# composites



## jms (Apr 21, 2011)

composites:

these are definatley the best choice when replacing wood coring - the composites will last indefinatley,will not rot.
problem is,they will not hold a screw,nida core is the absolute worst - it's a honeycomb material
this is an example of the incorrect technique for mounting equipment to a composite cored surface.this "t" top was mounted on the deck,using "toggle" style bolts - my experience has been,these fail - seen these fail numerous times.there's one true way to mount equipment onto a composite cored surface - thru bolting and sleeving.in certain applications,this isn't possible - t top mounting is an example-these applications require the core surface be removed and the area where the fasteners be filled with epoxy mixed with the appropriate thickener.this will hold a screw,also holds threaded machine screws,when the holes are the correct size.
remember this,when you're mounting grab bars,seats and consoles,on a composite cored deck...


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## Izzy11 (Dec 23, 2011)

Great advise ! .... I've got a minor in nidacore LOL after rebuilding a few boats.... You ABSOLUTELY must fill ALL edges and holes with fiberglass filler of some sort and double rap your rails and edges with glass ! I even pre cut my rod holder holes and hollow out the inner circle and fill it with fiberglass filler ! 
You have to because even though core will not rot it can still allow water to intrude !


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## Izzy11 (Dec 23, 2011)

I also wanna give a pointer .... I use a big syringe for the fiberglass filler and I drill the end hole out to be a little bigger and use it for my filler to get into those hard to reach areas . So wherever you are going to put a screw you just pre drill your screw holes. Fill them with filler, then re drill your screw holes in the dry filler, and install your rod holders or whatever .


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## jms (Apr 21, 2011)

> Great advise ! .... I've got a minor in nidacore LOL after rebuilding a few boats....  You ABSOLUTELY must fill ALL edges and holes with fiberglass filler of some sort and double rap your rails and edges with glass !   I even pre cut my rod holder holes and hollow out the inner circle and fill it with fiberglass filler !
> You have to because even though core will not rot it can still allow water to intrude !



that's imperative for nida core - water will intrude it - nida core is a honeycomb,as you're well aware of,it's hollow,uses plastic as a stiffener - terrible stuff,i do not use nida core for anything....

penske board,coosa,these will not absorb water...


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## Izzy11 (Dec 23, 2011)

So I got a call from a forum member about nidacore. I wanted to explain so nobody waist there time that you do not have to fill all edges... Such as where the core meets the hull. So if you are putting in a deck and you go to install it you only need to glass it in from above and below. 
Also , from what I've been told nidacore is more lite than dyvinicel when finished. It also cost less. 
I do believe it is the most difficult to finish properly but it does work great. Just takes twice the amount of time to work with :... 

If you read this I would like to hear what you use for composite material and why... Thanks


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## jms (Apr 21, 2011)

there's a big reason nidacore is much cheaper than a dense foam composite,such as divinycell - it's called "quality"

this is nida core - it's basically a hollow honey comb composite,made from recycled milk jugs,with a light scrim backing










this is what it looks like with the scrim backing removed










this is a side view of the same product










not much there - it's hollow between the honey combs,these areas,they can and will become filled with water,from improper sealing,and improper fiberglassing techniques used.this design does have a pretty good compression rating.think this would hold a screw ? this type of core relies on a fiberglass skin,to provide rigidity - kind of like an "I" beam...

this is a structual composite - penske board,a dense foam composite,with a glass fiber in it.has excellent compression resistance,and it's dense,not hollow,it will absorb no water,half the weight of plywood,weighs slightly more than nidacore.this is a product i use and endorse.










side view










this is an excellent choice for stringers,bulkheads,decks and transoms


big difference huh ?


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## Recidivists (May 9, 2011)

I'm gonna say that nidacore would be the least desirable plastic or composite material I would want to have on my boat. If I were to have thru bolts or any type of penetration, I would prefer a solid material. Is it light and does it cost less? Yes. Do I condemn any one for using it? No.


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## Izzy11 (Dec 23, 2011)

From what I've heard.... Nidacore is actually the least water intrusive if done correctly.   And this comes from a guy who sells it all and knows I would buy anyone of them if he told me to. 

Now... I'm not in anyway trying to cause a feud ! I really would like to know which one is the best OVERALL. 

Lightest, strongest, cheapest , and easiest to work with ???


