Sluggish out of hole- May need new prop

[TheChugBoat]

I read the thread that details the info I need for a meaningful response but I am missing some answers. But here goes..

My problem is my boat is sluggish out of the hole but great once on plane.
Boat is a 1990 Wellcraft Eclipse. 20ft long. Has a 1997 Mercruiser 4.3L Vortec. Approx 200hp. WOT rpm range is around 4400-4600. Top speed is 43MPH on gps with 2 people onboard.

Iam not sure what I currently have for prop size but was hoping that may be enough information to point me in right direction.

PS I tried Smart tabs and they helped a good bit but Im still looking for a better hole shot.

 

[Silvertip]

Re: Sluggish out of hole- May need new prop

Unfortunately the one piece of information you left out (prop type, material, diameter and pitch) is the piece of the puzzle you are trying to solve. Not knowing what you have now makes it difficult to tell you whether what you have is right, close, or what you may need. Check the barrel or hub of the prop for diameter and pitch (14-3/4 x 17P or some such numbers) or a series of number that represents the prop manufacturers part or model number.

 

[steelespike]

Re: Sluggish out of hole- May need new prop

Ok good job.Can you put sluggish in a time frame?Unfortunately if we throw out any of the key info it pretty much makes the rest ineffective.Are you saying your run around 4400-4600 rpm?Can you pin it down?See if the rated rpm is on a label on the motor.I think 4,800 is the rating.Speed seems in the ball park rpm a little low.we need the prop size.Should be on the barrel or under the prop nut.Prop size and material.

 

[TheChugBoat]

Re: Sluggish out of hole- May need new prop

I might be wrong but it seems like there is a prop calculator i keep reading about in some posts? If thats true can I use that to calculate what I need? Then when Iam at the marina I can compare to what I have?

I do know its a 3 blade stainless steel but Im sure thats probably not enough to make any suggestions off of.

Sluggish in time frame would be up to 10 seconds to plane out. I can ease into it...then after full throttle is applied it takes up to 10 seconds from there. Lots of gas and strain on the engine.

Oh and thats w/o smart tabs. When smart tabs were on the boat it would plane out in about half that time. But the tabs were recently broken so there not on the boat. Im hoping I can get the tabs put back on and possibly a new prop and have a "new boat" next weekend.

 

[imoutnumbered]

Re: Sluggish out of hole- May need new prop

An example of a prop calculator using your inputs, but you'll need information about your boat that has already been mentioned and then some, unless it's changed since I've used it last:

http://sites.mercurymarine.com/portal/page?_pageid=126,53050,126_53052&_dad=portal&_schema=PORTAL​

 

[hwsiii]

Re: Sluggish out of hole- May need new prop

What is gear ratio and what out drive do you have on it?

H

 

[TheChugBoat]

Re: Sluggish out of hole- May need new prop

I ran up to the marina this morning to get the #s off the prop.
Heres what I got:
13x21
033005-1
K6546
Prop is stainless steel.

I didn't see any manufacturer etching or anything other numbers at all. Checked the inside and outside of prop.

 

[TheChugBoat]

Re: Sluggish out of hole- May need new prop

Ok so for an update:

Problem: Boat is sluggish out of hole, up to 10 secs to plane after full throttle
Boat: 1990 Wellcraft Eclipse- 20ft
Engine: 4.3L Vortec - approx 200hp
Current Prop: 13x21 stainless steel...unsure of brand
RPM/MPH: about 4600rpm @ 43MPH w/ 2 people and gear

 

[hwsiii]

Re: Sluggish out of hole- May need new prop

If you have a 1.65:1 gear ratio, your prop slip is 22%.

H

 

[TheChugBoat]

Re: Sluggish out of hole- May need new prop

What exactly is prop slip and how can it be fixed? 22% sounds like a hell of a lot.

 

[Tail_Gunner]

Re: Sluggish out of hole- May need new prop

Ok so for an update:

Problem: Boat is sluggish out of hole, up to 10 secs to plane after full throttle
Boat: 1990 Wellcraft Eclipse- 20ft
Engine: 4.3L Vortec - approx 200hp
Current Prop: 13x21 stainless steel...unsure of brand
RPM/MPH: about 4600rpm @ 43MPH w/ 2 people and gear

What type of drive is this a alpha..

"13x21 stainless steel...unsure of brand"

A 13" barrell on a alpha drive is not good are you sure its 13"

 

[TheChugBoat]

Re: Sluggish out of hole- May need new prop

Yes it was definitly a 13. I noticed a small etch/nick to the right side of the 13 inbetween the 13 and the X...couldn't tell what it was...but Iam 100% sure the 13 is infact a 13

Yes, Alpha 1 drive

 

[Tail_Gunner]

Re: Sluggish out of hole- May need new prop

Thats your issue..New prop time..

 

[TheChugBoat]

Re: Sluggish out of hole- May need new prop

Any idea as to what prop would be ideal for my boat? Id like to keep the MPH above 40 but have a good hole shot too. Not sure if thats having my cake and eating it too. Any suggestions would help alot.

 

[Tail_Gunner]

Re: Sluggish out of hole- May need new prop

Your going to have to guess,If you can get your hands on a 19-20 3 blade ss for a demo that would be a good place to start.

Notice all the diameters are 14 plus "

http://boatpropellers.iboats.com/Me...andard&**********=875276128&*******=657845469

 

[TheChugBoat]

Re: Sluggish out of hole- May need new prop

So If Im understanding things correctly I will want to increase the diameter of my prop? Then maybe decrease the pitch so Ill have a few more RPMs? My boat is usually running between 4200-4600 at WOT..so theres still room for the reccomended 4800.

Im just now understanding what the diameter and pitch is so correct me if Im wrong. Im leaning towards trying out a 14.5 x 19. Does that sound like a safe guess?

 

[Dhadley]

Re: Sluggish out of hole- May need new prop

3 blade props in the 13 - 13 1/2" range are intended for the 4 1/4" gearcases. 3 blade props for the 4 3/4" gearcases are in the 14 - 15" diameter range generally.

 

[Tail_Gunner]

Re: Sluggish out of hole- May need new prop

So If Im understanding things correctly I will want to increase the diameter of my prop? Then maybe decrease the pitch so Ill have a few more RPMs? My boat is usually running between 4200-4600 at WOT..so theres still room for the reccomended 4800.

Im just now understanding what the diameter and pitch is so correct me if Im wrong. Im leaning towards trying out a 14.5 x 19. Does that sound like a safe guess?

While i cannot say for sure but if you will take a look at where your prop but's up against the drive there should be a gap. That is your prop is smaller in dia than your drive. That will create a disturbance in the water flow allowing the prop to cavitate or slip as hwsiii tables have pointed out above..22% is way out there.

Until you get a prop on with the proper dia it is hard to determine what it will need...the boat that is.

 

[steelespike]

Re: Sluggish out of hole- May need new prop

You don't need to select a prop based on a specific diameter just a prop designed to fit your outdrive.I looked very briefly at iboats prop store MCRUISER 4.3 All props were 14" or more.
Try to get your prop in an exchange program so you can try different ones.
All that being said; select a stainless prop intended for your 4.3 outdrive.
I think a 19 would be a good starting point.

 

[hwsiii]

Re: Sluggish out of hole- May need new prop

I think you will find that an 18" Pitch will give you the maximum RPM and hole shot for your setup, without over revving the motor.

H