New prop & hub yet I still have minimal speed

[Fclake]

1989 Mercury 25 hp 2 stroke
Old prop took a good hit so I replaced it with a new one & hub kit. Both 10/38 x 13
Now I can only reach about 1/5 speed & the engine just revs with no gain in speed.
Have I damaged a shaft spline or gear?
The engine runs smooth as silk at any rpm.

 

[jimmbo]

It is possible that the New Prop has a bad Hub, or was installed incorrectly. What brand is the new prop?

 

[briangcc]

This the boat?

1967 Sea Star Mustang

I just purchased this little beauty & I have lots of questions! Not sure if this is the correct place to post though.

forums.iboats.com

Cause if it is, and unless the camera is playing funny tricks, it appears your cav plate is MUCH lower then the keel of the boat. It's submerged 6-12" below. If that's the case, you're MUCH too deep and a prop isn't going to fix that. Jacking the motor up would.

 

[Fclake]

This the boat?

1967 Sea Star Mustang

I just purchased this little beauty & I have lots of questions! Not sure if this is the correct place to post though.

forums.iboats.com

Cause if it is, and unless the camera is playing funny tricks, it appears your cav plate is MUCH lower then the keel of the boat. It's submerged 6-12" below. If that's the case, you're MUCH too deep and a prop isn't going to fix that. Jacking the motor up would.

Interesting. The motor is in the same position that it was with the former prop. The new prop is a different brand but same specs.

 

[Fclake]

Is it possible that the nylock prop nut isn’t torqued down enough? Would that cause it to feel like, or actually be slipping out of gear with increasing rpms? If that sounds like a rookie question it’s because I am a rookie at this! Thanks for your advice & patience everybody!

 

[Fclake]

It is possible that the New Prop has a bad Hub, or was installed incorrectly. What brand is the new prop?

 

[Fclake]

This the boat?

1967 Sea Star Mustang

I just purchased this little beauty & I have lots of questions! Not sure if this is the correct place to post though.

forums.iboats.com

Cause if it is, and unless the camera is playing funny tricks, it appears your cav plate is MUCH lower then the keel of the boat. It's submerged 6-12" below. If that's the case, you're MUCH too deep and a prop isn't going to fix that. Jacking the motor up would.

Yeah that’s the boat & motor.
I haven’t changed the motor height at all.
Everything preformed great before I spun the prop.

 

[Fclake]

Turning Point Hustler. OEM specs pre the shop manual.

 

[Fclake]

Is it possible that the nylock prop nut isn’t torqued down enough? Would that cause it to feel like, or actually be slipping out of gear with increasing rpms? If that sounds like a rookie question it’s because I am a rookie at this! Thanks for your advice & patience everybody!

Here’s another possibly dumb question-
I’ve looked through the shop manual & it doesn’t seem to mention a break away pin or disk that some friends suggest it might have.
Does this motor have a safety device like that that would cause these symptoms?

 

[jimmbo]

Break Away Pin? Are you referring to a Drive/Shear Pin? Your engine doesn't use that, it has a Splined Shaft and Hub Insert.
Disk? Are you referring to the Thrust Washer that goes on the Propshaft and the Prop against it?

If either are Missing, or the wrong ones, various things can happen, and could produce the Results you are experiencing. If the Hub Insert is missing, the Propshaft is not Connected to the Prop, only pinched between the Prop Nut, and the Thrust Washer.
If the Thrust Washer is missing, then the Prop can be driven too far Forward, resulting in Damage to the Exhaust Passage, resulting in Exhaust Gases getting into the Blades, and the Blades not gripping the Water.

 

[jimmbo]

Not my favorite brand of Prop, but they are Inexpensive. Did you get the correct Hub Kit for it?

 

[Fclake]

Not my favorite brand of Prop, but they are Inexpensive. Did you get the correct Hub Kit for it?

Yes the hub kit is correct and it all fits together nicely.

 

[Fclake]

Break Away Pin? Are you referring to a Drive/Shear Pin? Your engine doesn't use that, it has a Splined Shaft and Hub Insert.
Disk? Are you referring to the Thrust Washer that goes on the Propshaft and the Prop against it?

If either are Missing, or the wrong ones, various things can happen, and could produce the Results you are experiencing. If the Hub Insert is missing, the Propshaft is not Connected to the Prop, only pinched between the Prop Nut, and the Thrust Washer.
If the Thrust Washer is missing, then the Prop can be driven too far Forward, resulting in Damage to the Exhaust Passage, resulting in Exhaust Gases getting into the Blades, and the Blades not gripping the Water.

