How to 'west system' fiberglass
(responses from MWCI e-mail listserve)

subject: How to 'west system' fiberglass (by Brian Koehler [bkoehler*at*georgiasouthern.edu])
date: Oct 31, 2006

Hey all,

I looked ALL OVER here (and even Savannah GA!) and no one carries west system anymore, but I finally found 'Boater's World' with staff that knew exactly what I was talking about and its use in fiberglasing. They now stock a brand that is about equivalent (even same mix ratios, pump spouts, etc). It should not soften-up after being in water like the Lowe's brands I have been trying to use (really, I had patches that later turned to rubber and I literaly peeled them up).

Anyways, this winter I planned to see how much (all?) old epoxy I could peel off my rib frame and re-do with proper glass cloth and this 'west-like' epoxy. I also need to work it up higher as I had way too much penetrable side area (~2 inches below!) last year.

Anyways, how do you all work the fiberglass onto the hull?
-- large pieces? or lots of small pieces (like a quilt)?
-- smear epoxy down first and lay cloth over it, or press it through with spatula?
-- build thick and work across? Or get one thin layer and then go back over with second?
-- should I wait between layers or pour fresh epoxy against earlier 'tacky' epoxy?

I can really almost see doing it all the way through (and some of these questions might not matter - might work either way). I just am curious about these details as I only want to re-do this once (and I don't want another 'rubbery' hull that flexes when I hold it in wrong places (makes me worry about poking a hole if I pick it up heavily-loaded, like after sinking ;-)

Thanks in advance,
Brian
subject: How to 'west system' fiberglass (by Tim Krakowski [tkrakows*at*gmail.com])
date: Oct 31, 2006

Brian - I have done a little work reinforcing ribs and such. I have even attempted to make a convoy ship hull using west system and fiberglass cloth. My experience is this:

For things like ribs or stringers, where you nees to reinforce a small area, use fiberglass mat. Coat the area you want to cover with the west system, and then place the cut piece of mat on the coated area. Then use a bit of extra resin (not too much!) on the top of the mat. Work the mat into the resin to make sure it is coated. Remove excess resin. It adds weight, not strength. If you are using 2 or more pieces in an area, overlap them slightly. The mat will intermingle and you'll have a nice strong bond. You can add multiple layers as needed. 2-3 layers will be quite think and quite strong. Use more if you have to.

To cover a hull - I wasn't trying to make a super detailed hull - I used glass cloth from Home Depot. There are tons of different cloth weights, but I used the standard cheap stuff. I think Lou has experience with the other stuff.

Good luck
Tim
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subject: How to 'west system' fiberglass (by Bart Purvis [bartpurvis*at*juno.com])
date: Oct 31, 2006

Hi Brian,
I'll stick to the answers I know. First, review my old article on glassing with CyA. It has much that applies to West, such as:
Little patches, big pieces don’t matter.
Use a size that you can work with.
Overlap a little, overlap a lot... doesn't matter. You can't tell after resin is applied.

Use 3M-77 or other spray adhesive to attach cloth to hull. You can move it around, smooth out wrinkles. The adhesive will not interfere with the resin setting up nor will it weaken the bond strength.

Use a few heavy cloth layers rather than many thin ones. This uses less resin, Excess resin add no strength, just weight and can become brittle. Two or three layers of cloth from the auto parts place should do fine. Do not use the lightweight cloth from the hobby shop.

Put resin on with a brush, work onto the weave. remove excess with a playing card or hotel key card. if you like, however some deft brush work should be all you need.

At the first sign that the mixed resin is setting quit with the batch immediately, if not sooner.

Start with a small area, very small, first and develop your technique.

Don't worry, Tis very easy, easy, easy.

Finish. Don't try for a smooth "professional finish". Why? 85% of the glass sides will be cut out and discarded. 100 % of the remaining sides will be covered with balsa and silkspan. 100% of the ship's bottom will be either on the work bench or under water. Remember a quote from Ben Rich, of F-117 fame, "Better is the enemy of good enough" and also remember we are going for function, not looks.

Bart
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subject: How to 'west system' fiberglass (by Au, Chris A. [Chris.Au*at*alcoa.com])
date: Oct 31, 2006

This place carries West System Epoxy.

http://www.westmarine.com/

To get a good bond with your (assume wood) hull structure, sand off the bad rubbery epoxy to bare wood. You can use West System mixed with micro fibers as a fill paste, for any uneven spots, then sand flush. I like to use a hand held orbital sander to do the hulls. Various grits disks, are useful depending on how much material you want to take off.

For the outside of the hull I like to drape the fiberglass cloth over the entire hull, cutting relief to avoid wrinkles, then paint on the epoxy with a disposable brush. Dollop a bit on from mixing cup- paint around- repeat until done. I like the somewhat coarse woven 4 to 6 oz cloth, it tends to drape better over the hull forms. I try to do as much of the outside hull at once as possible. However, often bow and stern block require separate work, due to complicated shapes. Wait for full hard cure before doing any grinding or cutting.

Once the epoxy is cured, you can cut the excess cloth/epoxy off with a grinding wheel and scissors. A light sanding, then a second coat often makes the hull smoother. Practice helps.

Keep in mind that epoxy won't stick to oily surfaces. Even skin oil will interfere with good bonding. For best bond between old and new epoxy, grind/sand old epoxy to expose fresh surface, then don't touch it.

A spatula does not work very well for spreading epoxy, brush works better. (most times)

For inside reinforcements area, often several layers are required. Precut your glass pieces, to avoid having to do it with sticky gloves. (makes a mess on your scissors)

Note that temperature is important in several regards to epoxy. At colder temps it get thicker and harder to spread. Also cure slower at colder temps. If you are tempted to heat the epoxy to get a more runny fluid, this works to a point, but your working time goes down a lot. And you can get fast thermal cure in the mixing cup. And smoke if you get too carried away.

The various cure agents and additives are useful to extend working time, or make paste for fill. And probably many other things. I like the glass micro fiber stuff, it make a good hard fill material. Good for fillets, gap filler, and damage repair.
Chris
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