Stringer Pre-prep

[drewpster]

After a thorough cleaning, I need to start removing the cores of the stringers in my old tug. They are 40 years old and look to consist of wooden cores covered in heavy roving. I intend to cap the stringers, remove the cores and re-core them. Hopefully I will do this by re-coring the fiberglass channels left after the old cores are removed. The question is, should I grind and sand all the bonding surfaces before removing the old cores? Seems to me it would be easier to grind all this roving while they are still somewhat stiff. After the old cores are gone the sides may be too flimsy to get a good cleaned surface. I intend to fillet the channels and re-cap them by wraping new roving over everything. I am still not certain how extensive the rot is, should I wait and determine how much damaged core is going to be needed? Or should I assume the complete 8 foot stringers need to be replaced?

 

[oops!]

Re: Stringer Pre-prep

hi buddy.....id just grind out the whole sha bang and re glass the puppies in.

it sounded like they tried to make the glass the stregnth of the stringer rather than the wood.

but its your call on how you want to do it....you know enough about this stuff, you could do it in your sleep by know, if your doing this....you may as well do all 8 feet, the problem is getting a good bond with the old laminate.

as uasual...pics would help...but it sounds like you are in for a bit of a struggle unless you can get a 7 inch flapper in there to rough and scuff

 

[gcboat]

Re: Stringer Pre-prep

hi buddy.....
it sounded like they tried to make the glass the stregnth of the stringer rather than the wood.

Actually the glass is the strength - the wood is merely a form.

 

[drewpster]

Re: Stringer Pre-prep

The truth is I have been dreading this part! One good thing about doing this in the colder temps is I can bundle up in protective clothing and be somewhat comfortable. I plan to look like a dusty marshmallow man. Pics to follow.

 

[oops!]

Re: Stringer Pre-prep

Actually the glass is the strength - the wood is merely a form.

uh ....that depends on the manufacturers


....some manns used the wood, some used the glass as the stregnth.....when ever you see lower style stringers.....2-5 ins high glassed over with considerable layers....its the glass.

when you see foam....its the glassthat is the stregnth. but there is lots of occasions where the wood was lightly glassed.....that means the glass was the water barrier, and the wood the stregnth......so it really depends on what boat you open up. some uesd the two in concert.

it was all a trade off till early manns started using foam as a shape to glass on rather than the wood being a structural component.

it just depends on what manufacturer and the owner of the shops standards.

cheers
oops

 

[oops!]

Re: Stringer Pre-prep

The truth is I have been dreading this part! One good thing about doing this in the colder temps is I can bundle up in protective clothing and be somewhat comfortable. I plan to look like a dusty marshmallow man. Pics to follow.

you dreading this part?????? ....heh heh heh....grab a set of tyvecs !
if you have any questions drewp.....just ask.....if i was closer....id help !

 

[jonesg]

Re: Stringer Pre-prep

the glass resists side to side whilst allowing limited flex,
the wood is fore and aft rigidity. Tabbing takes the load in this design.

http://marinesurvey.com/photos/HullFailP2photos.htm

This pic shows the problem nicely, the load should be borne by the glass in this instance.



I looked at this first pic of stringer work and thought, yeh nice work.
http://marinesurvey.com/photos/HullFailPart1photos.htm

But then I read what the surveyor David Pascoe wrote,

 

[drewpster]

Re: Stringer Pre-prep

Thanks for the offer oops! If I run into real trouble I may load up and head to Kelowana. The survey links are a help as well.

I ran into a driver at work that said he built boats up in Jersey for 11 years before the market went flat in the eighties. He said that simple folded cardboard would work to hold the stringers off the bottom to prevent hard spots. Cardboard? I was planning to find some foam strips for this. I worry about the cardboard soaking resin defeating the purpose. He worked for Sea Fox when they were still around. Ever hear of them in New Jersey? He seemed to know what he was talking about, but you never know.