Did I Select the Wrong Props for My Volvo Outdrive

AMMO DAWG

Petty Officer 1st Class
Joined
Aug 3, 2012
Messages
226
I have a 1999 Rinker Flotilla Deckboat, 24 ft (approx 3500 lbs) that I finally got in the water after four years (project boat!) I got the boat with no engine or outdrive and I installed a Marine Power 5.7 (fresh rebuild) and a Volvo Dual Prop outdrive (DP-SM 1.95) I took my best guess at the proper prop and put on stainless F6 prop set. The maiden voyage went well considering the extensive work I did on the boat, engine ran good, steering and trim all good, most of all no leaks! The only thing that was disappointing was the lack of a hole shot. According to the manual on the engine it is rated at around 300HP, however when I push it quickly to full throttle it bogs down and struggles to move out. If I bring the throttle slowly up to around 1000 tom 2500 RPMs it really scoots. At 2500 RPM I was running around 32 MPH. I can't go above around 2800 RPMs or it bogs down. So my question is do you all think I selected the wrong prop and if so which way should I be headed, lower number, F5 or F4? Another note the prop set I have as reconditioned by a fairly reputable shop so I believe the props are in good shape.
 

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Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
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47,309
I would have gone with F5's as a starting point
 

ChrisinPHX

Seaman
Joined
Jun 9, 2013
Messages
69
That sounds really odd to me. I have a 24' deck boat, similarly sized engine, a 1.95 ratio(DP-C), and my mph seems to run with my rpm on the top end. 3500 = 35mph, 4000 will get me around 40mph. Those are loose numbers of course, but they are close. I love my F6's.
 

Senior B

Petty Officer 1st Class
Joined
May 19, 2006
Messages
253
You've got something else going on. Is your boat fuel injected or Carb? Not getting over 2800 rpm is either a bad fuel pump or severely retarded timing
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,944
You've got something else going on. Is your boat fuel injected or Carb? Not getting over 2800 rpm is either a bad fuel pump or severely retarded timing

Check throttle linkage to see if the throttle plates are opening fully. If it has a 4bbl carb, the secondaries are not opening
 

AMMO DAWG

Petty Officer 1st Class
Joined
Aug 3, 2012
Messages
226
The engine is fuel injected, MEFI 3 system. The more I think about it I think you are probably right, prop is not the issue. It's a fresh rebuild and I had the injectors cleaned by a company that cleans and measures performance. The fuel is kind of old, think that could be a possible culprit?
 

ChrisinPHX

Seaman
Joined
Jun 9, 2013
Messages
69
Bad fuel can definitely do that. If you can't pump it out, put as much 91 as you can in there and even add some octane booster and try to run through the whole tank.
 
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