Soft deck repair

[sv lark]

So I'm psyching myself up for some deck repair. I have a 40 year old Ericson 36 sailboat and the poor old girl has several rather squishy spots on deck. This will be my first foray into deck repair and glass work of any kind. I'm posting here to ask for help planning how to tackle this thing.

Here is the basic approach as I understand it:

1. Find the extents of the affected area by tapping and listening for where it goes from a nice clean knock to a dull thump.
2. Cut around the area with the blade set shallow enough to only cut through the top skin.
3. Clean out the soggy core down to the inner skin.
4. Sand and clean the inner surface.
5. Dry fit new core.
6. Wet the inner skin with resin.
7. Fit the core into place.
8. Weight it down with sand bags until it cures.
8. Cut glass mat to cover the core.
10. Wet the new core with resin.
11. Lay the mat down.
12. Thoroughly soak it with resin.
13. Sand and paint.

Is that basically correct?

My equipment and supply list for this project is:

- core material
- mat
- resin, hardener, filler
- mixing containers
- painter's coveralls
- shop vac
- orbital sander
- skil saw
- extension cord

Anything I'm missing?

I'd welcome any pointers to other good resources or threads on the topic and any other advice you could give.

Thanks so much!

[Lepke]

You need rollers to saturate the mat. There are several sizes for length and diameter. Cut the cloth to fit, pour some resin under the cloth, roller the cloth to force resin up thru the cloth and add more resin on top to fully saturate the cloth. Cloth appears clear when fully saturated.
When making the hole, bevel the sides as much as reasonable, so your resin has a bigger area to adhere to. The core needs to fit tightly to the deck so the deck is supported. If you have a foam core, there is a 2 part expanding foam. It comes in various densities. If you do a foam core repair, you mix enough to expand out the hole, cut and sand off the excess and you have your base for resin and cloth.
Your deck was probably several layers. At least one should be RSM (random strand mat) that gives strength in all directions. Each layer/cloth or mat will be slightly larger because of the beveled edge on the hole. If you can do all the layers in the same day you get a chemical bonding that is better that the glue effect when you epoxy to fully cured resin.
Use epoxy resin, not polyester. Polyester resin doesn't stick well to anything, including itself. I use West System because of ease of mixing a proper ratio and reliability, but there are several good epoxies. Most have hardeners for different temperatures. Use the correct hardener. Fast hardener in hot weather can harden while you're mixing it and get extremely hot.
Acetone for cleanup and disposable gloves. Clean you resin rollers right away and they can be used many times.

[minaret]

First step: map out your repairs. Determine the extent of moisture, by purchasing a good moisture meter and/or hammer sounding and by taking core samples from beneath if possible. Once the full extent of the problem or problems is determined, you can plan your method of attack. If possible, make all your cuts at least 2-3" inside of the non skid. Depending on your nonskid layout, you can often do the whole repair making all cuts and glass work only on skid pads. This makes finish work dramatically easier, and can affect the decision as to which materials to use. This approach will often require you to make cuts in the top skin and then decore sideways to remove wet material under a waterway or along the deck edge. It is worth doing this way. Map it out with chalk and then post pics if you want better advice.

[sv lark]

Thanks you guys.

I'll add rollers, acetone, and gloves to the supply list.

The core is balsa, 3/4 inch (I think) and the skin is maybe an 1/8. So how do you get a wide evenly tapered bevel into 1/8 with any consistency? Is there some tool or technique for that or do you pretty much just eyeball it? Can I use the expanding foam to replace that balsa (just because it sounds a bit simpler) or is it important to use balsa again?

I've seen references to a type of mat that's woven on one side and random on the other. Is that something I should be looking for, or just the random? About how many layers of mat will I be able to lay to get that 1/8 inch thickness? Just one or two right?

Since this is July in Florida, I guess I'll be looking for a slow hardener then.

How far can you practically go sideways with the decoring? I imagine it will be tricky to adequately clean out and prep surfaces more than an inch or two in? When replacing core between intact top and bottom skins how do you get a solid bond between the new core material and both skins? Just weight from above?

