Problem with get on plain

Chapy204

Recruit
Joined
Sep 6, 2015
Messages
2
I have a 2007 chaparral 204SSi with Volvo Penta 4.3GX1 SX, factory 4-Blade aluminum 14x21 prop. With full tank of gas and 4 adults the boat will not plain unless at least one person moves to the bow of the boat. I have been told I need to lower the pitch to correct this, however, that will increase the RPMs on the engine. The recommended RPM is between 4600-4800 RPMs. Took the boat out this weekend and WOT is already running 5500-6000 RPMs, so lowering the pitch seems like it will make that even worse. How do I correct this and what size prop should I consider?
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,470
Took the boat out this weekend and WOT is already running 5500-6000 RPMs,

Ayuh,...... Welcome Aboard,..... My guess is, yer tach is Wrong,....

A stock 4.3l will float it's valves, long before 6 grand,...

Cross-check it against a known good shop tach,.....

So,... Get the actual rpms at Wot, 'n in the mean time, I'll move this to the prop forum for ya,.....
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
A few things one this is a mpi engine and there is a rev limiter set at about 5100 rpm your not doing 6000

Take a flash light illuminate the back of the Tach... there is a switch there you will note that it has three postion's 4,6,8, set it to 6....actually move the switch a bit they corrode.

Once this is straight if you can reach 5000 rpm with that prop Google Nauticus trim tabs they will get you out of the whole so to speak.
Read This First!! [COLOR=#6A6A6A !important]December 22nd, 2008, 10:11 AM[/COLOR]



ESSENTIAL DATA REQUIRED
When posting a question about propellers, you cannot get a reasonable answer unless you provide the following information in your post: Items 1-4 are essential for meaningful response to most questions.
1) Performance issue you are trying to correct.
2) Current prop manufacturer, model, aluminum or stainless as a minimum.
3) Current prop diameter and pitch (required).
4) Wide open throttle RPM and speed with an average load (very helpful)
5) Engine/drive make, model, year, and HP
6) Boat make model, year, length and weight

That makes life much eaiser and far less costly.
 
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