Why do we leave a gap under the stringers?

[Reserector_]

Why do we leave a gap between the hull and the replacement stringer when bedding them in with peanut butter or PL?

 

[GCartwright]

Why do we leave a gap between the hull and the replacement stringer when bedding them in with peanut butter or PL?

So that there is full contact between the stringer and the hull. It's difficult to cut a stringer to exactly match the shape of the hull so the paenut butter will fill in all the low spots and prevent one area of the stringer/hull from taking all the stress

 

[Reserector_]

So is it safe to say that if a bead of peanut butter were applied liberally to where the stringer will be placed, and the stringer is then squished down into the peanut butter causing the excess to squeeze out, that it could achieve full contact with the hull without actually using spacers? (Theoretically speaking, of course.)

 

[kcassells]

So is it safe to say that if a bead of peanut butter were applied liberally to where the stringer will be placed, and the stringer is then squished down into the peanut butter causing the excess to squeeze out, that it could achieve full contact with the hull without actually using spacers? (Theoretically speaking, of course.)

Yup, you hit it on the head.

 

[tpenfield]

[h=2]Why do we leave a gap under the stringers?[/h]
. . . because, that's why

As stated, the stringer will create a hard spot if it is in direct contact with the hull and the impact of water on the hull will tend to cause cracking of the gelcoat in the area of the hardspot.

Offsetting the stringer from the hull and providing a fillet area between the hull and the stringer distributes the impact forces better and avoids cracking the gelcoat.

My handy work in diagramming the difference is below . . .
.