89 BL Capri resto help

[Mad Props]

That foam supports are really Interesting..... how dense are they?

They are 1" thick polyisocyanurate rigid insulation boards... The ones you get at the home center with the foil face. You have to use that kind cuz the styrene in poly resin will dissolve the foam from the pink and blue types... The foil face peels off pretty easily.

 

[archbuilder]

the glass does all the work the foam or cardboard are basically just a form.

 

[Scherfz1]

the glass does all the work the foam or cardboard are basically just a form.

Ahhh ok and the ridges make it stiffer, gotcha.... well just got done at Lowe’s and got my hunny-do list soo I am gonna figure out what I want to do for the support......

so this means I have a long list to do tomorrow and Saturday, rather get the boss’s list knocked out tonight rather than when I have more time

 

[sopwithcamel74]

I'd just glass 3/4 inch ply and call it a day were I in your shoes. Just seems line an infinitely more direct way to address it. But, then again, I don't speak from the years of experience these other guys have on me - just seems a better idea from where I sit.

 

[Mad Props]

I'd just glass 3/4 inch ply and call it a day were I in your shoes. Just seems line an infinitely more direct way to address it. But, then again, I don't speak from the years of experience these other guys have on me - just seems a better idea from where I sit.

3/4 would no doubt be stiffer than 1/2 ply, but adding stiffening ribs can actually add substantially more rigidity than just thicker ply while barely adding any weight...

To get into the weeds a little.... the deflection of a beam is defined by d=FL³/48EI ... I is the moment of inertia which is bh³/12 where b is the width of the beams cross section and h in this case would be the thickness of the plywood... so if you work backwards, the h or thickness direction has a exponentially greater impact to deflection than the width of the beam... basically the same idea as putting a 2x4 on edge is substantially stiffer than a 2x4 on its side even tho it's the same amount of material

All that to say, adding ribs in the thickness direction will add a ton of rigidity without the need to increase the thickness of the plywood itself....

That was a lot to type on a phone lol

 

[archbuilder]

Very impressive Mad Props, takes me back to architecture school lol! I do have to criticize that you didn't mention that shear goes to max as moment goes to zero....but none the less impressive on a phone! I'd actually like to get the lecture on that, shear is a bit fuzzy.....but so was some of architecture school lol!:der: All non architect and engineers can ignore this paragraph

scherfz1 you are spot on, the ribs increase what is know as the effective depth of the member, in this case the plywood, which makes the deck stiffer over the span.

Sopwithcamel you are also correct, basically the same thing, making the effective depth (thickness of the deck) deeper stiffens things up. But it adds weight, where as the fiberglass ribs on the thinner plywood are most likely stiffer and much lighter.

The thicker plywood is for sure easier / cheaper (considering labor). But the ribs can do the same or more and be lighter. Just a matter of cost or time / labor. Neither one is wrong , just depends on what your end goals are.

 

[Scherfz1]

3/4 would no doubt be stiffer than 1/2 ply, but adding stiffening ribs can actually add substantially more rigidity than just thicker ply while barely adding any weight...

To get into the weeds a little.... the deflection of a beam is defined by d=FL³/48EI ... I is the moment of inertia which is bh³/12 where b is the width of the beams cross section and h in this case would be the thickness of the plywood... so if you work backwards, the h or thickness direction has a exponentially greater impact to deflection than the width of the beam... basically the same idea as putting a 2x4 on edge is substantially stiffer than a 2x4 on its side even tho it's the same amount of material

All that to say, adding ribs in the thickness direction will add a ton of rigidity without the need to increase the thickness of the plywood itself....

That was a lot to type on a phone lol

But I greatly appreciate it!!!!!!

 

[Scherfz1]

Very impressive Mad Props, takes me back to architecture school lol! I do have to criticize that you didn't mention that shear goes to max as moment goes to zero....but none the less impressive on a phone! I'd actually like to get the lecture on that, shear is a bit fuzzy.....but so was some of architecture school lol!:der: All non architect and engineers can ignore this paragraph

scherfz1 you are spot on, the ribs increase what is know as the effective depth of the member, in this case the plywood, which makes the deck stiffer over the span.

Sopwithcamel you are also correct, basically the same thing, making the effective depth (thickness of the deck) deeper stiffens things up. But it adds weight, where as the fiberglass ribs on the thinner plywood are most likely stiffer and much lighter.

