I'm sure this is a dumb question, but....

[Gpayne]

Are stringers 'glassed in for strength purposes, or is it more for water-resistance? I know they're glued to the hull with adhesive, then usually glassed tight. I was just wondering if the glass is used for structural purposes to help tie the hull together and add strength, or if it's just to help keep them from rotting. Thanks. Also, what would be a good choice to replace stringers in an old fiberglass runabout? I was thinking 2x12's. Or is there something else more favorable?

 

[tpenfield]

Re: I'm sure this is a dumb question, but....

Not all stringers are glued to the hull by the manufacturer. The fiberglassing serves both purposes. Strength and protection. and it depends how much glassing-in is done, etc.

 

[Mousejockey]

Re: I'm sure this is a dumb question, but....

Its only a dumb question if you and everyone else already knows the answer.....

 

[Woodonglass]

Re: I'm sure this is a dumb question, but....

If you really want to understand Hull and Stringer Design this two part series will be a good read for you...
NOTE: This is for larger boats but somewhat applies to smaller boats too!

http://www.yachtsurvey.com/HullFailPart1.htm
http://www.yachtsurvey.com/HullFailP2.htm

 

[jigngrub]

Re: I'm sure this is a dumb question, but....

In a nutshell, it's for both... but after constant exposure to water and moisture it will fail on both accounts over time.

Keep your boat covered and your bilge dry... and your boat will last forever!

 

[mrdjflores]

Re: I'm sure this is a dumb question, but....

use plywood for strirngers, not dimensional lumber

 

[Yacht Dr.]

Re: I'm sure this is a dumb question, but....

Are stringers 'glassed in for strength purposes, or is it more for water-resistance? I know they're glued to the hull with adhesive, then usually glassed tight. I was just wondering if the glass is used for structural purposes to help tie the hull together and add strength, or if it's just to help keep them from rotting. Thanks. Also, what would be a good choice to replace stringers in an old fiberglass runabout? I was thinking 2x12's. Or is there something else more favorable?

Glass = extra strength .. and most times used in structural support . Not really water resistance but In the build of structural.

Not all stringers are glued to the hull by the manufacturer. The fiberglassing serves both purposes. Strength and protection. and it depends how much glassing-in is done, etc.

This is kinda correct .. Glass is used for structural mainly.

If you really want to understand Hull and Stringer Design this two part series will be a good read for you...
NOTE: This is for larger boats but somewhat applies to smaller boats too!

http://www.yachtsurvey.com/HullFailPart1.htm
http://www.yachtsurvey.com/HullFailP2.htm

A lot of good stuff in there .. some things stated show inexperience .. but just MO ..

use plywood for strirngers, not dimensional lumber

I agree .. lets not get into the plywood debate here again please

YD.

 

[Gpayne]

Re: I'm sure this is a dumb question, but....

First of all, thanks for all the replies guys! And now, without launching into a huge plywood debate, are we talking two pieces of 1/2 laminated together? 3/4? I'm guessing you'd stagger the joints to create one long piece, kinda like a glue-lam beam?

 

[GT1000000]

Re: I'm sure this is a dumb question, but....

Depending how long you need them to be and how wide you want them...most stringers are roughly 1/2-3/4" thick...

I needed 5 stringers where one of them was almost 14 feet long, the other two almost 11 feet long and a couple at 9 feet...I wanted them to be 3/4" thick, which was a 1/4" thicker than what the factory put in and made them this way...

Basically two sheets of 3/8 A/C Douglas Fir Exterior Grade plywood...both sheets cut length-wise 2 foot wide, then one of the 2'x8' pieces I cut into 2 each, 2 foot by 4 foot...I laminated them with Titebond III WBP glue and then cut out my stringers from the resulting 2 foot wide by 16 foot long by 3/4" thick sheet...

I assembled a 2'x4' pc. to a 2'x8' pc., then butted up a 2'x8' pc to that, flipped it, butted 2'x8' pc, flipped, and then adhered the final 2'x4' pc...

Others have done just as well by sistering their stringers or even scabbing them...

Have Fun!

 

[mrdjflores]

Re: I'm sure this is a dumb question, but....

i would use to layers of 1/2" and make sure you stagger those seams.

of course, i have seen some boats that looked like the stringers were almost 2" wide...but turned out to be a 1/2" rigid foam core....covered with an obscene amount of fiberglass.
the glass was doing all the support...the foam was just used as a form to mold the glass over