Fiberglass reinforcements for transom and deck repair

[bobm]

I am doing some fairly extensive renovations on an 18 foot fiberglass center console boat, a Privateer 18. The transom is being raised to 25 inches from 20 inches, the glass covered plywood deck is being replaced and raised 2 and a half inches to make sure the boat is self bailing, the built in 18 gal aluminum gas tank is being replaced with a new 30 gallon aluminum tank, and the whole thing will be painted with a roll and tip awlgrip job.

My immediate issue is determining what fiberglass fabric (and how many layers) to cover the new plywood transom and deck with and where to buy it. It seems to me that if I was to choose only one material for the entire job it should probably be 12 ounce double bias (no mat) cloth set in epoxy. I have some traditional fiberglass cloth on hand and it would probably be just fine for the deck, perhaps combined with a layer of biax. Are there differences in "12 oz double bias cloth" from different suppliers or should price and customer service be the main critera for purchase? Fiberglass Supply in Burlington, WA has good prices, has anyone dealt with them?

It seems that lately most of the projects I read about are using System Three resins. I was able to purchase a number of gallons of West System resin for a good price so this is what I will use on this project. Does anyone have an opinion on the ease of use, wetting out, blush, etc, advantages of one brand vs. the other? Any tips on wetting out cloth and avoiding curing time problems?

Any input will be greatly appreciated.

Thanks

[Skipper599]

Welcome Bobm ... First of all, I'm no expert on fg or the application of same. Likewise, we do not know what experience you have either. Sometimes it's helpful to know how much "detail" you are looking for. If like me, you have very basic/limited knowledge of this type of work, I would suggest you google "West System" and pick out a manual or two on "How-to" (they are very detailed with explanations and sketches), because that would save a lot of "how do you " questions on your part.

I too use West System resin and hardner for projects on my boat. You mentioned you got some (resin) at a good price... Do you also have the proper Hardner and calibrated pumps for correct mixing quantities to go with it? ... Just trying to gauge what level of response is needed here.

[Rachel]

Hi bobm, and welcome,

I found myself nodding as I read Skipper599's reply. Your question has a lot of questions within, and although I read it when you first posted, I didn't feel I could really tackle it. Skipper599 has some good thoughts.

Here is a link to the WEST System manual he speaks of. It's a great publication and I keep one on hand for reference (you can often get it in free booklet form at stores that sell WEST). Each of the images here corresponds to a chapter in the paper booklet.

http://westsystem.com/ss/use-guides/

System Three's "Epoxy Book" is also a nice (and also free) online manual. Although their mixing ratios are not the same for resin and hardener, most everything else is pretty similar. I find it helpful to get info from two sources because sometimes one explains it a little differently or it's just nice to feel more sure I "get it" by reading it twice from different companies.

http://www.systemthree.com/reslibrary/m ... rature.asp

Rachel

[Zach]

Are you taking out the old deck and building the new on in taller? If you aren't you will want to punch a bunch of huge holes in the old deck and bring as much ventilation as you can. Even if its marine grade plywood you are going back with, if you just lay down wood strips and build a new deck on the old it will rot out in a heart beat as it will pull in moisture and won't be able to vent it... bad, bad, ju ju!

If it was me I would use 1708 biax, with a mat back. Each layer of 1708 yeilds roughly 1/8th of an inch of thickness. 1208 would take 3 layers to make a 1/4, I do like 1208 for working around curved surfaces... but on the deck thicker is better.

I do two layers of 1708 on plywood decks, by doing two layers on two different days. Side to side generally has less waste than fore to aft. Plus the juice runs down hill, so you may as well wet it out into the next layer rather than walk in it. I put down a piece that is 2 feet wide at the front of the first layer, and use full 4 foot widths the rest of the way back.

Use slow hardener, and mix it in gallon mixing buckets. Most of the mixes would be 5 lines to 1 line hardener on west system. For small batches I mix 2.5 lines to .5 hardener, or 3 parts total. Use a normal old red tree polyester paint roller, the green ones with the green core... they shouldn't be more than a buck each. Roll the cloth off the roll so the mat is on the outside. Wet the plywood deck with epoxy to the center of the boat, unroll the fiberglass into the wet resin, half way. Roll resin on top of the fiberglass you just unrolled, and then roll under the other half. You should have a scroll looking bit of fiberglass in the middle of the boat at this point. From here, unroll the fiberglass, and roll the top with more resin.

