I am certainly not the authority on all things boats, but I thought I would have heard of this before, but haven't. What does this mean?
Bunk and buttock
Bunk and buttock
Do you know your buttock location?
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Now you're getting in to lofting a boat. My mind has trouble visualizing all the relationships of the different lines involved, but the Buttocks are lines that run parallel with the keel at a given constant distance from the keel and as they go forward, they curve upward. There will be several of them at different distances from the keel and as they run forward they curve upward starting at varying distance from the keel and varying rates of curvature. That's the calculations that defines a "SV2" hull design on the Grady hulls in later years verses earlier years. All that lofting stuff takes a brain capable of more envisioning ability than my own. I have been in some old-time boat shops that had piles of plywood patterns to hold the shape as they built the wood hull. It all made my head hurt.
I interpreted the buttock data to show the distance form the various stringer off of the keel. In other words, where the bunks would be contact the hull. To be honest though, I am not sure and never noticed that term when looking up stringer spacing
That was confusing. let me try again.
If the boat was sitting level on the ground, the slopped sides would be farther away from the ground as you moved away from the keel. The buttocks measurement is that height under the stringer s. Of course the height gets larger at the outermost stringer locations due to the angled hull sides.
Did that make more sense?
That was confusing. let me try again.
If the boat was sitting level on the ground, the slopped sides would be farther away from the ground as you moved away from the keel. The buttocks measurement is that height under the stringer s. Of course the height gets larger at the outermost stringer locations due to the angled hull sides.
Did that make more sense?
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Yes, that's what I envisioned also. Then as each of those lines progress forward they start curving up to form the angled bow.I interpreted the buttock data to show the distance form the various stringer off of the keel. In other words, where the bunks would be contact the hull. To be honest though, I am not sure and never noticed that term when looking up stringer spacing
That was confusing. let me try again.
If the boat was sitting level on the ground, the slopped sides would be farther away from the ground as you moved away from the keel. The buttocks measurement is that height under the stringer s. Of course the height gets larger at the outermost stringer locations due to the angled hull sides.
Did that make more sense?
On Grady's I think your assumption is correct, it doesn't have to be exactly under a stringer.
On my newer non Grady boat, it is a different story. The hull is infusion molded with a thin outer and inner skin, filled with injected foam. In this case, I want bunks to allign with the internal stringers.
I wonder if the newer models use the same hull layup process. Solid is more expensive ( aren't all Gradys?) but also add weight which is not necessarily a good property.