To Rivet or To Screw: Marine vinyl / plywood floor

[Mainline9]

Hoping to hear some thoughts about the preferred method of fastening this to the original ribs from anyone who has already done so. I’ve accepted that either fastener will be installed with the head above the finished floor surface and want to understand the merits of screws with finish/cupped washers versus large head rivets. I’ve bought a pneumatic rivet gun and like the idea of using all aluminum pop rivets to attach this system to aluminum ribs.

1) Is there any reason to consider the screw option if I do not anticipate removing floor panels in the foreseeable future or don’t mind drilling out those rivets and replacing them should the deck need to be removed?

2) Is it feasible to produce a template that has the location of the existing rivet holes and transfer those to the new plywood floor panels or should I accept that newly drilled holes are the way to go?

Hope to get this done next week. Your insight is appreciated.


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[CedarRiverScooter]

Have done template on other projects with limited success, seems like holes are always a little off.

I cut the heads off screws, threaded them in 1/2 way, & used them to transfer the positions.

It is much less work just to drill new holes. You aren't loosing much strength.

Are you coating the ply before install?

 

[TheLastCall]

If the frame is aluminum going into aluminum boat. I’d use aluminum rivets, so you don’t have to worry about corrosion. As for the plywood, if you don’t plan on having to remove it go with aluminum rivets. If you anticipate making changes (running wiring, making live well) then go with stainless steel screws.


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[Mainline9]

Have done template on other projects with limited success, seems like holes are always a little off.

I cut the heads off screws, threaded them in 1/2 way, & used them to transfer the positions.

It is much less work just to drill new holes. You aren't loosing much strength.

Are you coating the ply before install?

Scoot - I like that idea you have about using those modified screws to mark the panel back. I had toyed with trying something like a Q-Tip soaked in ink but abandoned the idea.

After doing a dry fit of the plywood itself, I plan on sealing face, back, edges and fastener holes with epoxy, then securing Nautolux and finally installing finished floor panel.


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[CedarRiverScooter]

I forgot to mention tapping the ply with a hammer to indent screw positions, hope that was obvious.

I have had good luck thinning epoxy with Xylol (about 25%). It will soak in well. Homebrew version of CPES.

 

[Bob9863]

I'd go with the rivets, if you can reach behind the rib and add an aluminum washer to increase the hold then even better.
I don't like mixing metals with aluminum causes Galvanic Corrosion, that can chew the metal away or fuse it together together inba bad way, particularly in salt or brackish environments.
I was working on a jet boat once that we had to fasten some seats to, it was aluminum with a sealed hull so I gad to drill blind holes without puncturing the air pocket in the hull.
To solve that problem I tapped and epoxy the holes and put in stainless helicoils, that allowed me to use stainless bolts to mount the removable seats without fear of screws and aluminum fusing or eating away at each other.
Thats probly nit an option here as the rib won't have enough meat to helicoil.
But IMO the best way is to make aluminum tabs up to fix to the deck and then line them up with the ribs, that will be strong and let you rivet the deck in solid with no guess work as to where to center the holes for the rivets.

 

[FishinLite]

I went with screws and made a template from 1/4" hardboard. I located all the original screw hole with a tape measure, story sticks & painters tape.
I transferred the screw holes to the template aligned the template with two awls and screwed the template to the boat ribs. The template was in and out of the boat a half a dozen times.

Once I was comfortable with the template I fabricated the floor panels. Approx. 11' x 5'



If you look closely, you can see all the hole in the floor panel. There are over 100 stainless screws in the floor.

I then carpeted the floor panel. Marked the holes through the carpet with fishing line and installed the panel.

 

[LDUBS]

Attention to detail really pays off in the long run. Impressively done. That is a really good idea using fishing line to flag the screw holes. I think in this case mono would work better than braid. Haha.

 

[Bearclaw]

Now that's what I call a great job. I wouldn't have been able to get half the screws to line up with the original holes. I like the screw down idea better than rivets, my thought is if a rivet gets loose you can't tighten it up but the screws you can.

 

[user 18775]

I figured that the stainless screws that Crestliner had used had worked for the first 18 years that I had the boat. So I pulled every screw when I gutted it, and tossed the few that had bad heads. I did not rebuild mine exactly, so the screw location could not be replicated, so I made sure to place them in new holes. I then screwed the self-tapping screws in, and then backed them out. I placed a bit of Marine sealant around each screw and then tightened them.