I have an '82 Nacra 5.8. As best I can tell, my hulls are solid glass...no foam core. I have a couple of soft spots on the bottom starboard keel. One has some fissures running through it. When the boat was capsized I pushed on this spot and it felt like jelly, and I strongly suspect is the source of my leak. I will confirm before I repair, and could potentially have some other problem areas that will arise during my inspection.

I've read a bunch on how to repair if I had a foam core. Seems simple really. Drill some holes, squirt some epoxy in, cure, sand, paint.

But what do I do since there is no foam?? I've read a couple of comments here that say fixing a 100% glass hull is easier, but not sure what could be easier than squirting some epoxy in.

Any advice would be appreciated here.

--
Jeremy Soder
Nacra 5.8
Allen, TX
--

Grind out all of the damaged glass and replace. It's pretty easy and is a better repair than just injecting epoxy.

--
Greenville SC

Offering sails and other go fast parts for A-class catamarans
--

Generally the bottoms of the boats are solid the sides and decks are foam cored more so than the bottom. HTH, Richard.

--
Lake Perry KS
H-18
N-5.5 UNI +spin
--

Quote

Grind out all of the damaged glass and replace. It's pretty easy and is a better repair than just injecting epoxy.

x2. I do a lot of fiberglass work repairing bobsleds for my job so i feel fairly qualified to give some direction here... sand/grind the gelcoat off several inches passed the affected area (resin wont bond well to gel coat) when i do repairs i also grind into the fiberglass a bit. The closer to the crack the deeper i grind. This allows fiberglass to be built up thicker closer to the crack. There are 2 common types of resin as well. There is polyester (the stuff you can get at autozone) and epoxy resin (you would have to get at west marine or online) From what i have read epoxy resin is better because it bonds better to both types of resin. Polyester only really bonds well to polyester. so unless you know your boat is made out of polyester (which it is probably not) try to get an epoxy based resin. The fiberglass itself is pretty much the same. The autozone fiberglass cloth should work fine.

after doing all the prep work go buy some disposable paintbrushes, and gloves. cut the cloth into properly sized peices to fit the repair spot. I like to start with smaller peices at the source of the crack and slowly get bigger with more layers. Use the disposable paintbrush to apply the resin into the cloth till it is saturated then continue with your next peice. I like to do at least 4 or 5 layers but you might want to do more since it's the bottom of the hull (especially if it's where the boat sits on the trailer) Some people like to let it harden between layers but then you have to re-sand it before your next layer so i like to do it all at once. I also like to alternate between woven glass fabric and random oriented fabric. when you are done (you only have 5 or 10 minutes to apply the resin before it starts to get thick and hard to work with) you can take a plastic bag or plastic sheet of some sort and put it over the repair to smooth it out and work any bubbles out with your hands. The resin should harden in several hours then you can peel the plastic back and sand it smooth. Paint it and you are done.

Good Luck!

--
70's 18' Sol Cat "Venora"
70's 18' Sol Cat "Bumblebee"
60's 14' Sailstar Tallstar sloop "Arandora"

Heber City, UT
--

That was just the advice I needed. Grinding, cleaning, prepping, laying up the new glass all seems really easy from watching a bunch of videos, but I definitely needed guidance on the resin...I see where people use all different kinds of stuff...vinylester, polyester, etc... I also wasn't sure where to get the glass...Autozone is super easy.

Another question though, what if I want to do some similiar repairs to my dagger board bottoms and they are missing a corner? How can I build up the structure first before laying on the glass? Could I ball up a bunch of glass and build the missing structure with that first...let it cure, and then lay glass on top? Similiarly, I noticed the chip missing from the leading edge of my port bow that I'll need to fill in as well before laying glass.

