# Ideal core material?



## tightloops1900 (Aug 16, 2011)

What would be some good materials for building decks bulkheads floor ect?


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## cutrunner (Jun 8, 2010)

Balsa
[smiley=StirPotChef.gif]


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## tightloops1900 (Aug 16, 2011)

Balsa is wood right? Won't it rot? I'm really kinda asking what composite material is best for the $!


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## DuckNut (Apr 3, 2009)

One so strong that you don't need glass to strengthen it, comes prefinished and made so light that it makes the boat float shallower. ;D


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## jms (Apr 21, 2011)

> Balsa
> [smiley=StirPotChef.gif]



balsa coring,properly sealed,is an excellent choice !
i've replaced decks in older(40yrs in some cases),boat,the balsa coring in areas where water didn't migrate to,was in perfect condition - if that balsa coring is sealed from water intrusion,with an epoxy,it's an excellent choice.the problems begin when people start using inferior products,and begin using inferior techniques - examples: using a cheap polyester based resin,attempting to seal drainage holes with that cheap polyester resin,drilling holes and attempting to seal with a silicone,versus over bore,fill with a thickened epoxy and drill - the correct method...

every deck,deck hatch,i've recored - that damage was caused by failing to follow the above advice...


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## jms (Apr 21, 2011)

> What would be some good materials for building decks bulkheads floor ect?


there's alot of good materials out on the market = coosa,divinycell,penske - these are all good choices...


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## tightloops1900 (Aug 16, 2011)

My plan is to build a floor, aft, and bow decks on a Johnson skiff. Couldn I just use marine ply and not worry about weight? I've seen a build on here of the same hull using marine ply and the skiff didn't seem to squat that much in the water. I don't really plan on having much attached, cleats, rod holders, ect! Just want something basic that I can pole around the local flats with a buddy to toss some bugs.


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## DuckNut (Apr 3, 2009)

Certainly can use wood and with the savings you can buy a 5 gallon bucket of flies.

Read posts on how to use correctly.


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## firecat1981 (Nov 27, 2007)

Nothing wrong with using plywood and epoxy, and in many cases it will weigh less then going with composites for such a small project. If you use a good epoxy and make sure everything is sealed with a few coats then rot will never be an issue.


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## tightloops1900 (Aug 16, 2011)

I have seen some builds on here that I have fallen in
Love with, and wanna get a project started. I have the hull, now I just need tools and materials. What would be some of the most important tools I will need?


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## jms (Apr 21, 2011)

> Nothing wrong with using plywood and epoxy, and in many cases it will weigh less then going with composites for such a small project. If you use a good epoxy and make sure everything is sealed with a few coats then rot will never be an issue.



that's not quite right...
composites are lighter than wood every time...

true,nothing wrong with wood,provided it's properly sealed - number of coats of epoxy mean little,it's "thickness" of those coats - remember,to finish,it will require blush removal - in some epoxies - and sanding,a "thin" coating of epoxy,and you've got trouble - read that as potential water migration - and we all know what that means,right ?

think about it like this:

you're gonna take the time to do a project,you want it to come out as best as possible,right ? also,you want to save weight,right ? and,save a little money,too - as a bonous,right ?
using wood,adding epoxy,matting - this adds weight to a heavy product - pretty fair statement,right ? add in the time that's required to properly protect that wood - overboring any and all holes,and drilling just the epoxy...

using a composite:
a good composite,a good quality structual composite like penske or coosa,requires a considerible amount LESS work,than wood - weighs alot less too - added bonous,it won't rot - lasts indefinatley... an added bounous,is the fact,you can use a vinylester resin,versus an epoxy resin,vinylester resin is much cheaper - vinylester resin is a good choice for working with composites,it provides a much better,more waterproof bond than the cheap polyester resins...composites,such as penske board and coosa will absorb no water,unlike wood...technology changes,if it didn't we'd all still be fishing in wooden boats - kinda like "noah"...

truth is,you can do anything you want with your boat,and do any project,the way you want to do it - using any materials you wish


tools required:

tyvek "paint suit",respirators,gloves,lots of them,saftey glasses,"chipping brushes",rollers,a good quality angle grinder,with discs - i use 5" discs - 50 and 80 grit,should do it for you,and a good "da" sander,with discs
sounds like you've never done much of this before,yes ? get a resin mixing cup,this will avoid incorrect mixing - if you're using vinylester resin - epoxy resins,these usually have metered pumps - don't try and "wing it"...contrary to popular belief,you're gonna get dirty and a little dusty - wear a tyvek suit - guys who make claims they don't get dirty doing glass work,are like guys who claim their boat has no dings on it - the boat never leaves the dock,or the driveway,and they never do any glass work...


