Mercury Prop question

[bassinms]

I have a 2007 Stratos 486SF with Mercury 150 EFI. When I bought it they put a 23p 4 blade Trophy plus prop on the boat which caused it to stand straight up. Last night I put a 21p 3 blade Tempest Plus prop and the boat runs much better. With WAT (fully trimmed) I am running 58 at 5800 RPM's. I am also thinking about trying a 3 blade 19p as most people I talk too uses this blade on these boats. Would there be much difference between a 3 blade 19p and a 3 blade 21 p? Would it make the boat have better whole shot, faster top-end?

Also, I noticed last night when I was running full throttle and tried to trim up my engine, it got to a point to where it seemed like the engine would not let me trim any more. Is there a auto-cutoff on the trim to keep you from over-trimming during WAT??

Any informaiton would be great !!. Thanks, Jimmy

 

[walleyehed]

Re: Mercury Prop question

You're hitting max trim....a good sign the engine is too low mount-wise and needs to come up.
5800 is a good target RPM.
The 19 in the Tempest will gain you about 450 RPM, but you won't see any speed gain. You'll have to adjust engine heigth to gain speed.
That 23 Trophy is the same as about a 24 pitch 3 blade...I'd say you were way over-propped with the trophy without a good jackplate with moderate set-back.

 

[bassinms]

Re: Mercury Prop question

If I am hitting 5800 RPM fully trimmed up (as far as it will allow me to go) at wide open throttle, do you think I need to worry about moving my motor up a little ??? The boat is running great compared to the old prop, so I am happy with that.
How hard would it be to move the motor up some? Should this be done by a dealer?

Thanks again for everyones help,

 

[Texasmark]

Re: Mercury Prop question

Not capturing the thread but I asked myself that once. If you have an engine jack and a flywheel adapter, it's a piece of cake. I didn't have one then, but I do now. I made the adapter.

If not, a couple of friends to steady the 410# engine on it's skeg and use the tongue jack to move the transom down.

Use a good marine sealant on the holes when you put the bolts back in. I think I read on here where torque is 55 ft lbs like is on the prop nut. Maybe Walleyehed knows.

HTH

Mark