One of my biggest concerns has been about having the skin open and edges of good core exposed to the elements for too long with our frequent summer rain squalls here. I talked to a guy who said that I could have it all sealed within a couple hours of making the first cut in the skin. Should it be possible to cut the top skin, clean away the core, and then quickly coat all the exposed edges with the resin in a matter of a couple of hours? Would the good core be safe then?

The next vulnerable stage would be waiting for the bond with the new core and the bottom skin to set, with the top surface of the new balsa core open to the elements. Is there anything I can do to mitigate the risk of rain damage there? If I give the top a quick coat of resin as soon as it's in place would that do the trick?

I'm imagining doing this one spot at a time and a few steps at a time to try to keep it manageable for noob like myself. I'm imagining going from the first cut through to sealing up the edges of the good core in one work session; cleaning out all the rest of the old core and prepping the surface of the bottom skin in another session; putting in the new core and resin in a third session; doing the mat work in a fourth session; and finally sanding fairing and finishing in 2 or 3 final sessions.

Does that seem like decent plan or am I overlooking things?

[UNCIVILIZED]

1) This has been covered about 1,000 times on here, so searching will yield loads of info.

2) It's also covered in depth on the websites of any of the major epoxy manufacturers, & they have LOTS of free downloadable info. As well as videos on How-To.

3) Epoxy & mat aren't the most compatible, as it doesn't possess the proper chemical components to break down the styrene in Mat. Thus, the Mat never gets to perform it's function as a "tie coat" properly.
Both between layers of glass cloth, or roving, or in terms of connecting the new core to the new structural skins.
(Mat has crap for structural properties, as compared to other types of glass; stitched axials, or woven cloth. Especially so when it's not used with the resins which it was formulated to work with).

Epoxy, & if utterly necessary, Epoxy with a Structural Thickener, will bond far better than Mat, when it's used properly,. To any core material that is.
Mat is something of a hold over from the Polyester resin days. Although it's still used with said resin, & also with some Vinylesters.

4) To get a proper bevel on your deck skins, measure out & Mark On Deck, an 8:1 distance (based on a Measured skin thickness). Use tape, like the blue painter's stuff, as well as a magic marker to do this. And a bigger bevel is actually far, far better. Like 12:1 or more, so that each successive layer of reinforcement added atop the one below it, has more area to bond to the current deck skin.
- Needs be, it's wise to use a protractor (compass) to mark off how wide to make your bevel, before then marking it's edges with a magic marker, & tape.

5) You might look into vacuum bagging the layers down, in lieu of sand bags, especially both; when you first lay in the core, plus, for the first couple of layers of glass atop it. Just don't forget the peel ply, if you bag things until they're fully cured. Thus, you won't need to worry about removing any amine blush.

6) You needn't do all of this repair in one shot, or even one day. You can build a small dam system on deck around the area to be cut open, such that unless you get inches of standing water on the deck, the cut open portions wont get flooded.
Assuming that you also cover them with some duct taped down plastic, as well as have a good tarp system overhead. One which extends several feet beyond the area being fixed, on all sides.
- With 3 layers of protection like that, you should be good, knock on wood.

Also, not to overly judge, but given that you're at the dead vertical part of the composites learning curve, you'd be much better sticking to using cores in sheet form, rather than playing with 2-part, DIY structural foam.

Do some searches here. Read on the epoxy websites. And watch a few vids. It's not rocket science, & hundreds before you have done it successfully. Plus, if you goof, you can always break out the grinder, remove the error, & start over.

[sv lark]

Thanks for the response.

I haven't seen anything elsewhere about building a dam on deck but I like the sound of that. Can you point me at any resources on that? I wonder what you could build that would have a watertight bond with the deck but then come up without damaging it after the repair. Some kind temporary caulking material maybe?

The part about the bevel that I don't get is how to get it to taper evenly. Or is it not important for it to taper? Is there any reason to stop at 12:1 or should I just go ahead and go 6 inches all the way around?

