I think I have too much prop for my setup, but what can I do to verify this?

I’m running a new 25 Subaru, and its mounted on a 2013 GTR frame that a 35 mod motor came off. The prop was also for the 35. It’s a 2 blade, 10.5 or 11P, and tip to tip measures 12’’. Its stamped DB, and from what I was told it was worked and came from south Louisiana.

I ran the Subaru on my Backwater frame, and it ran fine. On this GTR, it revs up fine out of the water. If I barely put the prop in the water, it throws a hell of a tail but the boat barely moves. The RPMS stay up though. If I get the prop submerged until it gets good bite, it instantly boggs the motor down to where it barely stays running. It’ll push the boat just over troll speeds.

Is this a sign of too much prop, or should I be looking at other possible issues?

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Probably too much prop...

Put the boat in the water, put it in fwd and trim it up, give it some throttle and slowly trim it down until you start moving, bump the trim down as you gain speed until it's running on step and adjust from there. Won't fix your problem but might get you moving. Basically, ventilate the hell out of the prop so you can turn it until you get moving.

That's exactly what I tried to do. I was hoping I could get it moving little by little, easing the prop up and down. Didn't work how I hoped it would, and barely got above troll speeds.

I would check all of your fuel connections too since you just swapped everything into that boat.

I would also confirm that you are running on both cylinders.
Sounds like you are only running on 1.

U have an rpm reading on that it sounds like to much prop but that 25 should be able to handle that prop it's got a little wear on it.

I have been running a 35 prop on my 25 lately (all I could get my hands on during duck season) and my boat still planes out. Not the best speeds I have ever seen but needless to say the Subaru atleast has enough ass to put the boat up on top.


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I have the Subaru 28 hp and am running an 11"x12p prop. I ran the same prop on the 25hp that I had. It runs great on both engines

when you swapped engines did you swap gears too? that might be the issue. the 25 runs a different gear than the 35.

I'd get you the prop for the 25 from GT. My buddy and i have done a lot of messing around with props on his 25 gtr (3 blades, 2 blades, cut down, pitched, cupped), and the standard 11" prop that comes with the 25 has done the best from what ive seen.