First time Deck and Stringer repair

[Mechanicalmike08]

Hey guys,

My story is like many on here that you have heard time and time again. Bought my first boat has some floor and stringer issues. Not sure of the full extent yet as I am waiting for the season to be over.

Boat: 1995 Larson 174 SEI, 3.0 Mercruiser outdrive

I have read a ton of threads on here and most of the stocky how to’s. But there is a lot of mixed messages and confusion now.

The big one and most of my questions stemming from epoxy vs polyester… I understand epoxy will stick to poly but poly won’t stick to epoxy. For this reason I am leaning toward epoxy (feel free to convince me otherwise) it seems like a lot of threads are not real clear on which they are using which is creating most of my confusion.

One other big reason I am leaning that way is when and where I will be able to do the work, most will be done outside in the coming months hopefully finishing before first snow/ cold snap. Also my allotted work times, most of the work will be done in small stretches meaning I would most likely have to do filleting let it cure, next day or days later come and do the covering and so on… So most likely what I did the day or days before will be fully cured.

#1. With epoxy or poly can you let you different portions fully set up and cure before you do the next step? And if so what is the prep to be able to move on, do you have to sand it again?

A big question of mine comes from #18 how to replace transom, stringer and deck.
Woodonglass states: “Epoxy requires NO CSM and to use fabric of cloth”, which is fine until he later says:
“If you choose to use Epoxy for your Stringers, then you'll only need to use Fabric or Cloth to cover them.
2 layers of 17oz cloth will be adequate. The drawing is basically the same just won't use CSM or 1708.”

#2. Isn’t 1708 17oz cloth that you would use to cover the stringers?
#3. If I go with epoxy can I just use 1708 for everything (except making peanut butter obviously) including the tabbing and covering?

I have quite a few more questions but don’t want them to get lost so I will only ask a few at a time.

Is there a really good how to I haven’t found that includes exactly what they are using at each step with recipes for stuff like PB?

 

[Scott Danforth]

welcome aboard

if you plan on gel coating, you need to use poly or VE

with eeeeeeepoly, you need to paint

since the sanding is the same for either one, I prefer poly over epoxy because the materials are so much less

answers to your questions

1 - if you use lay-up resin (poly), you have a few weeks prior to needing a re-sand as the poly wont fully cure until you spray gel or coat with PVA

1b - use 1700 not 1708 with eeeeeepoxy. 1708 has CSM stitched to it.

2 - use 1708 with poly, use 1700 with eeeeeeeepoxy

3. no, 1708 has CSM stiched to it, you need 1700 (just the biax weave)

read link 14 and watch all the videos https://forums.iboats.com/forum/boa...r/295740-how-to-s-and-other-great-information

then read links 18, 2, 3, 4a, and 4b..... then the others.

 

[sheboyganjohn]

I use both when I build, but only poly on restores. When I build, the wood hull is structural so I use the epoxy and cloth as a waterproof cover on the exterior hull. When you start glassing over a wood hull with poly you chew through a ton of resin.

In general I actually like poly. Once it starts to set-up you have a very brief period and then it is hard. Epoxy will take its own sweet time. I had not problem doing a poly lay-up a few hours before rain is expected, I need at least 12 hrs, if not more, before rain if using epoxy. Poly has a long open time to create a chemical bond between layups, usually days. Epoxy has a very short window between layups. If you get a faster cure resin, you then risk the epoxy blushing which will require a through cleaning before the next layup.

 

[kcon]

Epoxy is conceptually easier to use, in that it's easy enough to use pumps for the ratio, and its more forgiving of atmospheric temperatures (should use you the correct hardener), and more forgiving of mess-ups should you use too much or something like that; but be prepared to spend a significantly higher amount of money than you think, upwards of a grand in just resin.

When you're working with epoxy, especially so in short bursts such as laying up, waiting, and doing more layers later, you have to be on top of prep work and cognizant of amine blush.

You can use CSM with epoxy, but there's almost no point in doing so, I used CSM with epoxy a few times where I needed to add panel material where it did not exist, the CSM helped me fix portions of a panel that essentially required no load bearing capabilities, sands much easier too.

Not to dissuade you, but it's very unlikely you'll be done before the first snow, prepare for the long haul, it's worth it!

 

[sheboyganjohn]

And poly will stick to epoxy, but it is a mechanical bond, not a chemical bond. So you have to rough up the epoxy for it to stick and it will be no stronger of a bond then using poly over another hard surface like metal.

