Question about installing seat base in aluminum boat

A while back I installed a seat base in the floor of my Horizon 1860. I use it mostly when I'm trolling cranks or longlining by myself. It was screwed into one rib then into the floor plate. It has worked loose and I need to do a more secure mounting job on it. The space under the floor plate to the hull is no more than 1 1/2 inches and it has foam sheeting in that space. I thought about the toggle fasteners that fold up, push thru a small hole then unfold inside a wall or space. I just don't know if I have the room for those. The floor is not flat, it has a slight slope down both sides to the middle. I have seen some sort of threaded nut that is used for trolling motor mounting but the thickness of my floor plate can't be any more than .100.
Any ideas or links? Thanks.

I think what you want to use is a rivnut. It installs much like a rivet, once installed you can bolt your seat or whatever directly to the floor. I have used these extensively on my jon boat, and have a seat installed using them and they hold just fine. They are great in locations where you can't access the backside of the install site - jon boat ribs for instance.

Link to inexpensive tool and comes with rivnuts.
45 Piece Threaded Insert Riveter Kit

Also google 'rivnut' and 'how to use a rivnut'

i've ran into issues with that a bunch. im a big guy so i have to have something stout. i obviously can't see your problem but i have always just fabricated some kind of bracket to reenforce the mounting area then had someone who works with aluminum to weld it up.bolt it on with stainless bolts and lock nuts and u will pull the boat apart before the seat loosens

Check out snap toggles at Lowe's, can run any length bolt into it. Same premise as a toggle bolt with better materials. Riv nuts suck

I think Joe is on to the right thing Mrdux check this out.

https://www.youtube.com/watch?v=SC1ZuxuZ2PU


Shop TOGGLER 30-Pack 1/4-in x 2-1/2-in Toggle Bolts at Lowes.com

Holds up to 1080 lbs

Rivet Nuts work fine when installed correctly. MHO

I've had great success with Jack Nuts
http://www.zoro.com/pop-jack-nuts-threaded-inserts/g/00105699/?gclid=CNSYv9myzMUCFdgDgQodhREA0A&gclsrc=aw.ds

No matter what you decide for fasteners, I woul get me a plate that would span 2 ribs, attach it to ribs the attach base to that plate.

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Originally Posted by cray

No matter what you decide for fasteners, I woul get me a plate that would span 2 ribs, attach it to ribs the attach base to that plate.

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I need to do something like this with my up front pole holders, but there aint no ribs there. One bump of the knee and it looks like I caught a flotilla of fish. You'll know what I mean.

A aluminum plate 3/16 thick will spread out the load better and take more stress. I have them for my seat bases and also my rod holders. I used large dia stainless self tapping screws all the way around with JB Weld on the threads. Works great.....plates are a lot bigger than the bases. Drill holes in the plate and floor and thread them.....fasten bases down with stainless bolts or large machine screws with lock washers and JB Weld on the threads.

Here are some pics of my installation using rivnuts (boat is a mess due to current modification project). I've personally never had a problem with rivnuts, if installed correctly. The rivnuts used for this seat installation has taking my weight without issue, and the seat installation can be uninstalled and reinstalled as needed.

Also included is a pic of a small rivnut installed on gunnel, I use this to install a series of rod holders for spider rigging when desired.

Attachment 203592Attachment 203593Attachment 203594

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Originally Posted by Cane Pole

I need to do something like this with my up front pole holders, but there aint no ribs there. One bump of the knee and it looks like I caught a flotilla of fish. You'll know what I mean.

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I was going to suggest just what G posted. Will stiffen the floor and make those holders a lot more stable.

Attachment 203595