Hello, new to the forum. I have a 2000 donzi 33zx with twin 500efi's. Boat was running 75mph at 5200rpm with 28 pitch bravo 1 props at sea level. I brought the boat to lake powell, which is around 3400' elevation. Purchases 25 pitch 4 blade hydromotives and cannot get on plane. Props blow out with only half throttle and k-planes out. Tried a buddies 23 hydros to see if getting a quicker holeshot would get me on plane, but blew those out even quicker. Didn't thing dropping 3 pitch sizes would have such a negative effect. Should I be running 26's? 27's? Props are too expensive to keep guessing. Some insight on this would be awesome!

There are several kinds of Hydromotive props. I'm guessing you have Q4's with no diffuser ring. Just get some 26 Bravo 1's.

I got the same boat ans just tryed bravo 1 26s and the boat didnt like them as much as the 28s. Also run both labed and unlabed 28s and thats what the boat seams to like. Tryed 24 maximus props and it didnt like them either. Next maybe will be trying maximus 28s to see how it likes them but like you sead it gets expensive. Sitting on 3 sets now. The 24s and the 26s i ran out of rpms really fast and was running on the limiters and lost mph. Only difference may be that i am running imco lowers not shorty's tho

Both the 24s and the 26s had the diffuser rings cut off as well

The diffuser ring will generally make getting on plane easier

i am around 500 ft above sea level i believe and with the 28s i fall off plan at around 40 as well. The labed 28s will get you more rpms and a little more top end.