WhoCaresOfName

GRP keel crack

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hello everyone.

recently bought my first s/v (Shipman 28 from 1974), was fairly cheap and of course, I never made false hope it would be trouble free. Many things I could seen on inspection before purchase, but obviously, this thing was under water. Anyway, the crack was under fouling and was revealed only when boat goes off water and cleaned, so even quick inspection with snorkel would not helped.

I knocked off most of that "sick" part, which does not holding with ballast/hull, so you can imagine from photos, how it looks like.

I really hope it was only due long years vibration stress and material fatigue, and not because ballast is not holding tightly. If it is released, well... I guess that will be another story. but hopefully not.

The obvious repair would be clean this exposed part and sand everything out, until the fibreglass part which is "healthy" and holding with ballast. Then put some filling epoxy and cover with new fibreglass skin (simplification). And finally antifouling.

So my question is: What everything need to be done (and what not), that such thing will not occur again next year/s? I do not like half-way job, so I want to do it properly.

What filling resin or chemicals need or should be used, that it will keep holding on ballast? Any particular process? Or particular brand of epoxy I should use?

Few pictures are here, some others + video you can open from onedrive link: https://1drv.ms/f/s!Avb-w5FGrZQNhfglU17pAJsYDtupjw

Thanks of any help.
M.
 

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Being American, I'm not familiar with Shipmans of the era.  What it looks like to me is that you have cast iron ballast.  Cast iron and seawater form rust as you well can see.  To me, that doesn't look like an encapsulated keel.  It looks like a bolt on keel that someone wrapped in fiberglass to keep water out.  Do you have keel bolts in your bilge?  If so, then likely the latter scenario.  As you likely also know, when cast iron rusts, it expands some, breaking the bond of the resin/epoxy/whatever bonded the glass to the keel.

What you are in for requires a fair amount of labor, but its not really rocket science, and an average DIY'er could do most of it.  

Assuming a bolt on keel, covered in a layer of glass, the first thing to do is grind all the glass off down to shiny metal.  Then get a good look at the keel to hull joint, to determine if that is still well sealed.  If water has gotten into that joint, and all the metal in there is rusty, then you likely need to drop the keel...which adds work/effort/labor, clean the top of the joint, chase/clean the keel bolt hole threads going into the keel, clean/replace the keel bolts depending on their condition, and remount the keel with new sealant.  

Otherwise its a job of taking the keel back to shiny metal, scrubbing epoxy into that just cleaned shiny metal to seal it, fairing with epoxy putty, then reglassing if that'f the way they were originally done.

Lots of labor and sweat equity, not to expensive though from a materials standpoint.  So if you do most of it...not too bad.  If the yard does it, much more expensive as its almost all labor.

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Sandblasting is the only reliable and durable method of cleaning rust off an iron keel.

Wire brushes, sanding, grinding etc. don't get the pitted areas clean and that is where the next round of oxidation will start.

Once it's blasted, immediately coat it with epoxy resin to seal it from the air then you can take your time filling and fairing it with thickened epoxy.

I've done it a couple of times - pics below.

Done this way it will last a long time.

 

9c Keel remounted.jpg

c4 (800x600).jpg

f12.JPG

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More than 1000 Shipman 28 were made 1969--1979. Rumors says production then moved to Ireland.

It's a nice boat, worth some care.

SJB is spot on - the iron keel must be painted directly after the old paint has been removed (directly means just that. Do not wait overnight, do it directly). I agree that sandblasting is the best method but if it isn't obtainable for some reason then other methods may be used.

To encapsulate an iron keel with grp is close to madness it will lead to encapsulated rust. Do not repeat that mistake.

Cracks between iron keel and hull are not unknown, often due to the difference in expansion when temperature varies (where I live this happens annually as the temps diffs are considerable). Could also be other reasons, I cannot remember Shipman 28 to have a bad rumor about keel fastening - I looked it up on the net, seems the grp close to the keel was improved from 1973.

//J

 

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The pictures look like they were taken in low light and then highly compressed, so they are pretty blurry, but I don't see fiberglass on the keel.  It looks like the only thing on the cast iron is primer and paint.

A crack forming between a fiberglass stub and a ballast keel is pretty common.  Different stiffness, thermal expansion, etc.  A layer of fiberglass tape around the joint might help.  After the cleaning and prep as described already.

While a crack is common without anything else being wrong, it could also be an indication of failure of the fiberglass stub or the keel bolts, which would be very serious.  Dropping the keel would be the way to check that.  Not a trivial task.  But if you are going to sand the entire keel clean and recoat it, then you already doing a big chunk of the work when it comes to dropping the keel.

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Putting a strip of glass along a keel stub/keel seam is a futile effort. There is always going to be some movement or flexing.

Filling the seam with a flexible sealant/filler of some sort is the only thing that will last any time.

