Correcting Air Around My propeller

[J.R.]

My Boat is a bit Newer and set up for Larger Motor Than I have.
Facts:
1. The Nose Cone of My Boat is Barely at the Bottom of the Center of the Transom.
2. The Propeller Creates a Large swirl of water and while running you can see where water isnt even touching the motor shaft a good ways down
3. The Smaller The propeller the Higher RPMs are before i get the spun prop effect (per say)

I can Not Lower the motor down any further, at 1/2 or a little over 1/2 half throttle with smaller prop I get the spun hub effect.

Questions:
1. Would dole fins correct this issue?
2. What position in relevance to the transom should the cavitation Plate be
3. Would adding fins up on the motor to maybe the splash guards help any?
4. please reccomend the Best possible solutions?

 

[JB]

Re: Correcting Air Around My propeller

What is the model number of your engine? What is the transom height?

Best possible solution is to have the anti-ventilation plate even with the bottom of the keel. That might mean converting it to a longer shaft length.

 

[J.R.]

Re: Correcting Air Around My propeller

Engine Model: 35530
1962 Evinrude lark IV, 40 HP, Manual Shift


The Transom is 21 inches
The Cavitation Plate is 3 inches above the Bottom of the center of transom

 

[Daviet]

Re: Correcting Air Around My propeller

Almost sounds like a short shaft motor on a longshaft transom.

 

[JB]

Re: Correcting Air Around My propeller

Almost sounds like a short shaft motor on a longshaft transom.

Sounds exactly like a short shaft on a long transom.

Convert engine to long (20") shaft or trade it for a longshaft engine.

 

[mercfixer]

Re: Correcting Air Around My propeller

If you are determined to use this motor, you could always buy a manual jackplate and reposition the transom mounting to suit your needs.
Ran into similar problem mounting 1996 Yam 115 on the wifes 1958 OWENS I HAD JUST FINISHED RESTORATION.

 

[kenmyfam]

Re: Correcting Air Around My propeller

Sounds exactly like a short shaft on a long transom.

Convert engine to long (20") shaft or trade it for a longshaft engine.

Have to agree with this response.

 

[samo_ott]

Re: Correcting Air Around My propeller

Post a picture of the set up if you can.

 

[J.R.]

Re: Correcting Air Around My propeller

I will Do My Best to get pic tomorrow Guys,

may be fuzzy i have a child like camera for pics to upload to pc

 

[J.R.]

Re: Correcting Air Around My propeller

I can not get a pic yet,

Since The Cavitation Plate is 3 inches above the Boats Bottom of the transom
would a product like a EEZ-IN Adjustable Outboard Motor Bracket seem logical for this?

The Motor Clamps on the back and is set up for the cable steering as nearly all motors in 1062 was however i have mine hooked to a teleflex cable used some ingenuity and steering is fine.

 

[kenmyfam]

Re: Correcting Air Around My propeller

Really needs a photo or 2 posted for all to review.

 

[ezeke]

Re: Correcting Air Around My propeller

EEZ-IN brackets are for kicker motors; you need a more stable platform than that.

 

[J.R.]

Re: Correcting Air Around My propeller

Here is The Pictures

See what you think

 

[BSDenning]

Re: Correcting Air Around My propeller

That is a purdy motor. It is too bad that the shaft is too short for your boat.

 

[HybridMX6]

Re: Correcting Air Around My propeller

Agreed. Measure how tall the transom is, top to bottom, then measure the motor as best you can, from where it's resting on the transom down to that cavitation plate. Looks like it's a few inches short.

 

[Daviet]

Re: Correcting Air Around My propeller

Cut a notch out of the transom just large to drop the motor down to proper height, just thinking.

 

[Lion hunter]

Re: Correcting Air Around My propeller

Have 2 options here:

1: Get a long shaft motor. The easiest

2. Modify the transom. I would make sure that transom is strong before you think about a jack plate. That splash well looks like a pretty tight fit. Is there even room for the tiller clamps to be lowered without hitting the bottom of the splashwell?

In the end I'm guessing that the long shaft option will be easier and cheaper. You start cutting on the transom and the materials required can get expensive. Looking at the motor it looks like it would be a tight fit to try and lower with a jack plate as well. I would sell your motor and put the money towards a long shaft

 

[kenmyfam]

Re: Correcting Air Around My propeller

Getting the correct shaft motor would be the easiest and quickest fix..

 

[J.R.]

Re: Correcting Air Around My propeller

The Transom is Custom Built Now. The original rtransom was broken by the 115hp motor that came with the boat. The top of the boat was removed and angle iron was placed up each side of the where the sides met the transom and Treated 2x6's was attached to the angle iron and fiberglassed to the transom. Then the top of the lumber had a diff piece of angle iron ran across it. Then the out side of the transom was fiberglasses over and thick layers were added then the top was put back on boat, and the few cracks were fiberglassed over on the top. Made this boat extremely heavy compared to what it was. However i bet the bow would split before the transom ever gave again lol.

I am considering a smaller boat for my boat in order to make the boat and motor fit. I can not afford a diff motor. Boat Hulls are cheap and ive rebuilt a few of them over the last few years. However finding one that suits me is hard I weigh 400+ pounds and like a lotta space and enjoy fishing.


What I am also considering is an extension kit , all i need is 3 inches. i know most kits are 5 inch kits which would be excellent. Does anyone have a clue where to aquire one for a 1962 evinrude lark 4 manual shift?