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## jms (Apr 21, 2011)

> From what I've heard.... Nidacore is actually the least water intrusive if done correctly.   And this comes from a guy who sells it all and knows I would buy anyone of them if he told me to.
> 
> Now... I'm not in anyway trying to cause a feud !  I really would like to know which one is the best OVERALL.
> 
> Lightest, strongest, cheapest , and easiest to work with ???



no fued here - just discussing products...

water intusion - a dense composite foam,like coosa board,penske board - these products will not absorb water,these products have no voids to allow water to collect - think about the hollow honeycomb pattern of that nida core,think of water migrating in the hollow voids - now throw freezing temps,in the mix...sounds like a recipe for trouble...

the lightest,strongest,easiest composite to work with,in my opinion is either penske board,or coosa board.


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## Izzy11 (Dec 23, 2011)

Great info ! So with these core materials you can just put screws or rod holders directly into it with no prep ? And it is half the weigh of wood ? What's the cost ? 
What do you think of divinycell ?


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## cutrunner (Jun 8, 2010)

What do you guys think of pvc board, minus the fact that its heavy as he!!?


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## jms (Apr 21, 2011)

> Great info ! So with these core materials you can just put screws or rod holders directly into it with no prep ? And it is half the weigh of wood ?    What's the cost ?
> What do you think of divinycell ?



no composites hold screws well - thru bolting and sleeving - 
perhaps you missed this "problem is,they will not hold a screw,nida core is the absolute worst - it's a honeycomb material
this is an example of the incorrect technique for mounting equipment to a composite cored surface.this "t" top was mounted on the deck,using "toggle" style bolts - my experience has been,these fail - seen these fail numerous times.there's one true way to mount equipment onto a composite cored surface - thru bolting and sleeving.in certain applications,this isn't possible - t top mounting is an example-these applications require the core surface be removed and the area where the fasteners be filled with epoxy mixed with the appropriate thickener.this will hold a screw,also holds threaded machine screws,when the holes are the correct size.
remember this,when you're mounting grab bars,seats and consoles,on a composite cored deck..."

i typed that,in the original post i made...

divinycell is another excellent structual product - there's a few grades of it,depending on application...


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## jms (Apr 21, 2011)

> What do you guys think of pvc board, minus the fact that its heavy as he!!?


trimming a house ?

never used that stuff,never would either...


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## Izzy11 (Dec 23, 2011)

Kreepa.... My bad.. I didn't miss it, I just was trying to get the exact info you gave in the last post. Nidacore is the cheapest and works well in my opinion though it does take more to work with it correctly. The other materials cost double and triple what nidacore does and nidacore is lighter. 
My technique is exactly what you suggested.... 

Pre fill your holes with filler then re drill your screw hole and install. If possible drill all the way through so that whatever water creeps in can have somewhere to go. Also... I like to grind the edges down and double glass them and fill the edges with filler......

My response about the PVC is this..... You can use whatever you want if it's strong enough. And people do ! Honey comb is PVC .


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## jms (Apr 21, 2011)

> Nidacore is the cheapest and works well in my opinion though it does take more to work with it correctly.  The other materials cost double and triple what nidacore does and nidacore is lighter.
> 
> Pre fill your holes with filler then re drill your screw hole and install.  If possible drill all the way through so that whatever water creeps in can have somewhere to go.  Also... I like to grind the edges down and double glass them and fill the edges with filler......
> 
> My response about the PVC is this.....  You can use whatever you want if it's strong enough.  And people do !  Honey comb is PVC .


price alone,will not provide a true comparison of value - remember that...


when drilling out and filling the hole,to provide a mounting area for fasteners,it's best to use an epxoy based product - polyester based products are brittle,and will break apart - epoxy based resins are a much stronger product,along with being waterproof,unlike pourous polyester based resins...

people use alot of different products on their boats - i often see examples of this - doesn't make it right or wrong - i stick with products i know are suitable for the application...


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## Brett (Jul 16, 2008)

At the moment this thread has been viewed 223 times, 15 of which are mine.
Every time one of you adds to the thread, I have to read it. Thanks.
All useful information regarding materials I have little or no experience with.
Very useful guys...keep it up.


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## Izzy11 (Dec 23, 2011)

I hear ya. 

I've seen great work whether it be with wood or composites. 

