Deck Core Soft Spot? -a Low Budget Amateur Repair

[sparrowhawk1]

Terra Nova all valid points but how do you keep everything up?

[Lojanica]

Originally Posted by colemj

No kidding - what an amateur!

Mark

Gnarly grinding outfit. You're gonna develop allergies to the stuff then you have to hire out if you don't protect yourself better!?!

[Lojanica]

Originally Posted by sparrowhawk1

Terra Nova all valid points but how do you keep everything up?

Cialis? Viagra?

[colemj]

Originally Posted by Lojanica

Gnarly grinding outfit. You're gonna develop allergies to the stuff then you have to hire out if you don't protect yourself better!?!

One doesn't develop allergies from gelcoat dust. That is usually due to liquid resin activators. If cured gelcoat caused allergies, no one would be able to be on their boats.

I don't do large fiberglass work full-time (or even more than once a decade or so).

Mark

[Lojanica]

If doing a repair from the inside: Prep, clean, abrade, wipe with solvent, paint with epoxy (or poly or vinyl) let it setup until it is sticky but not cured (this will allow the chemical cross bonding to occur for a good structural repair and also "wet-out" the old glass.) While the cabintop resin is curing take your precut matt/glass/roving, etc and roll out between your plastic. Let this get sticky. Once everything is tacky peel one sheet of the plastic of the glass/epoxy repair material and roll onto the cabintop with a foam roller to expel air and bond. No need for anything else if timed correctly and proper glass to resin ratios. Of course all the booboos need to be filled and faired before the glass and sharp corners need to be relieved so you get a good bond.

Sorry didn't mean to jack the thread but I love repair work. I apologize for posting seemingly clever uncouth comments

[Terra Nova]

Originally Posted by sparrowhawk1

Terra Nova all valid points but how do you keep everything up?

It is much easier to keep everything up than to try to make an exterior repair invisible.

As Lo mentioned, you time your application steps so the curing process helps tack things together. And you use cauls and sticks to hold things in place during the cure.

It's not hard--even girls do it.

[downunder]

Here is a good thread on deck repair - well illustrated.

http://www.cruisersforum.com/forums/...ck-100333.html

cheers

[minaret]

Originally Posted by Terra Nova

It is much easier to keep everything up than to try to make an exterior repair invisible.

As Lo mentioned, you time your application steps so the curing process helps tack things together. And you use cauls and sticks to hold things in place during the cure.

It's not hard--even girls do it.

Problems I have experienced when executing this method-


Rot often extends over interior cabinetry or bulkheads, or is otherwise inaccessible or partially so from underneath.


Headliner difficult to remove and even more difficult to replace. Often must be subcontracted to an upholsterer who specializes in this.


Extreme masking is required to prevent dust intrusion and damage from resin spatter, grinder disc scratches, etc etc.



Using bracing from underneath provides generally poor results on anything but small repairs. I generally vacuum bag the core. Doing this overhead is a nightmare, but at least it provides perfect core adhesion with no voids or unfairness.





Some cases certainly call for this approach, but they are few and far between IMHO. Once you get good at laying out where your cuts will be topsides, the matter is often simplified. I'm sure I'm biased, because for me it is much much easier to do finish work topsides than it may be for some.

[Blue Crab]

I'd think for the average guy the timing and so forth upside down ain't happenin'.

[minaret]

Originally Posted by Blue Crab

I'd think for the average guy the timing and so forth upside down ain't happenin'.

The first time you have a "helper" kick over a pot of resin in somebodies very nice yacht interior, you begin to get a bit leery of overhead interior lamination. Especially if it's carpet...

[Hudson Force]

Originally Posted by Lojanica

If doing a repair from the inside: Prep, clean, abrade, wipe with solvent, paint with epoxy (or poly or vinyl) let it setup until it is sticky but not cured (this will allow the chemical cross bonding to occur for a good structural repair and also "wet-out" the old glass.) While the cabintop resin is curing take your precut matt/glass/roving, etc and roll out between your plastic. Let this get sticky. Once everything is tacky peel one sheet of the plastic of the glass/epoxy repair material and roll onto the cabintop with a foam roller to expel air and bond. No need for anything else if timed correctly and proper glass to resin ratios. Of course all the booboos need to be filled and faired before the glass and sharp corners need to be relieved so you get a good bond.

Sorry didn't mean to jack the thread but I love repair work. I apologize for posting seemingly clever uncouth comments

Hey, - no apology required. I've done all the methods except this one from the underside and I want the experienced plan, but I reread this and I get lost at the point where you say, "...and roll out between your plastic." ...or... "peel one sheet of the plastic..." What's this? ...are you using the term "plastic" to represent a composite coring material where I would be refering to the end grain balsa core? Help me please,- I'm just getting a little lost with this "plastic" referrence.

[Nicholson58]

Originally Posted by CaptForce

Here are some steps I've followed at little cost and moderate tools for an in the slip repair of a wet balsa core soft spot.


The final photo does not yet show the replacement of the hand rail or the final finish on the white gel coat. This is the fourth deck area I've replaced and I expect to finish with a few more selected spots.

We do this from the inside. I drill 2 to 3 inch holes with a hole saw from inside the cabin. I have found the moisture meter is more reliable from inside where the influence of non-skid, fillers, etc does not exist. I then dig out the wet stuff and keep expanding the holes pattern until I reach dry balsa.

Let it dry and then lift a saturated Fab-Mat & epoxy layer to the cabin top - very messy. We fix this patch in place with a layer of Polyethylene/cardboard/thin plywood/ & struts. When its cured, peel away the backing materials. I only use US COMPOSITES 635 Thin epoxy resin for this. No blush, slow cure, hardens clear. The former holes are now windows.