Are you saying that I should not use epoxy then? Or not use mat? Or not use either? What should I use instead?

There really are thousands and thousands of sources on this stuff, aren't there? And what one source says the next will contradict directly. My problem is that after the searches I've done, the manufacturers' sites I've read, and the vids I've watched, I'm now struggling to figure out what's correct and what's not and what's relevant to what I'm trying to do.

Are there any of the multidude of resources that you could recommend in particular?

[Nicholson58]

We repair from inside. This way the deck surface in not disturbed. Its messy & dirty but you will not be re-building the fine exterior or re-painting. Time to complete about ten sq feet is about 6 days.

Materials:
US Composites 635 THIN epoxy resin.
Heavy FAB MAT or other thick structural cloth. Ours is 32 oz
US Composites - 3-M microballoons
McMaster Carr refillable calking cartridges
3-inch hole saw with SHORT center drill
Plastic polyethylene film; corrugated cardboard; 1/8" crappy plywood (or other junk planks); 1x1 sticks.
small flap wheel grinder
Junk paint brush - 1"
Screwdriver & various probes of convenience.
Moisture meter (Kinnetics)

Remove headliner.
Use the meter to identify the wet balsa from the inside. Fillers in the deck may fool the meter.
Use the hole saw to remove plugs of fiberglass.
Use the probes to dig out the wet balsa
Widen your area until you run out of wet wood.
Use the grinder to rough up the remaining glass
Carefully cut the plywood to be the exact size of your patch covering the excavation and holes. More than one patch is OK
Cut the glass cloth to fit the patch.
Cut an oversize sheet of heavy PE film.
Cut the corrugated cardboard to fit the patch.
Assemble the patch: Plywood; cardboard; PE film; glass cloth
Pre cut the 1x1 into struts to hold the patch in place. Be prepared to wedge the struts in place to apply pressure to the patch.
THE EXCAVATED AREA MUST BE DRY
Mix the 635 THIN resin and apply by throw-away brush.
Lift the wet mess in place and add the struts. work the struts to deform the patch to the hull for a good fit.
Wait two days and remove the struts, plywood, cardboard & film.

YOU will see the 3" holes as perfect windows
Find the lowest and highest points. You will need to find some rubber hose as short as possible to duct the filler into the void. The hose need to fit the end of the calking tube. Cut a V-Notch in the hose end and drill a too-tight hole in the high & low points. Press fit the notched end of the hose into the cavity through the holes. The low is for filling - the high is for venting. If your area is large you may want extra fill & vent.

Mix resin. The 635 is excellent for this because it is low viscosity and long cure time. Fold in as much microballoon to the mix as you think you will be able to pump. I had a helper refilling while I pumped. Pump into the cavity and observe the resin front fill the cavity. (remember the windows!!). When your cavity is full the last of the air will be discharged from the top of the most distant and high vent.

635 resin can be hand washed from your skin with FAST ORANGE as long as it has not begun to cure.

Compressive strength of the syntactic foam mix is about 3000 psi. This is both stronger than the original structure and will never hold water again.

[UNCIVILIZED]

Originally Posted by sv lark

Thanks for the response.

I haven't seen anything elsewhere about building a dam on deck but I like the sound of that. Can you point me at any resources on that? I wonder what you could build that would have a watertight bond with the deck but then come up without damaging it after the repair. Some kind temporary caulking material maybe?
For building a WT perimeter around the area on deck, you needn't use anything high tech or pricey. Some cheap wooden batten stock, silicone, & modeling clay. Any low strength, water tight adhesive, that's easy to clean off of the deck afterwards.

The part about the bevel that I don't get is how to get it to taper evenly. Or is it not important for it to taper? You DEFINITELY want a taper, & a pretty even one at that. And you can build jigs to enable some tools to cut such things precisely, but unless you're literally working on high tech, CF aircraft, experience & hand eye coordination work fine.

