@Dagwell: you're saying after your boat planes, then rpms go up about 1,500. I think you mean ventilates, not slips. I believe slip is the difference between the theoretical forward thrust vs. the actual thrust. Ventilation is when the prop is pulling in air, not effectively biting. If your prop is spinning up or ventilating during / after planing, that indicates a pitch that is too small, you're running a shorty or you're trimming too soon. Again, I would try a 5 blade to help with that issue. Is your lower a Bravo or a shorter Sport?

Did you have a sunsation 288 ?

Comparing the standard Bravo I with the pro-finished Bravo I FS.

https://e-ribbing.com/en/propellers/...ravo-1-fs.html“As shown by its name, the pro finished Bravo I FS (Four Stroke) propeller is designed specifically for high-horsepower four-stroke outboard engines and is positioned somewhere between the standard and the lab finished Bravo I.

In other words, Bravo I FS is a new version of the standard Bravo I propeller in which some specific modifications of its characteristics have been made. The most important of these are the following:

• its exhaust barrel has been shortened
• the cup height of its blades has been reduced
• the leading edges of its blades has been become thinner and sharper

”

As you can see, They are not the same. All the owners with the 288 525efi combo that reported 75-78 had 28” Bravo props. Not the FS version. These where before the FS became available.

Beg, borrow, or steel a untouched Bravo 28” in good condition. Friends/fellow boaters/marinas or prop shops with prop loaner programs

Who said this?
Are you trimming the drive down to get on plane then up once at speed?

If your tach flares up super quickly then I'd say it's slipping, but it's natural for a boat once on plane to increase rpm if you hold the same throttle position as the load on the engine decreases.

If this is the case why didn't you just wait on him and have him do a ride along with you on board to school you on the mannerism's of the boat before buying a new prop?

Cavitation damage, strike rocks or whatever so it's bent to hell, cracks from surfacing maybe, run 2 hours in sand (lol) maybe where it's abraded away.

If none of the above, which I call damaged.
I'd like to see what a "worn out" stainless prop looks like.

You are correct in that the drive shower can cause ventilation and / or additional slippage if it is in the wrong place. Remove it and try it without, just to rule that out. If the boat has a pitot tube or transducer mounted too close to the prop, that can also cause additional slippage, especially on lighter smaller boats. The Bravo FS has more differences than just the ventilation ports. The diffuser at the back is almost totally removed compared to the standard Bravo prop. That is supposed to give more bow lift, and less stern lift than a standard Bravo. It is also supposed to reduce the drag a bit, improving top speed slightly. I have 24 ft Checkmate with a 300R outboard, so totally different. However, I tried a standard 26P Bravo and a 24P Bravo FS. The 26 was a bit too much pitch, but what surprised me was the 26 Bravo came on the plane much faster than the 24 Bravo FS, it lifted the back of the boat more and the bow less, and almost eliminated all the chine walking, but it was 2 mph slower. The Bravo FS is also "Pro Finished" which means more accurate cup heights from blade to blade and better balance (supposedly).
The even pitch Bravo FS has less cup than the standard Bravo if I understood correctly. They make the Bravo FS in 1/2" pitch increments. So you can purchase a 26P Bravo FS, which has less cup than a 26P Bravo. If you buy a 26.5P FS, they just add cup to the 26P. If you buy a 27P Bravo FS, they add more cup to the 26P, and if you buy a 27.5P Bravo FS it has even more cup added to the 26P. Once you get to a 28P it has less cup again. More cup typically reduces slippage. For fast outboards they say that the 27P would be good but the 27.5P has almost too much cup making it more difficult to turn. Depending on your rpm, perhaps a 27P or even a 27.5P might reduce the slippage if you stay with the FS family??
I would try to get my hands on a

it is a standard bravo lower. I have the drive all the way in before coming on plane. Then trim after at speed. Comes up on plane at about 20mph. And rpm is around 2k easing into it. One on plane I can feel the forward momentum die out and only way to fix is to give more throttle and rpm and then it slowly gains speed and the prop catches up I guess you would say. I def wanna try a 5 blade. I didn’t wanna wait 2 weeks for him to come back from vacation because I was worried something major was wrong with the boat not just the prop. $1000.00 didn’t bother me to kinda rule something out. In in NJ so my boating time is limited here to get this fixed for next year. Looks like I’ll have a almost new bravo 1 FS 28 for sale soon 😬

Ok. A shorty can create problems you describe. I wonder if you're not giving it enough throttle. I would firmly bring it up to 3,000 rpm (not full throttle not easing into it), let it plane, then keep rpm and slowly trim. If you haven't, try this before a prop. I don't think there's anything mechanically wrong. Also, a short hub prop will provide less stern lift. That can mean slower planing and possibly letting the prop lose bite, especially if you have through prop exhaust.

Thanks, ill give it a try. Trim tabs down or neutral?

You are correct in that the drive shower can cause ventilation and / or additional slippage if it is in the wrong place. Remove it and try it without, just to rule that out. If the boat has a pitot tube or transducer mounted too close to the prop, that can also cause additional slippage, especially on lighter smaller boats. The Bravo FS has more differences than just the ventilation ports. The diffuser at the back is almost totally removed compared to the standard Bravo prop. That is supposed to give more bow lift, and less stern lift than a standard Bravo. It is also supposed to reduce the drag a bit, improving top speed slightly. I have 24 ft Checkmate with a 300R outboard, so totally different. However, I tried a standard 26P Bravo and a 24P Bravo FS. The 26 was a bit too much pitch, but what surprised me was the 26 Bravo came on the plane much faster than the 24 Bravo FS, it lifted the back of the boat more and the bow less, and almost eliminated all the chine walking, but it was 2 mph slower. The Bravo FS is also "Pro Finished" which means more accurate cup heights from blade to blade and better balance (supposedly).
The even pitch Bravo FS has less cup than the standard Bravo if I understood correctly. They make the Bravo FS in 1/2" pitch increments. So you can purchase a 26P Bravo FS, which has less cup than a 26P Bravo. If you buy a 26.5P FS, they just add cup to the 26P. If you buy a 27P Bravo FS, they add more cup to the 26P, and if you buy a 27.5P Bravo FS it has even more cup added to the 26P. Once you get to a 28P it has less cup again. More cup typically reduces slippage. For fast outboards they say that the 27P would be good but the 27.5P has almost too much cup making it more difficult to turn. Depending on your rpm, perhaps a 27P or even a 27.5P might reduce the slippage if you stay with the FS family??

All the way down for faster planing. Depending on the boat, I bring the tabs all the way up once it planes and then the drive. I didn't use tabs while running, just one tab if there was a cross wind.