JC's secret system for filling deck-core rot

I recently posted a comment responding to a core-fixing issue on the Hunter Owners Web.  I think this is valuable for most fiberglass-boat owners to consider.  Here is the whole text.

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JC:

I filled all of the 'rotted'/'questionable'-core spots on my deck with epoxy. It's so rigid you could hold a teenagers' hip-hop dance party on it.

Once I made a mistake and began filling too close after a rainstorm. I don't know what I was thinking; but when I [pumped with the syringe] I saw that the epoxy actually pushed the water up to the surface. I was very surprised-- thought I had wandered into a really fine mess. What I found was that by continuing to inject epoxy, the ugly baby-vomit-looking water/epoxy slime that migrated upwards eventually stopped-- all the water (and not very much had ever got in) was gone and now the epoxy was doing its job, saturating to the bottom of the void and filling towards the top. The result was a deck area as stiff as any of the other places I have filled.

The only drawbacks to my system of 'drilling and filling' is that epoxy weighs more than does foam or balsa. In very large repairs the weight difference could be a problem. In my 40 years of boatbuilding experience I have never found a point at which this is a problem. The sides of a small production sailboat's cabin are just not enough volume to warrant worry about any increase in weight. The average owner's toolbox would probably negate any theoretical savings.

While it is very true that 'Water migrates very far from the point of entry' [mentioned by the original poster], it is also true that epoxy does the same thing, perhaps even better than does water. Penetrating epoxy is made to do this. I have been filling voids successfully with epoxy since I first heard of the stuff in the 1970s and the only significant mess I ever encountered was when the epoxy would not seem to stop sucking in, and more and more got pumped in with the syringe, until I happened to notice an uninstalled drawer sitting in the pilot-berth area with one whole corner full of the stuff. Through the tiny voids between plywood edge-grain and the fiberglass, the epoxy had migrated 10 or 12 feet along the flange of the boat (and fortunately found something to drip into that was more or less replaceable). To this day that part of the flange on that boat is probably the strongest hull-deck joint we've ever had on one of those boats.

I would trust WEST epoxy with any wood-to-wood or wood-to-raw-fiberglass joint with my life-- and, oh, wait-- I do; because my boat has been restored, remodeled and improved based on that ethic.

 

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A friend, Pilot, then asked me:

'Can you describe the process and the materials you would use. Specifically the typical hole size drilled the distance between holes and the number of holes for a given area. I've read other articles for epoxy injection but would like a builders take on this process.

'My boat was surveyed 3 years ago and an area around the windlass was found to have an elevated moisture level. Rather than pull the windlass and start replacing plywood core and all that's involved in that, injecting may be the solution that stems the moisture migration and solidifies the deck.

'My own personal thoughts on wet core and soft decks is, it's a distraction, and after 37 years of sailing on many different boats some that I've owned I have never seen a catastrophic failure based on moisture or soft decks.'

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So I told him (writing a veritable book into the process!):

If you know there is water present you can drill a hole-- only through the fiberglass layer(s)-- from one side or the other and then apply a vacuum hose to suck it out. This works surprisingly well-- it's the first step I recommend in fixing rotted outboard-skiff transoms. They all rot (motorboaters don't seem to care for their boats like we do ours); and this is the best way to save them. (I am doing my motor bracket's backing board the same way.) You then drill a few smaller holes, sized to fit the syringe, maybe about 3/16" or 1/4", into the top of the transom and pump in the stuff.

I used to thin the epoxy with acetone (not what Gougeon Brothers recommend; though when I told of them of this they said 'Who are we to argue with the Cherubinis about treating wood?" ) But you really do not need to thin it; as it's only doing its job by penetrating the way it does.

You might go cautiously at first, with just a little (3-5 pumps' worth?)-- it will migrate down. When it comes out the hole you drilled for the water, at the bottom, you know it's done what it should (and you know the transom was toast). Next batch, tape over the hole and after it's kicked off, go for broke and really pump it in.