Although the use of a protractor to precisely mark out the edges of your bevel is a good tool, regardless of how much experience you have.

If you want some practice, epoxy saturate some scraps of (thin) pieces of plywood in resin, & do the whole marking off of a bevel, & grinding it, on them. Just use quality plywood, with as many layers per inch as possible. That way, it's easy to see how you're doing in terms of evenness of your bevel, via the lines due to the layers in the plywood.
- Or if you want to get fancy, make up a practice fiberglass laminate, using multiple layers of cloth, with different colors of pigments in the resin in every layer of cloth or three. BTW, Polyester resin's fine for this. Plus cheaper. Just use finishing resin on the outside layers.
That way, it's REAL visible as to how good you are with the grinder.

Is there any reason to stop at 12:1 or should I just go ahead and go 6 inches all the way around?
You can go with an even fairer bevel if you like. For instance, 20:1 is the recommended minimum for CF laminates. But there is a point of diminishing returns.
Basically, you want each layer of cloth which you're gluing down to have it's own bonding line/area to adhere to. And the higher the load/the stronger the material, the more bonding area you want, within reason.

When laying on your new reinforcements, when working from above (on deck). You want to pre-cut (and label, with witness marks on the glass & deck) your reinforcements so that each piece is slightly larger than the piece underneath of it.
Such is pretty well illustrated in the WEST System repair & use guides.
Thus, each layer has it's own, individual bonding area to the deck, around it's perimeter.

Are you saying that I should not use epoxy then? Or not use mat? Or not use either? What should I use instead?
Epoxy is the way to go, definitely. Especially as, depending on a lot of variables; present day, & when the laminate was first laid up. It can be tough to get a good bond using Polyester to repair Polyester.

As to Mat, I'm just not a huge fan, as it's more difficult to handle when wetted out than other types of reinforcements. That, & to get it's binders to properly dissolve, you need to use Polyester or some types of Vinylester resin.

Also, you may have noted, including in your own description of the sequence of a repair, that the use of Mat isn't always listed as being laid down underneath of the core, on top of the deck's inner skin. And yet, it's mentioned as being used on top of the core, prior to laying on any glass/real reinforcements.
So then Epoxy is good enough to bond the core to the deck skin on the bottom, but not the top? Flaw in logic somewhere there, me thinks.

IMO, wetting out the inner skin with neat (un-thinned resin), followed by a layer of troweled on, slightly thickened epoxy should do you fine. That, in addition to wetting out the core with a layer of neat resin, also.
- Then, when laying on the deck skin on top, just do the same, only, more or less, in the reverse order.


FYI: If you're using say Polyester resin, then you have to also get into juggling the whole Laminating, Finishing resin thing. Plus precise catalyst mixing ratios. And a number of other chemistry & environmental things rarely known, let alone mentioned. Even in the resin's product literature. The literature targeted towards geeks, not what you get with a can of Bondo or similar.

There really are thousands and thousands of sources on this stuff, aren't there? And what one source says the next will contradict directly. My problem is that after the searches I've done, the manufacturers' sites I've read, and the vids I've watched, I'm now struggling to figure out what's correct and what's not and what's relevant to what I'm trying to do.
Go to the WEST System site, & download their user guides, in addition to their book On Boat Construction. And maybe read up on a few of the projects of this type, on their site, which folks have done. And if you run into trouble, get a hold of them.

But bottom line, 99% of the info you'll need is in their use guides. And anything else should be findable in the book On Boat Construction. - Free for download, via their site.

It sounds like the confusion that you're running into is caused by;
- Information overload
- A multiplicity of epoxy based products out there which didn't exist 20yrs ago, & that you don't really need for this project. Including the user guides for them, & projects that guys have done with them.
- Guys doing projects with some of the newer products out there, which may/will, in the right hands, make things easier. But one needs the expertise in order to know which of them to use when, & how to use them in those circumstances.
- Info out there which is just plain wrong, & or incomplete. Such as folks using Mat with Epoxy, & suggesting such, without the mention of, or knowledge of the chemistry of the two.
- A plethora of other examples of partial information, & or misinformation out there.


