Boat won't plane. Propped wrong?

[Alan Dykes]

Hey guys,

I have a 1994 Chris Craft 282 Crowne cruiser with twin 5.0L engines, Volvo SX outdrives with 1.60 ratio. Props I have are 4 blade alum. 15" dia x 16" pitch and 3 blade Viper stainless 14.75" x 17" pitch. They both perform about the same. Engines turn up to about 3000 but will not push it over on plane. It will occasionally get on plane and the engines will only go to 3600 at WOT. We had the aluminum props repitched to 11.5 pitch, and it only made about 200 rpms difference (3200 until plane, then 37-3800).

Things I have checked: Bottom of boat is clean. Throttles open fully. Engine timing is right. I don't think it is an engine problem as they both run the same numbers. Trim tabs are working properly.

I am thinking it may be propped wrong since it has been like this since we got it. It has gotten worse lately because it won't plane at all now.

Thanks,
Alan

 

[Lyle29464]

Re: Boat won't plane. Propped wrong?

Any chance you have a double bottom full of water? I assume you mean redone to 11.5 diameter? Fresh gas?`

 

[steelespike]

Re: Boat won't plane. Propped wrong?

As far as I know you can't repitch a prop more than 2 inches and sometimes that doesn't work well. At 3800 planed you are about 1000 short.It would take about 5" pitch change to get that.
To me that doesn't make sense.A healthy single probably runs more prop than that.
I would suspect the boat may have absorbed a load of water in the flotation under the floor or in the hull. Just to compare you might try each engine by itself see if they seem even.You might do a compression check.Be sure all cylinders are firing.One cylinder could drag down the whole operation.

 

[Alan Dykes]

Re: Boat won't plane. Propped wrong?

Any chance you have a double bottom full of water? I assume you mean redone to 11.5 diameter? Fresh gas?`

I actually did have a bilge pump problem a few weeks ago, but it is pumping all of it out now.

No, the guy says he repitched them to 11.5" pitch. I am now under the impression that was not a good thing to do.

Gas is fresh and no ethanol, and we are going through a lot of it trying to run it.

 

[Alan Dykes]

Re: Boat won't plane. Propped wrong?

As far as I know you can't repitch a prop more than 2 inches and sometimes that doesn't work well. At 3800 planed you are about 1000 short.It would take about 5" pitch change to get that.
To me that doesn't make sense.A healthy single probably runs more prop than that.
I would suspect the boat may have absorbed a load of water in the flotation under the floor or in the hull. Just to compare you might try each engine by itself see if they seem even.You might do a compression check.Be sure all cylinders are firing.One cylinder could drag down the whole operation.

It would only do 25 knots at WOT (3600rpm) when it would plane out. I am thinking of buying some 15 x 13 props to try. The only ones I can find are Volvo and they will be $400 for the pair. I don't mind paying that if that will fix it. I wish I could buy props from somewhere that I could exchange them if they didn't work. Does such a place exist?

Chris Craft says the prop for the boat is a 14.5 diameter and 19 pitch with a 1.76 ratio outdrive. My outdrives are 1.60, shouldn't that change the prop size to about what I had before?

Thanks,
Alan

 

[Alan Dykes]

Re: Boat won't plane. Propped wrong?

I found some 15x15 3 blade props for $100 each. I am thinking of trying them. The way I understand it that will be the equivalent of dropping 2" of pitch from a 15x16 4 blade. Is that right?

Alan

 

[Lyle29464]

Re: Boat won't plane. Propped wrong?

Think you still going in the wrong direction. Sure at some point you can get a prop that will plane a boat that is full of water or has 4 dead cylinders. The props you have may be too much but not a thousand RPM's worth. When the pump failed how much water got in the boat. how long did it set? Have you noticed that after you pump it out you have more water "show up"? Does the boat seem extra heavy? Does any water run to the back when you are trying to plane?

 

[steelespike]

Re: Boat won't plane. Propped wrong?

Think you still going in the wrong direction. Sure at some point you can get a prop that will plane a boat that is full of water or has 4 dead cylinders. The props you have may be too much but not a thousand RPM's worth. When the pump failed how much water got in the boat. how long did it set? Have you noticed that after you pump it out you have more water "show up"? Does the boat seem extra heavy? Does any water run to the back when you are trying to plane?

15X13 props don't even make sense theres no other prop you could select if you needed to prop for water sports with a full load of people.I say you need to prove there is no other problemPull the boat and weigh it if you have to.
As far as your grear ratio if my math is right the deifferernce in ratios is something like 12% certainly not the same as a 6" reduction in pitch.I think that is over 30%.With those motors that boat should fly.

 

[Bondo]

Re: Boat won't plane. Propped wrong?

Ayuh,... Run a compression test on the motor,...
Not only is yer drive the Wrong ratio, I think the motor is a Dog for some reason...

 

[Alan Dykes]

Re: Boat won't plane. Propped wrong?

Ayuh,... Run a compression test on the motor,...
Not only is yer drive the Wrong ratio, I think the motor is a Dog for some reason...

The starboard engine is new and the port engine keeps up with it. That is why I don't think it is an engine problem.

I ordered 15x15 props to try since iboats had them pretty cheap. I am headed down there tonight. I am going to pull it out of the water and check her over good. Anybody near Orange Beach, AL want to come over and play?

Thanks to everyone for all the advice and ideas, I have several things to check now.

Alan