Jack plate help.

[bonz_d]

Thanks for all the input folks. Spent the day yesterday cutting, drilling, tapping and grinding the stainless that I already had on hand. Still have to cut some plywood for the transom board then remove the engine again and then mount this on the boat.

I now really do believe this will support the 120lbs of this 30hp Johnson. Yes I was a little leery of using aluminum because of the rotational force when under full power. With this stainless material I don't think it will be an issue. It's not pretty or sophisticated but I think it will be functional.

Bob Johnson, For the engine mount there are the transom clamps and 2 5/16" bolts, 1 on each side. From watching this while on the Mini Jacker as you state it looked as if I was only getting about 1/2" to 3/4" rise at the lower unit at WOT. Though that was still more than I could adjust for at this point and I was still getting a good amount of spray. Also the trim angle was changed after that picture was taken.

Hope to have this finished up today and then I'll post up some pictures of this thing so stay tuned!

 

[gm280]

Pictures?

 

[bonz_d]

As promised. This is just a ruff fitting, still lots to do. I really think this is going to work!

Still need to drill 4 more holes for the transom. Under the inside bracket there is a screw and a rivet on each side that needs to be removed so everything sits flat. No idea what the screws were for and the rivet is holding that extra aluminum plate on the outside of the transom. Then drill for the wood mounts and seal the wood. Right now I've got the wood cut 1/2" higher than level and will use that to move the engine down if needed. Not sure if I want to leave the wood that full width or if I should cut it back some.

I didn't extend those brackets down any farther because I noticed that the old Jacker was sitting on top of a rivet and had flattened the heads. So tell me what you all think so far. Still open to suggestions.

 

[Woodonglass]

IMHO.... Perfectamundo!!!! Almost makes be want to become a "Tinner"!!!!!:hail::crazy:

 

[Willyclay]

Looks great! Suggestion for the future since I know you want to do some fishing before it gets cold. After you get the "sweet spot" established for mounting height, you might consider replacing the motor boards with some contoured to fit the original transom cutout. I believe that will provide some splash protection as well as deflect the following wake during a quick stop. Good luck!

 

[bonz_d]

Thanks guys! I'm really glad I went with the stainless supports. With just the 4 bolts that the original was mounted with I was pulling on it and was able to move the whole boat and trailer and it didn't flinch. But I can understand why others don't use stainless angle because it can get expensive in a hurry. On this one that I built the flange area that mounts to the boat is also almost 1" wider than the mounting area on the Mini Jacker.

On those 2 support brackets I took one side from each and threaded the holes on the 6 bolts and then locked them down with nyloc nuts so hopefully they won't loosen up. Then I still have some angle left so I was also thinking of cutting some short pcs to use inside instead of those large fender washers and joining the 2 bolts that will go thru the transom next to each other. So when all is said and done I'll have only added 4 more holes thru the actual transom.

Willyclay, I'll have to see how much 3/4" ply I have left when I finish my Alumacraft and then I may do just that and extend all the way across the transom.

I'll post more pic's as I go. Oh and BTW there is no way I'd be doing it this way with a 50 or 60hp engine on the back.

 

[Willyclay]

Oh and BTW there is no way I'd be doing it this way with a 50 or 60hp engine on the back.

They make thicker SS angle!

 

[bonz_d]

Well everything is mounted. Now to get it on the water and see what happens.

 

[gm280]

Ha bonz_d, looks like you have it at the exact height it is suppose to be. You have to post back your results. I am interested in how it all works out...seriously...

 

[bonz_d]

I sure hope so. I think it will be very functional though I know it aint pretty! Hope to get it on the water later this evening and give'r a whirl. Actually as it sits right now it's high by about 3/16" which is ok because I can always cut it down. I'm still trying to figure out how this has to be this high. The engine is supposed to be a 20" shaft but I'm 22 9/16" over-all. But of course I'll get to see what it looks like when I run it.

 

[Woodonglass]

If that don't work...NUTTIN WILL!!!!

 

[bonz_d]

Well, the mount held steady and the performance is good, I'm still getting a lot of spray off the upper plate and still looks like it's too low in the water. So I have no clue now as to what's going on. I know the 35hp Johnson that is on the old Lund doesn't spray like this.

 

[Willyclay]

Bummer! Are you willing to go higher?

 

[bonz_d]

Bummer! Are you willing to go higher?

Not at this point. I don't think the transom could withstand the torque. To be honest I don't like it this high. There has to be something else going on that I haven't figured out yet.

 

[NAT1VE]

Have you thought about making a plate for the inside to take some stress off the backside? Something that could tie in the two lower bolts at least. Looks good otherwise.

 

[bonz_d]

Have you thought about making a plate for the inside to take some stress off the backside? Something that could tie in the two lower bolts at least. Looks good otherwise.

The problem with that is I see this transom wasn't the sturdiest built to begin with. The transom board below the motor is only 7" wide and there are only 2 small knee braces under the transom board. Also at this point I don't think I want to be drilling the transom full of hole just to try and reinforce it. I'm almost to the point that I may just start searching for a short shaft motor for it as use it as is until then.

Last night I spent some time on youtube watching videos of 30 and 35hp OMC's running the water and only seen a couple that were spraying water like this.

 

[gm280]

The problem with that is I see this transom wasn't the sturdiest built to begin with. The transom board below the motor is only 7" wide and there are only 2 small knee braces under the transom board. Also at this point I don't think I want to be drilling the transom full of hole just to try and reinforce it. I'm almost to the point that I may just start searching for a short shaft motor for it as use it as is until then.

Last night I spent some time on youtube watching videos of 30 and 35hp OMC's running the water and only seen a couple that were spraying water like this.

bonz_d, can you see exactly where the water spray is coming from? I mean is it actually coming off the engine or is there something else in the lower hull spraying and deflecting off the engine?

 

[Willyclay]

Years ago, another forum member posted his solution for relieving the stress on his transom by using some lightweight chains and turn-buckles at 45 degree angles to his rubrails. I will try to find that thread and post a link but with all the forum IT changes, that may not be possible. Looking at your pictures makes me think you are very close to optimum and maybe instead of cutting another higher motorboard, you could just rip a piece of 3/4inch lumber for a shim. Good luck!

 

[bonz_d]

bonz_d, can you see exactly where the water spray is coming from? I mean is it actually coming off the engine or is there something else in the lower hull spraying and deflecting off the engine?

Actually I can. Still coming over the top of the cavitation plate and washing up the lower unit and is being defected out by the plate above it. I was going to try and get a picture last night but like an old man I forgot the camera in the truck after we launched it. I too was wondering if this was a hull or design issue. I have seen many times with these small boats and smaller outboards that use transom clamps on the engine that once attached to the boat the cavitation plate can be as much as 1/2" below the bottom and I haven't seen spray like this.

It's almost as if the stern isn't coming up out of the water yet it gets to plane and most of the time I have to throttle back to about 3/4 or I take a pounding by the waves.

 

[oldboat1]

Just wondering -- If you trimmed the motor in another notch (if there is one), the AV plate might end up horizontal to the water when on plane. Mounted as it is, thinking it may end up trimmed out on plane, kicking up the spray.