geneseo1911
Petty Officer 2nd Class
- Joined
- Jul 3, 2011
- Messages
- 183
Boat in question is an '82 Cobalt 19' open bow. Cobalt brochure calls it 2900 lbs. It is a very deep vee with a 91" beam.
Engine is the original Mercruiser 260 with approx. 970 hours. 1.5:1 gear ratio.
Current prop is a Quicksilver SS 14x21, looks like new; not sure of the model.
Ran this weekend with about 1150 lbs people/gear/fuel. Got 47 MPH (GPS) @ 4100 RPM.
Ran Last weekend me alone maybe 350 lbs operator/gear/fuel and got the exact same speed/rpm.
My biggest concern is pulling power. It planes nicely with everyone on board, but it STRUGGLED to get on plane pulling me on a tube. As in minutes. Although, it was a small tube and I weigh about 260.
I'm also concerned with the lowish WOT RPMs. It seems to me the boat should be a bit faster at the top end with that much power; granted its a heavy, slow hull.
A 14x21 SS is what it came with new. The one on there now looks to be a direct replacement (could it be original?). So I'm wondering if it was overpropped from the factory (doesn't seem like something Cobalt would do) or the engine is just tired at nearly 1000 hours. The engine idles well, has great throttle response, and doesn't burn any oil. Doesn't even turn it black. The manual says max RPM is 4200-4600, so I'm not too far away.
Am I expecting too much of this engine? Should I drop to a 19P Al or maybe a 20P 4 blade Al? Or should I be looking for a something wrong with the powerplant?
Engine is the original Mercruiser 260 with approx. 970 hours. 1.5:1 gear ratio.
Current prop is a Quicksilver SS 14x21, looks like new; not sure of the model.
Ran this weekend with about 1150 lbs people/gear/fuel. Got 47 MPH (GPS) @ 4100 RPM.
Ran Last weekend me alone maybe 350 lbs operator/gear/fuel and got the exact same speed/rpm.
My biggest concern is pulling power. It planes nicely with everyone on board, but it STRUGGLED to get on plane pulling me on a tube. As in minutes. Although, it was a small tube and I weigh about 260.
I'm also concerned with the lowish WOT RPMs. It seems to me the boat should be a bit faster at the top end with that much power; granted its a heavy, slow hull.
A 14x21 SS is what it came with new. The one on there now looks to be a direct replacement (could it be original?). So I'm wondering if it was overpropped from the factory (doesn't seem like something Cobalt would do) or the engine is just tired at nearly 1000 hours. The engine idles well, has great throttle response, and doesn't burn any oil. Doesn't even turn it black. The manual says max RPM is 4200-4600, so I'm not too far away.
Am I expecting too much of this engine? Should I drop to a 19P Al or maybe a 20P 4 blade Al? Or should I be looking for a something wrong with the powerplant?