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The seam would still need to be filled with 5200 or something like that.  And of course the keel on tightly so it is not wobbling!

I think the idea is neither fiberglass nor paint will stick well to the flexible sealant in the joint gap when it flexes.  Paint will fall off over the seam, exposing a crack.  However a strip of fiberglass tape will still be adhered above and below the joint and that will keep the glass not adhered from falling off.  And if the glass doesn't fall off then possibly the paint will say adhered to the glass.  There would of course need to not be so much flex that the glass cracks over the joint.

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You can also do this.... After you sandblast the keel. You can fill and fair joint with a G-flex seam which will have a slight by preferred minimal flex. Once it is 80% cured, lay a west system epoxy-fiberglass tape over the joint. The epoxy impregnated fiberglass tape will have something to adhere to making a strong joint repair.It should all hold for a very long time. Paint iron keel with Interlux 2000 then finish with your choice of bottom paint.

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PYou're looking at 100 hours of labor, 500 in tools and 500 in supplies. This is not a repair that will teach you anything other than the value of survey.

If you paid less than a few grand, consider chain saw, dumpster & rum.

Otherwise, you need to take the boat off the keel, remove the rust, prime and then encapsulate. Probably replace the bolts and then reinstall, fair, seal and paint.

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4 hours ago, Moonduster said:

PYou're looking at 100 hours of labor, 500 in tools and 500 in supplies. This is not a repair that will teach you anything other than the value of survey.

If you paid less than a few grand, consider chain saw, dumpster & rum.

Otherwise, you need to take the boat off the keel, remove the rust, prime and then encapsulate. Probably replace the bolts and then reinstall, fair, seal and paint.

Not at all. Do not beleive these figures, all are completely wrong (as so often with some posters ...):

If you use an angle grinder (such can be had from $30 and up) it will take you ½ day to remove all old paint and grp (if there is any, I could not see if this really is the case). The rest of the day you spend on painting the keel with epoxy, you wil probably need 2 cans, each cost about .... $20 (you are free to buy more expensive, I would probably go with VC TAR which is easy to work with, think those is ~$40/can). You may be able to put on 1-2 layers this first day, then you come back the next day and continue with the epoxy  until you have sufficient number of layers. Usually something 4-6 layers is considered to be sufficient.

All in all, on just the iron keel, you spend 2-3 days (3 x 8 = 24) and $100. 
Prices local in Sweden, considered a high cost country. Ireland might be cheaper.  Prices in US and CA are certainly lower, that I have noticed.

Shipman 28 is a nice boat, worth some effort. Will give you years of nice sailing, not racing, but still.

Why are some guys always negative?

//J

 

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VC Tar doesn't seem to be sold in US anymore.  Maybe it's still available in Europe?  I used IP2k on my lead keel.  But cast iron is not the same and there might be some coal tar epoxy like vc tar that's a better choice.

I'd put on at least one coat of fairing compound after the 1st coat of primer.  You don't have to go crazy with battens and NACA profile templates and long boards and so on, but just a few hours with some epoxy based fairing will make it so much better.

I don't think Moondusters estimates are totally out of line.  Chainsawing the boat because the keel needs refinishing is a little overly dramatic.  I think if you asked a yard here to sand that keel to metal, you'd be looking at $500+.  Just to grind and sand.  Probably more like a $1k.  You'll need several coats of primer and paint with overcoating times between them, which means a lot of hours and several yard days.  Especially if you have a day job and can't hang out at the yard from dawn to dusk recoating (really from the dew drying in the morning to paint's dry time before dew exposure in the afternoon, you don't get many hours this time of year in the Northern hemisphere).

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My estimates included taking the boat of the keel, which I would recommend for a 45 year old boat with clear signs of neglect and corrosion.

If you think you can go from the mooring to the mooring with that mess in 24 hours, you're a dreamer.

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1 hour ago, Moonduster said:

My estimates included taking the boat of the keel, which I would recommend for a 45 year old boat with clear signs of neglect and corrosion.

If you think you can go from the mooring to the mooring with that mess in 24 hours, you're a dreamer.

Positive and soapy as always. Now the keel has to be removed as well. Sure, just add. 

It is just some surface rust, such we in the north always get. That is the only thing we can see from the pics. 

Myself, instead of dreaming, I have done exactly this job on a similar boat. The keel is quite small, with a 36 sanding plate on an anglegrinder it goes fast. 

Removing paint on the complete bottom on a 40 ft takes about 40 working hours - using 60 and 80 grit papers. Have done that as well (never ahain, please).

Painting with VC tar goes fast as the epoxy is diluted with a solvent. As the OP is living in Ireland VC tar might be available there, otherwise - if he want - it can easily be ordered from Sweden or Germany as we are all in EU. It happens I order paint from Germany or the UK to get the right colour, no problems.

asking a yard to to the job will certainly be expensive - but do you do that with a boat like this? 