Locate the high and low points of the hollow structure. Insert a fill tube at the low and a vent at the high point(s). The vents will be close fitting press in place tubes, say 1/4" plastic. Insert vents all the way to the under side of the deck. The top of a vent needs to have a V-notch to let air out. The fill tube, likewise, will need a large V-slot. The filler will be large as your pump can connect to.

PUMP: I acquired refillable calk tubes form McMaster Carr. Fill with a slurry of syntactic foam. This is low viscosity epoxy with microballoons. Again, Us Composites 635 THIN. and their balloons. Pump the cavity full of slurry until it reaches the vents. Mix in balloons until you risk the inability to pump.

This is a totally permanent fix. It does not compromise the deck skin. It is invisible from above and once the headliner is installed, totally hidden. The syntactic foam is extremely strong. My opinion, I would never put the work into a repair of this size and re-use balsa.

A few photos are here: Member Galleries - Cruisers & Sailing Photo Gallery


Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc. One particular fringe benefit of the 635 THIN is that its very slow cure time gives you plenty of work time and you will be able to wash off with GO-JO before it sets. This is the only epoxy I use and the cost is less than any other supplier, especially We$t. I generally buy the 3-gallon kit and their mixing pump. Price has gone up. It used to be 35/gallon.

[minaret]

Originally Posted by Nicholson58

We do this from the inside. I drill 2 to 3 inch holes with a hole saw from inside the cabin. I have found the moisture meter is more reliable from inside where the influence of non-skid, fillers, etc does not exist. I then dig out the wet stuff and keep expanding the holes pattern until I reach dry balsa.

Let it dry and then lift a saturated Fab-Mat & epoxy layer to the cabin top - very messy. We fix this patch in place with a layer of Polyethylene/cardboard/thin plywood/ & struts. When its cured, peel away the backing materials. I only use US COMPOSITES 635 Thin epoxy resin for this. No blush, slow cure, hardens clear. The former holes are now windows.

Locate the high and low points of the hollow structure. Insert a fill tube at the low and a vent at the high point(s). The vents will be close fitting press in place tubes, say 1/4" plastic. Insert vents all the way to the under side of the deck. The top of a vent needs to have a V-notch to let air out. The fill tube, likewise, will need a large V-slot. The filler will be large as your pump can connect to.

PUMP: I acquired refillable calk tubes form McMaster Carr. Fill with a slurry of syntactic foam. This is low viscosity epoxy with microballoons. Again, Us Composites 635 THIN. and their balloons. Pump the cavity full of slurry until it reaches the vents. Mix in balloons until you risk the inability to pump.

This is a totally permanent fix. It does not compromise the deck skin. It is invisible from above and once the headliner is installed, totally hidden. The syntactic foam is extremely strong. My opinion, I would never put the work into a repair of this size and re-use balsa.

A few photos are here: Member Galleries - Cruisers & Sailing Photo Gallery


Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc. One particular fringe benefit of the 635 THIN is that its very slow cure time gives you plenty of work time and you will be able to wash off with GO-JO before it sets. This is the only epoxy I use and the cost is less than any other supplier, especially We$t. I generally buy the 3-gallon kit and their mixing pump. Price has gone up. It used to be 35/gallon.

How does this method address the common problem of the upper skin deforming once the core is removed? If you are replacing say 1" core, and you decore a large area of the deck from underneath as described, the upper skin is almost certain to deform, probably causing a low spot. If you were replacing with sheet material from beneath, as normal, the upper skin would be forced back into place by the process of coring. This will not happen with injection. You cannot be assured of a fair outer skin this way, on anything but very small repairs. Shrinkage of injected material when post-curing will also create deformation, particularly on thicker cores.

Wouldn't you also need to grind off all the gel, or at least prep grind for adhesion if bare, the underside of the lower skin as well, before applying your fab matt? That is a whole lot of overhead grinding inside your boat.


Aren't you also concerned that the lower skin generally has at least one ply of heavy roving or biax to achieve its structural purpose, and you have made it into Swiss cheese and replaced it with only a layer of fab matt? How does this not have a negative affect on structural integrity?




For those who, in future, insist on doing this sort of repair; you might consider using a grease gun to inject your filler and screw in zerk fittings threaded into the deck. You can inject at vastly higher pressures this way without blowing the tubes out of your deck. Much fewer voids remaining this way, though there are always some when you inject. If you go to a pneumatic grease gun with disposable cartridges and crank the air pressure to max, it's even better. But still not a pro repair.

[Lojanica]

There' a million reasons not to repair from inside the cabin but it can be done. The headliner is typically the real deal killer as is the mess inside. Sometomes it can be a good approach.

The rolling between plastic was a reference to wetting out cloth between two sheets of plastic sheeting squeezing out any excess and keeping things neat. Once it starts to cure and becomes warm and tacky just peel one sheet away leaving one wet tacky side of wetted out cloth and yu stick the wet side to the tacky cabintop and the use a foam roller against the dry plastic sheet sticking it and rolling out any air. Clean, neat, and typically no need for to much support with sticks poles tape etc.

[minaret]

Originally Posted by Lojanica

There' a million reasons not to repair from inside the cabin but it can be done. The headliner is typically the real deal killer as is the mess inside. Sometomes it can be a good approach.

The rolling between plastic was a reference to wetting out cloth between two sheets of plastic sheeting squeezing out any excess and keeping things neat. Once it starts to cure and becomes warm and tacky just peel one sheet away leaving one wet tacky side of wetted out cloth and yu stick the wet side to the tacky cabintop and the use a foam roller against the dry plastic sheet sticking it and rolling out any air. Clean, neat, and typically no need for to much support with sticks poles tape etc.

Believe the mention of sticks and poles was for supporting new core when bonding it in place, not laminate. That would be strange.