Empty Boat Stringers???

1960Glastron

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Feb 25, 2009
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I am new to boats and this is my first boat and first restore any suggestion would be great. I have a 1960 Glastron fireflite 15' and just removed the floor and began checking the stringers. Drilled a hole into the 2 stringers and the main beam. To my surprise there is no wood in any of these.

So my question is are these to be empty and if not what type of wood is best to use or is it possible to use a foam in these empty cavities?
 

zarillus

Petty Officer 1st Class
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Jan 29, 2009
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Re: Empty Boat Stringers???

I noticed this too when tearing out the deck of my 67 larson.There are two main stringers which are completely hollow.Only the decking above was wood except for a few 1X4's going across.
 

erikgreen

Captain
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Jan 8, 2007
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Re: Empty Boat Stringers???

So the stringers are just molded glass? If there's nothing in them now, it's safe to leave them that way.

How big a hole did you drill? Can you see inside?

Erik
 

zarillus

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Jan 29, 2009
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Re: Empty Boat Stringers???

I noticed this too when tearing out the deck of my 67 larson.There are two main stringers which are completely hollow.Only the decking above was wood except for a few 1X4's going across.
 

1960Glastron

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Re: Empty Boat Stringers???

i only drilled a 1/4" hole in each stringer and the beam. I shined a light in there and could not see any existing wood or rot just empty stringers and beam. If it is to be this way can i add some expanding foam to the empty stringers for a little added support ?
 

zarillus

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Jan 29, 2009
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Re: Empty Boat Stringers???

Okay after more demo i can see that the stringer's are hollow.There is a drain pipe coming out of the two main stringers on the starboard and port sides near the stern.It also has a plug in the bilge area seperate from main bilge plug to drain water. ha didn't even know that was there.
 

Tail_Gunner

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Jan 13, 2006
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Re: Empty Boat Stringers???

i only drilled a 1/4" hole in each stringer and the beam. I shined a light in there and could not see any existing wood or rot just empty stringers and beam. If it is to be this way can i add some expanding foam to the empty stringers for a little added support ?

You could drill 3/4" holes spaced 12" apart and pour in 8lb foam..the holes are vents for the foam to expand and escape. Measure the volume closely and just do one big pour..It would be very strong....But id wait for Ondarvr to reply.
 

gcboat

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May 29, 2007
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1,822
Re: Empty Boat Stringers???

The strength of the stringer is in the glass itself, not necessarily the wood.
Some of the newer models ( and older as well ) use foam as their mold. Not much strength in foam. End core balsa was a similiar product but it's pretty tough stuff.
If it's not there then I'd just go on about my business and do other stuff.
 

BIGcarpy50

Petty Officer 1st Class
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Jun 15, 2008
Messages
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Re: Empty Boat Stringers???

id say your lucky, no wood=always good, just leave them alone, no foam will help it will only trap water potentialy. if the manufacturer was fine with the design leave it that way
 

Artpop

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Nov 18, 2008
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Re: Empty Boat Stringers???

The strength of the stringer is in the glass itself, not necessarily the wood.
Some of the newer models ( and older as well ) use foam as their mold. Not much strength in foam. End core balsa was a similiar product but it's pretty tough stuff.
If it's not there then I'd just go on about my business and do other stuff.

I am not an expert, but I agree you should not put foam in. These boats were built this way, and worked for 50 and 60 years. The stringers on my boat were made using 3" cardboard tubes sliced in half the long way. Then they were layed in the hull and fiberglassed over. Done.

Be sure to fill any holes you drilled with 3M 5200 or similar putty product. Also check for any weak spots and delaminations.
 

1960Glastron

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Re: Empty Boat Stringers???

I am not an expert, but I agree you should not put foam in. These boats were built this way, and worked for 50 and 60 years. The stringers on my boat were made using 3" cardboard tubes sliced in half the long way. Then they were layed in the hull and fiberglassed over. Done.

Be sure to fill any holes you drilled with 3M 5200 or similar putty product. Also check for any weak spots and delaminations.
Thank you for all the info is sounds like i may be lucky and not need to do anything to my stringers. As for the holes to fill them with 3M 5200 after they have been filled will i need to glass over it also?
 

92excel

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Oct 6, 2008
Messages
477
Re: Empty Boat Stringers???

If its only your inspection holes that you are filling with 5200 and there is no delam and the stringers are solid then you will not have to reglass them.
 

Mark42

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Oct 8, 2003
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9,334
Re: Empty Boat Stringers???

I agree with the "don't mess with them" opinion. If the stringers are in good condition, not cracked or crushed, then fill the holes and put on a new deck. If there is damaged areas, reglass those areas and be done with it.

Do NOT foam fill them.
 

ondarvr

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Apr 6, 2005
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11,527
Re: Empty Boat Stringers???

Don't even bother to cover the holes with anything, it won't make any difference.
 

Artpop

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Nov 18, 2008
Messages
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Re: Empty Boat Stringers???

Don't even bother to cover the holes with anything, it won't make any difference.

Do you think its not needed? I was going to fill my holes so that there won't be water sloshing around in them. Perhaps thats not a biggie?

Also... How is the sole supported? Was it glassed in? On many of the older boats I have seen with hollow stringers, there is usually some sort of wood running athwartships that support the sole. If there are bulkheads (aka frames) they can rot.

Check it out, and post what you find, I'm curious to see what it looks like. Post some pics and the experts can help you get your lady back on the water.
 

ondarvr

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Re: Empty Boat Stringers???

A few 1/4" holes will have no affect on the strength and there are already drains to let water out.
 

Artpop

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Nov 18, 2008
Messages
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Re: Empty Boat Stringers???

A few 1/4" holes will have no affect on the strength and there are already drains to let water out.

That makes sense, but I don't see 1060Glastron saying that his stringers have drain holes. If they are like mine, they are completely enclosed. Looks like zarillus posted in this thread that his have drain holes. Would it make a difference if there are none? I don't want to hog this thread, just trying to make it clear in my mind.
 

ondarvr

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Apr 6, 2005
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Re: Empty Boat Stringers???

If it didn't have any drain holes, I would drill some even If I hadn't drilled the 1/4" ones. Water will always find a way to get into a watertight compartment, but it needs help to find a way out.
 
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