Carbon to reinforce Deck

[Chotu]

Benz is right. I almost suggested the same. He’s not building a whole boat, nor with a brand new Outremer is probably worried about the cost of this little project. A pre-thickened epoxy like Benz suggested is the way to go.

[Spot]

Does he boat have a nice interior? Is the stiffener going to be applied where it will be visible or hidden under a headliner?

If exposed, what about a laminated timber+composite+timber beam that matches the existing interior trim?

[GordMay]

Originally Posted by Bill Seal

If you just glue it to the overhead, you'll end up with all the structural integrity of Polina Star III. Think of how deck beams are supported, or window and door headers in buildings.

Evidently, “POLINA STAR III” has been rebuilt, and sails now under the new name “CHAMPAGNE HIPPY”.
According to Boats.co.uk (the restorers):
“... “There was nothing wrong with the hull or the main matrix. What was wrong was the connection between the keel stub and the prefabricated matrix, which was insufficient to support it.
The keel was 20 tonnes and the loads had been transmitted to the hull, which is vinylester resin and very strong. But when [the matrix] snapped at the waterline on the starboard side, the boat then rolled and pulled the skin off to almost deck level on the port side. Then the vertical bonds above the keel stub snapped one by one and the keel fell off. “The hole in the bottom of the boat was so large that you could have parked a Transit van in it ...”
More ➥ https://www.yachtingworld.com/extrao...r-yacht-126434

[jimbunyard]

Ah yes, the advantages of quick and easy...17.00 for a 24 oz epoxy resin kit and 6.00 for bona fide Cabosil http://www.uscomposites.com/fillers.html , plus the advantage of having the ability to adjust the viscosity of the adhesive filler (and likely having enough left over for some other project), versus the 'money? who cares?' of 36.00 for a tube of 'miracle in a cartridge' (which will hopefully be enough), plus from 100.00-200.00 for a gun to dispense it and 17.00 per any additionally-needed non-reuseable mixing wand. (Though I might have found a place to buy a third of a pound of old-fashioned 'mix-with-stick' Proset for the bargain-basement price of 100.00...)

Of course, anyone who can afford an Outremer 4x surely wouldn't be concerned about such things...

[Sherpa17]

I have split carbon fiber tubes in half and bonded cut side up to the underside of the deck using thickened epoxy. Clean and easy

[valhalla360]

If you can find similar pieces in just standard fiberglass, those should work just as well and the weight difference will be negligible.

[RELENTLESS 1]

Chotu et. al.

Great input and ideas from all - and a bit of clarification is in order- and props to Chotu for speaking to that!

The particular area I am working in is in the forward bow lockers where fenders, sails etc. are stored. 6'3"+ of standing room and only the glass deck above - no headliners etc.
Where the hatch is it is as near to flat as anywhere on the deck - though I may need to shim a bit - the hatch is metal and it is flat of course, but the little bit of deck flexing seems to open up the seal just a bit and allow water in, ounces at worst, never a gallon.

FWIW - this is the 'thinnest' section of the deck - further back over the staterooms etc where the hatches are there is zero deck flex - so this has clearly been engineered to keep weight out of the bows and maintain maximum buoyancy - (we were out the other day in 24kts and 6ft seas and it was reasonably smooth - actually fun especially with the tillers - went out the next day in a friends Lagoon - similar conditions and it was horrible - like a bucking bronco ride - 1/4 mile out and we had had enough and returned.

Thanks to all of you think I have a good handle on it now - the ideas and input have really helped and thankfully the area is out of sight.

[zstine]

A few comments/questions...

Was the deck always flexible like that from new? Maybe the core is wet/deteriorating and causing flex. If so, better fix the core.


Keep in mind that carbon has a much high modulus of elasticity. So, if you bond carbon to the existing glass, essentially all the deck loads in that location will be carried by the carbon. It may need more carbon than you think to avoid delamination..? May be better to add some fiberglass cloth, vice carbon

[guyrj33]

you could also glass trapezoidal shaped foam hats in place, this would have similar flex characteristics to the original deck material thereby making the stiffness transition softer. 'no hard edges'.

[RELENTLESS 1]

zstine,
No core in the bow locker- strictly the fiberglass of the deck in this particular area - I had thought of stiffening the one area and not others so your point is well taken to maybe do a couple of more stringers overhead.

The hatch is about 18"' from the Bulkhead (where the deck is cored from there to the back of the boat) and does not flex when I walk on it. So I am thinking one piece on the front of the hatch and then maybe 2 or more towards the front where there is a watertight bow compartment and bulkhead where it narrows and is very stiff.