foam stringers?

looked at my glasstreams stringers today and they are some sort of foam instead of wood ,stuck a screw driver into one of them and sure enough pure FOAM??????????what?

Re: foam stringers?

I love foam stringers . . .

I don't know that boat specifically, but . . . with foam stringers, the foam is just the core material and the strength is in the fiberglass 'shell' of the stringer. So, as long as the fiberglass encasing the foam is good, then no worries.

Got some pictures? I wonder if the boat has been re-done during its life, etc?

Re: foam stringers?

Not intentionally hi-jacking the OP's question, But would love to hear more about this..??
For example: what type of 'foam' is this material - and is it possible to contemplate replacing (say) rotted-out wood stringers with this type of foam..??
Addit: I read in another thread that 'modern' boats (of the last decade) don't have a "core" as such, and the stringers consist wholly of ?pre-formed? lengths of FG..??

Re: foam stringers?

Jedo_03 said:

Not intentionally hi-jacking the OP's question, But would love to hear more about this..??
For example: what type of 'foam' is this material - and is it possible to contemplate replacing (say) rotted-out wood stringers with this type of foam..??
Addit: I read in another thread that 'modern' boats (of the last decade) don't have a "core" as such, and the stringers consist wholly of ?pre-formed? lengths of FG..??

Click to expand...

The foam has zero strength, All it is is a mold for the fiberglass or "engineered" stringers durring the milding process.

LK

Re: foam stringers?

Well... That seems to concur with *this post http://forums.iboats.com/boat-restoration-building-hull-repair/why-only-exterior-grade-594615-2.html ... (Post #26)
So... Can we conclude that stringers don't "essentially" or "absolutely" have to be WOOD...??
And that "any" material which provides longitudinal-ridigity to the hull would suffice..?
Foam-cored FG..? "Engineered" hollow Box-Section or Tube-Section FG..? Hollow Aluminium Box-Section or Tubing..? (Would 'glassing' even be necessary over Aluminium..??)
Just Wondering here...

Re: foam stringers?

Many new boats have a composite stringer system. Usually these are the bigger and more pricey boats, but even the economy boats have gotten in the composite game with the VEC hull system, which Larson and Glastron use.

Re: foam stringers?

Sorry to be a naive newbie...
But what do you mean (ref Stringers) by "composite"..??
An 'alternative' amalgam core for stringers..??
Rigid Plastics or Foams...?
What 'Do' 21st Century small-boat builders use in construction..?
And is That superlative to our 'traditional' materials..??

Re: foam stringers?

I don't think my Larson was built with the composite materials and VEC construction that tpenfield mentions (I think that began a few years after my boat was built), but I do have the foam-cored fiberglass stringers. There may be other considerations, but from the perspective of standing up to moisture and rot, the foam/fiberglass stringers are great. I pulled wet foam out of my hull, but the stringers and bulkheads were perfect. I think it's pretty likely that if those components had been wood-cored, I would have been replacing stringers as well. (The transom, which was wood, was pretty rotten.)

Even late 20th Century materials and techniques are OK, in my book!

Jim

Re: foam stringers?

When doing a restore, it is just so much more costly to create foam stringers. It takes much more glass, which is the expensive part. They say if you use wood it will be strong, and last forever if taken care of.

Re: foam stringers?

Thanks guys, that's exactly what it is -a FG shel filled with composite material, wouldn't that make the boat a lot more flexable
though?

Re: foam stringers?

here are preforms pre made foam stringer system.

Prisma_Preforms_BULKHEADS_STRINGERS_DECK_KITS

Re: foam stringers?

Composites are your fiberglass, kevlar, carbon fiber, etc. Usually composite stringer systems are filled with foam for energy absorption, sound deadening, flotation, etc.

Re: foam stringers?

Yeah sorry got em mixed up

Re: foam stringers?

OK, Im gonna drop my 2 cents in on this topic and revive an old thread.
If you find your boat has foam stringers you should probably breath a sigh of relief. Although replacing wood with foam will cost more during a rebuild due to the extra cost needed for stronger fiberglass, the benefit will be a long life for your structure.
I have researched the hell out of this topic now since I purchased my boat and found it has foam stringers.
The debate of which is better is simply ended with wood rots, foam does not.
The reason wood stringers rot so easily is for the same reason they are used. They normally are not very well encapsulated in fiberglass. I have seen rebuilds on this forum where the wood is simply just coated in epoxy or covered with one layer of glass. This is simply not good enough. With all the banging around your boat will do in the water and with all the stress it takes from being on a trailer I would expect small cracks to expose the wood no matter how well you think you sealed it.
With foam stringers since you not relying on the core material for strength you need tons of fiberglass to get the strength. While adding all of these layers of strength you are unintentionally adding layers of sealant. There is no PB needed to bed the foam, no wrapping the wood in fiberglass or coating with epoxy for sealing, you will be simply laying the fiberglass over the foam just to create the form. It will cost more, but will be much easier and stronger in the end. Oh yeah and will probably last much longer.

Re: foam stringers?

So the next question I have is what is the cost of wood stringers vs. composite? Just a slight comparisson would help. Thanks. I don't plan to do this anytime soon Just thought I ask.

Re: foam stringers?

Interesting perspective NewBoatGuy, I'm surprised that foam stringers don't require a bedding material of any type.

How many extra layers of fiberglass are required to reinforce foam stringers sufficiently to mimic a similar wooden core stringer?

What is the layup schedule for the additional required layers of fiberglass?

There are several alternatives to wooden stringers available to manufacturers. Some manufacturers choose wood, some choose something else. Backyard boat builders have a few options as well. The majority choose wood because it works, its usually readily available, and its available at a reasonable price.

I am fortunate that my FireFlite has empty fiberglass stringers. They have no core material at all.

Polyester wrapped, wooden stringers will stand up to regular use for decades, if the boat as a whole is well maintained by it's owner.

Abuse your boat, neglect it, don't maintain it, and no matter what material you construct your stringers out of, they can fail. Same for flotation foam.

If you'd like to start a thread dedicated to the fabrication, installation & longevity of foam core stringers in one of your projects, or to discuss them, that'd be great & I'd be interested to follow that discussion.

Re: foam stringers?

Subscribing.

Re: foam stringers?

1NewBoatGuy said:

OK, Im gonna drop my 2 cents in on this topic and revive an old thread.
If you find your boat has foam stringers you should probably breath a sigh of relief. Although replacing wood with foam will cost more during a rebuild due to the extra cost needed for stronger fiberglass, the benefit will be a long life for your structure.
I have researched the hell out of this topic now since I purchased my boat and found it has foam stringers.
The debate of which is better is simply ended with wood rots, foam does not.
The reason wood stringers rot so easily is for the same reason they are used. They normally are not very well encapsulated in fiberglass. I have seen rebuilds on this forum where the wood is simply just coated in epoxy or covered with one layer of glass. This is simply not good enough. With all the banging around your boat will do in the water and with all the stress it takes from being on a trailer I would expect small cracks to expose the wood no matter how well you think you sealed it.
With foam stringers since you not relying on the core material for strength you need tons of fiberglass to get the strength. While adding all of these layers of strength you are unintentionally adding layers of sealant. There is no PB needed to bed the foam, no wrapping the wood in fiberglass or coating with epoxy for sealing, you will be simply laying the fiberglass over the foam just to create the form. It will cost more, but will be much easier and stronger in the end. Oh yeah and will probably last much longer.

Click to expand...

Please take a few minutes and read the item that refer's to old threads contained within the forum rules.

This is not a revival but a pure hijack. You should have started your own thread.

Re: foam stringers?

****REMOVED***** So does not create confusion