help picking prop

[josh_2562]

I have a 1996 pro sports ff1800 nada has it at 900lbs net weight. It has a 1999 dt 140 efi. It also has a 6" back set jackplate. it also has trim tabs. i'm not sure what all info you need to help me out. The boat had a 1996 dt 115. I puthe the prop off of that engine and put it on the 140. It is a 4 blade ss but I can't find any name or #'s on it. The problem i'm haveing is when I try to trim the motor out it sucks air befor I can get it trimed out. with the 115 I could hit 44 mph on the gps at 5000rpms. now with the 140 i can only do about 35 before it starts sucking air. this is with the jackplate all the way down.

What would be a good prop to use on this boat. What size and pitch. I have to stay with ss
Thanks for the help

 

[steelespike]

Re: help picking prop

Is there a number under the prop nut?
The 140 probably has holes in the mounting bracket that allow it to be lowered.
See if you can get it down till it holds on better.For best setup you should be able to see the antivent plate(just above the prop) at speed.

 

[josh_2562]

Re: help picking prop

the engine is all the way down. I haven't found any #'s on the prop

 

[josh_2562]

Re: help picking prop

Ok I checked the prop again. I was looking for #'s on the hub. I found these #'s between the blades.
Power tech
Sz140rxb-18p. *9257895

 

[steelespike]

Re: help picking prop

I think you need to get your setup solved.It isn't likely the 115 prop couldn't handle the 140.It might over rev but I wouldn't think venting would be an issue unless the 115 had trouble as well.Did you change anything else?Are the motors the same shaft length?Did you add anything that might disturb the water near the prop.
Trim Tabs?A prop shop can measure the prop.

 

[steelespike]

Re: help picking prop

OK,an 18" pitch at least we will know where to start from if a change is in order.
Did you try it with the trim tabs all the way up out of the water?

 

[josh_2562]

Re: help picking prop

the foot on the 140 is from the 115. so every thing is the same. I have tried it with the trim tabs up and down. with them up it hops alot