Parting out H170 in AZ

Apr 16, 2017
841
Federation NCC-1701 Riverside
It has begun...
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MMA is a generic term for stuff like plexus ma300, 3M, Devcon, there are more brands than to count now.

I havent picked a brand yet. I saw on sailing anarchy someone had recommended a version that has longer pot life maybe plexus ma310.

I should probably fix this one bench to perfect my craft, then do the other, yhen the deck.

The foam is intact and the luran came right off with just a few sticky area. There are bubbles in the foam that i will pop and fill. Should layup nicely. There was water beading up under the luran. Its super smooth foam. Its occuring to me that the bench first showed signs of delaminated luran where those blisters are. Wonder if the blisters push the luran off the foam?

I think i know how they build the top deck. They start with a foam plug, then brush on some adhesive. Then a huge sheet of luran is heated up, lowered over the foam mold, and vacummed to the foam.

The section cut out is about 5 lbs. It is not salvageable as the warps wont go back down. Its about 0.10 inches thick. Thats about 3 layers of 1700 biaxial cloth (no mat).
 
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Sep 22, 2018
1,869
Hunter 216 Kingston
Nice neat removal, did you use a Dremel with a guide?
Is the shiny surface the foam or the glue they used? You know the FRP will stick to foam so maybe a light sand of the entire surface to ensure the new layer stick and get rid of the surface bumps?
I can’t recall but I think someone undercut the foam at the seam and laid the glass “underneath” the Luran???
 
Apr 16, 2017
841
Federation NCC-1701 Riverside
Lines next to the bench backrest were made with a round object (tire pressure gauge) that i could fit snug between the two sides, while dragging a pencil in the bottom tangent. The side near the leg was drawn with a speed square at the 2" mark. The radii are the top of a bucket. The cut took an 45 minutes with a dremel. I need a better way to make that cut, but i was able to stay on target most of the time. Got hit with molten luran slag once and a while but had safety glasses on. Tin snips cut Luran like butter, but i cant get close to the foam. Maybe use a pizza cutter :)

I was guessing at how much flat section to leave. I want the luran edge to be as close to a corner as possible for structure, yet have enough to stick back on the foam and have enough for connecting back to fiberglass.

Will definately rough up the foam surface. Its a wonder anything sticks its so smooth. The bottom of the luran is super shiny as well.

I like the undercut idea, going to make a compilation of posts and then build a project plan.

The rim of the cut also delaminated, more so by the legs, almost none at the back rest. Will inject 5200 or PL3X under the perimeter before the layup.

Maybe leave the delamination at the cut so the luran can move; like a wooden floor?
 
Apr 16, 2017
841
Federation NCC-1701 Riverside
Today was a big research day. I stopped by West Marine to see if I could pick up a small bit of 1700 biaxial fiberglass tape so I could do some tests, but no luck.
According to the West Marine website to make a 0.1" thick panel I need about 3 layers of 17 oz biaxial.

Anyone know if three layers will be too much or too little for getting to 0.1"?

It's looking like I'll need about 14 yards of the stuff if I go three layers. It's really hard to get a common layup schedule with thicknesses. I can get a single package of 3 yards and practice on the bench no problem and then get 11 yards on one roll later if everything goes according to plan.

Hunter170a.png


Found some info on the MMA. Loctite has a really good writeup on plastic that I'll share. Looking like it going to be MA310 for the Luran to fiberglass connection.
 

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Sep 22, 2018
1,869
Hunter 216 Kingston
Interesting article thanks for posting it. I did find in kind of strange that Luran is listed as an ASA on page 18 and again as a SAN on page 70, with quite different descriptors. The ASA version seems to line up with the characteristics and uses better in how Hunter used it. If there really are two “flavours” of Luran I wonder if this is related to the early production, bad batch of Luran causing cracking theory?

Your idea of leaving a little delamination for expansion and contraction might have merit. Tough call; let it breathe a bit to prevent cracks or nail it down so it can’t move to prevent cracks. Your in uncharted waters I’m afraid. ;)

There was another thread on here about a 216 owner not being able to get the hatch boards tight when the rigging was tensioned, happens on mine as well. I noticed the other day that my boards are fitting closer. The only factor that has changed is the air and water temp is falling, sort of proves the hull material is effected by temp.
 