Myself, I do all work on my boats. Don't trust the yards. 

//J

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10 hours ago, Jaramaz said:

Not at all. Do not beleive these figures, all are completely wrong

You can assume that with all of Moon's posts.

Just hit the ignore button.

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The suggestions to fully prep and then just paint the iron keel are in my (experienced) opinion completely wrong.

All of the work and a fraction of the lifespan of an epoxy coating and epoxy filling and fairing.

Put the IP2K over that, not directly on the iron.

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20 hours ago, xyzzy said:

VC Tar doesn't seem to be sold in US anymore.  Maybe it's still available in Europe?  I used IP2k on my lead keel.  But cast iron is not the same and there might be some coal tar epoxy like vc tar that's a better choice.

I'd put on at least one coat of fairing compound after the 1st coat of primer.  You don't have to go crazy with battens and NACA profile templates and long boards and so on, but just a few hours with some epoxy based fairing will make it so much better.

I don't think Moondusters estimates are totally out of line.  Chainsawing the boat because the keel needs refinishing is a little overly dramatic.  I think if you asked a yard here to sand that keel to metal, you'd be looking at $500+.  Just to grind and sand.  Probably more like a $1k.  You'll need several coats of primer and paint with overcoating times between them, which means a lot of hours and several yard days.  Especially if you have a day job and can't hang out at the yard from dawn to dusk recoating (really from the dew drying in the morning to paint's dry time before dew exposure in the afternoon, you don't get many hours this time of year in the Northern hemisphere).

I hated VC Tar. Used it once. It takes months to fully cure. Lowered the boat onto a trailer after a few weeks after application, pushed the keel over with my bare foot to center it better, lived with my footprint in the keel all season. I have had much better luck with IP2K. But that's just me, a DIY kind of guy.

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2 hours ago, Varan said:

I hated VC Tar. Used it once. It takes months to fully cure. Lowered the boat onto a trailer after a few weeks after application, pushed the keel over with my bare foot to center it better, lived with my footprint in the keel all season. I have had much better luck with IP2K. But that's just me, a DIY kind of guy.

then something was wrong with the VC Tar you used. Mix or maybe old - epoxies have a limited shelf time, and temp sensitive.  The advantage with VC Tar is the solvent, means it is easy to paint, drys quickly and one can apply the next layer after some hours. OTOH, the solvent must disappear completely before further actions. 

Epoxy without a solvent is in a way better, it just cures / harden. Trick is to find an epoxy without solvent which still has low viscosity, to make it easy to paint.  

VC Tar is in no way without flaws: today VC Tar doesn't contain any tar, at least not where I live, as tar is generally prohibited. The tar in itself was mainly a marketing trick, the epoxy is the main ingredient. VC Tar doesn't age well, on a boat we painted with VC Tar some 30 years ago, VC Tar was rather soft when tested last year - easy to rip off. 

My experience with Interprotect is limited, only once or twice decades ago. Then it was very thick to apply, a normal brush was not sufficient. Could have been the temp - springs are sometimes cold here.  MAnufacturer has probably changed the mix since. 

In a summary, use whatever epoxy you prefer. Test it before, and consider that you will probably paint it some kind of antifouling - paint doesn't attach very good on some epoxies. 

//J

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You might want to talk to the suppliers of commercial paint in your area. Big ships are all steel and are immersed for years between drydocking. A good epoxy primer paint + topcoat + antifouling. Sandblasting really preferred but angle grinder/wire wheel will do in a pinch; just don't expect it to last forever.

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21 hours ago, Zonker said:

You might want to talk to the suppliers of commercial paint in your area. Big ships are all steel and are immersed for years between drydocking. A good epoxy primer paint + topcoat + antifouling. Sandblasting really preferred but angle grinder/wire wheel will do in a pinch; just don't expect it to last forever.

Some shops use Intershield instead of interprotect.  I'm not sure about it's use below the waterline on fiberglass or aluminum boats, but I know of at least one shop using it on their new boats as well as dozens of boats each year without any complaints I've heard of.  It is a lot cheaper, feels thicker, and dries faster(less fussy on temperature too).  5 gallon bucket sized kits only.   Comes in aluminium or bronze colour and is used on the commercial ships(both colours are aluminium based).   I have seen some bottom paint peeling issues on jobs where the coating window for the bottom paint was missed.  Seems less tolerant of this than interprotect

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I get better results using a needle gun for rust removal and iron/steel surface prep.

Paint on Ospho or any phosphoric acid rust converter. [ READ THE INSTRUCTIONS ] This step solves a lot of problems re working in warm dry days only and applying primer within 30 minutes of needling. 

I have always used a zinc rich 2 part epoxy primer if I can get it. Sherwin Williams and Jotun are good makes.

Antifoul [ Again read the instructions you may need a tie coat ]

 

 

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