The larger the hose diameter the less friction loss given the same hose length and discharge pressure.
B U T ....a fire-hose is that traveling from a dead-stop to 60 mph in 2 seconds or so !
I guess you're missing the point Doc ? You're a Doctor of What ? Fiberglass ?
Fact is, the larger the diameter the less the friction loss is. A 1.5in line loses 25psi pressure per 100ft. A 2.5in line loses 14psi. A 4in line loses 4 psi....and so on.
A 5/16 line will have more friction loss than a 3/8in line....all things being equal. The velocity of the fluid has little to do with it....surface contact has everything to do with it. The larger the percentage of surface contact vs the total volume of fluid....the greater the friction loss.
All this is academic anyway....i agree that a 3/8-1/2 line is plenty for just about any application