For a deck, you do basically the same thing. You might drill a hole into the underside for your vacuum hose. Tape it securely to make an 'airtight' seal-- I have done this adequately enough with duct tape-- and run it till the vacuum cleaner's motor labors. For Diana I knew the deck to be already dried-out (but for a mistake involving a recent rain, as I said). Be sure to plug up or tape over any openings in the underside-- for the epoxy will definitely find them. You might station a partner below to watch for drips! --and be very wary of when you are pumping in tons of epoxy and apparently making no progress! Spots to watch are along the flange/toerail seam and anywhere silcone (or something worse) was used to bed down through-bolted deck hardware.

Topside, you drill a few holes to begin (you can always drill more if you think you have to). The best tactic is to choose a spot, maybe a few square feet and outboard (low) on the deck, drill pilot holes-- into the core only (mark the bitt with tape if you're worried, to be sure)-- near the highest border of the spot, and fill till you see the epoxy is no longer soaking down in your pilot holes. Don't make the mistake I've made too many times and go silly drilling too many holes-- when the epoxy makes it down to the lower holes you get a dribbling mess all over.

I generally make the holes about 4 inches apart; but it depends on the size of the area you are working with and how serious the rot is inside the core. In theory even rotted core is still 'there'; and epoxy will bond very well with wood or foam dust. As I said before, it is heavier than core material; but as I said too it's never been a terrible concern in the proportions we're talking about. For odd isolated areas it is a very solid, reliable, permanent fix. And if you do not get it all, the parts you do get remain strong and make a good base or boundary for you to fill other places.

If you choose to drill only in places where there is nonskid, you have only to fair over the holes and repaint the nonskid patches. For my deck, which was pretty bad, I resigned myself to repainting the whole deck (with Perfection) and I was redesigning the pattern of the nonskid patches anyway. The little indentations left when the epoxy is done flowing in can be faired with Marine-Tex or epoxy with silica gel, either of which will be rugged enough to not fall out in future and will be able to take paint (after the usual proper prep). Gelcoat, being polyester-based, will not stick well to epoxy (though the reverse is true). So in using epoxy you've pretty much given over the hope of refairing the affected area in polyester- (or vinylester-) based products.

This system should also be used any time you have to mount or re-mount hardware to a cored deck. Drill a pilot hole-- only through the fiberglass to the core-- for each mounting screw and fill it. Do the same in the area under the bit of hardware, like a winch and especially anything in compression or tension, like a padeye or halyard-lead block. When it's cured, drill through the solid-epoxy core you've just filled and bed down the part with 5200-- which will keep out water, hold like crazy especially in shear or tension, and provide needed flexibility. In many cases you will need only fair-sized fender washers with the under-deck locknuts because the epoxy block you just made can serve as an adequate backing plate, especially for anything in shear, like cleats and halyard stoppers.

I had doubts about the integrity of my hull after I rebedded the keel and so drilled a few exploratory holes into the bottom strata, between the keel bolts, to probe them with epoxy. This was supposed to be only solid fiberglass; and it was. No hole took more than a fraction of the syringe's worth. It was-- and is-- solid.

For Diana I had made a new, short little bulkhead at the back end of the cabin sole on which I stood the ladder/cooler shelf structure. I used 'high-quality' 3/4" MDO for it. Within too short a time this board was rotten from water behind it (from the cockpit-seat locker leaks), even though it had been well saturated (so I thought) before I installed it. (I blame it on using Dave's MAS and not my own WEST epoxy. MAS just does not penetrate as well; period.) Removing the bulkhead was out of the question; and it could not stay like it was. I drilled pilot holes down into the top edge of the plywood, straight into the depths of the laminations, just like I would have done for a plywood motorboat transom, and poured in the epoxy. It took three or four tries and made an awful mess (the stuff ran straight through the spoiled core and gushed out the bottom edge, finding gaps in the 5200 and dribbling into the bilge, where it glued down a stray PVC fitting that I still haven't ground completely away) but I sorted it and now it's solid.