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## tightloops1900 (Aug 16, 2011)

What's the cheaper of the two materials? Coosa or Penske?


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## firecat1981 (Nov 27, 2007)

> composites are lighter than wood every time...


This is absolutely not correct. Show me the technical data to prove your point. Because I've done a ton of research when I built my boat and I can tell you there is nothing I found out there that thickness to thickness or strength to strength that can match the weight of Okoume 1088 marine plywood, heck I haven't found anything that can match meranti either.

Saying a composite like coosa is easier to work with them marine ply is opinion, not fact. Foam composites require the same techniques and drill and fill plugging for strength and in most cases need additional layers of glass to avoid an easily punctured surface, which will make them as heavy or heavier then a well done wood composite deck. 

Why would you use matting for anything? And you can use vinylester the same way on wood and composites, but why? There really isn't a huge amount of savings on a small project and vinyester does not have nearly the same secondary bonding strength that epoxy does. Plus it is not entirely waterproof like epoxy, granted it is much better then poly in every respect, but it is still a step down from a good epoxy.

The reason they don't make wood boats like they used too is because it is too time consuming, and time is money. However we are talking about flat panels, not curved, in which there would be no real time difference.

Sorry for the rant, I'm not anti-composite, I'm just more pro-wood  Now if you have a good source for composites and vinylester resin already then go for it, but for my money I'm sticking to wood and epoxy especially for simple projects.


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## jms (Apr 21, 2011)

let's take that wood first:

1/2" okume wieghs around 40-42lbs - 4'x8' sheet

that same thickness penske weighs around 1.2lbs per square ft...

that penske board - it requires minimal protection - for use as a deck for example - there's quite a few longliners in nj with penske board decks - ain't getting more abuse than that,huh ? a layer of 1708,and a top of 1.5 chop strand - the bottom's were left,covered in resin only...

try that with wood ? 

as i stated - epoxy is allways the best choice - it costs more,it's not the best choice for wood - never will be.vinylester,it's fine for use with a composite,like penske,which will absorb no water...cheap polyester resin is allways the worst choice - again,i've covered all this previous...

price:
okume costs around $120 per 4x8 sheet - 1/2"

penske,it costs me $147 per 4'x8' sheet - 1/2" thickness


as far as sleeving is concerned - check some of the stuff i've typed,i've covered this pretty hard - i've put up pictures of improper ways to work with composites as well - i've covered the correct techniques required when working with composites...

for a project as simple as a forward deck is concerned :

only thing you're gonna mount on that would be cleats,and a trolling motor ? perhaps cut a hatch in it ?

wood - 

you're gonna need to properly seal all edges,and openings - you're gonna need epoxy - we covered that allready...
an easy way to do this is to make a "ledge",laminate that ledge to the hull sides,measure out and construct a rear bulkhead to support it - you're gonna want a hatch in there to provide access to storage,yes ?
again,every square inch of that will need to be covered and sealed with a waterproof resin - epoxy,covered in matting/fabric as well,hatch "seats" will need to be constructed as well....

as far as the composites are concerned : a vinylester resin is fine,minimal matting/fabric is required,due to the inherit strength of the compopsites,and the fact,it won't absorb water

as far as mounting cleats,and other equipment with a high load on them,these areas should be sleeved and thru bolted,with backing plates - wood requires backing plates as well...

question : would you buy a wood boat ?  a wood constructed boat will never sell - we're talking small boats here - the expense of mfg,the up keep required,all hinder their sales...

nothing wrong with wood - but,it requires a considerible amount of work,to protect and seal properly...most mfg's have switched over to composites,due to problems with rotting.grady white uses an xl green wood,it won't rot,but,it will delaminate - seen it on their boats,only after a few seasons of use - due to improper sealing techniques...only one mfg,i'm aware of that actuall seals their wood bulkheads - carolina classic - seen it at their factory...

most quality production flats boats are made with composites,not wood - wonder why ? hells bay,they're a good example,right ? any wood in their construction ? pretty light huh?

i've lost count of the repairs i've done on wood cored surfaces,where proper sealing techniques weren't used,end result was extensive rotting.the problem comes in when owners,and inexperienced techs start punching holes and not sealing properly-i've beat this dead horse,huh ?

using a good structual composite,like coosa,penske,these potential problems are avoided...

