Hull fiberglassing question

[PSwan]

Am about to fiberglass the hull of my Weekender. Have filled all the screw holes, faired the hull to keel joint and sanded everything fairly smooth. Am using System 3 epoxy and 45/45 bi-axial 9 oz cloth. Are there any major do's/don't's anyone has run into? I'm fairly novice on fiberglass work. Any advise would be very much appreciated.

[Charlie Jones]

Don't mix large batches- use smaller ones and mix more often.

Don't get in a rush- just work steadily.

Pee before you start

[Greg Luckett]

I often work alone, but it sure is nice to have someone mixing batches for you or helping position the cloth.

[PSwan]

Thanks for the feedback. How big is a small batch vs. large batch?

[Ken_Potts]

If I haven't done glass work in a while I'll go as far as rehearsing the entire operation minus the epoxy. I'll even pick up the mixing cup and stick, carry it to the spot I'm going to work, etc.

I know that might sound a little loopy but on more than one occasion I've found that I don't know where a preader is or something.

A small batch would be maybe several square feet - 2x3 feet? (for me at least). You can scale things up with succeeding batches until you find a good sized area for your conditions. It's better to start too small than too large.

[Pipefitter]

My ideal working speed amount of 2to1 epoxy (slow hardener) while glassing was 14 pumps of resin,7 hardener and I had to move relatively quickly to have totally invisible cloth upon wet out. This was temperatures in the low to mid 80's.

I used one of these fiberglass rollers to keep the cloth in the resin while it was starting to set up. As the resin started to thicken,this would keep it low in the mix.

I should also add that I had a little practice with the helm box and motorwell before I was ready for the larger hull bottom.

[wkisting]

I'd keep the batch size to about 8 oz. of epoxy at a time (less in tricky areas where you might work slower, such as at the stem). Any more than that, and you'll find it starting to set up a bit (unless you're using a very slow hardener) to the point that it doesn't wet out the glass as easily, nor allow you to squeegee away the excess as smoothly before you can get it spread around... This will translate into bumps, irregularities, and possible "floating" in the glass later, increasing the final sanding time exponentially.

At least, that's been my experience.

I agree with Greg, it's a real help to have someone on hand mixing epoxy for you as you need it.

Also, from a safety standpoint: Wear a respirator and ventilate your space as much as possible.

Edited to add: Oops, Charlie (below) is right. My advice depends heavily on the assumption you're working under conditions like mine. Sorry, should have clarified that. My experience was based on working in 70-90 deg. heat in the Midwest. At a colder temp, you might get away with mixing a bit more. In a hotter clime, you might find even 8 oz. setting up on you too quickly. And, of course, there are other factors... like how many folks you have on hand helping you (I'm usually alone or with one partner... perfectionists don't like having too much help with epoxy work ...sanding, though, is a different story). Probably, the smart route is to start with a small batch of say 4 oz. and gradually increase batch size until you find yourself running out of the batch and finishing spreading around the excess just a few moments before the epoxy begins to go off.

[Charlie Jones]

A small batch vs a large batch depends completely on what the temp is and how fast you work.

When I'm glassing a boat and the temps are close to or above 100 degrees, then maybe 10 pumps (2-1 mix) is enough. If the temps are in the 60s I might be able to work with 20 pumps or more. Also depends a LOT on WHERE on the boat you are working. If you are glassing a hull bottom that is upside down, so you are working down, then you can really truck spreading the resin and squeegeeing it out. So you can use larger batches. Of course when you get to working the chines and around the vee of the bow it slows down, so smaller batches come in.

Working on an almost vertical hull side it isn't as simple to get the resin in place or spread it with out making a mess, so much smaller batches are called for.

