New prop, same issue. Won’t go over 10 mph.

[Dberger820]

Just bought a used 17ft Crestliner 1600 with a 2004 Honda BF75A. Previous owner only took it out once this summer and said it was “sputtering” at full throttle. Gas tank was 3/4 full so I topped it off with high test. Took out to lake Sunday and tach was showing 5000 rpms but would only go about 10mph and not plane out.

Did some research and came across the most plausible explanation is a spun hub. Well, the previous owner included brand new prop with the boat. Put it on and took it back out today. Well, same exact thing occurred. This shows me probably not spun prop unfortunately.

What else may be causing the prop not to meet the rpms of the motor? What is the next part I should be inspecting? Any insight or experience is greatly appreciated.

 

[alldodge]

Is the ventilation plate even with the bottom of the hull?

 

[Alumarine]

Are you sure it's really going 5000 rpm?
How fast does it go at 2500 rpm?

 

[ahicks]

With 2 different props doing the same thing, I would agree it's not likely a prop issue.

5000 rpm is a good rpm for that motor, if that's actually what it's turning.

I'm interested in the engine mounting height too.

 

[Dberger820]

It MAY not be actually turning 5000 rpm, I'm just going off of what the tach is telling me. It could very well be incorrect. At full throttle, the nose is sticking up about 30 degrees trying to plane out, just never does. At 2500 rpm it definitely sounds like it's revving, but only going about 5 mph. Idles alright.

I spoke again this afternoon with the 91 year old gentleman I bought it off of. He is original owner and said he cleaned the carbs out after his trip out this summer. I didn't get much sputtering so that seems to have helped the issue he was experiencing. It has been suggested to replace the fuel line so I think that will be the next "easy and cheap" thing to try.

I will check out the ventilation plate and mounting height this evening when I get home and update with what I find.

Thanks everyone so far!