the most knot used, and you aren't a sailor until you can tie one in any conditions.
That being said if you line
rope work, there are soft shackles
(similar to metal bits it made from line
), splicing, and decorative stuff that all needs to be done onboard. You just have to spend the time to learn how. Heck with modern line
, even standing rigging and lifelines are switching to line, thus increasing the work you can do yourself.