Evinrude 135 prop selection

First off, thanks in advance for your help and response. I greatly appreciate everyone's input. I have a 1976 Evinrude 135 Bubbleback on a 1975 17ft Glasstron V172 Fish and Ski. It has the stock aluminum 19P 3 blade prop on it. The prop was in decent shape until I hit something last weekend with it. Before last weekend I was hitting 5800-5900 RPM WOT at about 42mph (GPS) with 2 people on board, no gear, and swivel seats removed. With 2 people, 2 coolers, fishing gear and swivel seats, I was still getting 5800 RPM WOT and about 39mph (GPS). I was planning on getting a taller prop anyways since my WOT RPMs seemed high. I was looking at going to a new aluminum 21P prop, but I wasn't sure if I should get a 3 blade or 4 blade. I am open to some other suggestions. I would like to eventually get a SS prop, but I don't have the funds at this time. I am fairly new to boats and this is my first boat as well. FYI my motor runs very strong, I'm getting 145-150 psi in each cylinder and have new plugs. Again thanks for the help and feedback.

Matt

Re: Evinrude 135 prop selection

Ayuh,... Welcome Aboard,...

I don't know the recommended WOT rpms of your motor, but 6 grand sounds about Right...
Keep it proped where OMC says it Should run,...
Otherwise, Over-proping will cause it to lug,+ burn down the motor...

Re: Evinrude 135 prop selection

Matt, on the older motors the guys in the know recommend that you keep your RPM high with today's gas. I am showing your motor has a gear ratio of 2:1. please verify this.

I am showing your prop slip to be 21%, and that is high in my opinion.

Prop Slip


Try reading the following and check your anti ventilation plate height, and the get back with me and we will figure out what prop would be better with your setup.

You might try reading this for a better understanding of changing props for better performance, and for the major differences between aluminum props and stainless steel.

http://forums.iboats.com/showthread.php?t=369057



H

Re: Evinrude 135 prop selection

Hwsiii,

Thanks for the info. Where would I find out the gear ratio for the gearbox? Also I forgot to mention I was told (by my local dealer) the recommended WOT for my engine is 5500. I also only run 100% gas, no E-10 in my boat. It is readily available here. I did check my anti-ventilation plate and it seemed to be the same height as the keel. Does this seem a little low? The old propeller was the original 3 blade 13x19P propeller from 1976, maybe that was some of the slip problems.

Matt

Re: Evinrude 135 prop selection

Matt, I am sorry it took me so long to get bak with you, I got your PM and got involved in something else and totally forgot about it.

Here is the way to check your gear ratio:
7. HP and gear ratio of motor IMPORTANT
If you don?t know the ratio, you need to pull the plugs out and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing then do the same thing on the flywheel and turn the motor until the tape lines up with each other on the prop, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches, use a board under the keel and sticking out to the anti ventilation plate for a reference

Here is the way to check your anti ventilation height:
Motor Transom Height


And yes your motor is too low, you need to move it up at least one notch preferably two, but if you will send about 4 pictures of the plate and the transom I will be able to tell you more specifically.



H

Re: Evinrude 135 prop selection

Hwsii,

I will be taking some pictures of my keel and ventilation plate later today and post them. However I did find out some other important info:

1. My gear ratio is 2:1 according to my manual

2. My blade is a 13x19P SS, not AL. I took it to a propeller repair shop and had it refurbished for $120

3. Also found out my Prop Shaft is slightly bent, my local propeller shop said he could bend it back

4. Recommended WOT Range is 4500-5500

Anyways, I will post some pictures later today!

Thanks,

Matt

Re: Evinrude 135 prop selection

Matt, I will be waiting.



H