Deck Delamination / Core Problems

[CapnK]

Hi Natalie -

Congrats on living your dream! I am too.

3" strips would make handling the core as you lay it in easier, I'd think., but you don't *have to* do it that way. If you made sure to get resin/glass between the strips as you laid them in, it would also significantly increase the strength of the deck (think lots of I-beams, 3" apart, under the top skin, if you did it that way).

Looking forward to seeing some pictures.

[Mike Goodwin]

Marine or any ply is almost the worst core you can choose . Use a closed cell foam and join the 21st century .

[natalie e.]

thanks for your replys. Do you know where to find this 21st century core and any idea of the thickness I would need??.

[Bill]

There is a thread on this. Please use the search button.

[mbd]

Hey guys, any of you that have recently redone your decks - I'm curious how it went. What worked, what didn't. Do's and don't do's and how to's? Materials that worked well and didn't? Tools, etc. Pictures pictures pictures!

I know this recore stuff is nothing for the pros here on the board, but having never worked with epoxy...

[ElBeethoven]

Mike:

I put a complete new deck and cabin top core on 220 the first week of August (not recommended) and while living aboard (VERY not recommended). It's not hard at all; it's just really, really disgusting. But if a bonehead like me can do it, anyone can.

I used a 1:1 epoxy recommended by Mike Goodwin of this site and was thrilled with it. It has a working life of around an hour at 70 degrees Fahrenheit, which for a novice like me was great. It is non-blushing and far cheaper than any other brand I could find after months of research. You can order it from www.fgci.com. I ordered six gallons total, and I still have some left.

For a core, I used Corecel which was recommended by both Mike Goodwin and "Sprite," also of this forum. I got six "remaindered" sheets on sale from Noah's Marine for $77 + $20 shipping, and I still have some left over. Given that it's closed-cell, it absorbs practically no epoxy. I was very happy with the way it sanded, how easily it cut, and the stiffness of the deck. The latter I tested after laying down a double-layer scarf joint and jumping up and down on it as hard as I could. I'm kinda small at 125lbs, but it didn't even flex. It's SOLID. The scarf joints I did with 2- and 4-inch 8.5oz FG tape from Jamestown Distr. It wets out very easily and is easy to work with.

The only "problem" I had was re-attaching the first piece of deck skin. I found that a peanut butter consistency epoxy was too thick as I could not physically put enough weight on the panel to get it back to its original level. I reduced the amount of silica after that and had no further problems.

I cut the deck skin off with a FG cutting blade on a DeWalt cutter/grinder. Worked like a charm.

I didn't take any pictures, because I don't have a digicam and there are a bunch of photos posted all over the web about recoring. All balsa looks the same when rotten.

Tips: 1) go ahead and buy a 10-lb bag of colloidal silica. It's the cheapest way to go, and you'll eventually use the rest on other projects. But find a place locally to buy it. It ships as "oversized," so that adds another $40 to the price if you buy it online. 2) In addition to good epoxy, FGCI has the best prices on 3M 5200 and 4200, latex gloves, tyvek suits, etc.

So that's what I did, and may I never have to do it again!

Jeremy

[mbd]

Perfect Jeremy! Thanks so much, and congrats to make it to "that end" of this project!

So I assume you faired, sanded, and repainted your rock-solid decks? sure would love to see some pics!

[Sprite]

I have run into the same problem with Sprite. My deck forward of the cockpit
needs replacement. The deck is like walking a tuna sandwich. The measurement of the thickness is 3/8 of an inch. This translates into roughly 9mm give or take. It is consistant through out the deck. I am using corecell because epoxy bonds to it better and it was designed with the yachting industry in mind plus it can take 200 pounds per square inch.

You can find it at Noah's
they are running a sale of A500 Blue Plain

John

[mbd]

I called Noah's Marine last week and asked about Corecell and what they recommended. I just ordered 6 sheets of CoreCell A500 (B) 9MM PL 23"x48" for $73.14, so that must be close to the same stuff Jeremy used.

[Sprite]

You can buy

by the gallons exact gelcoat and anti skids from spectre or spector products.
They are located in Florida and Washington state. They have anti skid patterns
for Pearson Boston Whaler with the correct color for gelcoat. They have a catalog. If you are looking for an anti skid pattern another place was treadmaster and they are based out of England they were in Good Old Boat
Their stuff is cool.


John

[mbd]

- from Noah's Boat Building Forum Admin in reply to someone's query about materials for a recore:
Foam core (Corecell) will not be affected by water, and installation is about the same (as balsa). One disadvantage is, unlike balsa, foam does not have good compressive strength so it will be necessary to insert plywood under winches etc.

Oy. I guess it goes without saying then that I should pre-plan where all my deck hardware will be re-installed and put something more solid in those locations? Lay-up with fiberglass or use solid epoxy or what?

[ebb]

We obviously have the experts here.

But here's my thought, since I've been messing with the deck on 338.
I'd have to know where all the fittings are going,
and as I don't really really know exactly,
I would proceed with the core and deck lamination and then when it got to placing the fittings, do the oversized holes*, fill with epoxy mush and redrill for exactly where the fitting goes - with a substantial backup plate. It's would be a pain to cut all those pieces of matt and buildup squares of solid glass everywhere in the recore. Yes?
I really like maranti marine plywood, think it's good to bed in epoxy as a backer, and seal with epoxy too.

Some places, like under the mast, I would argue that solid core is best, no foam.

* the divinyl-cell foam I use is closedcell and very non-compressable - so one may not have to clean out holes with a bent nail and fill with epoxy and redrill for a fitting. This is after all the balsa core fix.
But I'd argue that it makes a completely rigid installation of a fitting that way. Because the bolts cannot in any way compress anything. For Instance the lever bending force that can happen with a stanchion base.

[commanderpete]

Interesting. I wonder what the specs are for different core materials.

Might be more of a concern on a larger boat with higher loads.

I agree with ebb. Epoxy plugs would give you pillars of strength.

[mbd]

I suppose I'll have at least a general idea of the location of cleats, stanchions and other hardware and can "block out" a nice sized square for solid material between the skins. But what would that be? Expoxy plus micro balloons, coloidial silica (sp?), cloth fibers, wetted out fiberglass ???

...
OK, I seemed to remember Mike G's response to "mix-ins" for epoxy and found it in Post #131 of this thread: Thanks Mike. (Still waiting on that DVD to come out.)

[ebb]

When you get over to the sheer there is some shaping of the core to do. Why not go with one o Mike's Mixes and trowel in your solids? And fair at the same time. Cabosil with 1/4" or 1/2" chopped strand would be plenty strong. even stronger if you also used flox. Wouldn't have to make squares, eg for the stanshion bases they could be half rounds. Long strips of matt for the track bolts.... etc.
Personally I'm believes in mat and cloth for unadulterated strength and you still could level things up with any mix (not micro balloons in the composite) so your top layer goes on smooth.