what do you see here? advise needed

[swaycleveland]

Hey guys. I think its time for a new prop.
The facts.....
21ft 4 winns (85)
Omc 3.8 185hp
Omc stringer 800
Gear ratio 1.77
Suggested wot 4200 to 4800
Prop is factory 14.5x19
Boat weight is around 3000
here's the problem
I'm able to run the boat up to wot range but only get 30mph
oops almost forgot. New points cap...etc dwell and tach verified motor and drive are perfect!
Sooooo i normally run at 3000 and that gets me around 20mph
According to those figures i have easy too much prop slip. Which direction would you go if reproping.
I don't have tons of cash to spend so ill probly get an aluminum prop. Which is ok with me.
I fish alot trolling for walleye. max speed is not big on my list. However i think i should be seeing better cruising and top speed numbers
Any thoughts our suggestions are greatly appreciated!
thanks

 

[steelespike]

Re: what do you see here? advise needed

Has this boat ever had normal rpm and speed. about 42 at 4600?
Is your speed by gps? What is your actual rpm at 30?
Is the prop in terrible condition? Did you get the size right off the prop?
A spun hub is a remote possibility.Usually a spun hub is pretty much a total loss after a few wot runs,with max speed being
about fast no wake.
19" Is about normal. With those screwy numbers 38% slip about all i could suggest is if the prop is really bad
get a new 19 and give it a try.Just be sure the speed and tach are confirmed. Solas amita props have a good reputation.

 

[swaycleveland]

Re: what do you see here? advise needed

Speed is by gps. tach was confirmed accurate by 2 meters last week. 4000 is about all i ever really push it. That gets me 30 on gps the prop isn't in bad shape I've seen worse. I thought about the hub but how could i run up to 30 with a bad hub. So i figure the prop was worse then i thought
The prop size came off the prop itself. The gear ratio came from the service manual for the drive.

 

[Bondo]

Re: what do you see here? advise needed

the prop isn't in bad shape I've seen worse. I thought about the hub but how could i run up to 30 with a bad hub. So i figure the prop was worse then i thought

Ayuh,..... Have ya got a Spare,..?? another prop, just to try,..??

Yer not gonna have alota options, bein' a Stringer drive....

Ya do remember to bring in yer trollin' bags, Right,..?? 38% is atrocious,...
How much sea life lives on yer hull,..??
Is the trailer in the parkin' lot,..??

Even though ya run 4000 rpms, what will it do, Wot,..??

 

[swaycleveland]

Re: what do you see here? advise needed

No sea life lol clean hull. Yes i bring the bags in
So at this point I'll get a new prop. I'm thinking 4 blade 19 pitch (i could use the extra
cruising speed help) lake Erie gets rough in a min...

 

[steelespike]

Re: what do you see here? advise needed

An 85 boat you might check for water absorbed in the foam under the floor.
We'll need wot rpm and speed to evaluate your new prop results.Even if you do normally run at reduced rpm.

 

[Bob_VT]

Re: what do you see here? advise needed

An 85 boat you might check for water absorbed in the foam under the floor.
We'll need wot rpm and speed to evaluate your new prop results.Even if you do normally run at reduced rpm.

I would weight the boat and investigate. I bet a 4 blade slows you even more at that pitch....

 

[swaycleveland]

Re: what do you see here? advise needed

I just got back from fishing... I got the boat up to 4100rpm before she starts to lose grip. As far as water nope no never not this boat was bought in 85. The owner died 6 weeks after he bought it. It was fogged and stored till 3 years ago. Every possible thing has been gone over
By me! So I'm thinking that a. I'm over propped and /or b the prop just needs to be replaced due to hidden lake Erie treasures

 

[swaycleveland]

Re: what do you see here? advise needed

Unless someone sees something terribly wrong with this idea
I'm gonna order a 19x14.5 4 blade from iboats in a day or two

 

[steelespike]

Re: what do you see here? advise needed

We don't appear to have your wide open throttle rpm and speed so its difficult to evaluate your actual numbers.
Normally if your rpm was normal at wot it would be suggested to drop one inch in pitch when going to a 4 blade.
You are better off dropping one inch just to be sure the rpm remains in the existing range.
A 4 blade shouldl cruise easier, have better hole shot and handle better.