71 22-2 Flatback Re-build Watch and Comment Please

[RickK]

When cruising, the only thing for passengers to hold onto is the top and top's legs. If the top is connected only to the console, the console has to be connected to the sole very securely.
Way back before my 170 rebuild a friend and I were out in the gulf fishing and the weather changed  and we headed back in.  On the way I hit a wave and my friend and I quickly braced for the wave before the impact by grabbing onto the windshield and when we hit the wave, the console was ripped from the deck and tilted forward a lot  . It had only been screwed into the deck in about 15 places.

Also as you are towing your boat and hit highway speeds there is a tremendous amount of wind pressure on the top, definitely more than you cruising around fishing, so plan for that too.

[Marcel4t]

Thanks for all the replies about the t-top.I like the idea of wrapping around to the front of the console and onto the floor.
Here's my 11th installment in my rebuild. Check it out, you'll see this website is featured in it!
https://youtu.be/P7Om9S5Dfks

[mshugg]

The boat is looking good.  Your fillets are nice and neat.  The peel ply is awsome.  I wish I had tried it out earlier in my project. 

You may want to ad some other fillers to your fillet mix.  Silica alone can be a bit brittle.  I used a mix of silica, milled fiber and some wood flour in mine.  The fiber adds a bit more strength and the wood flour ads a bit of elasticity.  There’s no need to worry about the wood in the wood flour.  It absorbs the resin and becomes completely plasticized.

[Marcel4t]

Thanks for watching.  I will take your advice and add that to my recipe next time! What "milled fiber" do you recommend?  I wonder if USComposites carries those 2 other ingredients.

[mshugg]

They probably carry them.  I’ll look at the brand when I get home, but milled fiber is tiny fiberglass fibers.  It adds some strength.  When appearance is less important chopped fibers will add evenmore strength.

[Tampa Bay Mike]

Enjoyed the video like always. 

[RickK]

I found one of these that I used when mixing fillet material - whips it up real quick and smooth. Cleanup is blasting it with a garden hose and then dunking it in some acetone.
https://www.homedepot.com/p/HDX-1-gal-Helix-Paint-Mixer-HM1-HDX/206509381

Agree that you should use some chopped fibers - US composites should have them and you're close enough to go look to see what they offer.  Seems everyone has their own "mix" but it does add strength.

I got a lot of ideas and guidance from Chris (dirtwheelsFL) too.  Make sure you keep the shape of the stringers intact. The best way would have been to not cut out the entire tops and leave 3 or 4" bridges of glass across the stringer tops to keep them in shape. Since the tops are gone you have to figure this out, especially before you start pouring the foam. The foam can distort the stringers as it hardens.

[Marcel4t]

I found one of these that I used when mixing fillet material - whips it up real quick and smooth. Cleanup is blasting it with a garden hose and then dunking it in some acetone.
https://www.homedepot.com/p/HDX-1-gal-Helix-Paint-Mixer-HM1-HDX/206509381

Agree that you should use some chopped fibers - US composites should have them and you're close enough to go look to see what they offer.  Seems everyone has their own "mix" but it does add strength.

I got a lot of ideas and guidance from Chris (dirtwheelsFL) too.  Make sure you keep the shape of the stringers intact. The best way would have been to not cut out the entire tops and leave 3 or 4" bridges of glass across the stringer tops to keep them in shape. Since the tops are gone you have to figure this out, especially before you start pouring the foam. The foam can distort the stringers as it hardens.

Good idea on that mixer!! mixing stuff into epoxy succckkkksssss.   
And didnt think the foam would deform the sides, figured it would just expand out the tops.  Maybe bridge some glass strips over the tops to secure the shapes?  Better safe than sorry. 
So, some guy suggested just using 1700 for glass instead of 1708.  Says the matt doesnt really do much other than make it harder to conform to bends and sucks up more resin. Even suggested that places sell us that because they know we will use more resin. What are you all's thoughts?  Do you think there is a benefit of having that mat on the 1708? 

[Tampa Bay Mike]

Definitely brace the sides of the stringers. I ran a 2x4 down the sides of mine and it still bowed out a bit in one part where it wasn't braced well. As for the glass, I used 1700 and it worked well but it was mostly because I had a roll of 6" and 8" that I found cheap. I would use it again over 1708 though. I've always heard that the mat is mainly to help build bulk faster and doesn't provide as much strength.

[mshugg]

So, some guy suggested just using 1700 for glass instead of 1708.  Says the matt doesnt really do much other than make it harder to conform to bends and sucks up more resin. Even suggested that places sell us that because they know we will use more resin. What are you all's thoughts?  Do you think there is a benefit of having that mat on the 1708?

There are benefits to 1708.  The 1708 builds up thickness faster than 1700, and thickness means a stiffer laminate.  Mat in the 1708 helps layers bond together better too, because the mat increases surface contact between layers. The increased bond, while not strictly necessary with epoxy gives me comfort as a amateur builder.  As for the resin savings, if you’re going for a specific thickness, say 3/16”.  3 layers of 1708 gets you close.  Four layers of 1700 is thinner than 3 of 1708. Five layers is just over.  Biax Is stronger than roving and CSM originally used in our Aquasports.  You probably don’t need to build up the same thickness of glass, but as a non engineer, it gives me comfort in places like the transom, stringers and tabbing.

It’s true, 1708 doesn’t like wrapping around bends, particularly outside bends.  I have no real problem getting it to work on inside bends with a reasonable filet to provide a radius.  For outside bends I used 1200 biax.  It wraps around tighter bends much better and it wets out like a dream.

The bottom line for me is: builders have great results with either pick what works for you.

[RickK]

It's true that epoxy doesn't melt the binders in the CSM like polyester and vinylester does, so the CSM is a waste when using epoxy. As Michael said, it does offer bulk.

[mshugg]

To build off of what rick said, CSM is good for three things in a laminate; adding bulk, increasing bond between layers, providing a sacrificial layer to make fairing easier

It’s also important to note the CSM in 1708 uses the stitching instead of binder, so it is 100% epoxy compatible.   

West systems did some testing with epoxy and CSM.  They found that the bond was just fine, at least with their product.  I’ve done some testing and I find two downsides to CSM and epoxy; stays a kind of milky white color, and since the styrene binder isn’t dissolved, it doesn’t conform to corners as well as with poly or vinylester.

[Marcel4t]

Okay cool, thanks as always for all the input/response.  You guys are awesome.  I may get some 1700 for doing the stringers/under floor and save my 1708 for above deck, that way I can use the mat side for places I want to fair out later on. 
Oh, I just found a product that claims its "higher strength, better quality, and more consistent" than Coosa, and is cheeper, it's called Thermo-lite Board by Space age Panels.  Merret Supply down near me carries it.  The pics look just like Coosa, I think it's basically same construction.

[Tampa Bay Mike]

I've seen a few different brands that all seem similar. Kay-Cel is another one that the shop up by me sells but they are proud of it $$. Are you thinking about using that for the sole?

[Marcel4t]

Yes, I am contemplating it.  I like the way it can be shaped like wood.  The honey comb products seems to add another level of difficulty dealing with the sides?
Also I am considering a different layout for the front deck, to have a 2 benches and a small front deck at the bow, with a walk through. Under that walk through will be storage, and under the benches will be storage.  Im sure there is a name for this type of arrangement, many boats have it that way.