My thoughts on doing this project right now are that the hulls bottoms are in pretty sad shape altogether and that if I'm going to do the job, do it right the first time, in the least amount of time and get back on the water. So see if you agree with the following:

1. Disconnect the hulls, flip them over on top of saw horses
2. Grind away the hull bottoms and any other discovered problem areas
3. Lay new glass the entire length (any particular type of resin I should use?) (also, I assume would be better to run glass in different patterns as you mentioned...if you agree with this strategy, how many layers would you recommend?)
4. Cure, sand, clean
5. Then to fill in any low spots or pin holes, lay on a thin resin skin coat (do you have a recommendation here).
6. Cure, sand, clean
7. Paint or gelcoat (probably paint as cheaper)

I'm sure I'm naive about this, but sure seems like something that could be done over the weekend in 4-8 hours total time. Then I'm back on the water.

Thoughts?

--
Jeremy Soder
Nacra 5.8
Allen, TX
--

A few suggestions based on some experience.
1. If you have room flip the boat still attached to the beams without the tramp. Most hulls won't stand up on their own and must be strapped down in some way. This leads to straps in the way of whatever you are working on.
2. Grind/sand to remove all broken, de-laminated, or frayed glass then grind to develop a gradual taper into the repair areas.
3 Most of the boats that are gel-coated from the factory use polyester resin so polly is fine. If you want to use gelcoat over the repair area poly is required as gel will not stick to epoxy.. if painting then it does not matter. If you use poly you should alternate between woven and mat. For epoxy all woven is fine. Replace as many layers as you sand through.
4 sound simple huh.
5 thicken the epoxy or poly with filler such as colloidal silica or baby powder to about peanut butter consistency to fill in significant low spots.
6 more sanding...
7 again paint or gelcoat depends on what you use for layup.

Time: Depending on the extent of your required structural repairs and the power tools you have available you should anticipate that this process should take 10-30 hours of work time plus cure time for materials from mast down to mast up.

Remember to wear a good respirator while sanding. The dust bad news...

Quote

Another question though, what if I want to do some similiar repairs to my dagger board bottoms and they are missing a corner? How can I build up the structure first before laying on the glass? Could I ball up a bunch of glass and build the missing structure with that first..

I just did that with 5.2 dagger board. Resist teh usrge to ever "ball up some glass". In theory it sounds fine, in reality, as soon as you release the pressure on the balled up glass it expands, & you get air bubbles in the material.
Use 60 grit & your palm sander, or better yet an angle grinder. Peel away some gelcoat above the missing corner, sort of bevel away from the corner an inch or two on each side, depending on how much of the corner needs to be rebuilt.
Cut a section from a plastic juice jug, you will use this as a form. Cut 3 layers of cloth,(alternate orientation of weave for better strength)Cut the first to fully cover your ground out area + missing corner, then next will begin just a bit below the first piece & go to the end of the board, the 3rd stepped down a bit from the 2nd. I generally don't lay more than 3 layers at a time, excess heat weakens the material. Place all 3 layers together, wet them out & out lay up in position. Now lay your juice jug, or whatever you used to make the mold on top of the 3 layers,(the resin won't stick to it) wrap & tape it into position,(use foam wedges, whatever you come up with) so it conforms to the original curve of the board. Make sure you figure this part out BEFORE you mix the resin, you don't want to figure out how to make it stay in position as the resin kicks off. You want the matt to start right where the good gelcoat meets your grinding, hence you lay the matt, then apply the form.
Flip the board over, so gravity will keep the layers closely aligned with your form, which is now on the bottom. Don't worry about matt projecting below what will be the finished corner, it is very easy to trim later,using a jigsaw.
Let this set up an hour. Now start laying up additional layers to build thickness. As you get near the finished size,trim bottom with saw to slightly shorter than finished size, you can wrap a couple of finallayers around the leading/bottom edge of the board, holding them in shape with a piece of clear plastic bag & tape. This will allow you get pretty close to finished shape, & see & work out air bubbles. Finally, cut & sand to finished shape, then wipe a thin layer of resin on to seal any fiber you have exposed. In all layers, try to use just enough resin to wet the cloth. You do not want 1 layer of cloth to be 1/8" thick because of excess resin, you should be able to clearly see the cloth weave through the cured resin. It really is pretty simple, I finished 2 boards in under 2 hours, over 2 days.
Organize everything you will need,(forms, tape, pieces of matt), then dry fit, BEFORE you mix.
As for your hulls, depending on where the damage is, it may be easier to lay up from the inside, if you have a port that allows access. You can tape plastic sheet/styrofoam to the outside of the hull to act as a form. If this works in your case, the repair will be only a few hours. Organization/prep will take more than the actual glass work.