Apr 16, 2017
841
Federation NCC-1701 Riverside
Picked up some more PL3X and glued the luran around the perimeter down. All the foam was sanded with 80 grit paper. Also got sandpaper about 1-2 inches under the luran. The foam had surface cavities that were popped and cleaned out.

Figured out some techinque. The glue is only going to reach about 1-2 inches back. Before trying to get it under the luran, spread the adhesive like caulking a bathroom, right on the foam/luran corner. Then, take a crowbar and shove it between the luran and foam, the adhesive caulk lubricates. With the gap use a small kabob stick and push the caulk under as far as possible. Pull out crowbar and move down. When all done use a scraper to clean.

Found a new use for PL3X, foam cavity filler. It expands!
 

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Sep 22, 2018
1,869
Hunter 216 Kingston
take a crowbar and shove it between the luran and foam
I’m a little surprised that the foam didn’t “dent” a bit but maybe you didn’t actually pry the bar, just used it as a wedge. In any event that edge isn’t going anywhere now! Won’t this also eliminate the undercut concept?
Are you planning on using a roller on the glass layup? It’s been quite a while since I did any FRP stuff but I seem to recall the fine weave cloth being a little prone to bubbles.
 
Apr 16, 2017
841
Federation NCC-1701 Riverside
Crowbar is just a wedge. You are spot on with how easy it is to dent. Even when gluing it is important to only apply enough pressure for the adhesive to work. Too much pressure with a thick adhessive and the luran will be wavy with the high pressure areas lower than the areas that received no pressure. Thats why i like PL3X, its thick and it expands a little to fill the gaps.

The rim is adhered back to the foam nicely. Thats it for undercut. I lifted the luran and sanded a thickness of folded over 80 grit. The glue squeezed out from mostly natural pressure, ill trim that off. After the glass is layed down ill cut a new v groove all the way around. That would ruin the undercut. The gap is then filled with the Plastic adhesive.

3m has a beautiful write up on how to glue plastic that i should attach. We should be doing at least lap joints, butt joints are the absolute worst way to glue plastic. the crux...the only way to get a lap is to use prefab fiberglass and either glue under the luran and then glass to level, or use prefab fiberglass and lay over a perfectly fared repair. I thought about making fiberglass panels on the floor and then using thr tempkate to cut out and glue it on...but i dont know how level my floor is and if the boat surfaces are truly flat. Then i could mma the lap and pl3x the rest. With a 5 minute working time ;)

Roller is on order, also picked up a 50ml plunger gun.
 
Apr 16, 2017
841
Federation NCC-1701 Riverside
A better protocol for a plastic patch that includes lapping?
IMG_20190924_110720.jpg


Kinda like the 12:1 bevel for fiberglass. The cut would be with a router and the filler would be prefab strips. The glue would cover much more area.
 
Sep 22, 2018
1,869
Hunter 216 Kingston
Not that I don’t appreciate your artwork ;) but this came from the article in post #145
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Apr 16, 2017
841
Federation NCC-1701 Riverside
Not that I don’t appreciate your artwork ;) but this came from the article in post #145
View attachment 170069
I stopped reading once i got to the ASA plastic section and determined what adhesive to use. Its the gift that keeps on giving. Ill add the 3m write up tonight. The loctite pdf also says, and i nonquote, "Dont even think of trying to glue stuff with different rates of expansion."
 
Apr 16, 2017
841
Federation NCC-1701 Riverside
This is awkward.

There is definately going to be a noticable difference between the existing luran and the new fiberglass.

The 1700 stitch matt is pretty heavy and in my hands its feels much thicker than the cloth sold in hardware stores. I cut off a couple squares and built up a 3 layer sample and a 4 layer sample. The goal was about a tenth of an inch since that is about the thickness of the luran cut off. Almost wondering if i should have just bought fiberglass panels from lowes instead and glued that down. The 4 layers version averages out to .023 inches per layer, while west marine says it should be .035.

