3000 rpm on last trip

[tranceworld]

2003 Crownline 192 br.
4.3 Mercruiser (190 hp)
56 hours on engine.
recent tune up.
Half tank new gas, half about a month old.
Two light weights sitting in back, then two in the swivel chairs, so weight was more in the rear. (I don't think this played a major role, since in the beginning of the trip back to the ramp we had no issues.
Total weight carrying from gear >125lbs.
Trim full down, to 3/4 down...no difference
Drove with this for approx 5-7 minutes.

Was out on the water last week for a couple hours. On the way back to the ramp, we noticed that the boat was really working to move. For the whole trip there were no problems, the boat would take right off. It was hard to get up on plane. Dropped the throttle to an idle, and pushed it at a moderate pace to full throttle and the boat would only get to 3000 rpms, but still not to plane. When we let off the throttle again we could feel that the boat wanted to plane, but then speed dropped and set back down.

Once we got to the ramp, we noticed that there was a rather large ball of weeds on the front part of the stern drive (like the leading edge in front of the prop). We went through water that was approx. 5 feet deep (per the depthfinder) but afterwards it was 20+ all the way to the ramp. Could a large tangled mess of reeds (if I were to ball it up, it would have been slightly larger than a basketball) cause the boat to only go to 3000 rpms, or should I consider doing other checks before getting back out on the water? I would presume that the drag caused in the water would have prevented the prop from getting enough thrust to plane, since the prop would not be in free flowing water.

What are you thoughts, and thank you in advance.
I hope I have supplied enough information.

I have never rebuilt a carb, but checked the smell of it and it doesn't smell like varnish.

 

[tpenfield]

Re: 3000 rpm on last trip

My thoughts are to try the boat again without the ball of weeds and see what you get.

 

[LippCJ7]

Re: 3000 rpm on last trip

My thoughts are to try the boat again without the ball of weeds and see what you get.

I agree, interfering with water flow to the Prop would certainly cause the symptoms as described, especially a basketball sized wad of weeds.

Not drag mind you but the water flow to the prop, if you have ever felt the difference in thrust when you go through another boats prop wash I call it soft water as opposed to clean water you know what I mean, water that a prop has recently gone through is full of air and when your props get hold of it you will lose thrust, I imagine that your ball of weeds did something similar. Props need good clean water to make the most thrust, that's why your outdrive is shaped the way it is in front of the prop, attach a big block of wood to the front of your outdrive and I bet you get the same result.

 

[tranceworld]

Re: 3000 rpm on last trip

I agree, interfering with water flow to the Prop would certainly cause the symptoms as described, especially a basketball sized wad of weeds.

Not drag mind you but the water flow to the prop, if you have ever felt the difference in thrust when you go through another boats prop wash I call it soft water as opposed to clean water you know what I mean, water that a prop has recently gone through is full of air and when your props get hold of it you will lose thrust, I imagine that your ball of weeds did something similar. Props need good clean water to make the most thrust, that's why your outdrive is shaped the way it is in front of the prop, attach a big block of wood to the front of your outdrive and I bet you get the same result.

Thank you, and that's what I meant kinda sorta. The prop was in turbulent water and unable to get a good bite.