Edited by Edchris177 on Jul 06, 2012 - 06:28 PM.

--
Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--

A few more pointers.
Buy a 100 count box of latex gloves, the best $10 you'll spend. Don't try to reuse gloves, they remain tacky, & will pull fibers from the cloth as you try to smooth things out.
If you are not using the West System, with pumps,go to the dollar store & buy what looks like a baby bottle, marked in milli litres and/or ounces. Pour your resin into this, then invert,(with the cap on the dispensing tip obviously) Cut a hole in a carboard box that you can stand this bottle in, inverted. After the resin settles it now becomes easy to pick up bottle,(keep it inverted) pull the cap off & squeeze resin into your mixing container. By using the markings on the bottle you can measure precise amounts, down to 1/2 ounces. Use small plastic containers for mixing, once the resin hardens, the container can be flexed, & the dried material pops out. Popsicle sticks make good mixers, stir for one full minute to achieve thorough mixing. They, along with improvised pieces of plastic or spatula make effective squeegees for removing excess resin without disturbing cloth.
If you have never used the stuff before, mix up a couple of 1/2 ounce batches & fix a ding in a piece of scrap plywood. The first couple of times of hands on use will teach you more than 100 posts & 20 You Tubes.
I saw in a post that Bondo was not waterproof. I have used it for over a dozen fixes. There are two types, one marketed for bodywork, the other marine, it says "waterproof" on it. I don't know if they are the same product with a different label, but I used the marine stuff.
Go for it, you can make a strong good looking repair.

--
Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--

Jametown Distributers for 2,3,4" rolls of glas cloth or any other supplies. Pete

Quote

As for your hulls, depending on where the damage is, it may be easier to lay up from the inside, if you have a port that allows access. You can tape plastic sheet/styrofoam to the outside of the hull to act as a form. If this works in your case, the repair will be only a few hours. Organization/prep will take more than the actual glass work.

...excellent idea, if you can get to it. Glassing from both inside and outside will make it super strong, and glassing inside is easier because you dont have to worry so much how it looks.

Quote

I saw in a post that Bondo was not waterproof. I have used it for over a dozen fixes. There are two types, one marketed for bodywork, the other marine, it says "waterproof" on it. I don't know if they are the same product with a different label, but I used the marine stuff.

... this is true. Normal "pink" bondo is porous and not entirely waterproof unless painted. Use the green "bondo glass" it is waterproof and you can even get it with fiberglass strands mixed in, making it much stronger. I even use it for normal car repair. It would also be a great way to build up low spots, smooth out a rough fiberglass repair, or fill in missing chunks, like in your dagger boards. Just work it into the rough shape you want, wait for it to harden, sand it down into the shape you want, then use fiberglass cloth to go over it to make it strong.