I'd suggest starting with 6 - 8 pumps at first, on the bottom of the boat, and increasing the volume as you learn the motions. Wouldn't go over about 12- 15 pumps though til you really gain proficiency

[Howard]

Laying down glass cloth seems to be one of those Voodoo areas of boatbuilding that drives a novice nuts. Examples being West Systems advocating putting down the cloth and coating it and the wood underneath it dry (they call it the "dry method"), as opposed to the wet method which is to coat the surface and lay the dry cloth onto the wet surface and go from there. They don't recommend that, nor does anyone else that I know of.

System 3 also suggests laying cloth on a "dry" surface, but they suggest coating it with epoxy first, then sanding and fairing that (exactly as Ray suggested). The idea here being that the glass cloth is not structural to the boat....it's structural to the epoxy coating, so all you want to do is coat the boat, then lay the cloth on that after it's cured, or after it's reached at least the green cured stage (no longer tacky) and wet it out, using as little goo as possible, then filling and fairing the weave. Now for the Voodoo part. Guys like Rauel Parker will tell you NEVER try to coat cured epoxy...he says it won't stick no matter what anyone tells you. So you have a manufacturer who says do it and a boat designer who says never do it. Who do you believe?

Personally, I think the way S3 and Ray suggests is the way to go and wetout of the cloth will be much easier and you will get a more consistent job. If you fear the lack of bonding, then you can sand, fair and coat within 24 to 48 hours of laying on your sealer coat, and it will still chemically bond. Subsequent coats go on green. I'd suggest wiping down the hull between coats, just in case there is any amine blush. If I don't wipe down between coats, my epoxy tends to "clump" or spead out unevenly, as you might see a thin layer of grease do in a non-stick skillet. It ends up being uneven and forces you to sand a bunch later on. A light scuff sanding always seems to help reduce the surface tension and get the epoxy to spread evenly.

Next part. How to lay it down. If you are coating the wood first, you could use a thin napped foam roller if it's a large surface. If, when you are ready to glass, the surface is horizontal, you can use a squeegee. If it's vertical, like the topsides might be, then you use a roller.

Which way you go matters how much goo you mix up. If it's a flat surface and you want to use a squeegee, you will be dumping it from your mixing pot. About 1 oz per SF. Probably no more than 8 oz to start with.

If using a roller, then another problem pops up. You need to use a tray, which does two things. If the tray isn't big enough so that the goo can spread out into a shallow layer, you can get heat buildup in the tray and it will go off on you. A thick roller will have the same thing happen right on the roller. And you never get all the goo out of the tray, so it uses more juice.

And back to the theme of cloth is structural to the epoxy. For the exterior of the hull, or one that isn't going to be finished bright, a much better coating than glass is Xynole polyester cloth. One layer of this 4 oz cloth finishes to almost 3/64th's of an inch and it will be a tough, flexible coating.It's also flexible and stretchy, and will conform to your shapes and curves better than glass cloth. General consensus is that it's far, far superior to glass as the exterior sheathing for plywood boats. If you use it you will use 2 to 3 x the amount of epoxy. It really sucks it up. But again, that is building up a thick, uniform coating that when cured, will really be tough. It will also add some extra weight.

And last, but not least, go to S3's website, register as a member, and download the free epoxy book:

http://www.systemthree.com/members/m_index.asp

A lot of good information in there from some guys who make the stuff. Just be aware of the marketing inherent in such a publication. Pick and choose what makes sense and give it a go.

[umop_apisdn]

I have another question about fiberglassing. I have to repair a couple spots on my boat. Both spots are quite small, maybe 4-5 square inches each. The glass didn't stick to the wood, and bubbled up.

I'm assuming this is a pretty easy repair? cut/sand out the bad glass, scuff up the area with some 40 grit, make sure ALL paint is removed from the surrounding area, and lay down a patch of glass?

Is there any difference between the materials used on a boat, and those used for cars? West Marine is a 30minute drive from here, and Schuck's Auto is just down the street. Any reason I can't go get a fiberglass repair kit from Shuck's and use that? Or do I need to go by stuff specifically for boats?

