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Old 27-10-2017, 08:12   #1
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I hit an uncharted rock in Southern Chile

I am 7 years into a circumnavigation and am currently in Southern Chile.

I hit an uncharted rock. (there aren't many that ARE charted down here!)
My boat is a Fraser 41. Encapsulated, all fiberglass keel.

There is a section that's about 2 feet long it's been caved in about 2 inches at the bottom of the forward edge of the keel.

There is no one here that can help with this repair. It will all be me that does it. I have practically no experience with fiberglass repair. AND, there are no chandlers. On top of that, getting in things like West System epoxies, will be difficult. Oh the joys of going to far away places!

My first problem is how to dry out the keel. The forward watertight section that is damaged has the 8000 pounds of lead ballast in it. (pdf attached) I don't have any dimensions for that compartment, but if anyone does, I would love that. My initial thought being to drill some holes along the top edge, and then to flush with fresh water, then isopropyl alcohol or acetone. Any other ideas on how best to dry it out, keeping in mind that there is no fancy things like vacuums or moisture meters around?

Then, what would be the best way to do the repair. Is epoxy best? Or would a polyester resin work be better?
Should I build layer after layer until I've built up the whole two inches?
What kind of fiberglass matting should I use? Bi-axial cloth? Roving? Cloth and CSM in alternating layers?

I can get CSM and Roving mat down here. I haven't found any bi-axial cloth yet.

Any help would be greatly appreciated!
Thanks in advance.
Mark Aisbett
SV Merkava
Puerto Natales, Chile
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Old 27-10-2017, 08:42   #2
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Re: I hit an uncharted rock in Southern Chile

I would get some sanding out of the way before assessing materials. Firstly expose the gel coat back a good three feet from the impact to see if there are any radiating fractures, if not take the gel coat off to around 2ft to allow you to fair it out. You can readily find chop mat for building up any chunked out damaged areas just make sure you use it to cap it with a bunch of layers of good 6+oz woven mat. Some will swear off the chopped but itís cheap, easier to form and youíll most likely be grinding most of it away trying to reshape the leading edge. I would also suggest trying to source some Kevlar to cap the whole thing. More important will be your additives, only go epoxy, youíll want an aluminum or silica thickening additive for working and strength. Finish with a unthicked clear coat, coloured or not. Make sure to wash the blush off each coat before sanding, and sand every coat max 120 grit, better if 80. Should be nothing more than a light rough up on the last coat, you donít want to be sanding deep into the repair on the last 2-3 coats, just looking for s good surface and mechanical bond. Good luck hope this helps
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Old 27-10-2017, 08:53   #3
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Re: I hit an uncharted rock in Southern Chile

I've got a little experience with this sort of thing, enough to know the above is a good answer.

The only thing I can add, and open to dispute, but as far as drying out the moisture, I was told by one repair man that the heat from the grinder will drive out the old 'glass sufficiently, at least where you are working. I dunno, maybe that was just to satisfy me.
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Old 27-10-2017, 09:20   #4
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Re: I hit an uncharted rock in Southern Chile

What sort of day time temperatures have you got and will it go up much as summer approaches? Epoxy is temperature sensitive. Any chance you can make a tent around the hull?

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Old 27-10-2017, 09:36   #5
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Re: I hit an uncharted rock in Southern Chile

Good point on the drying. Get cheap easy to find methyl hydrate/methylated sprits etc and soak the area liberally, it will draw out the water and clean the surface prior to bonding. Just allow sufficient time for it to evaporate before doing any layup.. You can also throw a heat gun to it to warm and draw out the moisture. Epoxy is exothermic and while temp does play a role as long as youíre above 5-7 Celsius you should be fine, if not a small tarp and a heat gun will do the job.
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Old 27-10-2017, 09:56   #6
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Re: I hit an uncharted rock in Southern Chile

Are you sure there is moisture in there? I dont see any weeping out. Looks like a grind and layer glass repair to me.
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Old 27-10-2017, 13:52   #7
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Re: I hit an uncharted rock in Southern Chile

Hello Merkava,

Good on your cruising. Yup on uncharted rocks. We have a member here, El Pinguino, who will be returning to Chile. He has spent quite a few seasons there, and may be up on hard to find resources. You might try contacting him via Personal Message.

I took it upon myself to tell one of our resident expert boat repairers of your plight, and I hope he will show up here on your thread with some input for you.

Ann
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Old 27-10-2017, 14:43   #8
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Re: I hit an uncharted rock in Southern Chile

Do your best, don't sweat it too much.
It didn't sink your boat, not highly stressed part of the hull, so not a critical repair in my opinion.

Perhaps drill some holes in the bottom of the encapsulated keel area in case there is water below the damaged area.

But, you should also check interior floors, stringers, area above forward and aft ends of keel for damage from the impact.
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Old 27-10-2017, 14:44   #9
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Re: I hit an uncharted rock in Southern Chile

Almost every post so far focuses on epoxy for repair even though you stated the difficulty in getting epoxy locally.