Quote

1. Disconnect the hulls, flip them over on top of saw horses
2. Grind away the hull bottoms and any other discovered problem areas
3. Lay new glass the entire length (any particular type of resin I should use?) (also, I assume would be better to run glass in different patterns as you mentioned...if you agree with this strategy, how many layers would you recommend?)
4. Cure, sand, clean
5. Then to fill in any low spots or pin holes, lay on a thin resin skin coat (do you have a recommendation here).
6. Cure, sand, clean
7. Paint or gelcoat (probably paint as cheaper)

...that's pretty much what i would do. If you really think running glass the entire length of the hull is necessary i would use an angle grinder with a 60 grit "sanding disk" it will make quick work of getting through the gel coat and fiberglass. I would focus on the main trouble spot. If the rest of the hull is not soft just a couple layers of cloth to reinforce it and build it up should be fine. If indeed your boat is made of polyester you can just pick up a gallon of it at autozone. Fill your low spots/pinholes(you shouldnt have any pinholes if its done right) with bondo-glass. Gelcoat is not really necessary unless you keep the boat in the water for more than a couple days, or if you really, really want a durable finish.

a weekend of work should get the job done.
Good Luck

--
70's 18' Sol Cat "Venora"
70's 18' Sol Cat "Bumblebee"
60's 14' Sailstar Tallstar sloop "Arandora"

Heber City, UT
--

All good advice, I don't want to try to repeat it. I just did a bottom job on my P18. I second lots of gloves. You will change them often and go through lots. Curing takes time allow for extra. Don't expect that you can for sure get it all done in one weekend especially if you plan to gelcoat. After gelcoating my bottom I think that on old boats in the future I prefer to paint. Don't forget the acetone, you need to wipe down sanded areas before applying glass. Matt fiberglass is stronger than woven fiberglass and in my opinion easier to sand to a smooth surface. colloidal silica for thickening is harder to sand than the west systems high density filler sands easier if you need to fill/fair voids. You can gelcoat over epoxy just fine if you prep the surface properly. You can also bond to gelcoat just fine if you prep the surface properly since gel coat is polyester resin. I was taught to tear the the matt rather than cut it and to over lap the very outside edge of the gelcoat of the area you have prepped. Most of this will probably be removed in the sanding process. West systems is nice because of the meters pump system but pricey. I found these guys that have a metered pump system as well but I don't know much about them and have not tried any of it. They look to be a bit cheaper.
http://www.aeromarineprod…C-utqO9LACFQOEhwod5XHKiw

--
Dustin Finlinson • Magna, UT
Member: Utah Sailing Association
1982 Prindle 18
1986 Hobie 17
1982 Prindle 16
1980 Prindle 16(mostly)
1976 Prindle 16(mostly)
Check out "Prindle Sailors" on Facebook.
--

The boat is made of polyester resin and fiberglass.

Don't use CSM with epoxy.

--
Rob
OKC
Pile of Nacra parts..
--

Thanks for the advice everyone. I found a company in Fl called US Composites. Their technical engineer Steve seems to be very experienced and is suggesting the following:

1. Use DBM 1708 Biaxial Fiberglass, http://www.uscomposites.com/specialty.html
2. Use Vinyl Ester Resin, http://www.uscomposites.com/polyesters.html

In contradiction to everything I've seen online (which he says is wrong), rather than wetting all layers simultaneously, he says I should brush on the first layer of vinyl ester and wait until it is tacky (approx. 1hr), then lay on the first layer of glass, then wet, and like the first step, wait until tacky before laying the next layer. He said this is the correct way to lay glass.

He also said that woven is stronger than mat; however, the biaxial fiber above has one woven layer and one mat built together.

He also suggested that I add carbon fiber dust (10% by volume and costs $10) to the final layer of Vinyl Ester. This will turn the bottom of the hull black but will be nearly impregnable and the most advanced protection against bottom wear, and to not paint over it (obviously). I can lay a pin stripe and paint the top-half of the hulls anything I want. Would certainly give the hulls an interesting look.

I am taking everyone's advice seriously, espcially the part about planning the repair out in detail before starting. I want to do this right the first time.

As for the damage, it is more severe than I thought. The soft spot I was feeling was the mtex eroding from the hull. I got under the boat Sunday and gently started picking at the edges and it just started flaking off. The pictures are what I found. It was hard to get under the hull and I had to stretch my arm out to take these pictures, but it looks like the fiberglass is rotted and separated. The area is about 4" in diameter.

