# Building a Floor



## yobata (Jul 14, 2015)

I just picked up a 14' fiberglass skiff. I have plans to rebuild transom (divinylcel), and build front and back decks (nidacore). The part that I am stuck on is how to build a flat floor:

Should I build stringers (nidacore or divinylcell??), lay rigging tubes in, and use 2lb polyurethane foam to fill in the entire floor area? Should I leave the cavity empty? How would I add the foam? Should I lay the floor in and then cut a hole for the expandable foam or put the foam in first and then cut it back flat? Any advice is greatly appreciated! 

I am a ways out - just starting to sand, but I like having a plan...


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## DuckNut (Apr 3, 2009)

Too many questions to answer all at once...and no pictures add to the complexity of your questions.

But for starters, you need to add flotation of some sort, somewhere in your build. Does not need to be under the sole but that is usually the place to put it.


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## yobata (Jul 14, 2015)

Can you explain why I need to add floatation? Isn't buoyancy based on water displacement? How would extra foam help? If I use wood instead of a composite for decks/bulkheads, wouldn't that give more displacement and hence more buoyancy?? I'm considering using okoume and no foam under the sole/deck. Again I haven't started yet, just picked up the hull this weekend... I saw lwalker's osprey didn't have foam under the deck. I'll post some pics his weekend


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## DuckNut (Apr 3, 2009)

Now you have changed materials and that will make a difference.

Read this and pay partuicular attention to page 26
https://www.google.com/url?sa=t&sou...-d8FWXdEaU-BOIohA&sig2=-VrHTP37B8O5ytMb5sfDCQ


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## devrep (Feb 22, 2009)

yobata said:


> Can you explain why I need to add floatation? Isn't buoyancy based on water displacement? How would extra foam help? If I use wood instead of a composite for decks/bulkheads, wouldn't that give more displacement and hence more buoyancy?? I'm considering using okoume and no foam under the sole/deck. Again I haven't started yet, just picked up the hull this weekend... I saw lwalker's osprey didn't have foam under the deck. I'll post some pics his weekend


It's for adding buoyancy when the boat gets swamped, not for just floating around.


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## yobata (Jul 14, 2015)

thanks for the info guys! DuckNut - can you recommend the best way to fill those cavities? Should I use the template of the sole and cut holes in it to fill with expanding 2 lbs foam? I don't necessarily want to cut holes in the final sole. (I hope sole means the same thing as a false floor)


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## DuckNut (Apr 3, 2009)

If you cut holes in the sole after it is glued down you risk having the foam tear it right back off.

Do all of your rigging and get everything the way you want it and then pour in the foam. Go buy a wrapped guitar string and pull it tight to use it like a saw to cut the foam. Then attach the sole.


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## yobata (Jul 14, 2015)

Sounds good! I have used a tool before that had the piano wire but would also heat it up to cut through the foam like butter - I just don't have access to that tool anymore...


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