I believe I was referring to a break away pin.
I kinda thought the hub served the same purpose but I wasn’t sure so thanks for confirming that.
The new hub kit came with a thrust washer that buts up to another washer that was on the spline when I removed the old prop. The one that was already there - when removed & turned over to look at has notches in it that can be inverted to remove the carrier. Is that a thrust washer too? Am I running with 2 thrust washers and should I remove the new one & test it on the water under load? Or! Could all this be caused by lack of proper torque on the nylock hub nut? It’s snug but now I’m thinking it should be much tighter.

 

[jimmbo]

Take the old Thrust Washer off, and put the one that came with the Hub Kit on in its place. With both Washers on, the Prop is too far back, and not all the exhaust Gases are going thru the Hub of the Prop, some are getting out and causing the Prop to Ventilate(slip)
Turning Point should have a Torque Spec for the Prop Nut Torque. If not, just use Mercury's spec.

I remember something in the 1980 Brochure, when that Engine was introduced, that the Prop could be used to pull the Carrier out.

 

[1985 Century Mustang]

Take the old Thrust Washer off, and put the one that came with the Hub Kit on in its place. With both Washers on, the Prop is too far back, and not all the exhaust Gases are going thru the Hub of the Prop, some are getting out and causing the Prop to Ventilate(slip)
Turning Point should have a Torque Spec for the Prop Nut Torque. If not, just use Mercury's spec.

Now that's some awesome advice right there.

 

[Fclake]

This the boat?

1967 Sea Star Mustang

I just purchased this little beauty & I have lots of questions! Not sure if this is the correct place to post though.

forums.iboats.com

Cause if it is, and unless the camera is playing funny tricks, it appears your cav plate is MUCH lower then the keel of the boat. It's submerged 6-12" below. If that's the case, you're MUCH too deep and a prop isn't going to fix that. Jacking the motor up would.

This the boat?

1967 Sea Star Mustang

I just purchased this little beauty & I have lots of questions! Not sure if this is the correct place to post though.

forums.iboats.com

Cause if it is, and unless the camera is playing funny tricks, it appears your cav plate is MUCH lower then the keel of the boat. It's submerged 6-12" below. If that's the case, you're MUCH too deep and a prop isn't going to fix that. Jacking the motor up would.

Possibly a better angle here. I don’t think the cav plate is more than 6” below the keel.

 

[Fclake]

Take the old Thrust Washer off, and put the one that came with the Hub Kit on in its place. With both Washers on, the Prop is too far back, and not all the exhaust Gases are going thru the Hub of the Prop, some are getting out and causing the Prop to Ventilate(slip)
Turning Point should have a Torque Spec for the Prop Nut Torque. If not, just use Mercury's spec.

I remember something in the 1980 Brochure, when that Engine was introduced, that the Prop could be used to pull the Carrier out.

Great memory man! Yeah that’s exactly what it does. Seems like a genius idea.

 

[jimmbo]

Even that in photo, it looks like the motor is too long for the Boat. Take Picture, Level(not tilted up or down), at the height of the Bottom of the Boat

 

[Fclake]

Even that in photo, it looks like the motor is too long for the Boat. Take Picture, Level(not tilted up or down), at the height of the Bottom of the Boat

Thanks for the heads up! The boat is in a slip across town. I’ll measure it asap. So you’re thinking no more than 6” from the bottom of the keel to the cav plate right? It makes sense that if it is too far down it wouldn’t preform correctly but she was preforming fantastically the first few times I took her out with it set up like it is on the pic.

 

[fatlenny]

I agree with others comments, This motor looks like it is too long for your application. I know that is not your initial concern of this post, but running a motor too deep for your boat will cause performance issues and lead to hitting things in the water again.

what is your length of your outboard? #1, from top of transom to the anticav plate? around 15" would be a short shaft, around 20" would be a long, 25" would be an XL.

what is your transom height? #2, measure from top center of the transom to the bottom of the hull.

These 2 measurements should match. In the photos, it really looks like you have an XL on maybe a 20" transom. not Ideal at all. A proper length outboard or small jackplate could correct this but I wouldnt invest in a jack plate till your other issue is resolved first.