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TOPIC: Stringers???

Stringers??? 6 years 8 months ago #60434

My G3 is an early 60's model (open deck, pre-Larson, has the big sponsons).

I had previously split the deck from the hull, and last night I removed the floor and transom wood.

Interestingly enough, the stringers on this boat are just fiberglass boxes with no wood. That's kinda cool to see, but was there some sort of early 1960s fiberglass resin shortage that I wasn't told about? The fiberglass stringer boxes are thin and can be flexed with the push of a finger. The glass mat is so dry that it looks heavily starched cloth.

Are there supposed to be any wood stringers up the sides of the hull or anything?

Have you guys seen the same weak fiberglass, and did you just add more glass?

I had also considered completely removing the fiberglass stringers and fabricating a square tube "skeleton" for the inside of the hull, just because it would give me more usable depth inside the hull. Has anyone ever seen something like this done?


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Re:Stringers??? 6 years 8 months ago #60797

G'day Philip,
Surprised you have had no response yet.
The open deck G3s were made from '62 to '67 (or maybe '68) with none being made in '64. The later models had fiberglass stringers as you describe - the big advantage is that they didn't rot. The resin-starved, thin walls of those you describe sounds inadequate, but easy to reinforce. There were never any side stringers.

Never heard of using steel (as in a race-car space-frame) in a G3, but there is no reason why not except for weight gain. It should still be glassed to the hull in continuous webs, not patches. It would be wise to use stainless steel because water will always get in the void and rust would be inevitable. I would stay with your lightweight fiberglass stringers but add some glass - and resin!

The floor went full width and is an important part of the hull's reinforcement. If you reduce the height of the stringers to lower the floor, you may compromise lateral strength, and because the floor will no longer connect to the chine/sides, flexing or twisting could occur when under way.

When you replace the floor be sure to seal the underside to prevent rot from beneath.
Have fun.


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Re:Stringers??? 6 years 6 months ago #63307

  • 63g3
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The strength of fiberglass is in the glass not the resin. I have restored a glass stringered 63 G3. Think about it this way, the stringer verticles are constrained by the floor and the hull and there are are lot of them so length wise the boat is very rigid.
Try bending corrogated cardboard that way, the same for twisting the hull, you have the floor and hull seperated by the height of the stringers which makes quite a rigid system torsionally. Balsa is often use between two glass layers which is very rigid, the rigidity increases as the distance between the layers increases. so Glasspar seperated the layers: ie the floor and the hull with the corrogated stringer system, when all bonded together it is far stronger than the sum of the parts so don't be fooled. I routed my floor off the stringers so I never touched into the glass tops much. I just reglassed the tops overlapping a bit on the verticles and then laminated the floor on which was Okume Marine Plywood also with a glass layer on the top and bottom. I only run 70 h.p. which is OK on this size boat and this construction is fine for that type of use. Generally these boats fail due to rotted transom/floors sponson covering boards which weakens the whole structure and it loses shape thus the rigidity when flexing starts and further weakens the components now taking the extra induced loads. If you restore it with good materials bonded and protected well I would not worry about the integrity of the complete hull....just my opinion. I don't think Tritt who designed this particular structure would have done so if not adaquate. I also have a 64 Super G designed the same way, it is bullet proof, Tritt improved further by having a fiberglass floor instead of using wood so he must have liked this method. I thinke they stopped because of expense rather than strength. MFG did the same system but also foam filled the corrogated stringers to add more stiffness and deaden sound. Decades later many inboard ski boat makers did the same to eliminate wood in the structure so another sign it's a good method when done right.
Just my humble ramblings...

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Re:Stringers??? 6 years 6 months ago #63309

  • g3bill
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Great explanation Randy, as always! My '63 Seafair has glass strings, the floor is open and stringers are very thin also but I know it will be strong when the floor is bonded on. The guy that ground the floor off actually went through the stringers in a few places but thats a easy patch. I didn't look that close but looks like only 2 layers of cloth and can be flexed as Phillip said, sure glad i didnt get a early wood stringer model:)

ps. You might want to check to be sure the bottoms of the glass strings are bonded to the floor, in a few spots mine aren't so will need to rebond those areas...

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