Outboard Mounting Height

[boostncrawl]

I had this bracket build by a local machine shop. I'm looking for input on the mounting height of the outboard I'm running (25" shaft) and if it is too high. It's set on the lowest setting. I'm in the process of attempting to get it to run right as I'm unable to get it to WOT and see if I experience cavitation. In the event I'm unsuccessful with fixing it, I'm not sure if I should look for a 30" shaft outboard to get the anti-cavitation plate lower in the water or if I'm good where I'm at. A bit of info on the bracket: it's a 24" setback and I followed the 1" per foot of setback when initially determining the height of the bracket on the transom. The lower unit as you can see is right at 32" from he back of the transom. The red line is a LASER level inline with the keel. Thanks for any insight.

 

[racerone]

Is the motor running properly ??------It looks a bit high but with the setback it might be OK.----Should not be hard to move bracket down some I think.

 

[boostncrawl]

No, having issues getting it to run under load. Just falls flat on its face and stalls. The bracket as you can see in the first pic is about 1/8" from the Bottom of the hull so unfortunately moving the bracket down any more isn't an option.

 

[racerone]

I cannot get a hold of your motor ( Johnson V-6 ? )-----It is easy to trouble shoot these motors in your driveway.----You need to post compression numbers first.----Then check for spark on all leads.

 

[dingbat]

Every hull reacts different to a bracket.
What boat are you working with?

Generally speaking
If the motor is falling flat it’s too low
If you’re blowing out the prop is too high.

 

[Scott Danforth]

For every 4" of setback, you raise the motor 1"

 

[jimmbo]

A Prop designed to run partially submerged will be fine at that height

 

[racerone]

They offered a kit ( scoops ) for better cooling water intake at one time.----Not sure if still available but easy to make I think.

 

[Scott Danforth]

Low water pickup

 

[boostncrawl]

I really appreciate your concern racerone however, this is not a thread to determine what's wrong with my motor. This is also the non-repair outboard forum. My question was about the mounting height of my outboard. In an effort to get info on other individuals running their motor on a bracket and if the relation between the distance/elevation of the anti-cavitation plate to the keel of the boat could introduce additional issues if I purchase another motor with a 25" shaft vs. a 30" shaft.

 

[boostncrawl]

The boat is a '79 SeaOx 23ft Center Console I restored. I agree with you dingbat and understand all hull's react different. I'm hoping once I get it working right I will know for sure. I've just read and been told different ratios between setback and outboard mounting height and wanted to see what first hand experience is. I have a really crappy prop. Once I get it running right I will be researching the proper wheel specs to run with my setup.

 

[airshot]

Gotta have the engine running perfect or any adjustments on height will be useless. From your post, sounds like motor has issues that need corrected first.

 

[racerone]

Agreed----Post #1 clearly says that ---" unable to get to WOT "

 

[JimS123]

I really appreciate your concern racerone however, this is not a thread to determine what's wrong with my motor. This is also the non-repair outboard forum. My question was about the mounting height of my outboard. In an effort to get info on other individuals running their motor on a bracket and if the relation between the distance/elevation of the anti-cavitation plate to the keel of the boat could introduce additional issues if I purchase another motor with a 25" shaft vs. a 30" shaft.

Your motor is too high. That is the answer to your question as you asked it. (see post #6)

Regardless, not achieving WOT is not related to your question. If anything, you should exceed wot. On that basis, You need to post in the "repair" forum so fix the motor.

 

[boostncrawl]

Your motor is too high. That is the answer to your question as you asked it. (see post #6)

Regardless, not achieving WOT is not related to your question. If anything, you should exceed wot. On that basis, You need to post in the "repair" forum so fix the motor.

I'm going to have to remove that statement regarding WOT so y'all stop tripping over it and falling down on your face before being able to read the whole post and understanding the question I was asking.

I was curious what the "rule of thumb" ratio was used when installing an outboard bracket in relation to the Anti-Cavititation plate. We're not talking about sea trials, motor performance, cavitation, etc. Just the initial process someone goes through when they have a motor bracket, and a motor and they are about to drill holes and mount it.

So far it seems no one has ever done it themselves.

 

[racerone]

We can only go by the information posted !!-----We do not read between the lines.-----Visit your local boat shop.-----Pay for the professional help.----Get a refund here on your way out perhaps.-----I believe folks tried to help you.

 

[JimS123]

I'm going to have to remove that statement regarding WOT so y'all stop tripping over it and falling down on your face before being able to read the whole post and understanding the question I was asking.

I was curious what the "rule of thumb" ratio was used when installing an outboard bracket in relation to the Anti-Cavititation plate. We're not talking about sea trials, motor performance, cavitation, etc. Just the initial process someone goes through when they have a motor bracket, and a motor and they are about to drill holes and mount it.

So far it seems no one has ever done it themselves.

Reading the whole post is what lead to the answers you were given. When you wrote what you did it is logical that the reader needs to consider it as a whole because all the items are probably related.

If you need to remove any statement then it is you that fell flat on your face.

And once again, you must have missed post #6 which is all the info you asked for. The info was very succinct, indicating it came from someone who actually did it himself.

 

[Scott Danforth]

I'm going to have to remove that statement regarding WOT so y'all stop tripping over it and falling down on your face before being able to read the whole post and understanding the question I was asking.

I was curious what the "rule of thumb" ratio was used when installing an outboard bracket in relation to the Anti-Cavititation plate. We're not talking about sea trials, motor performance, cavitation, etc. Just the initial process someone goes through when they have a motor bracket, and a motor and they are about to drill holes and mount it.

So far it seems no one has ever done it themselves.

Start with the motor mounted to the transom, and level. from there, the AV plate is about 1" above the keel. then see post #6

 

[boostncrawl]

We can only go by the information posted !!-----We do not read between the lines.-----Visit your local boat shop.-----Pay for the professional help.----Get a refund here on your way out perhaps.-----I believe folks tried to help you.

Thanks