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Plascore Bottom Build-Up

Posted by Max 
Max
Plascore Bottom Build-Up
September 30, 2014 02:23PM
Hi Guys. Getting ready to put the bottom on my HD and am wondering what is the best way to build it up. Like how many layers of which weight glass cloth/ chine tape. I want to use 1" Plascore. Any suggestions?

Thanks Guys.

Max
Re: Plascore Bottom Build-Up
September 30, 2014 03:43PM
On my last boat, I started with a layer of 1708 Biaxial (17oz biaxial 45x45 w/ 8oz mat, good stuff) inside and out. Then a layer of Xynole, followed by a layer of 10oz plain glass and flow coats, finished with graphite. Overlapping and reinforced at the chine with biaxial tape and plain glass to finish.

Jeremy Christensen
Max
Re: Plascore Bottom Build-Up
October 02, 2014 11:02AM
tungsten Wrote:
-------------------------------------------------------

> Some other testing I did I found that the thicker
> the core the less give I got so the outer skin had
> to be thicker on the thicker core

Should I go less than 1" core? 3/4"?

Thanks for all the good info guys.
Re: Plascore Bottom Build-Up
October 02, 2014 04:03PM
Maybe. But maybe not overkill.

The stiffness of any stressed skin panel (plywood both sides over studs and/or fiberglass over honeycomb core) increases as the square of the diameter. In the honeycomb core case the weight difference between 3/4" inch and 1" inch is negligible. While the stiffness difference is great.

Perhaps 3/4" is plenty stiff enough. There is a point wear you don't need any more stiffness. Abrasion and puncture protection on the outside surface eventually become the dominant issues. I guess price is always an issue too.

I'm just saying. If stiffness and overall weight are the only considerations, 1" is stiffer without being heavier, because the weight is all in the two fiberglass skins.



Max
Re: Plascore Bottom Build-Up
October 04, 2014 04:58PM
Interesting. Thanks again
Re: Plascore Bottom Build-Up
October 17, 2014 12:50AM
Been away for a while and just catching up on the boat building stuff.

I have been using 3/4 for boat bottoms. Next time I will go up to 1 inch. Not enough extra weight to make a difference. Also will be adding more glass. Other then a piece of steel rebar, which I have seen on the river. I don't thing anything will poke through 1 inch plascore with extras glass, not past the outside skin anyway.
Max
Re: Plascore Bottom Build-Up
October 22, 2014 02:40PM
Thanks guys. I was away for a bit too. Anyway I just picked up 1" Plascore sheets which were in stock here locally so I'll go with that. Thanks again for the input.
Max
Re: Plascore Bottom Build-Up
October 23, 2014 12:16PM
One more thing: Do I want to lay-up the inside of the bottom panel before attaching it to the sides or will it become too stiff to bend the rocker? Thx
Re: Plascore Bottom Build-Up
October 23, 2014 01:03PM
You can layup one side and still bend. Which surface is your choice. I always layup the inside surfaces because working inside--after the boat takes shape--is harder than working outside.
Max
Re: Plascore Bottom Build-Up
October 23, 2014 01:11PM
Great, Sandy. Thanks.
Re: Plascore Bottom Build-Up
September 10, 2015 03:33PM
Digging up this old thread for some questions and updates about honeycomb or core construction:

Bottom thickness - there are plenty of threads here b/w 1/2" and 1". For a whitewater dory any consensus? Seems like there might be a trade off with impact durability and flexibility.

Bulkheads - 1/2", 3/8" or less? (Assuming Plascore or Core Cell/ Divinycell)

Decking and hatch lids - same question.

Thx much

- Jon
Re: Plascore Bottom Build-Up
September 11, 2015 02:02PM
It's not enough weight to make a difference. Load a boat with 2 people, camping gear, food, beer, for a long trip and the extra resin means nothing. Build strong you won't regret it.
Re: Plascore Bottom Build-Up
September 11, 2015 02:06PM
Tungsten, I would take issue with the fabric on the inside. From now on I will move in thickness of the core material and only use enough glass to get the inside sealed off. I have had several holes punched into the bottom of my last boat. That's where I will be placing most of the fabric from now on. 1 inch thick bottom, thick skin on the outside. With bulk head going to the bottom there won't be any deflection. Could be on a fishing boat, but a rising drift boat isn't going to see the big white water anyway.

My next boat will only have 1 layer of 6 ounce glass on the inside.
Re: Plascore Bottom Build-Up
September 11, 2015 02:45PM
RE> "one layer inside" ............ you can always add more. Well. That's a bit tough for a decked boat with lots of compartments. I have used two layers of six 0z inside for a long time.

I originally built my decked one man boat (now the rowdyak :=)) with a removable deck, bolted down onto a gasket. When I remodeled it last year I thought "I've never removed this once, so now I'll fix it permanently"

However, the removable deck worked just fine and now I'm regretting it. The deck on the boat I'm building now will definitely be removable. Bolted down onto a thick foam gasket. That makes repairs and maintenance a whole lot easier.



Re: Plascore Bottom Build-Up
September 12, 2015 02:14AM
lhedrick Wrote:
-------------------------------------------------------
> Tungsten, I would take issue with the fabric on
> the inside. From now on I will move in thickness
> of the core material and only use enough glass to
> get the inside sealed off. I have had several
> holes punched into the bottom of my last boat.
> That's where I will be placing most of the fabric
> from now on. 1 inch thick bottom, thick skin on
> the outside. With bulk head going to the bottom
> there won't be any deflection. Could be on a
> fishing boat, but a rising drift boat isn't going
> to see the big white water anyway.
>
> My next boat will only have 1 layer of 6 ounce
> glass on the inside.

Larry,

For discussion an education purposes, since you indicate you've had some holes in your hull, would you mind sharing the details of your interior and exterior glass layup of your hull bottom. I seem to recall from your web site that this core was a 3/4" and that you would go to 1" in the future.
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