208 Radar Arch Installation

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Mark DV

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hello all. I have decided to add a radar arch to my 208 Adventure this winter. Any advice on installation. Specifically backing plates. I plan on doing a side mount. I may use 1/2 inch G10 fiberglass epoxy board as a backing plate. Here is a link to what I'm installing. https://www.fishonsports.com/320.html Any advice? Thanks
 
Make sure the side mount clears the hardtop mounts. The G10 board or coosa will work but they need to be bedded to make sure that maximum contact is attained. That said, I would probably use aluminum plate, cut and drilled as needed. Same need for bedding. A nice layer of 5200 will work well on the aluminum. For the fiberglass or coosa, I would opt for epoxy. Note that the aluminum can't crack. The composites in theory could.
Add large washers and nylock nuts.
Make sure that you install any wires needed but if none on day one, install a drag line or two for later on.
 
Great ideas. I like the aluminum plate idea. Any thoughts on what size for backing plates? dimensions and thickness
 
I'd do metal backers if I had a choice. Depending on substructure you could add tube spacers (plastic tubes one size larger than bolt you plan to use) to ensure there is no collapse of the deck when you tighten everything down. You shouldn't need if you are going through a wood cored area but if something softer, look into these. Seal side walls with 5200 if you do. I like to use the phenolic washers where different metals contact (al top and likely SS screws) again, not a requirement. As stated above, seal well as these points can be a point of future water immersion. Also if you are doing any welding to the structure, do it before you pull wires. Good tip above to have a drag line of two for future additions (lights, horn etc). This will make life much easier.
 
I assumed that for side mount, crushing the coring won't be an issue since I expect the side of the helm mold to be solid.
 
Correct. The side is solid FRP
 
I believe it is, general comments - take what makes sense.
 
I’ll be following this.
I’ve been kicking around the idea on mounting a radar arch with my soft top maybe something I can fold down while transporting and storage.
 
It's been so long since I've had the side panels off, and I didn't do the original install, so I don't remember how ours is backed. But I'll pull a side panel off and take some photos when I get a chance.

IMG_7177.JPG
 
Great. Thanks. I would like to see how yours is backed up. I will probably end up over thinking it and over engineering it but thats what I do.
 
Here it is. The superstructure is at least 1 inch thick plywood, maybe 1.5”. Whatever it is, it’s thick. The radar arch is thru-bolted with flat washers. Looks like low grade 18-8 stainless was used as they are looking a bit rusty after 23 years.
0FA0BCB3-991D-4DDC-8FE1-07DB0325033C.jpeg
 
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OnoEric said:
Here it is. The superstructure is at least 1 inch thick plywood, maybe 1.5”. Whatever it is, it’s thick. The radar arch is thru-bolted with flat washers. Looks like low grade 18-8 stainless was used as they are looking a bit rusty after 23 years.
View attachment 17512
Click to expand...
Best to replace with doubled up “fender” washers which are easily twice the width of a standard washer. Get them at Lowe’s.
 
Lt.Mike said:
Best to replace with doubled up “fender” washers which are easily twice the width of a standard washer. Get them at Lowe’s.
Click to expand...

While that’s not a bad idea, they’ve been on there 23 years with zero signs of stress, so I don’t think it’s really needed.
 
If your coring is similar, backing plates probably aren't needed. Either stainless or galvanized washers will work. I am not sure if the fender washers at Lowes are galvanized.
I would still use a bead of 5200 under the washer to help 'distribute the load evenly. Do not super tighten the nuts, just enough to hold things and cause a little 5200 to ooze out. After the 5200 has set up (maybe a day) retighten the nuts.
 
Great that you have such access and a solid surface. Should make installation much easier.
 
seasick said:
If your coring is similar, backing plates probably aren't needed. Either stainless or galvanized washers will work. I am not sure if the fender washers at Lowes are galvanized.
I would still use a bead of 5200 under the washer to help 'distribute the load evenly. Do not super tighten the nuts, just enough to hold things and cause a little 5200 to ooze out. After the 5200 has set up (maybe a day) retighten the nuts.
Click to expand...
What do you mean by coring? The fiberglass wall on boat?
 
Mark DV said:
What do you mean by coring? The fiberglass wall on boat?
Click to expand...
In the photo posted as an example, the wall appears to be fiberglass over something that looks like plywood which is quite strong and not easily compressible as a foam coring would be.
If you have a softer construction, backer plates will help distribute the load over a larger area.
 
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