Anyone used plywood alternatives with a deck/stringer rebuild?

[JaCrispy]

I plan on digging into my deck and stringers in a year or two and wanted to use something other than wood for the substrate. Besides the worry-free factor, I think it would be a good reselling point.

 

[gm280]

Seems so many talk about doing that same thing...until they actually research and come to the mindset that the usual quality plywood IS the best option after all. I too wanted something that would never rot out again. But the materials just aren't there to accomplish that and be reasonable in cost and to obtain. So I am going the outside plywood route like everybody else. Look at it this way. It took many years to rot your present structure out and it wasn't installed with much care originally. If you follow the usual steps on these forums, that new wood will last even longer. You probably will never have to deal with it again and even selling it will allow the next owner that same rot free usage too... JMHO!

 

[Tnstratofam]

+1 on gm's comment. There are other alternatives, but cost is usually the big show stopper. Seacast may be a feasible alternative. I think archbuilder is gonna use it for his transom, and stringers on project fuggly. May want to keep an eye on his thread. I believe he also used it for the transom in his Mrs Morgan project as well.

 

[jbcurt00]

Seems so many talk about doing that same thing...until they actually research and come to the mindset that the usual quality plywood IS the best option after all. I too wanted something that would never rot out again. But the materials just aren't there to accomplish that and be reasonable in cost and to easy obtain.

Absolutely!

BTW: It is my firm belief that the materials used ARE NOT the problem. Poor care and maintenance are. Leaving a boat uncovered, stored bow down w/ bilge plug still in are all death nails to the structure and interior of a boat.

 

[Arawak]

I'd agree with pretty much all that's said above. However, if you really want to do it, Joel Shine shows how it's done in Rebuilding the Aquasport Classic "flatback"

 

[jbcurt00]

At $105+ per sheet IF you can find it local and pick it up, and still requiring prep and tabbing, the H80 Divinycel laminate stringer isn't likely an item I'd ever consider using for stringers. More expensive isn't always better, some times it's just more expensive, IMO.

IF I could find it locally, and pick it up, $90+ per sheet marine plywood may or may not be something I'd consider using. Since I can't find or order it local, it doesn't really matter. ACX or Aurauco plywood is an acceptable material choice and it's readily available to me locally.

I also would never recommend removing the back of a fiberglass transom for a repair, or out of an aluminum boat either for that matter, unless absolutely necessary. At least not for a novice DIY backyard boat builder or a novice in the application and finishing of fiberglass and working w/ gelcoat.

FWIW Joel is also using epoxy for his repairs not polyester resin. Makes it a nearly entirely different setup and process/method of repair.

 

[Woodonglass]

When I first joined the forum a little over 5 years ago, I got involved with this guys build. He did, to this day, one of the best Seacast Transom/Stringer pours, I've seen done on this forum. You'll learn a LOT about the process if you study his techniques. The Pour stage starts here....http://forums.iboats.com/forum/boat-...22#post4032921 but there's a LOT of good info starting on page 13 going forward. He's very meticulous in his methods and his final product is Outstanding!!!!

 

[sphelps]

Yep, you know I recommend seacast . But it is 200 bucks a 5 gal pail plus shipping /hazmat .. That is the only set back .. Sticker shock !
Resale value and peace of mind are the pro's

 

[jigngrub]

If I wanted a boat building material that wouldn't rot and is easy to work with I would use the CCA pressure treated plywood:

http://www.restorepontoon.com/pontoon/pc/4-x-8--3-4-CCA-Treated-Marine-Grade-Plywood-89p77.htm

Lifetime warranty against rot and it won't rot even if it gets wet. It's good for transoms, stringers, and decking.

 

[sphelps]

At 64 bucks a sheet thats not to bad... But is there any info on glass adhesion ? Wonder how bad shipping would be ...

 

[jigngrub]

At 64 bucks a sheet thats not to bad... But is there any info on glass adhesion ? Wonder how bad shipping would be ...

It's kiln dried after treating so glass adhesion isn't a problem and some of the higher end fiberglass boats are made with it at the factory.

Shipping can be expensive depending on how far it's shipped, but you may be able to find this material locally if you look in the right places. Look at boat dealerships with repair shops and marinas. Specialty wood suppliers would be another place.

