Prop recomendations?

[Destro1975]

Hello, this is my first post so go easy on me please.

This is my first boat, a 1989 18 1/2ft Dynasty Regency with a 5.0 Mercruiser 2 barrel carb and a Alpha 1 outdrive.

I think I may be over reving at wide open throttle with a normal boat load I am seeing 5,000 RPMs at about 40 mph which is about 500 more RPMs than I would like to see.

The information on the outdrive 1.65R which I think is the ratio & the serial is OC629711. I have a stainless prop that has M2 0 191 stamped on it, and looks to be 14 1/2 diameter.

It jumps out of the water super and gets on plane fast even pulling a skier or a tube.

Can someone tell tell me what the current prop pitch is and maybe recommend a prop that would lower my RPMS at WOT?

Thanks,
Jason in Kansas

 

[steelespike]

Re: Prop recomendations?

hwsiii has a program for figuring props. He will need more info
but does a good job.In the mean time take a look under the prop nut
for more numbers.A 2" decrease in pitch will put you at ABOUT 4,600.

 

[Destro1975]

Re: Prop recomendations?

So I need to pull the prop to get to more numbers?

 

[hwsiii]

Re: Prop recomendations?

Destro, we will try to help you as much as we can, but there is certain information that is needed in order to help you. The following form has all of the information that is needed to help you with your problems in finding the right prop. If you do not know all of the information that is asked for on the form please give us the most information you have available as I have a program I designed to find the right prop for any planing hull boat that needs this information, and most other people who are trying to help you will need the same information. It requires time to find all this information when we have to look for it and in my defense I expect you to be willing to expend as much effort in finding the right prop as I do. We hope to be able to help you get the exact prop you need for your particular uses, and this information is required to do that.
It is not as simple to pick the right prop as most people coming to this forum think it is, that is why we ask so many questions, it is for your benefit we ask all these questions. And if you have a stainless steel prop or are changing to one the blade geometry of the prop can make a lot of difference in speed and RPM.

Iboats Boat and Motor Info

1. Year, make and model of boat
2. Length, width and base weight of boat, look for boat decal on back of boat
3. Number of people and gallons of gas normally on boat
4. What do you use the boat for
5. Is it a Deep Vee and if so how many degrees of deadrise
6. Year, make and model of motor
7. HP and gear ratio of motor
8. Manufacturer?s recommended WOT range
9. Antiventilation Plate height above keel of boat if it is an outboard in inches
10. Make, model, diameter, pitch and whether SS or aluminum prop
11. WOT RPM and speed from each prop if more than one prop
The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.

H

 

[Destro1975]

Re: Prop recomendations?

boats Boat and Motor Info

1. Year, make and model of boat 1989 Dynasty Regency

2. Length, width and base weight of boat, look for boat decal on back of boat lenght=18'6" width = 7'9" weight = guessing NADA says 2100 empty so around the 3100 mark when in use

3. Number of people and gallons of gas normally on boat full tank 4 200lbs adults

4. What do you use the boat for Pleasure pulling tubes ect.

5. Is it a Deep Vee and if so how many degrees of deadrise not sure how to measure this

6. Year, make and model of motor think it is stock 1989 mecruiser 305 chevy 200 hp

7. HP and gear ratio of motor gear ratio 1.65 200 hp

8. Manufacturer?s recommended WOT range 4400-4600

9. Antiventilation Plate height above keel of boat if it is an outboard in inches don't know

10. Make, model, diameter, pitch and whether SS or aluminum prop don't know Diameter = 14 1/2 stainless


11. WOT RPM and speed from each prop if more than one prop
4,900-5,000 at 40mph

 

[hwsiii]

Re: Prop recomendations?

Destro, how many people and gear were in the boat when you got 4,900 to 5,000 RPM at 40 MPH. As soon as I have that I will have the analysis ready.


H

 

[Destro1975]

Re: Prop recomendations?

I really does not seem to matter because I have taken a lap by my self and had similar results. I had 4 adults probably 750 combined wieght.

 

[hwsiii]

Re: Prop recomendations?

Destro, Here are my recommendations for the prop for your boat, it should be a 19" Pitch and hopefully ought to bring your RPM down if you use the same make and model of prop you have now. Not knowing the RPM range means I cannot predict exactly what will happen with your RPM, but this is the right prop for your boat.


Prop Picker

H

 

[Destro1975]

Re: Prop recomendations?

Thank you very much for your help I have a whale tail on it now and am planning on trying it with that off on Monday to see if that helps. So going up in pitch will bring the RPMs down right? I really think that it is a 19 pitch prop on it now and I need to bring the RPMs down about 300-400.

Also what would a 4 blade 19 do?

I will post back after I see what she does without the tail.

Thanks Again!

 

[hwsiii]

Re: Prop recomendations?

She will pickup top end speed. It is better if we know about trim tabs and whale tails ahead of time. LOL I should have asked.

H

 

[Destro1975]

Re: Prop recomendations?

Update after I pulled the whale tail: same RPM's maybe even 50 more also I gained about 2-5 MPH so I am seeing 5,050 WOT at 43-44 with about 700 lbs of people and 100 lbs of gear and a extra battery.

I have pulled the prop and I have no markings behind the nut but after filling the marks I have with crayola the marks may be M200 19P any idea how I can measure the pitch?

I am thinking about trying the Michigan Wheel Vortex XHS in a Material: Aluminum
Diameter: 14?
Pitch: 20?
Blades: 4

Do you think that would be a good fit to lower my RPMs 200-300 and not hurt my holeshot?

 

[hwsiii]

Re: Prop recomendations?

It is a 19" pitch prop you have now and going to the 20" Vortex 4 blade you should not lose any hole shot and it will lower your RPM and should lower your prop slip and hopefully inrcease speed because of that. Your prop slip right now is at 20% at WOT and that is very high.

Prop Slip

Please come back and let me know the results for my database.

H

 

[Destro1975]

Re: Prop recomendations?

Thank you so much! What aluminum 4 blade would you recommend?


Manufacturer: Michigan Wheel
Brand: Vortex XHS
Material: Aluminum
Diameter: 14?
Pitch: 20?
Blades: 4


Would a 21p be to much?

Manufacturer: Solas
Brand: Amita
Material: Aluminum
Diameter: 14?
Pitch: 21?
Blades: 4

 

[hwsiii]

Re: Prop recomendations?

It is hard to say, I believe the 21" pitch will bring it down to about 4600 RPM but it may bring it lower, but I think it will do fine.

H

 

[Destro1975]

Re: Prop recomendations?

Alright Solas Amita 4 blade 14x21 = 45MPH 4500RPM with 450lbs of people a 2 big full coolers.

and 4100RPMs @ 40MPH with 6 adults, 1 very large same big coolers.

Huge wake, overall I think the prop will work well for me most of the time I had a full/heavy boat most of the day overall I like the way the 4 blade handles and feels turns better and it more stable. I think a 20p 4 blade may be in my future.

Thanks!

 

[hwsiii]

Re: Prop recomendations?

I am glad you are happy Destro.

H