I think this is a good solution for your [Pilot's] windlass mounting bolts. Given enough epoxy in the surrounding core, it will take the very severe shock and shear loads very well. Once epoxy has found something to latch onto-- the rough inner surface of the fiberglass deck, the rotten core, the remnants of any plywood-- it will stay in place and provide a very sturdy inner stratum through which you can drill even big bolt holes. And it takes 5200 very well, adds stiffness, and displaces all gaps that might otherwise find condensation or stray moisture. The one thing it does not do well is flex-- but for a windlass mount you had better not have much flex (let the nylon rode take the shock loads!) and a rigid deck is always stronger and thus more secure underfoot than one that moves and flexes to the point of fatiguing the glass fibers within and weirds you out when you step on something you'd prefer to feel solid.

Epoxy and wood = perfect together.  :)

Lost Star Yacht Club’s restoration-project quiz

An informative and entertaining self-examination


Anyone involved in restoring his own boat for any length of time will readily recognize the answer for each that best represents reality here!
(Note: as though you can’t guess, ALL of these are based on real-life experiences.)



The best-laid plans

Apparently, the previous owner of your boat was

1. A dedicated yachtie who kept it in pristine order
2. An older guy who let it go during the last few years he had it
3. A complete idiot

Carefully-drawn plans or instructions for your intended projects

1. Serve a valuable purpose in organizing, scheduling and budgeting the work
2. Give a general idea which usually gets changed once you start the work
3. Are likely to be left in the bathroom at home and thus disregarded in place of ‘just winging’ it when you’re already at the boat to work

Schedules and budgets are

1. Valuable guides to keeping a sense of sanity and proportion
2. Seldom absolute
3. Completely pointless

The last time you had a completely new idea about what to improve on the boat was

1. The last time you sailed it
2. Right before you began an organized plan of restoration
3. Five minutes ago

Parts catalogues will

1. Be worth browsing to what’s available and what can be ordered
2. Be important sources of ‘how-to’ information
3. Get comprehensively marked-up with underlining, highlighting, circling, arrows and diagrams as well as notes and gift hints to family members who will really never see or heed them

Tools of the trade

The average yacht restorer’s tools and supplies are stored in

1. A shiny metal rollaway tool chest with locking doors
2. A handmade mahogany-and-plywood toolbox
3. A mismatched collection of eleven (or is it twelve?) lidless containers and damp cardboard boxes, organized, if at all, in such a way that Rube Goldberg, Charles Manson and PeeWee Herman would consider it crazy

Your stepladder is

1. A new orange fiberglass one from Home Depot
2. An old aluminum one that has seen many years of dependable service
3. A really crappy wooden one that was surreptitiously ‘borrowed’ from some other guy in the boatyard

The tool vital to starting the next job will mostly likely be found in the

1. Tool box
2. Last place the tool was used
3. Bilge

Your electric extension cord is

1. A brand-new blue one, 100 feet long, 12-gauge, with a heavy-duty plastic recoiling reel and a molded-in 4-outlet box with circuit breaker
2. The two lengths of orange cord relied-upon for the hedge clippers at home
3. Possibly more duct and electrical tape than actual electrical insultation

A flashlight’s most common function is to

1. Illuminate poorly-accessible areas
2. Attack would-be burglars or wasps’ nests
3. Store dead batteries until you decide to throw them away

The usual condition of the average cordless drill/screwdriver’s batteries is

1. Both at full charge as soon as possible
2. The one in the unit dead, the other one charged and waiting in the charger
3. The one in the unit dead, the other one, which died last night, nowhere to be found

Wood plugs are frequently sealed in the screw holes using

1. Weldwood wood glue and an overnight drying process
2. WEST epoxy and an acid brush
3. The varnish, when you noticed the missing plug(s) right after you started to brush it on

Your boat-work shoes are

1. High-quality leather moccasin-type deck shoes
2. Sturdy, sensible work boots
3. A pair of ripped, stained and punctured CVOs with the soles completely blown-out or held together with duct tape; and your wife wonders why on earth they are still in the house

