Glass stringer questions

[SHyde]

Hi all,

I recently started my first boat restoration and have a few questions. Well, I admit, I have a zillion questions, but will start with a few today. My 18ft 1980 Glasply runabout has foam filled glass stringers. I pulled the deck and several hundred pounds of soggy foam from under it, but have no idea how I will get the foam out of the stringers. And once out, will they need to be foamed again? In other words, does the foam in the stringers serve any function other than flotation?

I removed a 4 cyl Volvo and outdrive, and my plan is to re-power with an outboard on a bracket. The transom looks sound, but I will drill some test holes to be sure. Since I will mount a bracket on the back, I have a hunch that the transom will need to be tied into the stringers somehow for extra strength. Any ideas on how to do that would also be appreciated. The HUGE outdrive hole has beveled edges, which would make it challenging to plug easily. I am wondering if a new transom is in order to solve a few of these questions. One last question, after pulling the deck up, some of the rotted deck was left stuck to the tops of the stringers. I know I need to get after them with a grinder, and to clean up the edges and get down to the hull. I bought a 7 inch grinder and an assortment of grinding wheels and disks. What would be best to start with grit wise? I'll also mention that I am fairly mechanically inclined, but have never worked with fiberglass. I've been enjoying reading all the posts here. Thanks in advance for any help!

 

[mark1961]

Re: Glass stringer questions

In other words, does the foam in the stringers serve any function other than flotation?

I would say they are almost certainly structural as well and besides, whats going hold your deck up if you dont refill em?

 

[Cadwelder]

Re: Glass stringer questions

This thread comes to mind here http://forums.iboats.com/showthread.php?t=469836 when changing an I/O to an outboard. It's a bit more involved than you may think. If you're going this route I would at the very least replace the transom completely with new solid plywood, rather than a patch of the exisitng hole.

As far as you stringers most likely the foam was there as a "form" for the fiberglass which is the actual structural part of the stringer system.

 

[steveclv]

Re: Glass stringer questions

I agree - the foam is just what was used to create the stringer shape - the strength is in the fiberglass. And I would also replace the entire transom as it's probably an easier (and safer) method than trying to patch the old, probably partially rotted one that's on there.

 

[SHyde]

Re: Glass stringer questions

Thanks for the quick replies. I don't think the foam was used to form the stringers, it appears to be the type that was sprayed or "injected" into the stringers after the fact. I can see quarter sized holes in several places along the tops of the stringers where it appears the foam was injected. Do I need to dig the glass out of the stringers somehow, or maybe let the boat sit in the sun for a few months and hope they drain and dry out? I was wondering if I should just cut the tops off the stringers and dig the crap out, then re-glass them back over with or without rigid foam inside? Here's a pic of my exact same boat finished with the bracket. This is what I am thinking of doing, but I haven't completely ruled out just going back in with another I/O setup. I think I'll start thinking about pulling the cap and replacing the transom all together.

This may be a stupid question, but could one fabricate a splash well and just hang the outboard on the transom traditional style?

 

[steveclv]

Re: Glass stringer questions

This may be a stupid question, but could one fabricate a splash well and just hang the outboard on the transom traditional style?

As long as you replaced the existing transom I see no reason why not. Lots of boats are made with the same hull and both an I/O and an outboard option.

A lot of boats are also made without a splash well - but I can see that would be a nice addition and probably safer to have than not - if you got swamped from the rear it's going to protect the inside of the boat although a decent bilge pump should clear it pretty quickly.

 

[Cadwelder]

Re: Glass stringer questions

Thanks for the quick replies. I don't think the foam was used to form the stringers, it appears to be the type that was sprayed or "injected" into the stringers after the fact. I can see quarter sized holes in several places along the tops of the stringers where it appears the foam was injected. Do I need to dig the glass out of the stringers somehow, or maybe let the boat sit in the sun for a few months and hope they drain and dry out? I was wondering if I should just cut the tops off the stringers and dig the crap out, then re-glass them back over with or without rigid foam inside? Here's a pic of my exact same boat finished with the bracket. This is what I am thinking of doing, but I haven't completely ruled out just going back in with another I/O setup. I think I'll start thinking about pulling the cap and replacing the transom all together.

This may be a stupid question, but could one fabricate a splash well and just hang the outboard on the transom traditional style?

View attachment 90652View attachment 90653

In this case the foam was mostly likely there for floatation. Personally I'd replace it, but somtimes I tend to overkill safety.

 

[Yacht Dr.]

Re: Glass stringer questions

Welcome to Iboats SH ..

There are several reasons why your " molded " stringers are filled with foam.

Float foam..yea mebbe.. structural ? hmm mebbe again..USCG regs on open compartment rules..( you do know that open compartments of boats are not recommended .. smuggling and such ) .

Regardless of reasons of why they foamed the stringers I would suggest you fill them back up with 2 part foam.

Now the tricky part is getting the wet foam out..

The Only way I know how to get wet foam out of a molded stringer system is remove the stringer system..or cut the tops off as you suggested.

Neither has a good forthcoming on repair ..lots of grinding etc..

YD.

 

[SHyde]

Re: Glass stringer questions

Welcome to Iboats SH ..
The Only way I know how to get wet foam out of a molded stringer system is remove the stringer system..or cut the tops off as you suggested.
YD.

Thanks for the info. I don't mind the extra work to open the stringers up and then glass them back over, but what method of "opening" them do you recommend? Do I take a sawsall to them and slice the tops off? Do I grind the tops off? Would it be ok to go back in with rigid foam, like the pink or blue stuff at Home Depot?

 

[ondarvr]

Re: Glass stringer questions

the fastest method is to use a circular saw and a grit edge blade, but many methods will work.

 

[Yacht Dr.]

Re: Glass stringer questions

Do I take a sawsall to them and slice the tops off? Do I grind the tops off? Would it be ok to go back in with rigid foam, like the pink or blue stuff at Home Depot?

I would take a sawsall to them..but measure and/or jig your tops of the stringers before you do this so you can put those glassed tops back where they came from ( not the cutouts..but the Build of your new glass over them).

You can grind the tops..just alot of extra dust.

HD foam Vs 2 part density foam is your choice.. Im not going to debate this again .. Research and decide for yourself. (cough2partfoamisbetter cough ).

YD.