again,technology changes,composites are a great example of this - again,most mfg's have made the switch to composites - weight savings,and longevity of the boat itself - the composites will last indefinatley...


the problem we have here is,the fact i do this stuff every day,i see the end results,and i got a million stories of some of the stuff i've seen

i use the best materials available,this avoids problems down the line - i've stopped using wood for coring,for over a year now - it's proven to be a smart move...

again,you guys can do anything you want with your boats,use any materials you wish - when i explain things,i give examples of what i use,based upon my experience...there's an old saying,"you get what you pay for"

extensive reasearch and actual experience are 2 very different things - think of it like this:a few years ago,i had hernia surgery - went to one dr,had a cat scan - results were shown - he explained he was gonna do it laprascopic...i went for a second opinion -older surgeon,he explained to me a physical guy like me,having that surgery done that way was not gonna end well - the dr was straight to the point - i like that.he explained his procedure - he did it open - he cuts the area out sutures meshing in,in a cone shape,then sutures another piece in place over that - he made the claim,he never had a reoccurence in 25yrs - his technique made sense to me,the other much younger surgeon's didn't...wanna guess who i went with ? only problem was,i went back to work in 3 days,complete with 15 stapels on each side and 6 in the center - i ruined his record - my own fault - carrying cinder blocks and unloading boats at my shop,tore up the repair...this time i followed his advice,and i've been 100% since...

sorry for the rant,i'm obviously pro composites...


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## Recidivists (May 9, 2011)

http://www.thehulltruth.com/boating-forum/278848-coosa-vs-penske-what-density.html


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## tightloops1900 (Aug 16, 2011)

Kreepa I wanna pick your brain when the project is finished I wanna take you fishing and buy you a drink!


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## firecat1981 (Nov 27, 2007)

> 1/2" okume wieghs around 40-42lbs - 4'x8' sheet
> 
> that same thickness penske weighs around 1.2lbs per square ft...


ok 1.2lbs per square ft. well 4x8 = 32sq ft, 32sq ft x 1.2lbs = 38.4lbs! 38.4lbs, vs 40lbs.....Kind of splitting hairs there if you ask me. 

And all you would need for the ply is a covering of 6oz cloth for abrasion protection on the top and epoxy coat the edges and bottom prior to installing it (you can argue this with the guys at boat builder central if you want, I've already seen the decades old proof). Except you wouldn't really need 1/2" for a small casting deck, 3/8" would work just fine. After you add 1708 and mat to the penske......How is that any lighter?

I appreciate you have repaired boats for a while and all, but how many of these wood repairs you did were on boats build using epoxy? I'm betting none as that is how wood got a bad name, builders using cheap poly resins on wood to save on costs. 

Again I appreciate you do this stuff a lot, but I've said this many times before here, I've met guys who have built boats for 30 years, but I wouldn't let them change the oil in my 4-stroke. I'm not knocking you, but I don't know you and the statements you are making I have seen proof to the contrary.

Going back to the topic at hand, what is the ideal core material? There isn't one, you really have to do a cost/benefit analysis and come up with one that works well for you. Plywood, Solid wood, PVC, Foam core....they will all do the job. Heck as someone on here once said you can use cardboard for a core if you use enough glass, lol.


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## jms (Apr 21, 2011)

> > 1/2" okume wieghs around 40-42lbs - 4'x8' sheet
> >
> > that same thickness penske weighs around 1.2lbs per square ft...
> 
> ...



no need for 1708 cloth on a fwd deck,on a small boat ,like the one were discussing here - you're missing that - that's how a gentleman i know replaces decks on long liners -perhaps you should go back and reread ? think you missed that point   1708 would be overkill,in that application - common sense shoulda told ya that,as well as understanding what you're reading,versus,attempting to discredit good information - perhaps you should put the claws in ?

you made the statement,that wood weighs less - you're wrong...no splittin' hairs,wrong's wrong...gave a good example with hells bay boat as well - you made the claim,composites weigh more than wood,again,wrong's wrong...

you're quite correct,you don't know me,and trust me,your knowledge isn't impressing me - book smart,and computer search smart,and someone with real life experience are 2 very different things...

made repairs on wood bonded with epoxy,that was a question you asked,yes ? as a matter of fact,i have,a few,the problems came from owners drilling holes,failing to seal properly - remember that point ?

the problem with internet message boards like this,is guys with little practical knowledge spout facts,they honestly know little about - when a person only works,or "sees" one or 2 boats a year,that person certainly has a very limited experience,fair statement,yes ?

tell me again,why you would want a boat builder to change oil in a 4 stroke ? working on engines and building boats are 2 very different things...