Rubber gloves and dust masks are

1. Essential, for safety and hygiene
2. Frequently necessary for really ugly jobs
3. Unheard-of

The procedures

You tend to have help in this project

1. Most of the time
2. About half the time
3. Pretty much never, unless you count the times when somebody from the yard comes by with a beer and talks while watching you work

‘Cutting corners’ in quality is

1. To be avoided
2. Sometimes necessary
3. Totally acceptable, so long as the task gets done

When you encounter a necessary task involving an area of expertise in which you have no experience, you will

1. Seek help from an expert
2. Read up on the procedure and treat it as a learning experience
3. Get out the tools and epoxy and start doing it

During a restoration, the bilge usually contains

1. Dirt and liquids, till they are cleaned or pumped out
2. Hoses and wiring that would be unsightly if run elsewhere
3. Wet pencils, locknuts and expensive electrical connectors you thought you mislaid and have had to buy again

When working on the boat, trash is

1. Stuffed into a 5-gallon paint bucket which is emptied at the dumpster each evening
2. Brushed into a corner of the cabin sole or cockpit
3. Pitched out the companionway hatch at the spur of the moment; and may God have mercy on the poor people who may have stopped below to look over the boat

Some of the fiberglass lay-ups in your boat may contain

1. Small air bubbles
2. Dust or wood chips
3. Sandwich lettuce, Dr Pepper and your blood

When installing fittings on spars, you will use

1. One thread tap, carefully maintained with oil
2. Maybe two or three taps
3. So many taps that you must make the 20 minutes’ trip from the boatyard to the auto-parts place several times a weekend

When you are kneeling or balancing on hull timbers to install new cabin-sole panels, the electric drill that gets in your way will most likely end up with the point of the new spade bitt in

1. The bilge
2. Some finished woodwork
3. Your leg

The usual procedure for electrolytically isolating stainless-steel fittings from aluminum spars involves

1. Applying nonconductive thread-locker liquid to the threads
2. Smearing both sides with white lithium grease
3. Sticking a piece of white electrical tape under the part before screwing it down

When cutting plywood outside, the rain will begin

1. The moment the pieces are cut
2. In the middle of the job
3. As soon as you have run the extension cord, clamped down the part, and switched on the jigsaw

The most valuable application of white Krylon is for

1. Gas grilles, bicycles and outdoor furniture
2. Models made of metal parts
3. Anywhere you neglected with Durawhite, Bilgekote, or Awlgrip when it’s time to put the boat in the water

When cutting Plexiglas, the typical experience will involve

1. A slow, clean cut with the jigsaw
2. Easily peeling off the protective paper backing
3. Having the blade get stuck in the middle of the cut when the material melts itself back together and then using hacksaws, grinders or lots of sanding to ultimately finish the part

When cutting G-10, you should use

1. A brand-new, fine-toothed jigsaw blade
2. An old blade that is almost ready to be thrown away anyway
3. Someone else’s blade (and saw)

With the spars out of the boat, the usual procedure for reeving new halyards involves

1. Carefully ‘sewing’ and whipping the braided messenger line to the new halyard
2. Tying the messenger line to a paperclip ‘buried’ into the new halyard
3. Hastily wrapping the messenger line to the new halyard with about half a roll’s worth of electrical tape

The 5200 is usually applied

1. In assemblies that must hold out seawater and are not likely to be dismantled in the regular course of maintenance
2. For anything and everything that goes together
3. All over the cabin sole, your knees, the clipboard, most of the tools and half of the sub sandwich you had intended to finish

The usual disposition of an unfinished tube of 5200 is to

1. Cap it so it stays airtight and store it in a cool dry place
2. Stick a machine screw down the nozzle and wrap tape over the end
3. Leave it where you last used it and expect to throw it away next week after the remaining half has cured in the tube