 

[Mechanicalmike08]

I have read almost all those links, again the big issue for me is most of them just say "yep made my stringers, pb'd and tabed them in" without much recipe or exactly this. I plan on reading most of them again.

you guys are swinging me to poly, I didn't know you had such a long time window to recoat. I thought once it was hard your done so the short working window scared me.

can you paint poly or does it have to be gel coat.

 

[CrazyFinn]

I have read almost all those links, again the big issue for me is most of them just say "yep made my stringers, pb'd and tabed them in" without much recipe or exactly this. I plan on reading most of them again.

you guys are swinging me to poly, I didn't know you had such a long time window to recoat. I thought once it was hard your done so the short working window scared me.

can you paint poly or does it have to be gel coat.

Sure you can paint it.

As far as a "recipe", I just mix start with a measured amount of Poly resin, mix in some chopped strand glass (for strength), and then keep mixing in some Cabosil (fumed silica) until I get the consistency I want. Then I stir in the right amount of hardener for my original amount of resin and away I go... The trick is to have everything ready before you mix the hardener (especially when I was mixing a big enough batch to glue in my new transom).

Here is how I set in & tabbed my stringers - not sure how everybody else does it, but it works for me... I set the stringers in place with a few shims underneath to create the gap I wanted between the hull and stringer. I then tabbed in the "downhill" side of the stringer. Once that was set, I pulled out the spacers, and then used a plastic drywall spreader (those little yellow things they sell at Home Depot) to squeeze in the PB mixture under the stringer from the other side. You can see when it fills up the gap through the hardened fiberglass on the other side. I smoothed out the side where I squeezed it in, and once it was hard, tabbed in the other side.

If you're using Poly resin, make sure you get the unwaxed (laminating) resin so you don't have to sand between layers.

 

[Woodonglass]

I highly recommend using Metric for measuring Poly. It's also sensitive to temps soooo, Here's the formula I use for Poly Mix

65-75 degrees. 250 CC's resin & 4.5 CC's of Hardener (catalyst)
7

5-85 degrees. 250 CC's resin & 3.75 CC's of Hardener (catalyst)
85 degrees plus 250 CC's resin & 2.5 CC's of Hardener (catalyst)

Using this formula you'll get about 20-25 mins working time. You can "Fool" the resin a bit by placing the container in Warm Or Cold water and then adding the catalyst at the last minute. Warm water for cool temps Cold water for High temps. Good thing about poly is it sets up quick. With EEEEEEEpoxy you have to baby sit it longer especially on vertical surfaces.

Poly has NO strength by itself. CSM is it's binder material. The thin fibers of the csm act like a spider web in the mix to keep the hardened product from becoming brittle. Poly has Styrene and the styrene breaks down the CSM and blends it with the resin. The Fabric provides the STRENGTH for the mix.

Epoxy has built in binders and there fore can stand alone. In some cases no fabric is required. Again Fabric just adds more strength to the mix. It also cures much slower than Poly

Poly has UV resistance EEEEEEpoxy does not.

Most mass produced boats are built from Poly based products. So repairs with poly work fine.

Wood boats should use Resorcinol or Epoxy ​

PB is nothing more than Resin mixed with Chopped Milled fibers and Cabosil.

For 1 quart I recommend 1000 CC's Resin, 2000 CC's Cabosil, 50 CC's Chopped milled fibers. Mixed to the consistency of Creamy Peanut butter. Add or subtract Cabosil to get the correct consistency. You don't Have to use the fibers but it makes the mix more strong and structural.

 

[Mechanicalmike08]

Alright I'm convinced to go with poly, it was mentioned 1708 has csm in it. So would it be wise to just use 1708 for everything tabbing, full coverage and decking? It's seems to be people do it in different methods.

I've read ur suppose to use csm as the first layer then cover with 1708... but in link 18 he seemed to use 1708 for everything but sometimes put csm over the 1708..

 

[Woodonglass]

Since 1708 has CSM sewn to it, you don't need addition CSM. But for the Deck I'd recommend just using resin and CSM on the bottom side and then a layer of 1708 on top followed by a layer of CSM IF you want it smooth. If you want a bit of a Pattern surface to help with grip, then just use one layer of 1708.. The Pattern from the glass will bleed thru just a bit and give kind of a textured surface. Stringers and transom gets two layers of 1708