454 bowrider prop size??

[parnell]

I have a 97 sea ray bowrider 26ft. I think its 5500lbs with a 454, it has a 21p prop on it now but seems extremely sluggish. Is the a better prop choice for this boat. I know its not a race boat however, I would like to increase my top speed as much as possible. Please let me know your thoughts. Thanks, Mike

 

[UncleWillie]

Re: 454 bowrider prop size??

Read This First.

What WOT Speed and RPM are you getting, the prop diameter, and what is the outdrive gear ratio. (e.g. 1.62:1)

 

[parnell]

Re: 454 bowrider prop size??

Read This First.

What WOT Speed and RPM are you getting, the prop diameter, and what is the outdrive gear ratio. (e.g. 1.62:1)

sorry for not giving more information. I am not too knowledgeable on all the specs but at wot im abt 48-4900 and poss 44mph. prop diameter im not sure on but its a mirage 21p if that helps but probably not. Its a factory bravo one outdrive but gear ratio im not sure of. sorry for being unable to give more details

 

[tpenfield]

Re: 454 bowrider prop size??

Since you are getting 4800 RPM at WOT, you could go to a 22p. It will kill your hole shot, but might get you a few more mph at about 4500 RPM. I think a 23p would kill it in general.

That boat is kind of in the 'middle ground' between a big single engine and needing twin engines, so 44-46 mph might be all you get with it.

Mirage is the right prop for that boat.

 

[Philster]

Re: 454 bowrider prop size??

^^somewhat agree.

You might gain 2 MPH +/- from prop design, rather than prop size at this point. Aren't you right at the top of the RPM range? It's right about 4900, I believe. That's where people want to be. That's pretty ideal/sweet. Maximum response and speed propped that way.

"Sluggish" needs to be defined. Sluggish is typically used to define slow acceleration. Top speed in almost every case will scrub off even more acceleration.

The OP needs to define 'sluggish'... and I feel there is no pitch issues that can improve the top speed. A maximum bow-lifter prop of the most modern design with proper raking/cupping, etc might return just 1-2 MPH but perform better overall.

The dynamic that has the most potential for change and feel is acceleration and mid-range feel from a 4-blader that actually knocks off 1-2 MPH.

 

[steelespike]

Re: 454 bowrider prop size??

Your gear ratio may be stamped on the outdrive.If we can get your wot rpm and gps speed with the prop size we can tell better how well your setup is working.
I ran a couple of quick calculations using broadly spaced gear ratios came up 26% slip and 35% slip.
way high.
I would first suspect our numbers.Is speed by gps? You may need to confirm the tach.
And of course the gear ratio off the outdrive will help