Direct, Don't Read
Your voiceover will likely make sense to your audience if it makes sense to your talent. Here's how to make that happen.
Direct your talent. Be sure your talent knows who is presenting the message and who is listening. Explain the tone that's appropriate and the pace, too.
When it comes to individual phrases, ask for what you want, like "more emphasis on LARGE", "we need the contrast between THIS week and LAST week", "the fact that there are FOURTEEN men is more important than the fact that they're green, because of the amazingly small size of their craft". This takes practice and a lot of preparation for each session, but if you can't explain the purpose of a line of copy, why is it in the script?
Please don't read the script to your talent. Your "performance" may actually lead them astray. Try especially to avoid "it's not WATER, it's WATER". The talent may not be able to hear in your voice the subtle difference you want. If you could utter exactly what's in your mind's ear, you'd be at the mic!
For highly technical reads, of course, understanding every concept isn't just impractical, it's impossible. But even when you're wading through dense copy, it's a lot easier for everyone if you agree on where you're headed before take one.