The thicker plywood is for sure easier / cheaper (considering labor). But the ribs can do the same or more and be lighter. Just a matter of cost or time / labor. Neither one is wrong , just depends on what your end goals are.

Well i will be making ribs, I think I have some extra wood 1x1’s that I’ll use to make these ribs on the bottom of the front decking.

 

[Scherfz1]

so here is another question looking forward......

i really dont want to put any carpet back in this boat. i am going to do the foam teak deal for what you actual stand on. but for the sides i was thinking i would paint them will gelcoat type deal or another marine paint. i would like to find another option besides gelcoat because i really dont want to have to worry about mixing it, and something a little more cost effective....

so what options do i have for "paint" on fiber glass?

 

[Redtruck12]

I went with the “tractor paint “ recipe”
worked great for me inside and out
way cheaper, easy and looks great

 

[Scherfz1]

I went with the “tractor paint “ recipe”
worked great for me inside and out
way cheaper, easy and looks great

where is that recipe? i know someone has it in there signature lol

 

[Redtruck12]

Woodonglass I think it’s in his signature
Maldonado the bottom sticky “how too’s and other great info

 

[Scherfz1]

So last night I got the floor panels cut, cross member, and battery box top as well.

Today ill be getting the crossmember installed along with the pvc pipe for wires installed, along with the floor glassed and installed (hopefully tabbed in as well). Battery box top glasses and hopefully installed too.

if I have enough time I will try to get the front seat boxes cut and fitted, maybe even glassed.

 

[Scherfz1]

It’s suppose to be crazy hot on the heat index so I’ll be battling that while doing all of this. I hope I can make it lol

 

[Scherfz1]

Oh and a huge picture dump will be coming this evening. I will be bringing home the laptop so I can upload them, I hope I don’t run into issues uploading them (I run a MacBook) cause that’s why I haven’t been uploading them.. every time I try it times out

 

[chevymaher]

Oh and a huge picture dump will be coming this evening. I will be bringing home the laptop so I can upload them, I hope I don’t run into issues uploading them (I run a MacBook) cause that’s why I haven’t been uploading them.. every time I try it times out

LOL I can't do pictures from the shop computer. I feel your pain. To much of a pain in the azz to do it. I wait till I hit the old faithful next to my recliner computer that has all the bells and whistles.

 

[Scherfz1]

LOL I can't do pictures from the shop computer. I feel your pain. To much of a pain in the azz to do it. I wait till I hit the old faithful next to my recliner computer that has all the bells and whistles.

Well I use my own laptop at work and just generally leave it there, and it’s a MacBook. For some reason this site doesn’t like safari or Mozilla that I have on my laptop, internet is fast at work but lately I have been having to upload one file at a time and it has been taking too long to do at work.

 

[Scherfz1]

Alright y’all pics to come tomorrow when I have set in the back floor piece.....

but as for what I did get done, glasses all the decking plus battery box lid, set up the crossmember that I had missing in the aft floor section. PB’ed the front deck in with added structure support!!!! No flipping flex either!!!!! (I think this is the biggest mile stone for me so far!)

on tomorrows agenda, get the cross member glassed, add the rear floor and PB it in. Wouldn’t mind starting to tab in the front floor section but I don’t think time will allow for it....

now for the bad news, I have ran out of 2oz CSM and I really though I had more than what I did, I got very lucky cause I had just enough to glass the three pieces that I did need to get done. Also I have quite a bit of 1708 still and will use that like I planned to tab in the deck......

chevymaher also was very correct about the heat here in KY today..... glassing was very hard if you weren’t Johnny on the spot with resin..... thank god my front porch is covered as I used that area to do my glass work until the sun set. But by god If you finished coating something in glass I could have drug it into the sun light, went in to the house to grab a beer, come back and it would be ready to work with again....

 

[archbuilder]

Yeah you better have your act together with poly in the summer time, if you don't it doesn't care lol!

 

[Scherfz1]

So I went out to look over the boat this morning and bask for a min in the glory of the front floor being installed. But what amazes me is how “solid” the hull has become with the front floor being set up and just PB’ed in.

i can honestly say too I am getting supper exited seeing this hull turn back into an actual boat! And a buddy at work told me about a raft up here in Ky in lake Cumberland and it’s august 9th. So I am now shooting for a rough as a cob Splashed date for that day, she might not be the prettiest, and she may not be the fastest boat out there, but at least we’ll be at the dance!!!!