Yamaha 130 hp 20 " shaft mounting height

[maineiac5586]

Going to be installing a 2001 yamaha 130 hp 2 stroke 20 inch shaft on my 97 wellcraft 190ccf. If you zoom in on my picture you'll see the bottom of the transom is higher than the actual keel where the drain plug is. Do I make the cavitation plate even with the drain plug or even with the bottom of the rear most transom area? Hope that makes sense

 

[racerone]

The Johnson is a wonderful unit , smooth running and reliable motor.----I would repair that as needed myself.----Yamaha is over rated in my opinion.

 

[boscoe99]

Yamaha endures.

OMC (Johnson and Evinrude) are in the dustbin of history.

 

[racerone]

I have no issues finding parts for OMC motors.

 

[boscoe99]

It is correctly known as an anti-ventilation plate.

The motor is typically positioned so that the plate is even with or above the keel of the boat.

The further the setback of the motor the higher the plate needs to be. Ideally when on plane at your chosen cruise speed, with the motor trimmed to the cruise position, the anti-ventilation plate will be skimming the surface of the water.

 

[boscoe99]

I have no issues finding parts for OMC motors.

Given that many OMC owners have long since discarded their motors for the remaining brands, it stands to reason.

 

[racerone]

I have a 2005 Yamaha 4 stroke that was discarded.---And a few more-----Not worth fixing.

 

[boscoe99]

Most Yams are mounted by boat builders using the number two hole for the top bolts. Second set of holes from the top. Testing is then performed so as to see if the motor can be raised another hole or two. For best performance.

 

[99yam40]

I have a 2005 Yamaha 4 stroke that was discarded.---And a few more-----Not worth fixing.

why did OMC go out of business if they were so good?

 

[maineiac5586]

It is correctly known as an anti-ventilation plate.

The motor is typically positioned so that the plate is even with or above the keel of the boat.

The further the setback of the motor the higher the plate needs to be. Ideally when on plane at your chosen cruise speed, with the motor trimmed to the cruise position, the anti-ventilation plate will be skimming the surface of the water.

Here's another picture. The anti ventilation plate should line up with the bottom of the surface the motor is mounted to or further below where the drain plug is (stepped transom?)

 

[boscoe99]

Think of your boat as having an integral bracket.

 

[maineiac5586]

Think of your boat as having an integral bracket.

Ok so I won't have any setback mounting the motor directly against the transom. So I'm thinking the plate should be even with the very bottom of the keel (below the drain plug)?

 

[99yam40]

from the pics you posted you motor will not be right next to the bottom of the boat.
what am I missing?

 

[maineiac5586]

I guess I'm trying to say the motor will be bolted directly to the transom using the motors bracket not a jackplate bracket

 

[boscoe99]

I am seeing set back.

The motor is mounted on the transom. The transom is set back from the aft portion of the hull bottom by what looks to be a foot or more.

 

[boscoe99]

 

[boscoe99]

Are you not envisioning the water starting to rise after it leaves the bottom of the boat? The end of the bottom of the boat being a foot or more in front of the motor. The motor height is adjusted to take this into account.

The bottom of the transom in this case is not the bottom of the boat.

 

[maineiac5586]

Are you not envisioning the water starting to rise after it leaves the bottom of the boat? The end of the bottom of the boat being a foot or more in front of the motor. The motor height is adjusted to take this into account.

The bottom of the transom in this case is not the bottom of the boat.

Ok so cav plate should line up with bottom of boat not the transom?

 

[boscoe99]

No. Not with the bottom of the boat.

An inch or two above the bottom of the boat.

 

[maineiac5586]

Ok I got it now. Thanks for your patience