If you do it in halves, one side can start getting gummy and you don't have to throw away the whole pot. You also can do the job in direct sun... if you try to roll resin on the whole area of the deck 4 feet wide by how ever long the resin can tack up... and tacked up resin in cloth doesn't let more resin through so if you have a dry spot it stays a dry spot.

From here, just butt up the next layer beside this one repeat the process till its done. If the boat is on the hard, or the area is small... you can wet up the cloth in the same manner on a piece of plywood with plastic stretched across it and stapled to the underside. Use at least 2 mil.

After the cloth is wet, have an air roller on a paint roller stick ready. I use the 4 inch side more often than not, even on huge areas... as they put more pressure down. You have to roll more passed, but in the end I don't feel my arms... Rolling a 6 or 8 inch by 3/4 roller 4 feet away trying to get that last air bubble, you feel it later on.

The next day I hop out and grind off the top of the surface with 40 grit sandpaper on an 8 inch soft pad. I don't hardly ever have blush problems, unless someone goes wild with extra hardener in the mix. Though I do check. Amine blush is a waxy substance on top of the epoxy, if it feels slimy to your fingers after it is cured you will want to do a water wash with scotch brite. I get blush once every few weeks... the rest of the time, its a grind and go sort of deal. Fast with west system seems more temperamental to dew landing on it and blushing to beat the band... You could use a random orbital, but I like a variable speed pad sander. I use a Makita 9227c with a medium weight foam backer pad, and stick on sandpaper. I like closed coat paper, with zirconium grit. The brand I use the most of is sungold abrasives, as it is cheap and I can get it locally... 3m green production paper is good stuff for the cost too.

Pretty much a repeat of the process of fiberglassing, except this time on each layer of fiberglass I mix up microballoons and hot coat the glass so that when it cures I don't grind away any of the fiberglass strands in order to get a fair surface. When that kicks off enough to step on but is still chemically active (check the charts of the system you are using...) Use a cheap roller frame, and a 1/8th inch nap Red Tree adhesive roller, with a phenolic core. These are 3.50 cents for two of them. West systems rollers are 7 inch, and they do work... but they lose their fuzz and don't do as nice a job as the Red Tree's. I mix my ballons thicker than whipped cream, and pay attention to the bottom of the bucket otherwise there will be a pool of resin at the bottom. I use 3m scotchlight microballons... the phenolic ones are easy sanding, but they cost an arm, a leg, and your first born. If you mix it up where it is easy to spread immediately, it will go runny as the resin heats up and starts to kick. Some people add cabosil to the mix, I don't as it doesn't self level as easily, nor is it as easy to sand. If you are putting Awlgrip 545 right on top of it, you would be well served to add some of West systems white pigment to the mix to make it easier to cover... But Awlfair is a lot easier to sand.

I tend to walk out and either pull more microballons in the obvious low spots, or pull a quick layer of Awlgrip's Awlfair.. while everything is still kicking off and chemically active to save on a sanding cycle the next day. Don't stray much from the awlgrip systems guidlines... Though I use acetone to do the wash most of the time, rather than their surface prep... But that is just how its done in my area. A little birdy told me that adding enough thinner that the primer sprays nicely, and doing a few more coats rather than a few heavy coats yeilds a nicer finished product... I use the little foam hotdog rollers to put 545 and high build on. If it is something I really care about the finish of, I will roll 5-6 coats of high build on over the course of a day once it hits 80 grit and the shaping is done. If you are sanding something that sands the same rate, it is a lot easier to make things flat. Fiberglass is a whole whole lot harder than primer... highbuild doesn't suck as bad as awlquick does if it sits out in the sun. You can mix a pot of 545, and a pot of awlquick, and after they induct and then mix them together for something that is halfway between the two as they are chemically compatible. Awlquick goes rock hard after a week or two in the sun....

From here you will want to rough sand the high spots with 40 grit, and then use a long sheetrock taping knife 1-2 feet, and pull the deck from side to side with awlfair bridging the seams of the fiberglass. Pull it tight, meaning that you should still see some white ballons here and there. You can either use an inline sander, or a hand powered long board and some black spray paint to see the lows. Since it is a deck, it doesn't have to be perfectly smooth as some of the spots will be hidden by the non-skid. The closer it is to perfect, the nicer it will look... as those little low spots will be where the dirty water gathers and evaporates.