Keep your project KISS. And in the grand scheme of things, it wouldn't be that costly to build a mock up panel using the same materials which you'll be using for your repair... From scratch/start to finish.

Are there any of the multidude of resources that you could recommend in particular?

Ah, to make things simple for yourself, print out 2 copies of the WEST System guides. Making notes on your "shop copy" to yourself (in multiple colors for clarity, needs be), & keep them on hand when you're doing the project.

Including breaking down things into a series of steps which you yourself can handle. As well as practice a time or two, with the materials (dry, no epoxy involved) a time or two first.
AKA, literally do a couple of dry runs. You'll be saving yourself time & $ in the long run. Plus you have to trim your reinforcements fairly precisely anyway. And, it gives you a chance to both think things through, as well as working out any kinks in your process, prior to mixing up any resin.

NOTE: Wear gloves when you're handling, & trimming your reinforcements, as well as the cores. As sweat & body oils Do get onto, & have some effect on adhesive properties.


PS: You now owe me dinner & the bar tab, @ say Davis's Pub in Annapolis (East Port).

[UNCIVILIZED]

Nicholson58,
Not everyone enjoys working upside down, taking epoxy showers while wearing plastic clothes, gloves, & Shower Caps. And more importantly, has the luxury of having headliners, to cover up any of the sins of re-construction ;-) afterwards.

That, and grinding off, & then re-molding in upside down, pebble grained headliner. Followed by doing a perfect gelcoat match to it's nearby gelcoated, sister panels, AFTER fixing the core & structural skins, is a Bitch!

BTW: On the more serious side. Isn't betting the farm, on one bond line of resin, using 32oz cloth a bit dicey? Especially sans significant pressure holding it in place, relatively speaking, throughout it's cure.

Vacuum bagging a full fix in one shot (& even infusion) is a lot simpler & tidier. To say naught of the lack of below decks fumes.

[colemj]

Having done a bit of core replacement, the ONLY reason I could see to address the problem from below is not wanting to cut away and replace teak decks.

10sq feet/week? You can recore an entire deck and cabin in that time from above.

I don't see any problem with a single layer of Fabmat - particularly on the inside skin and bonded across the holes in the picture.

Mark

[Sailorman Ed]

Lark,
I am starting my decks this WE (already completed all the vertical/sloped walls) and I will post some pictures next week.
Both Nickolson and Unclivilized have given good advice but completely opposite sides of how to do this. Doing from underneath makes the deck finish much better but is a lot harder to do.
Couple of suggestions:
Get a bunch of Cool Whip tubs for mixing and as soon as you empty one tub, give it 3 pumps of resin wo hardener and mix it around, will keep it from hardening for hours.
Buy a box of 1" chip brushes from Harbor Freight.
Be sure to have some Cab-O-Sil (fumed silica) and I would suggest 1/4" chopped fiber for strength. I ended buying the gallon size from Noah's (nice people).
Get a bottle of vinegar, much safer for your body than acetone and works just as well.
Get some butyl caulk if you want to use the "dam" approach, easy to use and to clean up later.
Depending on your area, buy a larger size of resin and hardener than you think you need. Mix in smaller batches and spread it out as soon as you can mix it so it sets up slower. Once it starts to gel, put it aside and do not use it. In FL, you will not have much time.
Get ALL of the questionable balsa out, even the stuff that looks OK but probably is no longer bonded well to the inner or outer skin. Be brutal. I used balsa for the walls but will be using Dyvinicell foam for the decks. Appox 2' x 3' wall panels took me about 1/2 day each but most of the time was because I formed them with the window cutouts. Heavy PE film is your friend. I used large 2-3 mil bags, cutting correct size pieces as you need them. The thinner film will not strip away as easily. Note that when doing some thick sections in the sun, it got hot enough to melt the PE film right into the cured epoxy - tough to grind back out!
And like Uncivilized suggest, practice on something first.
Good luck!!
Ed
oh, and start at sunrise.

