Water from bilge infiltrating keel with encapsulated ballast

[chris95040]

Originally Posted by minaret

Nobody is debating that epoxy will generally provide a superior bond on most substrates. What I had a problem with was your statement that a poly repair is "likely to fail". Properly done poly laminates have more than sufficient bond strength, without any of the numerous drawbacks of epoxy. Vinylester is sometimes superior to epoxy for bond strength. The current boating world is IMHO doing itself a disservice with a focus on epoxy for repairs. Poly work is not voodoo magic, and has much to recommend it over epoxy. Don't know why people fall for the "user friendly" line, either. A bit of study and effort would show you that some basic poly layup and gel coating skills would stand them in much better stead. I am actually teaching a class this winter.

I never said "likely to fail", I just jumped in mid convo to point out/verify that epoxy makes a superior secondary bond to old polyester, compared to polyester on old polyester.

[minaret]

Originally Posted by capt jgw

For just filling a void like this polyester would work. For laminating fiberglass onto an existing hull polyester does not work so well. It is not a very good glue and the patch might not hold. The fact that the boat was originally made with polyester doesn't have anything to do with it. The original lamination was done pretty much all at once and it is a homogenous matrix. Poly is fine for that, but putting new glass onto old, not so much.

OK, "not a very good glue and the patch might not hold" sounds a whole lot like "likely to fail".

[minaret]

Originally Posted by brantleychuck

Thanks Mineret, I got it now. Going to give the technique a try in a couple months


Sent from my iPad using Cruisers Sailing Forum

Don't forget the vent hole, grease guns can produce thousands of psi with a zerk fitting!

[chris95040]

Originally Posted by minaret

OK, "not a very good glue and the patch might not hold" sounds a whole lot like "likely to fail".

Yeah those aren't my words either, but that doesn't matter. The fact is about 80% of that guy's paragraph was correct, so you're "Just not true" response could end up misleading folks trying to learn about this stuff. Not trying to bust balls.

[Don C L]

OK, so a question to all: My friend's boat had a number of shallow blisters, but it has three that are quite deep. The glass has not appeared to be widely saturated, just pockets that fill and separate certain layers. I was thinking of drilling into the blisters (about 3 in. diameter) top and bottom, injecting a baking soda solution, followed by acetone, followed by epoxy resin, rather than grinding them out and reglassing the whole area. (The glass is strong around the blister and not soggy.) Good idea or bad idea?

[coastalexplorer]

I just looked back in here and am surprised to see that my quibble about people viewing Epoxy Resin as such a miraculous material stimulated so much debate. The fact is that there are some materials that epoxy resin will not adhesion to. and one of the most common is plastic. My boat is built from millions of little pieces of wood held together with Epoxy resin so I have to pay out hugely and use the stuff.

During the manufacture of Glass reinforced Polyester resin boats: they are usually laid up with un-waxed resin so that each successive layer will adhere to the previous. IF the manufacturer tried to lay-up the entire hull thickness in one shot: Especially on a large hull the chemical reaction could set the whole mess on fire. and I have put out a catalyzed resin fire in a boat building shop.

For the last coat a liquid wax called 'air dry' is normally added to stop the inside surface from feeling sticky. (During the heat build up from the chemical reaction this wax melts and rises to the surface thus excluding the air.) If this is done: All areas of internal attachment are 'scuffed up' with a soft grinding disc on a mini grinder, to remove the wax and expose the raw top surface layer of the glass reinforcing which is often somewhat porous, to which the additional resin can soak into causing a very strong bond.

An alternative to this I have seen is to attach the interior to the un-waxed lay up and then spray; or selectively hand brush, waxed gel-coat internally.

Thus IF you have to do a repair or modification, scuff the area with a grinder. (protect your skin while doing this) Make absolutely sure it is dry. and then commence laying up the repair by applying resin first and then rolling the glass mat into it. So that the puddle of resin rising up through the mat or cloth expels all the air. Pre-wetting out glass on a board and applying it as a wet mass/mess is not the usual way professional boat builders do it. Though perhaps when working in awkward places this has some merit for the Do It Yourself owner. Be careful to exclude the air. IF it looks white it has air in it and is weak.

In closing my Father worked at the British institute of Oceanographic Sciences. Where they used GRP tow fish filled with urethane foam to carry transducers deep into the ocean. At these depths and resulting pressures water would eventually saturate the foam and make them too heavy. So they spent several million pounds on a research project experimenting with ways to remove the water. Including building the foam cores with passages to blow hot air through. Or attaching electrodes. Nothing was successful and the conclusion was that they should be considered a disposable Item. So the ultimate real answer to the OP's problem is probably to make a new keel casing. or radically rework the existing.

[JMK]

So the final plan from the FG guys is to dry out the area as much as possible over the next few months then repair with Core bond and cloth/mat with vinyl resin. For the inevitable water incursion into keels with this type of construction we will install two Perko garboard plugs port and starboard at the base of the keel where it looked like most of the water ended up draining from so that I can empty any more accumulations during future haul outs. Not cheap, but it preserves the integrity of the hull.

[HappyMdRSailor]

Originally Posted by minaret

OK, "not a very good glue and the patch might not hold" sounds a whole lot like "likely to fail".

Maybe I can help him minaret...

If one has extensive experience with "patches failing" I suggest that the polymer utilized is completely irrelevant...

Maybe you need to glue your corners down better???

[minaret]

Originally Posted by coastalexplorer

I just looked back in here and am surprised to see that my quibble about people viewing Epoxy Resin as such a miraculous material stimulated so much debate. The fact is that there are some materials that epoxy resin will not adhesion to. and one of the most common is plastic. My boat is built from millions of little pieces of wood held together with Epoxy resin so I have to pay out hugely and use the stuff.