I agree epoxy is the best permanent solution and would be the preferred repair. However, if it's not available locally, or is outrageously expensive (or schedule) prohibitive to import, there IS the option of repairing with polyester resin (or vinylester if it is available) and monitoring.

Yes there's a chance you'll get osmosis there in the future, and the repair may need to be redone, but if done properly it will still get you safely down the road for a while until you're in a place you can redo it (if it even becomes necessary). One of the things you do have working in your favour is that it is lead that is encapsulated.

Once you've ground back a bit and can see if there's stress cracking beyond the immediate damaged area, you'll be in a lot better position to figure out the final repair strategy.

I had one boat builder remind me a while ago.... "These boats were built with polyester resin and many were repaired with polyester resin before expoxies came about"

Good luck.
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Old 27-10-2017, 17:36   #10
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Re: I hit an uncharted rock in Southern Chile

You could repair it with latex paint if you wanted too, eventually youíll have to deal with it. Even some two part marine repair kit slathered on would work but itíd be a pain getting it out again later. There is also the issue if the boat stays in longer than anticipated and water finds its way into the laminate which could cause a real problem. He really needs a hundred bucks worth of resin, catalyst, admixtures and cloth. Shipping will probably be more IF it can be shipped to the location.
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Old 27-10-2017, 18:11   #11
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Re: I hit an uncharted rock in Southern Chile

given your location and the difficulty of getting more than basic materials a polyester resin and chopped strand mat fix will be fine,it is also easier to work with in lower temps bu increasing the catalyst ratio to 3% if below 5C.

you can also use car body filler,as a filler for initial fairing.
most difficult is getting an all round bond if there is water dripping out.

this is where body filler is useful to get a seal as it goes off very fast if slighyly over catalysed and stops the leak.
fill and grind untill you have no more water seepage.

looking at the size of repair you are going to need about 10- 15 kg of polyester resin, 250 ml catalyst and 5- 7.5 kg of 450G/m2 Chopped strand mat ,5L acetone ,lots of small rollers and brushes, probably 2 kg of body filler and a liter of gel coat if possible,rags buckets and scrapers as well as about 5 x 40 grit fiber grinding discs.
plastic sheeting masking tape

MO grind back damaged area as explained by other poster.

identify any areas that are damp or leaking,try to dry out as best as possible.

a wet and dry vacume cleaner is usefull for sucking out bigger leaks.
once it is dry fill voids with body filler,sand and leave for 12 hrs
check for any leaks /seepage dry as best as possible then repeat filling process untill no further damp areas.

acetone and heat area to be glassed making sure there is no surface moisture.

you can then start the layup,which will want to be about 1" thick when finished or aprox 18 layers of csm

you can probably progressively laminate up to about 4-5 layers at a time before the resin kicks off.

prepare layers of cloth before hand and lay out on a board near the repair also,prepare batches of resin and catalyst
have rags and acetone handy as well as some acetone for cleaning your roller in a bucket if your batch of resin starts kicking off

if you taper each layer of cloth ie start with the smallest piece to cover the repair and overlap each succesive layer by 2" to give about a 10!-12" border at the outside of the first patch this gives a nice taper.
let this cure for about 6 hrs.
then check for leaks,grind back and repeat another 4-5 layers increasing the overall outside size of the repair by another 8-10"

grind and repeat untill you have built up to about 1" thickness where the hole was with an over lap of about 2-3 feet around the effected area.

sand and fair then apply 1-2 layers of gel coat.
then prime and antifoul

always tear chopped strand matt cloth rather than cut it as it bonds better on the edges.
i generally find i can work with no more than 500g-1kg of resin per mix,less if the repair has to go round corners or is complex.

a small set of kitchen scales makes weighing the resin and getting the catalyst ratio much easier especially if having to over catalyse if working in low temps.
resin should be kicking off in 30-40 minutes.
so start slow with less resin and small areas untill you are confident.

if resin does not cure for any reason you can always scrape/grind it off and clean with acetone and start again (and use a higher ratio of catalyst)!
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Old 27-10-2017, 18:42   #12
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Re: I hit an uncharted rock in Southern Chile

Quote:
Originally Posted by atoll View Post
given your location and the difficulty of getting more than basic materials a polyester resin and chopped strand mat fix will be fine,it is also easier to work with in lower temps bu increasing the catalyst ratio to 3% if below 5C.

you can also use car body filler,as a filler for initial fairing.
most difficult is getting an all round bond if there is water dripping out.

this is where body filler is useful to get a seal as it goes off very fast if slighyly over catalysed and stops the leak.
fill and grind untill you have no more water seepage.

looking at the size of repair you are going to need about 10- 15 kg of polyester resin, 250 ml catalyst and 5- 7.5 kg of 450G/m2 Chopped strand mat ,5L acetone ,lots of small rollers and brushes, probably 2 kg of body filler and a liter of gel coat if possible,rags buckets and scrapers as well as about 5 x 40 grit fiber grinding discs.
plastic sheeting masking tape

