DIY: Engine Panel Stiffeners

[audisnapr]

When picking up the rear 910's from Wakemakers for my 2017 Mondo, I saw the suggested stiffener set on WM's website as well. After doing a bit of reading here on the forum and also knowing that the OE bags deform the panels already, I figured I would pull the trigger on WM's set. Except, for whatever reason, they were 4-6 weeks out on production, and the bags, shockingly, shipped right away. So off to Home Depot I went.

Unfortunately, my HD does not carry a 1/8" thick, aluminum u-channel shapes, only 1/16" thick and thinner stuff. I'm sure I could have shopped around and found what I needed but... I was lazy and didn't want to shop around during the COVID lockdown. I ended up with 1/8" thick, aluminum angle 3/4-inch by 3/4-inch.

With that said, having the paint I needed on hand as well as the tools and supplies, my bill was a little over $60. Not a huge savings from the WM set but feel I got more for my money and stiffeners that were purpose built for my boat.



I'm no engineer but my guess is you lose a little bit of strength by not having the second leg of the u-channel when using the angle but I was willing to roll the dice. Plus, since I was buying two, eight-foot-long pieces, I could create four, +/-24" long pieces for each side, versus the three 19" long pieces that come in the WM set. The number and length of brackets is a personal preference.

Materials:

• 2X, 8ft long, 1/8" thick, 3/4-inch by 3/4-inch aluminum angle
• 24X, 1/4"-20 by 1-inch long stainless steel screws (my HD had a box of 25 stainless steel "truss head" screws which appear to have a lower head profile from a traditional screw)
• 24X, 1/4"-20 stainless steel lock nuts
• 400-600 grit wet/dry sandpaper or brillo pad
• rubbing alcohol or similar cleaner for paint prep
• 1 can of dark primer
• 1 to 2 cans of black paint (for projects like this, I prefer paint that has texture - it looks more like a factory powder-coat and will sort of hide imperfections in the material) https://www.rustoleum.com/product-ca...-rust/textured

Tools:
Obviously, the more equipped you are with the tools and the handier you are at using them, the better the finished product can be. With that said, these live under covers next to an engine so it's not super critical that they are perfect.

• Saw (can be a chop/miter saw with a wood blade which will cut straight through aluminum no problem or a hand, hacksaw with metal blade)
• 1/16" & 1/4" Drill bits (ideally you have a set of drill bits so that you can drill pilot holes)
• Screw driver (using the screws I did, it could be a Phillips or flat-head. You can opt to spend a bit more and get a hex head "cap" screw but my HD doesn't carry anything like this in bulk)
• Box/adjustable wrench, socket or pliers (to hold the lock nut while tightening)
• Center punch (not absolutely required but helpful to mark the drill locations on the aluminum)
• Clamps of some kind (c-clamp, box clamp, spring clamp, trigger clamp, etc)

Tips/Suggestions:

• Assuming all of the different boat models and years have different size panels, be sure to measure the panel for the maximum length for each aluminum stiffener. For a 2017 Mondo, I could get away with 24" pieces.
• Depending on the thickness of the saw blade that you are going to use, it's a good idea to measure each piece to be approximately 23.75" to make sure there's enough material to make them all the same size from a single eight-foot pieces. Measure twice, cut once. Measure off the first piece, cut, then measure off the second piece, cut, and so on.
• If you have a miter/chop saw, you can cut a 30-degree angle piece off of the rib of the angle so that the ends of the aluminum pieces aren't sharp, 90-degree cuts. I did this after I cut each length so that I only have a 30-degree cut on the rib, not the base of the aluminum angle, similar to the image below.
  
• Create a template out of a sturdy piece of material to use as the drill pattern so that the spacing of the holes are all the same on all of the aluminum stiffeners and the engine panels. You can use one of the aluminum stiffener pieces as your template.
• If possible, use a small drill bit (1/16") to create the holes in the template. You will use this template to drill all of the holes in the aluminum stiffeners and the engine panels. The pilot hole method will take you twice as long to drill because you have to drill each hole twice but provides a much more accurate hole location.
• If using an angle-shape versus a u-shape, consider which way you want each angle to face since there is only one leg. They can all face the same direction or maybe two face one direction and the other two face the opposite direction, similar to what I did.

Continued in the next post...