When painting decks or soles, the usual experience involves

1. Careful planning so that you can work from a ‘wet edge’ in painting from one end to the other
2. The occasional oversight requiring that you lean over wet paint to reach neglected dry spots
3. A completely disorganized nightmare involving spills, runs, blots and numerous opportunities to wear your work home

When the tarp that covers the boat needs to be changed, the wind will pick up

1. As soon as the new tarp is tied down
2. As soon as you arrive at the boatyard to do it
3. As soon as you get the old tarp stuffed into the dumpster and begin spreading the new one over the cabintop

Your primary motivation for doing painstaking work is one of

1. Interest in the value of your investment
2. Concern for the durability of the boat for the future
3. Pride, to demonstrate your superior ideas and craftsmanship

After-work bathing typically entails

1. A long refreshing shower
2. A rush to finish and get on to other tasks
3. Dishwashing liquid, Fast Orange and Scotch-Brite to remove all the paint, 5200, epoxy and resin from your raw skin

Beat the odds

The likelihood of damaging or dislocating a seacock is inversely proportionate to

1. The cost of the seacock
2. The importance of the supply line attached to the fitting
3. The need to replace it

The likelihood of drilling a hole through a spar or bulkhead and breaking into a length of electrical or plumbing conduit is inversely proportionate to

1. The cost of the conduit
2. The importance of the hole you’re drilling
3. The amount of time left before the Travel-Lift comes

The likelihood of tossing a screwdriver up into the boat and damaging something is directly proportionate to

1. The cost of the screwdriver you toss
2. The proximity of the object it hits
3. The amount of work you put into what it hits

An example of an unexpected negative correlation may exist between

1. The quality of the varnish job and the cost of the foam brushes
2. The cost of a VHF radio and the time it takes to receive it from the supplier
3. The time and effort you take to install the paper-towel holder and the importance of the paper-towel holder to the overall project

The costs

The way to really recognize a yacht owner who is performing his own work is by

1. His smile of sublime satisfaction at the launching banquet
2. His nearly-empty wallet at the end of the weekend
3. The 5200 under his fingernails at church

One of the most humiliating things about taking so long to restore your boat is

1. Your friends’ nagging impatience to go sailing
2. Paying 12-month dry-storage contracts
3. Discovering that the state-of-the-art CD stereo system and FireWire computer network you installed 4 years ago have become obsolete before you got to use them

One way to be sure you’ve spent too much money on parts is by

1. The smiles on the faces of the staff at West Marine
2. Your wife’s interrogation about the Visa bill
3. The way the UPS guy, who is not a yachtie, is on a first-name basis with your dog and knows all about the product lines carried by Defender.com

The Bible verse that may best approximate the current status of your restoration project is

1. Hebrews 11:7 (‘By faith Noah, divinely warned, built this ark to save his family’)
2. Ezekiel 15:3 (‘Is wood from this tree fit to make anything useful?’)
3. Luke 14:30 (‘This man began to build, and could not finish’)

Life lessons learned

One thing you’ve found out about yourself that you never expected is that

1. You’ve learned many new things and gained a priceless experience
2. You have physical strength and stamina you didn’t know you had
3. Falling sweat actually splashes

By now you are convinced that marine-toilet plumbing should be

1. Replaced every three years
2. Replaced by every new owner
3. Made of heliarc-welded and polished 3-inch schedule-40 type-316 stainless-steel pipe and never changed at all

One maintenance cycle you did not expect to need to know is that

1. Bottom paint, no matter how old, should be reapplied within two weeks of launching
2. Spars should be removed and inspected every three years
3. The screw threads on jackstands should be oiled annually

When your restoration project is complete, you will know your boat

1. Better than most yacht owners know their own boats
2. Enough to trust it in nearly any conditions
3. More intimately than you know your wife

Your restoration project has taken

1. More or less the amount of time you expected it would
2. A season longer than you expected
3. Several years longer than you expected

The one most likely to perform future major maintenance and repair on your boat is

1. A trusted yacht-service facility
2. The next owner
3. You

When the boat is finished