 

[Scott Danforth]

I would go with Nida core (http://www.lbifiberglass.com/NIDA/nida.html) myself if I was looking for an alternative to the ACX and could afford the material. However Plywood's only down side is that if you screw up the workmanship (gaps in coverage, do not seal any mounting holes, etc,.)...... and mess up the storage and maintenance (plug in, bow down, full of water), you are back where you started.

todays higher end boats have no wood at all, however rely on highly engineered stringer tubs pulled from their own plugs and molds, and bonded into the hull with lots of adhesive.

Seacast is nothing more than ground up boat hull chips added to equal parts Bond-o and resin. Here is what nobody thought of with sea cast. if the boat hulls were waxed prior to being ground up, the resin/bond-o blend doesnt stay adheared to them.

 

[sphelps]

A little more to it than ground up boats , bono and resin .. Can you post some links to some Seacast adhesion failures please .

 

[jbcurt00]

At 64 bucks a sheet thats not to bad.
Wonder how bad shipping would be ...

Shipping can be expensive depending on how far it's shipped,

That place is in Indiana

I checked, and to me in WV, a single sheet costs $10 to ship, so $75 for a 4X8 sheet of 3/4ply, IMO, not bad, if you want to use 3/4" plywood.

To me in WV, just buying 2 sheets makes shipping free.

 

[hadaveha]

I was looking at the CCA just the other day that could be a game changer, my crestlinner has CCA from the factory its a 1984, it was never glassed over it was put down much like a pontoon deck, and in the transom also, once again no glass at all , and it lasted almost 30 yrs with carpet on it and allways in the weather, the only soft on the transom is from where a PO mounted a homemade swim platform. and 75.00 to the door whats that maybe 15 20 bucks more than a good outdoor 3/4 ply and no sales tax

 

[jbcurt00]

The difference between the 1/2" CCX and 3/4" CCA (besides thickness) is that the CCX only has 1 side sanded, the other (the 'down' side) isn't sanded.

2 sheets of CCA, delivered to a business address, is $130+/-, $65/sheet. No shipping, no tax

 

[Scott Danforth]

A little more to it than ground up boats , bono and resin .. Can you post some links to some Seacast adhesion failures please .

not much more according to the MSDS sheets and Wolfgang Unger himself. his process uses up to 35% post consumer recycled FRP (old boat hulls). I mixed up my own resin/bondo and tested the material properties along with the seacast back when I did my Avanti. performed a cantilevered load test as I was at home didnt have a charpy notch test rig. I used weights to add load until failure in bending, and the results were similar (within a few %). when the samples broke, the substrate separated on the gel-coat side of the hull chips.

 

[sphelps]

The material that I used in my seacast pour from what I could see did not have any gell coat sides . I left a chunk of it in water for several months floating around . Pulled it out of the water, dried it with a paper towel then cut into it with an angle grinder cut off wheel .. The inside was dry as a bone . No absorption what so ever .. I don't recall anyone ever pouring transom or stringers coating the inside of either with gell coat as prep for the pour .. Proper prep as with any type of transom/stringer replacement no mater what you use is the most important part for good adhesion .
That having been said , I still have not seen ,read , or heard of any Seacast failure to date that was properly prepped ..
I will stand corrected when that happens ...

 

[sphelps]

The difference between the 1/2" CCX and 3/4" CCA (besides thickness) is that the CCX only has 1 side sanded, the other (the 'down' side) isn't sanded.

2 sheets of CCA, delivered to a business address, is $130+/-, $65/sheet. No shipping, no tax

That sounds doable ! Less than M/G and just a bit more than reg ext ply ....

 

[tpenfield]

If I ever do a full stinger restore, yes, I would go with a synthetic material and not wood. For the time being, my 2 recent repairs have used wood, pretty much for convenient sake.

The challenge to using the synthetics (like divinycell) is that it is crazy expensive. So, the challenge is to find something at a reasonable cost that is compatible with the resins that you will be using to 'glass' everything together.

The newer wood that is KDAT plywood (that JnG mentioned), like Perma Panel or Greenwood XL, is better than the wood of old, and many manufacturers have switched to using KDAT PT Plywood. My issue with using wood is that it still wants to absorb water. So, it will absorb whatever it can during its life cycle. As to whether that causes rot or not is another story.

A synthetic core to the structural components will not readily want to absorb water, so it is better than wood in that regard.