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## DuckNut (Apr 3, 2009)

I can relate to the two guys with the boxing gloves on: 

I have over 30 years of real life experience with fiberglass and I agree with Firecat. Wood is a good choice and a suitable choice for many aspects in the marine world. Kreepa is right that the failure in wood comes from water somehow getting in, whether it is from an improper hole or a hairline fracture that you can't see. 

I also agree with Kreepa. Man made materials are a lifetime product.

I'll give you my real life scenario. In 1985 I built a duck boat with a wood skeleton. 10 years later I had to replace the transom. 10 more I did it again only this time I used Seacast. A couple years ago I gutted the entire boat and removed all wood because it was jelly and used foam products. 

Here is a realistic comment on your original question: If it were my boat and I was 26 years old I would make the floor out of wood. Why you might ask? Because with that scenario I would expect my economic situation to change. Wood would be fine for several years (maybe forever but don't count on it) and then as my economic picture changed I would be looking to change boats. 

If I was planning to keep a boat forever then I would not use wood. I have several boats that were built with early generation composite products and they are as good as new. The only way I would use wood is for an experiment.

Either way you decide to go would be acceptable, look at the whole picture and make a decision, get on with the job...it's been a little dry spell with boat porn and getting a little old looking at the same build that have been going on for months.


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## jms (Apr 21, 2011)

what we have here is,differing opinions - think about this for a second:
you're paying for this job - what would you like to have as a core material ?

last transom job i did was over $5,000 - made from penske board...labor's basically the same,materials are a little different...

notice what i stated "labor's basically the same" - what that means is,you have to make the same steps,to replace - why not use a product that's gonna last forever ? makes sense,huh ?
allways use the best materials available,using the best techniques - that way,you don't have to worry about how long it will last...do you make a repair on your motor,with a time line in mind - "this water pump impeller,well,it's worn,but,i should get a few more trips out of it,i'll put it back in"...
i only understand one way,NOT THE ONLY WAY,what i understand is the best method,based upon extensive experience...
can you build that deck out of cdx plywood,screwed together with drywall screws ? sure,and somebody's gonna tell you it's fine...


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## Izzy11 (Dec 23, 2011)

Dang ... I've been missing out on this discussion  ......

This is great info but here's what I think about when I'm rebuilding a boat .    I think about quality, longevity, and resale.  Ive never been one to ever even thinking about keeping a boat forever though I would like know the boat last forever !   When reselling a boat the question of what its made out of rairly even comes up. The over all quality of the 
boat is almost always evident.  Now if you mention the boat is however made of composite material that is obviously a plus.  
My point is simply this ....  In most cases the fact that the hull is composit doesn't even matter.  The overall quality of the boat is what matters.   

I ONLY started using composites because I was rebuilding gheenoes.  Weight was the only reason I ever even decided to use composites ! Now I'm still building micros and that's why I use nidacore.  Nidacore is the litest of all of them.  And I take great care in preparing my nidacore during a build so it will withstand the test of time.

There is no such thing as a best material. There is however a best material for certain builds to get what an individual wants out of his skiff .  

I don't care what material you use.... Over time wear and tear is in fact inevitable ! I dont care how well you take care of it...    The pounding of waves , anchors being dropped, people jumping onto your deck from a dock, trailering down a bumpy road,, ... Whatever it maybe ... It all does the inevitable. 

What you want your skiff to be able to do is what matters.  You want lite weight ? Do you want more weight ? Do you want it to be tough and rigid? You want to ho deep or do want t go shallow?  These questions are what drives my builds ...


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## tightloops1900 (Aug 16, 2011)

I want to build my 14ft Johnson so that I will have a boat that will pole the flats of Tampa bay. Don't think there will ever be more than 2 people at once. I don't need a go fast boat just want to be able to fish it skinny! Gatorgeist I believe you built a Johnson right? If I'm correct your build is one that I to mock for the most part.


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## Izzy11 (Dec 23, 2011)

> I want to build my 14ft Johnson so that I will have a boat that will pole the flats of Tampa bay. Don't think there will ever be more than 2 people at once. I don't need a go fast boat just want to be able to fish it skinny! Gatorgeist I believe you built a Johnson right? If I'm correct your build is one that I to mock for the most part.


Yuppers... That is me ;D. JasonP also has our same exact 14 Johnson. His is finished and looks great !


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## Chris2000 (Jul 27, 2020)

Penske/space age/coosa. Amazing material, easy to cut and mill. Doesnt soak in resin like most cores, but readily bonds


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