[sv lark]

Nicholson, thanks so much for that suggestion. I really appreciate you giving such a specific and detailed procedure. Because my soft spots are inaccessible from below without dismatling a bunch of stuff inside, I think I'll be better off working from above. I sure wouldn't be worrying about the rain if I did it your way though.

Thanks for info on the dam, Uncivilized and Ed. I think I will definitely do the dam for my spots on deck. I have a spot in my cockpit floor that reaches right to edge where the surface rises vertically to the cockpit seat. A dam won't work there, but I'd still feel a lot better if I could protect the edges of good core once it's opened up. For that, would it work to immediately get a coat of resin onto the exposed edges as soon as the top skin is off and the bad core dug out? Would that be sufficient to keep things dry for a few days as the project progresses?

Do you know of any videos or illustrated write-ups where they demonstrate the putting in the bevel? I'm just having really hard time getting my head around how to make a smooth taper across something that's only 1/8 inch to start with.

I understand what you're saying about the layers and each having its own bonding area. I like the suggestion about the witness marks.

If not mat what's the best choice with epoxy?

I'll definitely go get On Boat Construction as soon as the West System site is back up. Thanks for that pointer.

I think you're exactly right about the sources of confusion for me as a neophyte. Thanks for understanding.

Thanks so much for your help, and it will be my pleasure to pick up the check at Davis's if I ever have the misfortune of drifting that close to DC.

Ed, what's the Cab-O-Sil and fiber for? Thanks so much for all your tips as well. I will most definitely plan get an early start.

[Nicholson58]

I do encourage you to lurk about on the US Composite site. As I noted above, they have all manor of reinforcements, glass, Kevlar, Carbon fiber, Microballoons. I have used many epoxy resins and I have settled on their 635 THIN Epoxy :Â*Epoxy Resins and Hardeners for all major repairs & layup. Lower cost than West or MAS. Better wet-out. Long work time - hours. Easy cleanup with Fast Orange hand cleaner. No amine blush so you can re-coat without issues. If you can make it work for you as filler, consider the microballoons in 635 THIN epoxy as the filler instead of wood, foam or balsa. USC also sells WEST if you insist.

In my Rudder rebuild, (below) I mixed two 4-gallon pails of balloons and 3 gallons of epoxy using a large drywall paddle with my 1/2 inch drive drill in two 5-gallon buckets. It look like Kraft marsh mellow cream. As filler, I poured it up to 5 inches thick into my rudder mold. Total 30 gallons. Cure is 3-4 days so no heat problems. Density is low and strength is high. ALSO totally waterproof. It can be sanded and faired with a right angle grinder or flap wheel grinder. The mix pours slowly and feels dry to the touch so its easy to handle. As it lays in your form it will eventually wet out the contact surfaces and bond well. It will flow slowly into every crevice. If you can pour in and form with PE film & plywood; dams where necessary you might find favorable results on mostly horizontal pours.

[sv lark]

Thanks Nicholson. Lower cost and slower cure sounds good. I'll check it out.

[UNCIVILIZED]

svlark,
I'm bowing out of this thread, as my time, explanations, & expertise, are going down a bottomless hole.
Specifically, your repeatedly placing roadblocks in the way of solutions to (easy) problems for which the answers to same, have already been handed to you.

Ask WEST System for the full (print edition) article below, & they'll likely send you one (online & or via snail mail), especially including all of the illustrative pictures in it. Replacing Damaged Balsa Core | Epoxyworks

- BTW, the above info literally took 30 sec online to find (IF that long).


I wish you luck with the project. But offer up this last tip, in the interests of safety.
When a boat gets swamped/pooped, several thousand pounds of seawater can wind up in the cockpit. So if repairs in said locale aren't done properly, then the sole could collapse, possibly with dire consequences. Especially if there are other big seas about.


Nicholson58,
Sweet rebuild on the rudder. Such strikes me as a FAR better option, than the (sadly) "standard" foam job.