I sent Steve the pics and he said the damage is more severe than he knew and that he has been legally advised against suggesting remedies or products. And further, he suggested that I take the boat to a professional and let them do the restoration. Kind of freaked me out to be honest...maybe this is worse than I realized?! But I pressed on and we were able to have a conversation between the lines that went something like, "I was considering using the 1708 biaxial cloth you mentioned the other day."

"That would be an excellent choice."
"And I was thinking Vinyl Ester might be better too"
"Another excellent choice."
"How much resin would I need?"
"I can't give you advice"
"Let's just say I'm talking about repairing the fender of my car and not the boat"
"You would need 1qt per one yard (36x38) of the cloth"
"Do you have any suggetions on how to build the supporting structure after I grind out all the damage?"
"Sorry, but I cannot talk about your repair..."

You get the idea.

So wanted to run by all you salty dogs and see if this is bad enough that only a pro should fix, or my original plan will work.

I opened the front port to see if I could access the damage from the inside. There is a bulkhead right there separating me from the spot. So once I grind open this big gaping hole from the outside, what can I do to provide structure to start laying the first glass? Some type of carboard/poster board/thin plywood/ect....with a string to hold it up against the inside of the hull?"

Here are the pics:

http://s1058.photobucket.…/t418/jsoder1/?start=all



Edited by jsoder12 on Jul 10, 2012 - 02:58 PM.

--
Jeremy Soder
Nacra 5.8
Allen, TX
--

This is more than a bottom job for sure but it can be done. Regarding the products recommended I personally think you are being oversold. What he is recommending will work but it appear that is will cost you about 50% more than it should based on the resin prices on the link you provided for vinylester vs std marine layup poly.

For structure inside consider using a bit of expanding foam injected through a hole drilled in the bulkhead. It will not provide a solid smooth surface for you to work against but should give enough support to hold up a layer or two of wetted glass to reestablish the hull shape. Just don't overdo it and fill up the entire area as it could expand the crack. The foam will also retain water but if you are judicious with its use it should be negligible.



Edited by Rider_55 on Jul 10, 2012 - 04:18 PM.

You need to check out the post by smackdaddy, he just picked up a Spirit 17 and dived right in on major repairs, he did a bottom job similar to yours, check it out here:-

http://www.thebeachcats.c…c/13621/start/0#pid38459

Notice how he made a shaped backer by laying up over waxpaper, when cured he cut and fit it into the hole as a backer plate and then laid up over it. Learned by watching YouTube.

PS, notice his pricing?



Edited by turbohobo on Jul 10, 2012 - 07:29 PM.

--
TurboHobo
H14T
H16
P18
G-Cat 5.0
P16
--

Good pictures and technique. Thanks for the link. I think this will work for me. It sounds like the Vinyl Ester might be overkill in your opinion? I'm all about saving money if possible...I just don't want to be penny wise and pound foolish. I expect to get years of use out of the this boat so want the repair to last.

Do you or other members here have an opinion on this guy's suggestion about how to lay the glass in single layers with a little cure time in between to let the resin setup?

--
Jeremy Soder
Nacra 5.8
Allen, TX
--

Quote

Do you or other members here have an opinion on this guy's suggestion about how to lay the glass in single layers with a little cure time in between to let the resin setup?