[audisnapr]

...Continued

Steps/Process:

1. Cut all of the stiffeners to length.
2. Cut or sand down the 90-degree ends of the brackets so that they are not sharp.
3. Using the center punch or sharp object, mark off three, equally spaced holes on the template. (I left about four inches on either end of the stiffener for my specific setup) (Be sure to account for the diameter of the lock-nut on the backside of the aluminum angle when locating the center-width of the aluminum stiffener) (Do your best to make sure the two holes at the ends are equally distant from the ends of the stiffener and the center hole is equally distant from the two outer holes)
   
4. Using the 1/16" bit, drill the three holes in your template. (do not enlarge the holes to the 1/4" diameter)
5. Clamp your template to the next stiffener and drill the three 1/16" holes using the template as the guide. Repeat this for all stiffeners.
6. Decide on the spacing of the stiffeners on the panel. Pay careful attention to the location of the thumb locking hardware on the existing panel. It's also important to note if the 3/4" stiffener will interfere with any engine components in the engine bay so double check to make sure you have proper clearances. (one way to easily create equal spacing is to measure the width of the panel and divide that width by one more than the number of stiffeners - in this case, five. So if the width of the panel is 30", 30" / 5 = 6". From the edge of the panel, measure and mark 6". Do this 3 more times and you will have four marks and five separate gaps) (to complicate this even further, I decided that I wanted the two end stiffeners to be 4" from the sides of the panel and then created equal spacing for the two inner stiffeners)
7. Once you've marked out the spacing of the stiffeners it's a good practice to draw a line on the engine panel to make it easier to align the template before you drill. Be sure the line is square to the side/top & bottom so that all the stiffeners are parallel to one another.
8. Be sure to note how far from the top and bottom the stiffener needs to be placed on the panel. For the 2017 Mondo, there needs to be a small space at the bottom where the panel slots into a frame. I left approximately one inch from the bottom, about one-half inch more than needed.
9. Once you are happy with the stiffener locations, align your template with the first line you want to drill in the panel. (one easy way of aligning the template is to locate the line on the panel through the three, 1/16" holes you drilled in the template). Clamp the template in place and use the three holes in the template as the guide to drill the holes in the panel. Remember to use the 1/16" drill bit when drilling through the template into the panel. Do this for all of the stiffener locations.
10. After you have drilled both panels and all of the stiffeners using the template, go back and re-drill all of the holes with a 1/4" drill bit. Take your time to assure that you are enlarging the pilot hole right down the center.
11. Painting. If you plan to paint the stiffeners, read on, otherwise skip to step No. 23.
12. Prepping the aluminum is important. If you have a drill bit set, use one of the larger drill bits to deburr all of the holes in the stiffeners on both sides. If you don't have a larger drill bit, a utility knife will cut the burrs off the aluminum as well. Otherwise, sandpaper will knock the burrs down.
13. Lightly sand the entire stiffener, using 400-600 grit wet/dry paper or a brillo pad. You want the surface to be smooth, free from obvious burrs and misc imperfections.
14. Wash the aluminum stiffeners, dry and then using rubbing alcohol or similar cleaning product to clean the stiffeners of oils, and other debris before painting.
15. Hang all eight of the stiffeners for paint. (I ran a line from which I could suspend all eight stiffeners to be painted at once. Use old wire hangers to create a hanger that will suspend each of the stiffeners from the line. All of the stiffeners together are heavier than you might think so make sure the line is tight and taut and that there is enough spacing between the stiffeners to get your hand and a can of paint between them to get paint on the stiffeners from all different angles)
16. Apply one light coat of primer. I can't stress enough how important a light coat of primer is. It will bond to the material and dry much faster than a medium or heavy coat. It's not critical that every inch of the aluminum is covered. A light coat will be somewhat transparent.
17. Wait 10 minutes and apply a second, light to medium coat of primer. This time, you should see mostly full coverage. If not, don't worry about it as it's not critical. Some transparency of the primer is OK.
18. Wait 20 minutes and apply a light coat of the color of your choice. (black seems like the obvious choice here but this could be a bling opportunity)
19. Wait 20 minutes and apply a medium color coat. By now you should be getting full coverage.
20. Inspect your work. Look for areas that you may have missed, including the bottoms that may not have been easily accessible to paint. Don't worry so much about the holes, they will get covered by screws and nuts.
21. If necessary, wait another 20 minutes and apply another medium coat to pick up any areas that you may have missed.
22. Let dry per the paint instructions. (I let dry at least a few hours before I handled them, then 24hrs before I installed)
23. Installation. This is pretty straight forward. I'm not sure there's much I can add here besides being careful of your fresh paint job as you screw things together. Install all of the screws and nuts finger tightened before doing the final tightening to make sure you are able to get all of the screws in the holes.

I know there aren't many photos of the process so hopefully, my descriptions are adequate. If not, feel free to ask any questions you might have. I'll be happy to respond.

The final product certainly does the job. I do see some minor deflection of the panel but only slightly. The OE panels that sit next to the newly reinforced panel deflects a lot comparatively.

[996scott]

Great write up, if Wakemakers doesn't have the kit i will be following what you did.