Best stronger jack plate mount

[egreen024]

Need everyone’s opinion again.
I’m mounting a 9.9hp high trust outboard on a bobs machine shop motor jack, which is mounted into the transom of an oday 28. Hope you all follow so far.
Will post pictures of transon ( with old mount to be removed, and pictures similar to the mount I’m looking into.
What’s stronger and more solid if a mount, Wedges and have motor jack plate mounting bolts threw wedges and transon, or have built an aluminum angle plate similar to picture below where it would be mounted to transon and then jack plate bolted into it?
Will have either one fabricated, pictures are just so everyone has an idea of what I’m thinking.

 

[FastOlson]

That design appears to have been designed and built for a shaft-drive 11 hp diesel. The transom was not engineered for the torque of a cantilevered OB engine. Managing the engine controls would be quite difficult, also.
Your post seems to assume that an OB motor should be on that transom. At about 7500# (plus) in sailing condition, that is not a boat really suitable for an OB aux.
Is this an experiment, being done on a free boat, just for fun? The back story would be useful to know. Thank you.

 

[jssailem]

I had an outboard on a 15ft sailboat. It was a small 2-cylinder on a fixed mount. The issue was getting the motor out of the water when sailing to minimize drag. The lifting motor mount on the boat looks to be accomplishing that job.

The proposed "Bob's Machine Shop Jack Plate" looks to be designed for speed boats with large outboards in the water "all the time." The jack plate design is strong (heavy) and moves the outboard 6-12 inches up or down while running to optimize the boat's speed. The unit aims to enable power boats with their motor deep in the water to lift the outboard in shallow waters.

The O'Day 28 has a keel and rudder that are lower than the outboard prop. I'm not sure this project improves your sailing experience.

 

[egreen024]

That design appears to have been designed and built for a shaft-drive 11 hp diesel. The transom was not engineered for the torque of a cantilevered OB engine. Managing the engine controls would be quite difficult, also.
Your post seems to assume that an OB motor should be on that transom. At about 7500# (plus) in sailing condition, that is not a boat really suitable for an OB aux.
Is this an experiment, being done on a free boat, just for fun? The back story would be useful to know. Thank you.

Yes, that’s correct. Since 2004 that boat gas run on the set up in the picture, it’s a 15hp Mercury, the Yamaha 9.9 hp high thrust will push boat just has easy, the new bracket from bobs is actually a kicker jack with 16” vertical travel commonly used for trolling on bigger power boats, anyway I’m just trying to figure out if wedges or something like in the picture. Old jack was a manual panther with wedges made out Of 2x4, has lasted 20 years, new jack is hydraulic but lighter motor

 

[egreen024]

I had an outboard on a 15ft sailboat. It was a small 2-cylinder on a fixed mount. The issue was getting the motor out of the water when sailing to minimize drag. The lifting motor mount on the boat looks to be accomplishing that job.

The proposed "Bob's Machine Shop Jack Plate" looks to be designed for speed boats with large outboards in the water "all the time." The jack plate design is strong (heavy) and moves the outboard 6-12 inches up or down while running to optimize the boat's speed. The unit aims to enable power boats with their motor deep in the water to lift the outboard in shallow waters.

The O'Day 28 has a keel and rudder that are lower than the outboard prop. I'm not sure this project improves your sailing experience.

This new jack has 16” travel, throttle and gear controls are at padestal, boat has outboard since 2094 but set up was on wood wedges made out of 2x4, replacing the panther with bobs it’s just so instead of pulling motor up by hand I will do it with the push of a bottom.

 

[Project_Mayhem]

Assuming your O'Day 28 is similar to my 25...
That wedge is a huge help in getting the motor low enough into the water while allowing it to be tilted without hitting the transom. I did not have it on mine and I was unable to get it out of the water. It's too low and heavy for a spring loaded mount to be useful. I have also considered a jack plate.

In order for my outboard to have adequate control, I had to get the motor as close as possible to the waterline. When motoring, the wood on the mount would catch quite a bit of water as the stern squated.

Last winter I experimented with a push/pull mechanism for the outboard's tilt lock as well as a block and tackle setup to pull the outboard up. Both were successful but never completed as I ended up selling the boat when I found a C30.

 

[Will Gilmore]

instead of pulling motor up by hand I will do it with the push of a bottom.

Otherwise known as a 'goose'.

I agree with jssailem's concerns about clearance while sailing, otherwise, both options seem sounds enough. All else being equal, cheap and simple are how I'd choose.

Old jack was a manual panther with wedges made out Of 2x4, has lasted 20 years, new jack is hydraulic but lighter motor

Are you expecting to get 20 years from hydraulics on the water, just as you did the 2x4s? Hopeful.

-Will

 

[Timm R Oday25]

I'm in the exact same position as you . Currently I have an 8 horse 2 stroke Johnson with a 25" shaft .
It easily would get deep enough to have the cavitation plate fully underwater .
The problem was that ,the prop wasn't clearing the water when I raised it up .
If I tilted the motor then it would clear . Pain in the but two step process .
This fall I bought a 8 horse electric start Yamaha with power trim .
When I removed the fiberglass mounting pad from the transom of our 25 'Oday ,I discovered the wood core was nothing but mulch .
I ended up making a replacement mounting pad . I currently am on my 7th layer of woven fiberglass cloth encasing it .
I will mount a 3/4" plywood soaked in epoxy on the inside of the transom to support the pad and outboard motor tilting bracket .
I will also use a 1/4" aluminum plate on the exposed side of the plywood mounted on the inside of the transom .
This will spread the load from the through bolts that bolt the tilting bracket ,through the pad and go through the transom ,plywood and aluminum plate .
The shoulder bolts and nuts are 316 stainless 5/16" stainless as are the nylock nuts inside .
The outboard weighs just underr 90 pounds . That comes out to roughly 25 pounds of force per bolt. It might be a bit overkill .I'd prefer not to lose a motor . Hopefully this will help

 

[Project_Mayhem]

The outboard weighs just underr 90 pounds . That comes out to roughly 25 pounds of force per bolt. It might be a bit overkill .I'd prefer not to lose a motor .

Probably 200lbs of thrust on a 25-30" "lever" from the prop. I think I had 3/8" bolts with unistrut washers for backing plates on 1.5" of plywood tabbed to the transom. I had no idea how much wood it needed so I went with three layers!

 

[jssailem]

I discovered the wood core was nothing but mulch .
I ended up making a replacement mounting pad . I currently am on my 7th layer of woven fiberglass cloth encasing it .
I will mount a 3/4" plywood soaked in epoxy on the inside of the transom to support the pad..

Sorry to hear about the Wood core. As you might imagine the boat maker never considered that owners would want to power their boats so that they can get somewhere if the wind died. Otherwise, they would have strengthened the transom.

I am sorry there is not much support for you Timm, but for other owners facing this challenge, an alternative to the use of plywood is COOSA. It is a composite product that can be worked like wood, lighter than marine plywood, and non-absorbant.

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It is a good product for transom improvements or repairs.