Yes, he is right. wet one layer at a time. I use a disposable paint brush and start by wetting the hull first, then sticking the first layer of glass to that. (it tends to stick in place better) then wet the first layer by brushing on resin. He says to wait till it's tacky before continuing on, which isn't a bad idea but then you would have to keep re-mixing resin and it would create a lot of waste, and take a lot of time. You may be able to put your used brush and resin container in the freezer to slow the curing process while the first layer sets up a little then take it out to do the next layer, ect... personally i wouldn't worry too much about letting the first layer get tacky before continuing on. A few minutes per layer would probably be fine, which is the time it might take to get your next layer ready anyway. I think letting it cure after 3 or 4 layers is more reasonable. I've done plenty of successful fiberglass repairs using this method. He is, however, probably very knowledgeable when it comes to fiberglass and resin since he sells it for a living... I've used the cloth you mentioned before. It's pretty good but takes a ton of resin to wet (which may be why he recommends letting it set up between each layer. Also keep in mind that he is probably trying to sell you his companies product, so he may be a little bias. I honestly think that the stuff from autozone or west marine would be fine. I've never heard of adding carbon fiber dust but if it works the way he says it would be pretty awesome.

Quote

Notice how he made a shaped backer by laying up over waxpaper, when cured he cut and fit it into the hole as a backer plate and then laid up over it. Learned by watching YouTube.

this sounds like the best way to do it, but might take a little longer...

if you can fit a piece of plastic/ heavy paper/ expanding foam in there that would work too. whatever gives you a reasonable backing. It doesnt have to be perfect because you can fill low spots later.

--
70's 18' Sol Cat "Venora"
70's 18' Sol Cat "Bumblebee"
60's 14' Sailstar Tallstar sloop "Arandora"

Heber City, UT
--

Thanks for advice. So do you think the polyester resin will be ok, or should I use the vinyl ester for added strength?

--
Jeremy Soder
Nacra 5.8
Allen, TX
--

If the area in the photo is 4"...that really is no problem. I wouldn't bother with injecting foam, or using plywood, they will eventually take on water.
If the hole is large enough to insert a small triangle trim sander, or angle grinder,(you usually have to remove the handle from the grinder), do that & feather outwards from the hole. If not, you just have to use more elbow/finger grease to sand some material from the inside...you want to get rid of any contamination, & thin the old hull, then lay up a couple layers on the INSIDE. Everything I have read from the manufacturers say you can go 3 layers without excess heat.
I never finished this album, but it shows an easy way to conform to hull shape. Cut a base from a plastic jug, slightly larger than your first layer of cloth. Punch 2 small holes in the center, so you can thread a piece of nylon string through. Now cut out 3 layers of cloth, largest against the plastic, you will need a needle to thread the line through the cloth. (I used SS aviation lock wire, because I had it handy, but braided string, or even stron thread would work better.
Once everything is prepped,(don't forget to wipe down the inside with acetone, or even rubbing alcohol), wet out the 3 layers you have on the plastic disc. Fold the disc, like a Taco shell, & insert into the hole. Once you let go the disc will pop back to its original shape. Now, using the string, pull the disc & cloth snugly against the inside of the hull. Tie the string around a stick placed across the hull to keep things in place til it kicks off. You may need to have an extra hand, and a couple small foam blocks to hold the stick off the hull. Dry fit things first, so you have everything ready & figured out, before you wet the cloth & stick it in the hull. Some resin will run down the outside, just wipe it off before it sets.
You will now have strong backing to build on, cut the strings close, add another couple layers , remember use as little resin as it takes to wet the cloth, sand to smooth & fair the patch, then finger wipe a very thin layer to seal any fibers your sanding exposed. It will be stronger than the original hull. The plastic will probably fall away, but it won't rot, absorb water, weighs almost nothing.
http://www.thebeachcats.c…ictures/?g2_itemId=77105

--
Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--

Quote

Thanks for advice. So do you think the polyester resin will be ok, or should I use the vinyl ester for added strength?

In my opinion polyester should be fine. Maybe some others here have an opinion... I've honestly never used vinyl ester... but if it is stronger it certainly can't hurt if you want to spend the extra money.

--
70's 18' Sol Cat "Venora"
70's 18' Sol Cat "Bumblebee"
60's 14' Sailstar Tallstar sloop "Arandora"

Heber City, UT
--