MO grind back damaged area as explained by other poster.

identify any areas that are damp or leaking,try to dry out as best as possible.

a wet and dry vacume cleaner is usefull for sucking out bigger leaks.
once it is dry fill voids with body filler,sand and leave for 12 hrs
check for any leaks /seepage dry as best as possible then repeat filling process untill no further damp areas.

acetone and heat area to be glassed making sure there is no surface moisture.

you can then start the layup,which will want to be about 1" thick when finished or aprox 18 layers of csm

you can probably progressively laminate up to about 4-5 layers at a time before the resin kicks off.

prepare layers of cloth before hand and lay out on a board near the repair also,prepare batches of resin and catalyst
have rags and acetone handy as well as some acetone for cleaning your roller in a bucket if your batch of resin starts kicking off

if you taper each layer of cloth ie start with the smallest piece to cover the repair and overlap each succesive layer by 2" to give about a 10!-12" border at the outside of the first patch this gives a nice taper.
let this cure for about 6 hrs.
then check for leaks,grind back and repeat another 4-5 layers increasing the overall outside size of the repair by another 8-10"

grind and repeat untill you have built up to about 1" thickness where the hole was with an over lap of about 2-3 feet around the effected area.

sand and fair then apply 1-2 layers of gel coat.
then prime and antifoul

always tear chopped strand matt cloth rather than cut it as it bonds better on the edges.
i generally find i can work with no more than 500g-1kg of resin per mix,less if the repair has to go round corners or is complex.

a small set of kitchen scales makes weighing the resin and getting the catalyst ratio much easier especially if having to over catalyse if working in low temps.
resin should be kicking off in 30-40 minutes.
so start slow with less resin and small areas untill you are confident.

if resin does not cure for any reason you can always scrape/grind it off and clean with acetone and start again (and use a higher ratio of catalyst)!


He says he's got some woven roving available, let's throw at least a few plies of that in there as well!





Here's a few pics of a vaguely similar but much worse repair I did at the beginning of this thread:

Pics from the Boatyard


Note in the pics of the damaged area after being back-ground, you can clearly see the original laminate schedule. This is why grinding back a damaged repair area is sometimes called "scheduling back" by the pros.
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Old 27-10-2017, 18:51   #13
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Re: I hit an uncharted rock in Southern Chile

Once the OP has ground out the damage, the original laminate schedule should be clear. He/she should attempt to match this schedule in the repair. This shouldn't be hard, as the original schedule is likely to be CSM and 24 oz roving in alternating layers, as depicted above. Original layup was in poly, repair will be fine if done properly in poly as well. Especially if properly epoxy barrier coated after completion.

Next step after scheduling back the repair is to make a plastic pattern to cut the layup with, as depicted here, in this thread, albeit on a much larger scale:

Keel sump repair
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Old 27-10-2017, 19:03   #14
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Re: I hit an uncharted rock in Southern Chile

Tape the clear plastic for the pattern in place, or for a complicated shape apply spray adhesive in light layer to the repair and then the plastic, with pleats cut if necessary. Be sure to remove all spray adhesive with acetone before laminating! Use a Sharpie or other marker to draw a line at each visible ply of roving in the original layup. Then draw lines in between those for layers of matt. Pull the pattern off and lay it directly on the material on your cutting table (sheet of ply + horses). Cut the largest piece first, and then keep going, with the pattern getting smaller as each piece is cut. Stack the pieces as you cut. Orientation or "up" arrows or register marks around the edges prevent misalignment. Be sure you have back ground to minimum of 12-1 scarf angle, ie if the hull is 1" thick grind back 1' all directions. For a repair on the bow below the waterline in poly in those waters I would ratchet it up to about 20-1 scarf angle. Wet out the repair area first, then apply pieces one at a time starting with the smallest. Don't do it backwards! Lots of people will tell you to. When all patterned pieces have been applied, tear pieces of matt by hand and apply them to any visible lows. Glass the whole repair just a little high. Then grind and sand fair. This will result in little or no fairing compound below the waterline, which is what you want. Good luck!
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Old 27-10-2017, 19:06   #15
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Re: I hit an uncharted rock in Southern Chile

PS: When you back grind, grind until you have the schedule in an even easy to match shape. It makes layup and fairing much easier if you are doing an oval instead of a kidney bean, even if the original damage was kidney-bean in shape. Hope that makes sense!


Grinding will also reveal if there is a moisture problem, whether the ballast will be exposed (probably), full extent of the exterior damage, etc.

Be sure to inspect thoroughly for interior damage as well, I have seen many examples. Check all bulkhead tabbing, stringers and frames, engine alignment, etc.

While you are grinding it is wise to grind off the bottom paint at the leading and trailing edges of the keel stub, or other keel/hull joint, as impact at the bottom of the keel can lead to hard to detect fractures in these places. Inspect carefully. Grind to gel and apply blue steel dye, as used for finding cracks in steel. JMHO, YMMV, etc. etc.
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