Reply
 
Thread Tools Search this Thread Display Modes
 
Old 08-13-2018, 05:03 PM   #1
Ensign
 
Join Date: Aug 2018
Posts: 6
Default Unable to get over 20MPH

Hi everyone,
Want to start by saying new to this forum and second year boating.

I have a 2005 Maxum 2400SC3 5.0L. Boat ran great in June. Was able to plain and get up to 35MPH. Was away for a while in July but he next time I was able to use boat was late July.
Now I am unable to get boat to plane, and max mph is 19. RPM's seem to stall around 3100.
I did start season with a 21 pitch prop, but I changed it last week to a 19. Did notice RPM's go to 3500 and MPH to 22.

I do have marine growth as it is unpainted. Could marine growth cause this type of problem?

Engine has 480 Hours. Boat was very well maintained by previous owner.

Thanks!
__________________

IT-Man is offline   Reply With Quote
Old 08-13-2018, 08:00 PM   #2
Lt. Commander
 
Join Date: Dec 2015
Location: Florida
Posts: 130
Default

Growth will definitely keep you from planning out..
__________________

jparsons121 is offline   Reply With Quote
Old 08-13-2018, 08:16 PM   #3
Ensign
 
Join Date: Aug 2018
Posts: 6
Default

Wow, I had no idea. Right at waterline the growth is about 2-2 1/2" long, further down much less.

Is it possible to test engine by seeing if rpm's can reach 4000? I tried but the warning alert buzzer started sounding.

Thanks again.
IT-Man is offline   Reply With Quote
Old 08-13-2018, 08:20 PM   #4
Admiral
 
Phillbo's Avatar
 
Join Date: Mar 2012
Location: Arizona
Posts: 1,019
Default

Is it a carberated engine? If so it sounds like the secondaries are not opening.
Phillbo is offline   Reply With Quote
Old 08-13-2018, 08:23 PM   #5
Ensign
 
Join Date: Aug 2018
Posts: 6
Default

No, its a MPI 5.0L
IT-Man is offline   Reply With Quote
Old 08-13-2018, 09:45 PM   #6
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Essex, Maryland
Posts: 6,492
Default

I would start with a bottom cleaning. This has a bigger impact than you would think.
__________________
Mike
mmwjr is offline   Reply With Quote
Old 08-13-2018, 10:06 PM   #7
Admiral
 
biggerseagar's Avatar
 
Join Date: Dec 2010
Location: central Illinois
Posts: 2,034
Default

If you are going to leave your boat in the water without antifouling paint rent a slip with a boat lift...

Roger
biggerseagar is offline   Reply With Quote
Old 08-14-2018, 10:20 AM   #8
Lieutenant
 
MoonRiver's Avatar
 
Join Date: Oct 2017
Location: Spokane, WA
Posts: 94
Default

I wonder if your gas is bad/ old after setting. Also depending on where you are boating the water is hotter in July which could effect your water & fuel temps. I can't imagine 30-40 days of marine growth would slow the boat that much. Was your U/W configuration the same each time ie; fuel, water, people, and gear?
MoonRiver is offline   Reply With Quote
Old 08-14-2018, 02:24 PM   #9
Ensign
 
Join Date: Aug 2018
Posts: 6
Default

Quote:
Originally Posted by MoonRiver View Post
I wonder if your gas is bad/ old after setting. Also depending on where you are boating the water is hotter in July which could effect your water & fuel temps. I can't imagine 30-40 days of marine growth would slow the boat that much. Was your U/W configuration the same each time ie; fuel, water, people, and gear?
Last year filled tank and added proper amount of stabilizer.
As for U/W config, pretty much the same.I have been out about three times since, including the last time with prop change.

Should I test the rpm by racing engine in neutral? Or could this damage the engine? I just ant to see if it will reach 4K.
IT-Man is offline   Reply With Quote
Old 08-14-2018, 02:28 PM   #10
Moderator

 
Join Date: Apr 2008
Posts: 4,187
Default

Quote:
Originally Posted by IT-Man View Post
Wow, I had no idea. Right at waterline the growth is about 2-2 1/2" long, further down much less.
This is too much growth. Haul the boat and clean the bottom. Max RPM should be between 4400-4800.
__________________

shrew is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 08:37 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2018, vBulletin Solutions, Inc.