Using oak for boat decking

I’m helping a friend with a project boat and they have had oak beams delivered for a new deck. It’s a 50ft trawler converted to a live-aboard but in need of “updating”.

What thickness would the planks need to be for the decking? Yep the beams need planking first.

Thanks in advance, appreciate any help/guidance you all may have

 

White oak, I hope.

Is there a substrate? Plywood, glass, steel? If so, the decking can be fairly thin, 3/16" - 1/4" even thinner if you don't mind working with it.
Laying the Deck – Mastering Skills with the WoodenBoat School https://skills.woodenboat.com/books/laying-the-deck/

-Will

 

Welcome to the forums Rob.
As Will implies, there can be some issue with red oak, an open grained wood, as a decking. Prone to splinters and checking, you will have to give it some sort of thick coating to prevent weathering and water intrusion. "English" or "European" oak (Quercus robur) is classed as a white oak and has less water and rot issues, will work well for deck beams, but is not really a preferred choice for deck planking. Unless you have pockets deep enough for teak, generally, on this side of the pond, softwoods (fir, cedar, and pine) are used for deck planking because of their better workability and weathering. Lots of trawlers out on the west coast have fir or cedar decks and as long as you keep them oiled or painted, are effectively life of vessel.

 

Plank thickness depends on the deck construction. A traditional laid deck with caulked seams has different needs then something with a plywood substrate. Even a deck with a substrate has different thickness planking depending if it's screwed or glued.
On a traditional deck I would expect planking between 1 1/2 and 2 1/2. Decks screwed to a substrate need a minimum of 1/2 because of the plugs, while glued decks usually top out at a maximum of 3/8.

Oak decks are encountered only on working vessels in nordic waters and are a nightmare you don't want. If local english woods are preferred, first choice is larch, second is scots pine or douglas fir. Otherwise there are a bunch of tropical woods, right up to teak.
You can always go to the low maintenance option, fiberglassed plywood followed by paint.

 

You do NOT use red oak.

The planking dimension is already established. If you change it; you'll encounter problems.

 

This sounds like an interesting project - can you tell us some more about it please?
And if you can post some photos of the vessel as well, then even better.

I have a feeling that the Forum members here will be able to help you and your friend with many other aspects of the rebuilding of this project trawler, as well as the useful advice offered above re the timber decking.

 

Oak is good for beams but a poor choice for deck planks. It moves too much for deck exposure and will blow out pretty much any fastening system. When it wants to warp due to differential temps or moisture on the top/bottom surfaces, It's going to warp, and it will take the rest of the boat with it. That's not how you want decks to work. Find a more dimensionally stable material whose movement can be constrained with proper fastening, bedding, and calking. Either that or you pay someone to swab the deck 24/365.

 

What Rumars said. Having lived with traditional decks, I would go for plywood and epoxy-glass sheathed. Most of these boats rot from the deck down, usually around the bulwark stanchions. If you go traditional, there is options for larch in long lengths, though imported Opepe can often be had at better pricing.

 

My friend has already brought many many oak beams to plank and use as decking - not always the best at researching projects before jumping in. Is there a way to use the oak over a plywood “base” more for the aesthetic look than as a functional deck?

 

Yes, he could rip it into 50mm x 15mm strips and screw into a plywood sub deck, but everyone of those screw holes is a potential pitfall down the road, unless first bored oversize then filled with epoxy. Oak can be problematic with epoxy due to acids within the wood, so the whole lot would need to be bedded down on some kind of Sika/tar/bitumen.

 

https://www.google.com/url?sa=t&sou...AQFnoECA4QBg&usg=AOvVaw15DSTYWQBTLY2R-bArYFvp
This article compares polyester resin vs epoxy resin. It recommends epoxy over polyester when working with oak, among other woods.

Lay a plywood glassed deck and adhere the oak strips over it. I don't see any reason to use fasteners if you get a good adhesion surface. Be sure to clean the oak with acetone, to remove surface oils and acids. Perhapse the natural acid in the oak would loosen the bond over time, but they should be easily reglued, or replaced as necessary.

 

Of course there is. Build the deck from plywood, glass it over, glue down 9mm thick oak planks. Search for "glued teak deck" to see examples.
Sell the unused oak beams, or use them for something else.

 

Are the beams old? That may help a little here. You need to find out what species and where harvested, and if possible, how old. After resawing (dimensions will depend on species), you can try to treat the oak to make it more compatible with structural epoxies. This is easier with old wood. You will need to tell the epoxy formulator you are working with oak. If you are staying up north, this has a decent chance, but I wouldn't even attempt it in the tropics.

 

Check out these links that delve into testing and detailed methodology of using white oak and epoxy: White Oak Redux - Epoxyworks https://www.epoxyworks.com/index.php/white-oak-redux/

Recommendations for using epoxy and oak species: Using Epoxy with Oak - Epoxyworks https://www.epoxyworks.com/index.php/epoxy-with-oak/