# Homemade Jack Plate



## Specknreds

After a failed first attempt, I now have a great looking and working homemade jack plate. 

At first, I tried using 2" x 2" aluminum angle. I drilled 3 holes in one piece and 3 matching slots in the adjoining piece. This only gave me 2 1/2" of set back. The clamps on the motor hit the transom. Then I was back to the drawing board.

After a lot of head scratching, I talked to rick50 and he gave me a piece of 3"x4" aluminum angle. This angle did the trick. It gave me 5 1/2" of set back. The next roadblock was a flaw in my pod design. I made them too wide. They come within a 1/2" of the motor on both sides. After scratching my head more (I think I'm making my hairline recede) I turned them inside out. You can see all of the bolts now. I had to notch the jack plate a 1/4", but you would never know. I have 1 1/2" of travel up and down. I can not sea trial it due to it raining nonstop for the last few days. I might need to cut longer slots. I didn't get the height I think I need. I didn't take into consideration the angle of the transom. Staight up, I could get 1 1/2" to 2 1/2" of lift on the motor. When I installed it, I discovered that the angle of the transom was severe enough to only give me a 1 3/4" max lift. I hate to mess with it until sea trials. All the bolts are 5200'd in #-o .

I will try to sea trial it after work one day this week.


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## Specknreds

More pictures.


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## Specknreds

A few pictures of failed first attempt.


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## Usmctanker

wow specks it came out great. you should write an article.


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## Jim

Usmctanker said:


> wow specks it came out great. you should write an article.



Agree! I'm going to link this to the organized thread.


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## lckstckn2smknbrls

How thick are the Alum 3x4's?


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## Specknreds

lckstckn2smknbrls said:


> How thick are the Alum 3x4's?



1/4" I checked with an engineer and he said that it should be more than sufficient to support my 4-stroke. I'm not sure what the capacity is, but I'm sure that it would support a lot more than the 200lbs I have on it. I really tested it at the house. I stood on the cavitation plate and picked up on it and had zero flex.


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## lckstckn2smknbrls

Specknreds said:


> lckstckn2smknbrls said:
> 
> 
> 
> How thick are the Alum 3x4's?
> 
> 
> 
> 
> 1/4" I checked with an engineer and he said that it should be more than sufficient to support my 4-stroke. I'm not sure what the capacity is, but I'm sure that it would support a lot more than the 200lbs I have on it. I really tested it at the house. I stood on the cavitation plate and picked up on it and had zero flex.
Click to expand...

How long are the pieces?


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## rick50

All I have to say is, one word ,three letters.............WOW!


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## Waterwings

Nice work!


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## ben2go

Just think how much you spent and how much a manufactured piece cost,what a mark up.Maybe we should get form a company making jack plates. :LOL2:


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## huntinfool

Looks great, Congrats!


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## caver101

sweet! I like it! Good job!


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## caver101

sweet! I like it! Good job!


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## Dave Deutsch

What size bolts did you use to mount the jack plate to the transom? I just ask because the bolts I have holding my 25 horse 4 stroke onto the transom look to be about twice the diameter. I just don't want to have your plate rip off due to the weight of the motor?

Dave


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## Specknreds

Dave Deutsch said:


> What size bolts did you use to mount the jack plate to the transom? I just ask because the bolts I have holding my 25 horse 4 stroke onto the transom look to be about twice the diameter. I just don't want to have your plate rip off due to the weight of the motor?
> 
> Dave



The are 7/16" high tensile stainless just because I have a whole box of them. I might should have used 1/2" but the engineers at work gave me a 500lbs shear rating per bolt the way I have it bolted.


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## Specknreds

My wife went with me to go test out the jackplate this morning. It did everything that it was suppose to do. I raised it up as far as it would go and I still need another 1 1/2" :shock: . I knew that I didn't get it as high as I wanted because of the angle of the transom.

I gained my 2 + MPH back  . I ran a consistant 30MPH. The waterline is still about 2" above the cavitation plate when WOT. When I raise the motor again, I should gain several more MPH. I have no doubt that I could reach the high 30's with a different prop and a few tweaks.

I need to take off the jackplate and remachine my mounting holes and slots to be able to have another 2" of lift. This will need to wait because I'm leaving for vacation Thursday with it. 8)

The only issue I'm seeing so far is, once I start getting over 29 - 30 MPH, It's like it wanting to use the pods as a plaining pad or due to my boat carring a little Vee in the back, It's wants to plain on one side of the boat or the other. It's plaining real high in the water (very little of the boat is in the water). I do have trim tabs and I hate messing with them because of the drag they create, but I may not have a option. I have a feeling that it's going to get real squirrly if I gain a few more MPH. Any suggestions would be appreciated.

