Sundancer 300. Won’t get on plane.

Ryan Dykhouse

New Member
Jul 13, 2019
13
Boat Info
2004 Sundancer 300
Engines
(2) Merc 5.0’s
2004 Sundancer 300 with twin 5.0’s. I know this the the standard engine setup and the boat certainly isn’t overpowered. But, if I have full fuel and 6 adults on board, I can’t get the boat on plane. Literally drove for 2 miles last night before the right wave combination set me up to gain some speed to get the boat on plane. Any thoughts??? New outdrives and new bottom paint.
 
2004 Sundancer 300 with twin 5.0’s. I know this the the standard engine setup and the boat certainly isn’t overpowered. But, if I have full fuel and 6 adults on board, I can’t get the boat on plane. Literally drove for 2 miles last night before the right wave combination set me up to gain some speed to get the boat on plane. Any thoughts??? New outdrives and new bottom paint.

Is this a new condition?
Has anything, other than your new drives, changed with the mechanicals on the boat?
Can you reach rated RPM’s at WOT?
You may want to consider talking to a good prop guy.
 
Fresh or salt water? Has the boat sat for an extended period of time since being used? Vibrations?
 
Were the outdrives the same ratio and props?? Is the drive trimmed all the way in?

I had a boat that wouldn't get on plane and I had to use full down tabs and send a couple people forward to get her up on plane.

The solution was to trade the boat in on a larger boat with the largest engines the factory installed. Since then, I've always looked for the most powerful engine offered from the factory when upgrading.
 
I had the same boat, same year with the 5.7 350Mag and BIII. If all six adults were in the back of the cockpit I had to use the tabs to get on plane with full fuel. I think it's just the nature of the boat, but maybe Ididntdoit or another 300DA owner will add their experiences.
 
yes - something is definately wrong - i have run my boat heavily loaded and never had a problem....do you have BIII drives? should be 2.20 with 20p props.....once you were on plane, were you able to hit at least 4600 rpm on both sides? does one motor lag/require more throttle than the other?
 
All good feedback.

Props are p22 but yes BIII drives. Both engines run similar and I can get the rpms once on plane. When the boat starts coming over the top to plane though, the rpms do come up a bit and it sounds like some cavitation possibly.

There is a highly regarded prop shop near me. Definitely going to seek their advice.
 
Is this a new condition?
Has anything, other than your new drives, changed with the mechanicals on the boat?
Can you reach rated RPM’s at WOT?
You may want to consider talking to a good prop guy.
Has been this way since I’ve owned the boat....both before and after outdrives. I can reach the RPM once I break plane but I’m fore sure going to consult with my local prop shop.
 
Ryan, I'm guessing when you're trying to get on plane with that number of people and full fuel and water there's just too much weight aft.

I had a 330 with 5.7L's and had no trouble getting it on plane but had to use quite a bit of trim tab if I was running with full fuel and water and several passengers.

Also, how clean is the bottom on the boat? It doesn't take much gunk on the bottom to make getting on plane difficult.
 
Has been this way since I’ve owned the boat....both before and after outdrives. I can reach the RPM once I break plane but I’m fore sure going to consult with my local prop shop.

Google PropMD. That’s who I called back when I had my 300 Sundancer. Their recommendations were on the money and they had great prices at the time.
 
22p props are a problem......my load last week was 4 people (3 on the aft bench) a 200 lbs dinghy on the swim platform, full fuel, full water and enough bottled water and food for 4 people for a week, and the boat has a gennie too.....also, thats with no tabs
 
IMG_3179.PNG
yes - something is definately wrong - i have run my boat heavily loaded and never had a problem....do you have BIII drives? should be 2.20 with 20p props.....once you were on plane, were you able to hit at least 4600 rpm on both sides? does one motor lag/require more throttle than the other?
That's interesting. According to the parts list from 2004 the 22" cup is correct. Did you change yours out?
 
just looked at the prop and drive matrix for 2004 and 2005 - all use a 2.20 drive - in '05 it uses 22p cupped props with no bottom paint and 20p (non cupped) with bottom paint (which mine had from the factory) in '04 it lists 22p cupped props with no bottom paint and 22p (non cupped) for boats with - same exact boat and motors.....

FWIW - If I was getting new props, i would go 19 or even 18p
 
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For what it's worth I bought a boat in 1999 and it came with a 5.7 with a Bravo III propped with a set of 24 inch pitch. I felt from day one it was over propped but the dealer argued with me that the manufacturer set it up like that so it must be right. I could only get to the bottom of the WOT range. I ended up calling the boat manufacturer direct and they said that's the correct prop, I ended up calling Mercruiser who after I gave them all the details called the dealer and setup a prop swap. We switched to 22 inch but I have no idea about cupped or not anyway I picked up about five hundred rpm and the boat instantly performed much better. I think your boat is over propped.
 
Is this a new condition?
Has anything, other than your new drives, changed with the mechanicals on the boat?
Can you reach rated RPM’s at WOT?
You may want to consider talking to a good prop guy.
You obviously do not understand how operate your boat…bury the tabs and drives as she gets bow down raise your tabs and adjust drives as needed, your water should breaking approximately drivers position.
 

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