Thanks,

Noel

[Howard]

Noel:

Lots to learn from you question. For starters, what did you use to glass the boat with the first time, and what method of application did you use? As for what did you use, was it epoxy or polysester? The latter might have come from West Marine as "Boat Yard" fiberglass resin. If so, delamination patches could be expected.

The same would be expected if the stuff from Shuck's is polyester resin. That means that little tube of clear catalyst instead of an epoxy hardener. I'd stick with epoxy....no matter what you used the first time. If that means an hour's drive, so be it.

Anyway, you have the right idea. Sand it down to bare wood and "feather" the edge of the adjacent glass layer. Put in your patch, wet it out, coat the weave, etc. In short, treat it just like a new glass job. Once it's cured, sand, fair and paint it just like you did the first time.

[umop_apisdn]

Howard,

I am not the original builder, so I have no idea what was used for the original glass job. I was mulling about in my mind what kind of boat I wanted to build, and whether I really had time to build a boat from scratch when I found this one for sale.

Anyway, the original glassing leaves a lot to be desired. No sanding or any attempt to fill the weave or anything. Lots of runs and a few wrinkles in the cloth. For the most part I am ignoring all of that, but I am going after a few places where the wood is exposed or in danger of having water trapped under the glass.

So I just need to make sure that what I use is epoxy, not polyester, and I should be good to go, right?

Thanks,

Noel.

[Barry Pyeatt]

Noel,

The auto repair kits are all polyester resins as is Bondo. Here is the primary issue. Polyester doesn't even stick well with polyester. Repairs to Polyester resins are best made with epoxy.

I don't think your boat was done with polyester resin though. I think that is is epoxy but kinda a rush job with not a lot of attention paid to getting it to lay flat on the wood surface below it.

You can get Small quanties of glass cloth from Thurman's in Woodinville. They also sell small quantities of Epoxys that would work just fine to make the repair.

I would advise not trying to make any repairs using the auto repair products. Some of them are labeled as epoxy but when you begin to look at the details they are really polyester resins. Same story, they have an issue with bonding to existing resins. It has to be a mechanical bond so 40 grit will leave enough of a tooth to allow it to grab on. Just wipe down the surface with soapy water, rinse and be certain it is totally dry before applying the patch.

Otherwise, just do as you planned and you shouldn't have any problems.

[JMetzner]

PSwan,

All excellent ideas from the group. The only thing I would add is don't even think about fiberglassing the keel. Just. Don't. Do. It. I thought I knew better, "Oh, surely TWO layers will work fine." Yeah, no. I had to strip off what remained of my two layers at the end of the first season of sailing. Just don't do it.

If you find yourself thinking about coating your keel with fiberglass, go over to your workbench and get your sliding compound ruler. Take the ruler out of the fixture. Place your left hand on the bench, palm down. Taking the ruler in your right hand, begin slapping the #$@()%*# out of the back of your left hand like Sister Solastica in 2nd grade, until you see the light....Switch hands if necessary. :shock: Don't. Glass. The. Keel.

--John M.

Alaskan-in-Exile

[Ken_Potts]

John,

I just want to be sure I understand your position - You think he shouldn't glass the keel?

[Barry Pyeatt]

Just in case John didn't get his point across! And with all due respect for those that have glassed over their keels. Some of which are holding up just fine.

I too, seriously recommend not glassing over the bottom of the keel.

Here is the reasoning behind this recommendation on my part at least.

Most builders to not use either quartersawn, straight grain or vertical grain (riff sawn) lumber to build up the three laminations of their keels. It is just too expensive to get that type of lumber and/or almost impossible to find in any of the box stores.)

Most from what I can determine, use softwoods for the most part and it is plainsawn lumber for the general construction market. The plain sawn lumber will cup as it drys out. (Straight grain, quartersawn or vertical grain does not cup.)