Obviously if you're using cores then that beats wood all day long "but heck" ,... There are wood boats out there that have withstood the test of time when treated with respect. 

I believe that you and I are both correct in different ways ... 

Yes ... Nidacore will not rot but it is the most water intrusive if not used properly. It is however the most lite and the least expensive of the core materials out there.

Coosa and divinycell "may not be spelled correct", they are stronger and MUCH MUCH easier to work with. They are also not as water intrusive.

But they cost much more and are heavier.

I have no doubt that you have much more experience than I and that's all right with me. But at least I'm learning ;D
I hope we can talk in the future when I need help. I still have a lot to learn . One thing for sure.... Ive got the bug ! 

Thanks


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## jms (Apr 21, 2011)

weight difference:

when working with a core material like nida core,you're gonna use more glass and resin - it's how it is...adding these adds weight - every gallon of polyester resin,or vinylester resin is 10lbs,plus the weight of the cloth/matt...

the weight difference between all composites is minimal - not really a factor...

people will have differing opinions,but,experience tells me what's a better product for differing applications...


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## jms (Apr 21, 2011)

nothing wrong with wood coring - the problem with wood coring is,failure to seal the wood - using a polyester based resin on wood,that's not the best choice,due to polyester being pourous...
the biggest problem with wood is installing equipment and not properly sealing the holes - properly sealed,it's not a factor

yep,there's alot of old wooden boats out there - but,let's be serious,technology evolves - if it didn't,we'd still have wooden boats - products evolve and technology changes - composites - i've stopped using any kind of wood on repairs - i use strictly composites - mostly penske board and coosa,in core repalcement applications...

bottom line is,there's allways more than one way to skin a cat...


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## DuckNut (Apr 3, 2009)

Kreepa- since you have the best avenue to actual prices put together a workup.

Compare the cost to build a front and rear deck with a hatch in each and just assume that you will be using 1/2 sheet for each. And illustrate a couple of the types you like and nida.

Include the weight and price of each raw material and then how much resin/cloth to make safe. Include the amount of time a non-professional might take to make the product but assume labor is free.

I think some might find out just how inexpensive and light nida really is.


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## Izzy11 (Dec 23, 2011)

Here's what I know ... 

I use 3/4 nidacore and 4x7 sheets that cost about 80 bucks.

Then I apply about 5 1/2 yards of 1708 and 4 quarts of Poly resin per side ....  Gallon of resin cost 20 bucks and weighs 10 Lbs ,  a yard of 1708 is 10 bucks .    
That's about 180 dollar sheet of nidacore finished.


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## jms (Apr 21, 2011)

> Kreepa- since you have the best avenue to actual prices put together a workup.
> 
> Compare the cost to build a front and rear deck with a hatch in each and just assume that you will be using 1/2 sheet for each.  And illustrate a couple of the types you like and nida.
> 
> ...



sure,later on today,i'll put something together - i use mostly penske board ...

1/2" penske board is around $145 per sheet -4'x8'


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## jms (Apr 21, 2011)

> Here's what I know ...
> 
> I use 3/4 nidacore and 4x7 sheets that cost about 80 bucks.
> 
> ...


using a polyester resin isn't the best choice...also,nidacore with it's scrim backing,is a tough product to get a reliable bond to...also,the nida core requires much more glass and "working" to provide a useable product,where as a dense foam composite,like penske,it requires minimal glass coverage,and minimal"worktime",meaning,it actually saves time,due to the product being more structually stable.again,the coosa and the penske board have a layer of woven glass in it,penske is 25lb density,coosa is available in various densitys - nida core is just nida core,no differing densitys - it's recycled milk jugs,hollow,held together with a light scrim backing...

what you've paid out in additional materials,and additional working time,is time and money wasted...

look at it like this:

you bought nida for $80 a sheet - added all that matting,and resin,and additional time...

a dense foam composite,will require minimal matting,especially for the application of a forward,or aft deck - minimal matting,menas minimal resin - using a good resin,a polyester based resin is cheap,low quality,and pourous - a vinylester resin is a better choice...no need for all that 1708...it works out to be real close in agrivation saved and money spent...again,price alone will not provide a true comparison of value...

common sense tells us what's a better product:

this:



















or this:


















pretty obvious choice


when doing a project,using the best materials available is allways the best choice - not allways the cheapest route,but,the results will be much better...


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