Prop question need advice

[badbowtie]

I have a 85 wellcraft 21' 260hp mercruiser I had a 14-1/4 21p michigan wheel
it would rev all the way up to 5500 rpm and push 45mph with gps. It is not a slipping hub because I tried two different hubs. So I bought a 14-1/4 23p hustler turning point and used it yesterday it would take the whole lake to get up to speed, I could get 35mph and be pushing just under 4000rpm. I was reading that michigan wheel are about the cheapest out there and slip out the most. Should I buy a hustler 21 turning point since I just bought a new hub kit for it? From what I am reading I guess that is a pretty high end alum prop. What do you think?

 

[hwsiii]

Re: Prop question need advice

Bowtie, welcome to Iboats prop forum and we will try to help you as much as we can, but there is certain information that is needed in order to help you. Working over the internet and not being able to see the boat or prop the question is about, and most people don?t know the make and model of the prop, makes it much harder to propose a solution to the correct prop that you need. When we get information in bits and pieces we are continually having to look back and forth to try and piece the information together. 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. 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 best prop we can 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 IMPORTANT
8. Manufacturer?s recommended WOT range
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches
10. Is it a bass boat or does it have a pad bottom
11. Does it have a hydrafoil or trim tabs
12. Make, model, diameter, pitch and whether SS or aluminum prop
13. WOT RPM and speed from prop, how much gas and how many people in boat for test data

REMEMBER, The numbers I give you will be NO better than the information you give me

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

 

[badbowtie]

Re: Prop question need advice

1. 1985 Wellcraft 210 Elite XL
2. 20' 6", 8 ft width, 3100 lbs.
3. Normally 4 people, totalling 800 lbs, with cargo, 40 gallons.
4. Pleasure, skiing, slalom skiing and wakeboarding.
5. It is a deep vee, 20 degrees.
6. 1971 Chevrolet 350 with all marine parts.
7. 280 hp, Alpha One mercruiser outdrive.
8. Pretty sure it's 4600.
9. Not sure.
10. Neither.
11. Trim tabs.
First prop
12. Michigan wheel prop, 14.25 diameter, 21 pitch, aluminum.
13. 45 mph, with 5500 rpm, and about 800 lbs., and full tank.

Second prop
12. Hustler turning point, 14.25 diameter, 23 pitch, aluminum.
13. 35 mph, just under 4000 rpm, 800 lbs, full tank.

All these tests were done with a GPS for speed.

thanks.

 

[hwsiii]

Re: Prop question need advice

You did an excellent job with information but I need the lower gear ratio, would you please get the serial number off of your outdrive and go to this website and get the gear ratio for me. I need that information to be right.

http://www.sterndrives.com/mercruisersterndrives.html


H

 

[badbowtie]

Re: Prop question need advice

it says 1.50 r on the side and it says 6887719 I remember looking at the ratio for something else one time.

 

[hwsiii]

Re: Prop question need advice

Bowtie, I don't know whats going on but if I use the numbers you gave me the results are not right. You either have motor problem or a tach problem it appears. Are you running these tests on the same day. I am perplexed. Here are the numbers and your prop slip is exceedingly high for such a light power to weight ratio. Could your trim tabs be stuck in the down position when you are running the tests.


Prop Slip

H

 

[badbowtie]

Re: Prop question need advice

I also know my trim tabs are working I was using them yesterday I will post back after another run then. I did them both this weekend the 21 on friday morning headed to another lake to go camping and tried the 23 saturday afternoon. I wish I would of never went to the campground and the lake it was the size of my bathtub. That is what I came up with I am heading to the bigger lake that I tried the 21 on I hope tomorrow afternoon for another run and see what will happen it will only be my wife, 8 year old son and I. I have checked the tack acouple of times last year with another one and once this year and been right on. I will take another one with me to try if I can get it back.

 

[hwsiii]

Re: Prop question need advice

Which model of Michigan prop are you using so I can compare them in my mind, because 1,500 RPM is a large difference for such a small pitch change. As a normal course of events it shouldn't be that big. Exactly what trim tabs do you have on your boat. If they are stationary or self adjusting please measure the angle they are from the transom.


H

 

[badbowtie]

Re: Prop question need advice

I will go double check on the exact prop but I do remember buying the cheapeast one they had which was like 85.00 dollars or something. Also it does have adjustable trim tabs, but not sure what I need to measure I am confused their.

 

[steelespike]

Re: Prop question need advice

If the Michigan was a real plain jane prop might account for the large change in performance.Kind of like going from al. to ss. But I don't understand the huge slip figures from the Hustler prop.

 

[hwsiii]

Re: Prop question need advice

What brand of trim tabs are you using, and if you could take a picture from the side of the boat about level with the trim tabs and show the tabs and the side of the boat I can tell if they are adjusted right hopefully.


H

 

[badbowtie]

Re: Prop question need advice

I am not sure on the brand of the trim tabs but I think they are factory I thought my 21p prop was michigan wheel but I am not sure now here are the numbers on it. 48 832832a45 21p I know it was not more than around 85.00 dollars new. Here are the pictures

 

[badbowtie]

Re: Prop question need advice

Okay I took the boat out today only had about 350 lbs of weight and 40 gallons of fuel. I only was able to try the 23 pitch hustler. I was able to trim out today and was able to get 41 mph and 4100 rpm. I am thinking about getting the same brand maybe in a 21 p. What is the best brand prop in aluminum that will not slip out as bad?

 

[junior1113]

Re: Prop question need advice

4 blades have little slip and great hole shots. you'd need a 19 pitch 4 blade to get around 4500-4600.

 

[badbowtie]

Re: Prop question need advice

I found a 4 blade 18p for a good price locally but 4 blades you go that much lower on the pitch.

 

[junior1113]

Re: Prop question need advice

when going to a 4 blade you go down 1" in pitch to acheive same wot rpms as a 3 blade.

 

[junior1113]

Re: Prop question need advice

i think a good ss 19"x4 would do you good