Which prop?

[sim]

But it still doesn't go higher than a 21p.

 

[Shameless]

Thanks for the info SIM!!!!

 

[Mark]

What Powertech are you running you your Diplomat?? I am in the process of redoing my little Diplomat and my prop people for my Formula told me to go with a Powertech. I just installd a CMC electric jackplate with 5.5 inches of setback ans hydraulic steering. I have a 115 Rude on the back of the little 16, so we are thinking a 13.25X21 RXB-4 Powertech.


Bill

Sorry, been out of town. I have run several PT props on my Diplomat and the RXB-4 is the best. In fact amazing. I am running a 19" @ 6000 RPM with a Yamaha 130. I am not familiar with how strong the Rude is but I would think it would get the 21" to 5500 RPM. You won't need more than 21" as all PT props are a little steep in the pitch. They also make a 20".

 

[Mark]

Mark- What are you running on the starliner propwise? Also, what is your engine? I've got a 3 litre 225 merc on my starliner with a 21 pitch laser 2. i'm thinking of something in a 23p for higher top end (I'm pretty happy with the handling otherwise)-any thoughts? You steered me right on the rxb4 on my predictor with the 115 merc.

I am running a 24" TRO4 with a 200 2.5L EFI. A 21" Laser seems underpropped for your rig. Do you have a jackplate?
The thing about the TRO4 is you can jack it higher than just about anything. I run at 2" under the pad with an 11" JP but I can jack it to 1" under w/o losing any grip. The water pressure drops when I trim it up so I dropped it down an inch.
I'm a broken record on this one, but the Starflite(liner) likes the small hub 4 blades like the Trophy and TRO4 for best all round perfomance.

 

[sim]

Mark-I'm running about 6" back- so would you recommend a 24p- a 25p?

 

[Mark]

I would say 25" with 225 3L but...what RPM were you turning the 21" Laser?

 

[sim]

best I can remember it was right around 5800 (I think)-right at the top of it's safe range. Which would tell me that if i go up in pitch its gonna drop a few hundred rpm and cancel out the pitch gain EXCEPT i wonder if it might do the same rpm because i hear the 3 litre is a real torque monster. Thoughts?

 

[Shameless]

Sorry, been out of town. I have run several PT props on my Diplomat and the RXB-4 is the best. In fact amazing. I am running a 19" @ 6000 RPM with a Yamaha 130. I am not familiar with how strong the Rude is but I would think it would get the 21" to 5500 RPM. You won't need more than 21" as all PT props are a little steep in the pitch. They also make a 20".

very cool! Thanks for the info!!!

 

[Mark]

best I can remember it was right around 5800 (I think)-right at the top of it's safe range. Which would tell me that if i go up in pitch its gonna drop a few hundred rpm and cancel out the pitch gain EXCEPT i wonder if it might do the same rpm because i hear the 3 litre is a real torque monster. Thoughts?

Hmmm. Something doesn't seem quite right. That 225 should turn a 21" Laser to the moon. What kind of MPH are you getting? Is your hull or bow foam waterlogged?

 

[sim]

Mark-you're right- went out and doublechecked. prop is a 23- roughly 64 mph at 5800 rpm. does that sound right?I haven't checked for waterlogging in bow foam. Back to the TRO4- do you think a 25 (or even higher) is spinnable? would rpm go down and what do you think it would pick up speedwise?

 

[Mark]

You're numbers seem OK. My guess is you running that Laser buried deep. What is the propshaft below the Vee? You will pick up revs and MPH if you start raising the motor with a TRO4. You do not want to go steeper than 25" because you do not want to spin any less revs than 5800.