Almost almost but not quite on a plane.

[obwhan]

The problem I have is. The boat goes the same speed at 2000 rpm as it does at 4800 rpm. The bow (front)of the boat comes up like it's going to take off on a plane but doesn't go any faster. At the higher RPM the bow stays up high. And the Temp will climb after a time but comes right down when I come back to idle. Is there anything in the stern drive that would slip. Not totally sure the if the propeller and hub is okay, It an older prop. I am new to this forum and to Volvo eng and outdrives. I just bought the boat. A 78 Bayliner with a 4 cyc Volvo eng. I did find that the Dip stick on the OD shows it is way over serviced looks like 2 times as much oil as needed over half way up the stick.
dont know if this is a cause but I do not think it helps. what other things can cause this mushing.

 

[Dunaruna]

Re: Almost almost but not quite on a plane.

What size bayliner?

 

[Maclin]

Re: Almost almost but not quite on a plane.

I know that a prop can do that, I followed a net buddy's trials with that problem on a 25 foot boat with V8 and single prop. It acted just like that and turned out to be the prop that would hold somehow at lower rpms but would slip as the HP came up. I only mention this because it is a fairly cheap thing to try. You can mark across the blades and hub and go drive it then check the mark again to see if it is a situation like that.

 

[wkb2460]

Re: Almost almost but not quite on a plane.

If your engine temp is rising when you increase power it may be your engine coupler slipping. Please posted engine & drive info.

 

[obwhan]

Re: Almost almost but not quite on a plane.

Thanks, Dunaruna, Maclin and wkb, For the replys. I Have a 21ft 1978 Bayliner the drive is a 280 serial # ends with a D The Engine I am not sure of model Its a 4 Cyc with two carbs on it I have not found an ID tag or any other #s yet. It takes a little while for the temp to come up 8 or 10 mins. I think I will try a new prop. thats ease and if its not I can always use a spare. now I just need to find one

 

[wkb2460]

Re: Almost almost but not quite on a plane.

Put a mark on the old prop across the hub. Then run the boat and check to see if the lines are misaligned. If so the hub is spinning inside and it will need to be replaced.

 

[obwhan]

Re: Almost almost but not quite on a plane.

Thankz wkb will try this Al

 

[Bondo]

Re: Almost almost but not quite on a plane.

I did find that the Dip stick on the OD shows it is way over serviced looks like 2 times as much oil as needed over half way up the stick.

Ayuh,... Drain alittle out the bottom,+ see if there's Water under the oil...

 

[sdoomaha]

Re: Almost almost but not quite on a plane.

Really hate to state the obvious and please take no offense...but you mentioned you just bought the boat...have you owned previous boats? You have the lower unit trimmed all the way down when trying to get up on plane? If it is trimmed up when trying to get on plane it will stick the nose high in the air and never come down. Other option is you may be "overpropped" and need to come down in pitch a little bit to get you up on plane easier. 21 foot is a pretty good sized boat to push with a 4 cylinder...the pitch of the prop is normally noted on it....do you know or can you tell the pitch?

Sorry if you are a seasoned boater and already took into account just would hate to see someone chase a problem if there is not really one that exists.

Return to lurking mode.

 

[obwhan]

Re: Almost almost but not quite on a plane.

Thanks Steve O No offense taken. I have some pretty thick skin after 23yrs. in the navy. And I learn something every day weather I want to or not. I did check the lower unit trim. It was down and locked. I will try to get the prop off. tomrrow I hope. and see if I can find any #'s.