For the most part, rebuilding exactly what was there for structural stuff is about all that needs to be done. If it worked and didn't fail, and was still working even when rotten... when you rebuild it with marine plywood, instead of exterior grade. Epoxy, instead of polyester... and biax instead of mat and roving... and you actually care about the life expectancy of the job, it is overkill right from the start. So if it had a 1/4 inch of glass, put at least a 1/4. If it had 1 layer of 3/4, you can figure to go back with 1 layer... etc.

If you don't care about weight and want a bomb proof transom:

If it is flat you can laminate two layers of 3/4 inch marine grade plywood together using fender washers and #8 square drive swan secure screws. I use 1 5/8's on stuff that is blind to the back side and screw holes don't matter. If you will be looking at the back side, you can use 1 1/4. A full sheet of 3/4 plywood weighs between 66 and 70 pounds. Okume is heavier than meranti. For me meranti is more expensive than Okume, but that is just because its not used around here very much. From what I understand, this is opposite most places. I paid $96 a sheet for Okume a few weeks ago, but there is a pretty big supply crunch for it... the country that produces most of the logs has stopped exporting, and is trying to get some mills online to peel the logs before export.

If the transom is off:

For the most part don't even mess around with exterior grade plywood. Douglas fir marine grade is ok stuff, but it doesn't bend worth a flip and the veneers are flat sawn not peeled so you will run into more voids. It is a half step up from exterior grade. The veneers are a lot thicker, so you don't have as many plys which makes its rot resistance lower than Okume or Meranti... more wood that has less glue soaking it.

To rebuild a curved transom, you can do it from the outside easier than the inside, though on a glass boat it'd have to be a really bad transom to cut it off and start fresh.

If it is curved, you can laminate 3 layers of half, or 4 layers of 3/8ths. Half inch will show the seams through the glass on a tight bend unless you strip it diagonally... meaning you rip it into 10-12 inch wide boards, and run them in an X pattern over a form. This is stronger than using full sized pieces and pulling them into shape, as you've effectively built a wooden spring that is held under load by the epoxy.

Sand the plywood with 60-80 grit on a random orbit sander on both sides before you cut it up, so you don't have to grab a sander while gooped up with epoxy. Blow off the dust or sweep it off. Now cut out your pattern. Use a luan template if its complex, as a curved piece of plywood is like wrapping a piece of paper around a basketball. From here if you are working from the inside you'll either want stifflegs off other structures inside the boat to hold the plywood in place, or you will want to take 2x4's or 3/4 plywood stood on edge outside the boat on standard spacings (10-12-16 inch depending on your curve. Now you'll take your stack of plywood pieces, and number them. Grab your box of screws and your drill and pull the plywood down into place. Now take a sharpie, and circle the holes that have screws and fender washers in them so it is easy to see which hole has a screw on which layer... Then put up the next layer and repeat the process until you hit the disired thickness.

From here you'll wet the plywood with resin on the one face, and the edges. You'll take a notched spreader and put epoxy thickened with cabosil on the inside of the transom and start screwing it in place through the outside of the hull to your stiff legs. If you just put the epoxy on the face of the surface your bonding to, the cabosil doesn't fully wet out the other piece of plywood and makes things not as strong or as void free as they would be with both sides wet. I use the bigger notches on the west system spreader for most stuff... but then again I like overkill.

The shortcut here is to take a piece of plywood about 2 foot by 2 foot, and set the screws standing straight up with the fender washers on top of them. Grab a hand full with a few fingers, and lay them in the palm of your hand so you can bounce them between a thumb and a finger, then start going to town. Drill straight in for the first few so the panel won't shift, but after that start drilling just off of center... but do them at the same angle. An angled screw doesn't warp the fender washers as bad as a straight in screw...

Once all your screws are in place, you'll take off your gloves, and kick back until the epoxy in your pot has kicked off... or wait until the next day, and back out all the screws. If some of them have glue in them, take a screw on your #2 bit in the drill, and drill into the square hole, then take the screw and pick out the corners. It is pretty easy to get even the most glue filled screws back out with that method. If some of your washers want to stay stuck, take a hammer and tap around... hard enough to shake them loose but not so hard as to put hammer marks in the plywood.

Lastly, see if you can get your hands on some Coosa board and bed it into a mish mash of cotton fiber and epoxy. It doesn't like bolts or screws in it, so you'll have to over drill the holes and back fill them with ground glass fiber and epoxy, but that would be a transom that'd last forever...