During the manufacture of Glass reinforced Polyester resin boats: they are usually laid up with un-waxed resin so that each successive layer will adhere to the previous. IF the manufacturer tried to lay-up the entire hull thickness in one shot: Especially on a large hull the chemical reaction could set the whole mess on fire. and I have put out a catalyzed resin fire in a boat building shop.

For the last coat a liquid wax called 'air dry' is normally added to stop the inside surface from feeling sticky. (During the heat build up from the chemical reaction this wax melts and rises to the surface thus excluding the air.) If this is done: All areas of internal attachment are 'scuffed up' with a soft grinding disc on a mini grinder, to remove the wax and expose the raw top surface layer of the glass reinforcing which is often somewhat porous, to which the additional resin can soak into causing a very strong bond.

An alternative to this I have seen is to attach the interior to the un-waxed lay up and then spray; or selectively hand brush, waxed gel-coat internally.

Thus IF you have to do a repair or modification, scuff the area with a grinder. (protect your skin while doing this) Make absolutely sure it is dry. and then commence laying up the repair by applying resin first and then rolling the glass mat into it. So that the puddle of resin rising up through the mat or cloth expels all the air. Pre-wetting out glass on a board and applying it as a wet mass/mess is not the usual way professional boat builders do it. Though perhaps when working in awkward places this has some merit for the Do It Yourself owner. Be careful to exclude the air. IF it looks white it has air in it and is weak.

In closing my Father worked at the British institute of Oceanographic Sciences. Where they used GRP tow fish filled with urethane foam to carry transducers deep into the ocean. At these depths and resulting pressures water would eventually saturate the foam and make them too heavy. So they spent several million pounds on a research project experimenting with ways to remove the water. Including building the foam cores with passages to blow hot air through. Or attaching electrodes. Nothing was successful and the conclusion was that they should be considered a disposable Item. So the ultimate real answer to the OP's problem is probably to make a new keel casing. or radically rework the existing.

Epoxy vs poly is a long standing many years long debate here. I've been trying to convince people of exactly what you said for years, with little success. They'd rather believe info given to them by the manufacturer of one of the products in question.

[coastalexplorer]

Minaret,,,Well said...It is good to see that someone on here is professional enough to have the knowledge!

[chris95040]

Originally Posted by coastalexplorer

Minaret,,,Well said...It is good to see that someone on here is professional enough to have the knowledge!

Wait, whats 'the knowledge' again?

I seem to hear a lot of people saying the same thing, but some have a strange angry/defensive tone while doing it.

Crosslinked polyester is good strong stuff. Its not crosslinked when new polyester is applied to old and long since cured polyester. It is crosslinked when laying up a hull, even if it's not all done in the same day, because oxygen inhibits complete cure and there will still be some crosslinking available when the next batch is laid down on top. Waxes etc in "finish" resins prevent oxygen from inhibiting the cure and allow the polyester to completely cure.

Repairs are often done with Epoxy because it will have a superior mechanical bond strength, in these non-crosslinked scenarios, to existing polyester. Polyester will do too, though I'd suspect that bond area (bevels, etc) should be adjusted to accommodate different bond strengths. I imagine a proper engineer would consider these properties before deciding on a repair strategy.

[coastalexplorer]

Chris. No intent for a strange angry tone on my part, just an attempt to be informative.

It is known that while polyester resin will not adhere to cured Epoxy resin. It is accepted the epoxy resin will adhere to the correctly prepped cured polyester.

The essential point being made is that with the correct amount of prep economical, reliable, serviceable repairs can be effectively made with the same materials that the hull was made from in the first place. So in consideration that cruising boat owners on here probably come to the activity from all walks of life and professional experience? There are sure to be those who have absolutely no concept of how their yacht was made. or even knowledge of how wax is used in the process of manufacture of their GRP hulls. IF the wax used for mould release or oxygen exclusion is not removed adequately; it will not matter much what they use because it will not adhere/stick/bond adequately.

Technically: using correct procedures Epoxy might make a repaired area stronger than the hull its attached too. but at four times the price for the material the argument can be made....What is the point?

So IF people want to believe the sales hype and use the more expensive material, let them enjoy that belief. I just think they need to know before they spend that money. That in general practice boat builders and repairers 'in the trade' most likely would not do that: because it is unnecessary. This is the knowledge being referred too.

[chris95040]

Originally Posted by coastalexplorer

...

Gotcha, and its a good point about polyester's incompatibility with cured epoxy surfaces.

Anyone know why this is?

I don't think I really understand adhesion in general. Adhering to a hard substrate, like an epoxy + fiberglass repair, I'd think all that was necessary was mechanical keying with the right grit paper, but clearly theres more going on with bonding/adhesion than the brute, mechanical attachment of the new goo filling in the scratches of the substrate...

[Boatyarddog]

Originally Posted by minaret

Buy a cheap new manual grease gun, so it's not contaminated. Drill, tap, and screw in a zerk fitting. Drill a hole to relieve air pressure. Fill grease gun with catalyzed poly goo, attach to fitting, and pump. Refill and repeat as necessary till goo comes out your top vent hole. Voila!

And not epoxy?
What about working time, in the grease gun, sounds simple but is it really?


Sent from SV Cloud Duster

[coastalexplorer]

IF you are planning to pump resin with a grease gun. Your normal working time on a cool day for Polyester might be 20 to 25 minutes, and a a clean out with acetone might save it if you are quick.

Epoxy resin needs to be excessively stirred at least two minutes in order to cure correctly; This actually builds up some friction heat within the material. So while different hardener formulations have longer predicted cure times. The working time is unlikely to exceed ten minutes. Thus IF you feel that you must use it. have everything ready and planned and go fast. Have the white vinegar handy if you plan to try and save the equipment. and good luck with that.