1998 Mercury 225 slipping at high speeds

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wjhuskey

Petty Officer 3rd Class
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Apr 28, 2011
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I have a 1998 Mercury 225 EFI on my bassboat. When I almost get to full throttle, driving straight down the lake, the stern of the boat suddenly slides to one side a bit. Scares me every time lol. A guy at the boat ramp said it could be a rubber washer missing at the prop??? Not sure what he was talking about. Anyone know what could be causing this? Thanks in advance.
 
Dukedog

Dukedog

Captain
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Oct 6, 2009
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3,420
agree, probably set up.. boat type, motor (3.0 or 2.5 PM), offset, height, prop?

i always liked a little "wiggle" at times.. kept me on my toes and payin' attention!
 
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wjhuskey

Petty Officer 3rd Class
Joined
Apr 28, 2011
Messages
80
Dukedog said:
agree, probably set up.. boat type, motor (3.0 or 2.5 PM), offset, height, prop?

i always liked a little "wiggle" at times.. kept me on my toes and payin' attention!
Click to expand...
Motor is a 3.0, not sure about offset and height, has a 4 blade prop. It's the original motor that came on my 20 ft Ranger bassboat.
 
Texasmark

Texasmark

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Dec 20, 2005
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wjhuskey said:
I have a 1998 Mercury 225 EFI on my bassboat. When I almost get to full throttle, driving straight down the lake, the stern of the boat suddenly slides to one side a bit. Scares me every time lol. A guy at the boat ramp said it could be a rubber washer missing at the prop??? Not sure what he was talking about. Anyone know what could be causing this? Thanks in advance.
Click to expand...
What "rubber" washer at the prop? If a pressed in rubber hub it encompasses thewhole space between the splined brass center and the "shell"....no washers in the prop area. could be slipping but not not with the indications you mention.
You didn't mention if you could correct the problem with engine height (jack plate) or trim position. You aren't talking about "chine walking" boat rocks back and forth....are you?
 
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wjhuskey

Petty Officer 3rd Class
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Apr 28, 2011
Messages
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Texasmark said:
What "rubber" washer at the prop? If a pressed in rubber hub it encompasses thewhole space between the splined brass center and the "shell"....no washers in the prop area. could be slipping but not not with the indications you mention.
You didn't mention if you could correct the problem with engine height (jack plate) or trim position. You aren't talking about "chine walking" boat rocks back and forth....are you?
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That's just what the guy at the boat ramp called it, a rubber washer, but he was only guessing...I have no idea. The boat doesn't have a jackplate. I notice it at about any trim setting, especially a higher trim setting which everyone rants about giving the boat a better ride...maybe I should lower the trim some and see if it does it...
 
Texasmark

Texasmark

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I have no experience with 200 HP engines but I have run the "Pad" and have experienced "Chine Walking" from exceeding the boat and setup parameters speed limit, also "Blow out" from too much trim, and "Ventilation and then the prop grabbing" caused by air induced ahead of the prop, like a keel on the boat and in a high speed, tight turn, generating air bubbles ahead of the prop, and then a parameter changed, like I straightened out somewhat and it quit, allowing the prop, now turning at max RPMs, to grab a chunk of water and "shoot" you forward.

In all those cases, I was paying attention to how I was operating the boat and realized that I don't need to be doing that unless I want more of the same......so I quit doing what I was doing.
 
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wjhuskey

Petty Officer 3rd Class
Joined
Apr 28, 2011
Messages
80
Texasmark said:
I have no experience with 200 HP engines but I have run the "Pad" and have experienced "Chine Walking" from exceeding the boat and setup parameters speed limit, also "Blow out" from too much trim, and "Ventilation and then the prop grabbing" caused by air induced ahead of the prop, like a keel on the boat and in a high speed, tight turn, generating air bubbles ahead of the prop, and then a parameter changed, like I straightened out somewhat and it quit, allowing the prop, now turning at max RPMs, to grab a chunk of water and "shoot" you forward.

In all those cases, I was paying attention to how I was operating the boat and realized that I don't need to be doing that unless I want more of the same......so I quit doing what I was doing.
Click to expand...
The rear is shooting to the side, not forward...and it's a 225, not a 200. I'm running it normal and gently, not doing anything out of the ordinary...I'm not even quite full throttle when it usually does it. It's not a chinewalk - the rear suddenly jerks to one side while driving straight down the lake...but it quickly corrects itself.
 
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