Hard edges and no sanding = truly impossible?

How much can sanding be reduced with vacuum bagging? I've done it before, and I really didn't like the waste, but I'd do it again if I can avoid sanding.

Specifically, I'm interested in hard edges good enough to channel water on ribs of a boat.

From my experience before with release film, I think it's possible to do no sanding at all. Zero. But I can't find much info on this.

 

Perhaps you might explain what you're trying to accomplish.
What does a "hard edge" have to do with channeling water?

 

Epoxy https://ibb.co/album/HT4gJ4

 

Best way to reduce sanding is moulds.

 

Can you give me an idea of how much sanding a mould can reduce with vacuum infusion
or
how tight an edge corner wrap can be achieved?

Apparently, a bit of super 77 glue to hold the fiber in place at the prep state is needed.

Last time I did vacuum infusion I was making swimming fins. Being so thin, I didn't need a mould.

For potential future projects, I'd need to rebuy all the equipment again, but I don't want to do the project if there's still loads of sanding even if the mould has reduced that.

I'd also take a lot of time to practice getting the fiber in place on small practice parts.

Just scoping it out and planning ahead.

 

Don't get bogged down in the "Majoring in minors" or "Chasing rainbows" or "Mental gymnastics" trap.
If working with a female mold the apex of your "sharp edge" will basically be composed of either gelcoat or resin whether the fabric is 20 oz cloth or 2 oz mat.
If working over a male mold, (a plug,) your "sharp edge" will largely be determined by how tightly you can keep tension on the fabric over the edge of the plug whilst the resin kicks.
The smaller the radius the more easily damaged that edge is.
Be realistic on what you're trying to accomplish.
Is your definition of "sanding" a few hours using 80 grit or endless hours using 2,000 grit compounds?