Adding Floor to Old Aluminum Boat

I have an old 12′ aluminum boat that I’m thinking of taking out the bench seats and adding a floor as a winter project. I’ve read some things that this may cause some hull integrity issues but some say not to worry about it. I just have a 6 hp on it and use on small water. I’ll (try) post a couple pictures of what I’m thinking of doing, nothing fancy. Just wondering if anyone has do’s and don’ts to add.

Most likely the bench seats provided bracing and strength to the side walls. Many 12′ boats are not built too ridgedly but rather for their light weight. Might want to add some pics to get the best advice as different builders used different structural designs on the hull.

A lot of those bench seats are full of flotation foam for safety.

True, have also heard of the foam concern. I’d probably add some under the floor, but honestly am not too worried about it (I know, famous last words). These couple pictures are screenshots from a couple other sites, similar to what I think I’d want to do. The one shows braces that were added to help with structure. The other shows framing up a floor support with aluminum. Hopefully they post

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I did this on a 1980 Lund S-16 deluxe and it was totally fine (used the boat for ~8 years after the project).. removed the middle bench seat and made a large floor in the middle and added a casting deck up front with storage underneath. Due to the layout of the S-16 deluxe, I hardly removed any foam at all. Yes I totally get the concern with removing foam but you have to remember if you’re adding a bunch of wood to it, that wood is buoyant. I also added some spray foam under the middle floor. Just make sure you account for the weight of the wood added to the boat when adding up the weight of gear/people to make sure you don’t overload it beyond its stated capacity.

I’ll see if I can dig up some pics.. it was 13 years ago

I think there is a significant difference in modifying a 16′ vs. a 12′ boat.

Tiny Boat Nation. How to videos, and supplies.

Brittman wrote:

I think there is a significant difference in modifying a 16′ vs. a 12′ boat.

sorry for adding my personal experience that is directly related to the OP’s question…

for what its worth, my buddy did the exact same thing at the same time as me with his 14 foot lund. He also had no issues and used the boat for a good 5ish years after the remodel before he sold it.

The foam in the bench seats doesnt add bouyancy when floating normally. It’s to keep the boat from sinking all the way if it flips or gets a hole.

Riverrat wrote:

The foam in the bench seats doesnt add bouyancy when floating normally. It’s to keep the boat from sinking all the way if it flips or gets a hole.

I saw a post a couple years ago where a guy wanted his boat to float higher in the water (he changed to a heavier motor).

So he added foam blocks inside of the boat to help

Dead serious

Riverrat wrote:

Tiny Boat Nation. How to videos, and supplies.

This is the best advice you can receive. You can even call them and they’ll walk through your project and get you a supply list. They are good folks too.

Thanks guys. I have watched some TBN videos, but will have to watch a bit more. Some of their mods get wayyyy fancier than I’m looking for.