As far as composites go three layers of 1700 is more than enough for covering foam, but its looking like id have to put down 8 layers to be level (3/16 inch) with the luran. Thats bs. Maybe i squooshed the fibers out while saturating the cloth with the roller and didnt use enough resin, but it got fully saturated.

The panel that got removed weighed 75 ounces, the three layers of 1700 ive cut weigh 40oz and requires at least 80 oz of resin, already going to be heavier when a composite really only needs the one layer. In addition, ive got two coats of neat epoxy over those, but the 2:1 ratio of expoxy to cloth is supposed to include that.

Ill probably know by the second layer how this build up is going to go.

At the very least, the first step will be adding a high density low angle camber fillet between the luran and the foam. That will help transition the glass up and over the lip without a bubble under the glass. It will mostly likely be dremeled out afterwards to add the MMA.

I dont mind if there is a recessed area of repair, but it would probably hold water when left outside.

Additional notes: The total volume of the cut out luran is 180 cube inches, or 0.8 gallons. If i need 0.6 gallons of resin, then that means the remaining 1700 glass needs to be 0.20 gallons or 50 cube inches, thats a cube of solid glass 3.6 inches on a side. My pile of glass when tightly rolled up is about 86 cube inches. I know it wets out so maybe im close?
 

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Sep 22, 2018
1,869
Hunter 216 Kingston
Maybe I’m crazy thinking but what if you poured a thin layer of foam on the existing foam to bring it level with the Luran, maybe hot knife it level?? Then glass over that? Finish would sit a little proud but in my thinking that would be better than hollow.
 
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Apr 16, 2017
841
Federation NCC-1701 Riverside
Maybe I’m crazy thinking but what if you poured a thin layer of foam on the existing foam to bring it level with the Luran, maybe hot knife it level?? Then glass over that? Finish would sit a little proud but in my thinking that would be better than hollow.
Thats an interesting idea. That stuff cuts easy and it could be sanded down with 60 grit to the level that supports a layer of 1700 and two overcoats. it would be challenging to pour a large area, maybe pour 2part foam all over, spread it quickly, then lay a flat board over it to squeeze it laterally.

With that scenerio it might be good to remove about a 1/4 inch of foam, then, build it back to level. With that technique, one could then refill the area with prefabricated fiberglass panels.
 
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Sep 22, 2018
1,869
Hunter 216 Kingston
I was just thinking the foam would be less weight than the glass but I don’t have any hands on with two part foam so you are the expert on that.

I would be careful about going too thin on the glass layer as you will be stepping on it etc.

I’m having trouble understanding the need for perfect level if you are planning on re-covering with your blue comfy seats?
 
Apr 16, 2017
841
Federation NCC-1701 Riverside
I’m having trouble understanding the need for perfect level if you are planning on re-covering with your blue comfy seats?
I would like the repair to be better than factory. I am OCD about broken stuff in my care.

The foam seats are just sections that would fit in the depression, Not cover the transition up.

Just 3 layers of 1700 is much tougher than luran. I cut the sample biscuits in half with a tin snips and it was nearly impossible without making relief cuts first. The luran has almost no resistance to the tin snips. Luran is as strong as about 2 layers of 1700.

If after 3 layers there is still an edge up to the original level, i will sand the luran down to match and then extend the sanding to the side of the benches and to the rear so water drains.

If 3 layers is that bad, then I will use the foam technique elswhere. The problem is i still need fiberglass to cover and more epoxy to "hot coat", even if i remove foam to stick coosa board in there.

Coosa board on the deck sounds amazing at this point. There is a section where there might not be foam under the foot stop.
 
Sep 22, 2018
1,869
Hunter 216 Kingston
I share the perspective of repairs being as good or hopefully better than original. I thought maybe there was some technical reason such as the MMA joint that I wasn’t getting.

I had a quick look at the Coosa stuff. That’s pretty cool material, do they make it in the thickness you need?
 
Apr 16, 2017
841
Federation NCC-1701 Riverside
I had a quick look at the Coosa stuff. That’s pretty cool material, do they make it in the thickness you need?
The thinnest is 1/4" so i rejected it, but your idea to mess with the foam inspired me to remove foam, potentially opening up more options for replacement substrates. Might find something that can be painted, yet no requirement for faring other than to glue in.