When it is purchased, it is kiln dried, fine for general construction work. As it drys out further it will cup and pull apart from the other layers. You can put epoxy, screws, etc. and it will still cup and the layers will seperate. If it is glassed over, you won't see the seperation until long after it has reached the stage of needing significant repair work. When it is glassed over and it seperates, the void will collect moisture in it. No air circulation, moisture, changes in temperture and freeze/thaw cycles in some climates and you have sure enough pockets of rotted wood. It doesn't take long for a lot of damage to occur. Just the off season under cover, outdoors, heat up a bit, freeze again, off and on and you can have a lot of damage that you won't see if it is glassed over :shock: .

There have been a number of posting by builders that were willing to admit it happens and has happended to them. Some of them faced serious challenges in removing the rot and making a repair. In all cases the glass has to be removed first and repairs made. But that isn't the end of the story, it will continue as the wood goes thru seasonal changes and freeze/thaw or broad humidity swings.

If there is not glass over the bottom edge, cracks and seperation is evident to anyone that is looking to see if it happens. Air does circulate and help dry it out. Less of an environment condusive to rot forming and causing significant damage. Relatively easy to take off paint and fill the seperation with epoxy and paint over it.

Those of us that have worked on a lot of wooden boats will know that it can be a most difficult and sad situation. Certainly frustrating in the least. Lots of boats sitting on old trailers, or in the bushes because the owners didn't know what toe do or it was more expensive and trouble to make the repairs than to just let it go. End of story.

[PSwan]

Wow, thanks to all for the great feedback. Fear level dropping significantly. Regarding the keel, I didn't plan to fiberglass it; however, now I fear I may have done something even worse. I epoxyed and screwed (brass screws) a 2" wide x 1/4" thick strip of brass to the entire bottom of it as a wear strip and to add some ballast effect. Am I in deep trouble here?

[Barry Pyeatt]

Probably not if you epoxied the entire bottom edge of the keel. The challenge with wear strips can be with the screws that hold it onto the keel. It would pay to remove the screws one by one and put thin epoxy in the screw hole then wipe some vaseline on the threads of the screws and put the screw back into the holes. If things seperate below the strip, you probably won't notice it quickly. But you probably won't have moisture incursion where the screws get banged around. This way you can remove the strip if necessary to check things out and still have epoxy coated wood below it.

[Pipefitter]

I am guilty of glassing over the keel but I never saw anything to the contrary when I was looking into building this boat. Didn't even know there was forums about building wood boats. Read the info that came with the plans. I did install the wood to where it would cup towards the hull and the wood was kept outside in my shed for a year before I used it. The pieces were sanded with 36 grit across the grain before they were glued in place.I will watch for it now though and I appreciate the heads up and if it gives me any trouble,I will back the screws out and remove it with a sawzall and a power planer/sander until it is no more and redo it. Being it is a false keel,it shouldn't be too bad being I built the boat.Live and learn I guess.Wish me luck.

I was also under the impression that alot of glassing the keel woes came from those who had a true keel that extended through the hull. When they glassed the exterior,they in effect created a bucket in which water could get under the glass on the outside from inside the hull at the bottom planking/keel juncture via the bilge, even as soon as they got water in the bilge the first time out. Maybe thats just one more way it can happen.Just a stab at trying to be optimistic here for my own sake.

[Barry Pyeatt]

On the Weekender and Vacationer the builders are using wide planks to create a three layer laminated keel. On the PC they are using two layers. These end up being glued/screwed on edge to attach them to the bottom plywood. If they are using plainsawn lumber the wide widths end up looking kinda like this.

()( or ))(

You've all probably seen how wide board siding looks after a few years on an old house or barn or how deck boards look after they have been out in the weather for a year or two. When they are laid flat with the cup side against the bottom, it isn't so noticable or as much of an issue. And narrower plainsawn boards will often want to twist as well as cup. Amazing the forces Mother nature builds into her products. :wink: