Dumb question about prop diameter

[Pantera2]

I have a 98 Mariner 200 hp 2.5 L Magnum EFI on a 98 Bass Cat Pantera 3. My boat came with a 23p Tempest plus 3 blade and I’m getting 57 mph gps running 5,800 rpm but I’m also only at about 3/4 throttle. So after doing some research I’ve been told I need to run a 25p fury or trophy 4 blade. After talking with some buddies I got 2 25p trophy 4 blades to try out. Both of them are a lot smaller diameter that the prop I have now. I did try one of the props but was getting serious cavitation around where it meets up at the lower unit. I’m assuming there’s no way I can do anything to make them work?

[Chuck33]

They have what is called a blow out ring that is plastic snaps in to take care of small barrel props. At least my etec has one on my trophy plus winter prop.

[Midnight Rider]

You need a blow out ring.

[Pantera2]

Will this effect the normal performance of the prop at all?

[mrdeath]

Will this effect the normal performance of the prop at all?

No. What PVS plugs have you tried in them? If you're trying to run that Trophy without plugs, it probably won't work since it vents so much around the barrel.

[Midnight Rider]

Should have NO effect, other than you'll have to play with the ventilation holes to tune your hole shot. No impact otherwise.

[Pantera2]

Thank you guys a bunch! I know that one prop has tiny pvs holes in it but they aren’t threaded for plugs. The other one doesn’t have PCs holes

[Fatshaft Merc]

Thank you guys a bunch! I know that one prop has tiny pvs holes in it but they aren’t threaded for plugs. The other one doesn’t have PCs holes

PVS holes are 7/8" in diameter and are stepped on the edge for the plastic plugs to snap in. There are plugs with different size holes and solid plugs that allow you to change how much the prop ventilates. If the trophys you have do not have PVS holes, they are older versions and may not perform as they should. I'd look for a newer trophy w/PVS holes and the flo-torq hub.