So I'm probably doing something wrong, but I've taken the classic boiler/steam turbine design and tried to mimic it with the scaling pipes (all +1), but it looks like the offshore pump is never reaching maximum flow. The most I've seen is 1709/s of 4800/s. The Offshore pump is connected straight to the first boiler (then the boilers are connected together), and it looks like water gets about 6 boilers deep and then tapers off. From the 9th boiler on, they are not receiving water at all. Thanks for your help!

This is a good question, and a good example as well.
The main reason of why it is not an exact mimic of original scale, comes from the fluid sink (input fluid box) of the boilers. Fluid pressure drops faster than going through pipe +1. They are not acting as the ideal pipe +1, so not ideal for fluid transfer.

So try to avoid fluid (water) getting through more than 5 boilers in a row.
There are a few solutions to get the full 4800/s flow:
A/ Use a pump +1 after every 5th boiler. So for the classic 20× boiler chain design using on boiler +1, you will need 3× pump +1, after 5th, 10th, 15th boiler. (Lower of the screenshot.)
B/ Spread out boilers +1 to two branches. By carefully placing the pump +1 between two branches (so shared by both), only 1 pump +1 is ever needed. (Upper of the screenshot.)
C/ If you spread out to four branches just right after the offshore pump +1 (using pipes and/or pipe to ground) and limit to only 5 boilers +1 in a branch, then not a single pump +1 is needed.

Got it, thanks for your help! I swear every time I think I understand fluids in this game something new happens :)