One other fact is that I get zero bow rise when taking off. It instantly jumps on plain with very little throttle. I can't wait to test the fuel mileage.


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## caver101

Between this thread and your floation pods thread I have got a ton of ideas for my boat. THANKS! =D>


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## Rat

Specknreds said:


> The only issue I'm seeing so far is, once I start getting over 29 - 30 MPH, It's like it wanting to use the pods as a plaining pad or due to my boat carring a little Vee in the back, It's wants to plain on one side of the boat or the other. It's plaining real high in the water (very little of the boat is in the water). I do have trim tabs and I hate messing with them because of the drag they create, but I may not have a option. I have a feeling that it's going to get real squirrly if I gain a few more MPH. Any suggestions would be appreciated.



That's called chine tripping and is prevalent on narrow hulls with a tunnel, or like your set up with flotation pods. It is doing exactly what you think it is doing, bouncing from chine to chine on the flotation pods. You are also right in thinking it will get worse at higher speeds. At higher speeds you will have less of the planing surface in the water. You need to get more flat planing surface in the water; you can do it two ways:
1) Slow down
2) Add trim tabs

Adding trim tabs will help because they push the bow down into the water. You will loose top end speed and could get into a situation where you have bow steer (although not as likely on a flat bottom boat with no vee). As long as your tabs are adjusted correctly this is likely your best bet. Having said all that, moving your motor up and adding trim tabs may still result in a net gain on your top end from what you have now; it may not be what it would be without the flotation pods though. 

Boats are all about compromises, and for the extra flotation you needed you may have to sacrifice a little top end speed. 

Here is an example of chine tripping, it is an extreme example but shows what I am talking about:

[youtube]<object width="425" height="344"><param name="movie" value="https://www.youtube.com/v/1UEETjztLqI&hl=en&fs=1&rel=0"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="https://www.youtube.com/v/1UEETjztLqI&hl=en&fs=1&rel=0" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>[/youtube]


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## Specknreds

caver101 said:


> Between this thread and your floation pods thread I have got a ton of ideas for my boat. THANKS! =D>



Sometimes I feel like a guinea pig on some of these projects. Trial and error. It will amaze you at how far a lot of Tinboat members will go to help you. =D> 


Rat, over 30 years on the water and you taught me a new word "chine tripping". That is what my boat is doing. It's searching for a planing pad "if you will". I had a Ranger with a 2.5 liter Mercury that would do the same thing and also chime walk at high speed.

My boat came with welded on trim tabs. The problem turning them down a little is that they will hit the bunk boards on my trailer. When I get back in 2 weeks, I'm going to play with it and see what can be done. I think that I would only need to move the bunks in 3" or so. 

I think that I'm going to rename my boat "Never Done"


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## bige818

Hello,thats an awesome job!! May i ask where you got the angles?? Hardware store,welding shop??? Thank you


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## Specknreds

I got the angle from Rick50 (tinboats member). He has a welding shop on the side and he had it laying around leftover from a job. I found some the other day at a local scrap yard that wasn't bad priced. You might be better off buying a premade jack plate if you have to buy the angle new$$$$. You can find set back brackets for under $100. If you find the angle and have any questions, let me know.


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## bige818

thanks


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## jspano

how are you moving that motor up and down. i don't see any means of a manual or electric
lift

i thought there are outboard brackets that move the motor back and then jack plates that move it back and has the ability to move up and down.
did i miss something in the post?

looks good either way

joe


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## Specknreds

jspano said:


> how are you moving that motor up and down. i don't see any means of a manual or electric
> lift
> 
> i thought there are outboard brackets that move the motor back and then jack plates that move it back and has the ability to move up and down.
> did i miss something in the post?
> 
> looks good either way
> 
> joe



I cut slots to slide the motor up and down. There isn't any mechanical means to adjust it like you are referring too. I just loosen the bolts and pick the motor up. Once adjusted, I haven't found the need to move it any further.


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## jspano

ok i see that!
down here they like the ability to move the motor at will to get to that real skinny water

hey i'm restoring a 21 ft starcraft center console. it's alittle bigger but still a tinny

thanks
joe
spring hill,fl.


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