U Channel for an outboard support plate

[MadGar]

I have read a few times, mostly by Warthog5, that a good choice for supporting an outboard bracket, jack plate, or outboard is to use a 4” U Channel. Well, recently I have been doing some maintenance on my boat, including the wiring, which has lead me deep into my bilge area where I cleaned it up and reorganized my wiring. Unfortunately, I realized I overlooked the mounting of my motor when I purchased my boat 3 years ago.

My boat has a jack plate on it and it is working slick however, when they installed it they only used washers, square washers, which has dug into my transom. I want to do it right and have a couple questions.

What is the thickness of the aluminum and where can I purchase this channel? I don’t have an easy local source as I ran around this morning looking for it. Also, is there a certain type of aluminum I am look for? Lastly, do I need to add a specific spacer where the bolts sit on the aluminum to avoid corrosion?

Thanks in advance for any help

 

[mheltunen]

I sourced aluminum channel and hardware from (http://www.mcmaster.com). Any place where stainless steel hardware can make contact with aluminum nylon washers (or a plastic style equivalent) should be used. Regarding the thickness of the channel I’m a fan of 1/4” if your bolts will accommodate that. The thicker the channel (within reason) the more it can spread out the load evenly.


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[MadGar]

Thanks Mark. I took a look at the McMaster website and unless I am totally just missing it, I don’t see 1/4” thick, 4” wide aluminum U channel. Did you buy this recently while you were working on your boat? If so, can you shoot me a part number. Thanks for the help.

 

[mheltunen]

I used aluminum angle iron for a similar but different project on my bracket. Check out this : https://www.mcmaster.com/#9001k4/=1efe34l. Perhaps this would work . When I installed a kicker motor on my bracket the addition weight of the engine would flex the bracket itself and I was concerned about possible stress cracking. I added two aluminum angle’s on the bottom of the bracket to help spread out the load. It worked well. Not exactly the same application you are doing but a similar concept.

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[MadGar]

Thanks Mark, appreciate the help. Will let you know how it works.

 

[roncpi]

I believe this is 1/4” thick by 4” wide aluminum u-channel.

https://www.mcmaster.com/#9001K4


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[warthog5]

Here is 4in 6061 T6 in 3/16 https://www.onlinemetals.com/merchant.c ... top_cat=60

Here is 4in 6061 T6 in 1/4 https://www.onlinemetals.com/merchant.c ... top_cat=60

You will be fine with the 3/16

AND...... Here is a savings code. Coupon code ERJ8A

 

[MadGar]

Thanks Roncpl, appreciate the help.

I ordered the 1/4” one warthog5 listed as I could get it in a 2’ piece. Also the 1/4” was actually cheaper than the 3/16”. Thanks warthog5 for the response and link, appreciate it and coupon.

Will let you all know how it goes, expect to have the part in by end of week.

 

[warthog5]

I want you to note the pieces that mheltunen posted........ Yes..... I know we are talking about a whole different piece in a different place on the boat.

But specifically the 90deg coroners on his cuts.

All those corners should have a rounded radius..... Not only to look better.... but be safer and the 90's are a stress point as you say in the Square washers.

 

[MadGar]

Ok, I got my u chanenel in and it was much more sturdy than I thought it would be, that’s a good thing. (I can see why you say 3/16 would work)

Any way, I’m posting a picture to see if this is where you say to round the edges. I’m assuming all 4 corners on each end and should I smooth out the edge length wise, it’s surprisingly very sharp but that may be overkill.

Lastly, do I need (or is it recommended) to prime and put coat of paint on it? Nothing fancy, I have some left over easypoxy from a canoe I built that I would use, just for a little protection.

I guess that’s it. Now if it would stop raining I could get some epoxy work done first on the transom and then mount it. Thanks again for the all help offered.

 

[warthog5]

Yes on the corner.....Lay a washer on it as a pattern and draw around that with a Sharpie....Cut and sand to the line.

But also.... Mark out 2in in from each end......Then every 6in along those 2 edges that will stick forward of the transom....Drill 1/4in holes on

those marks about 3/8in in from the edge. This will give you a place to install tyewraps....and run fuel line or wiring neatly along those 2 edges...

You will be suprized how handy this is to make things look neat.

Yes Not a bad ida to paint it.....I install flat nylon washers....Then stainless flat washers then the nut.....The Nylon is to isolate the 2 dissimilar metals.

 

[MadGar]

Awesome, thanks Warthog. Already drilled the holes for organizing the wiring/bilge hose (great idea). That will work out great as I can get all those damn screws out of my transom and seal them up with epoxy while working on the rest of it. They looked like they had been there for many many years and sadly they don't show any sealant on them, hope there's not any rot (doesn't appear to be).

 

[Brent]

Thanks!

Post some pics!