Hull flex?

[BigI]

I was checking out an old Offshore the other day. When I banged on the side of the hull midships, between the gunwale rod holders, it flexed and wobbled more than I expected. As I went forward or back it diminished. What is the structure that gives rigidity to the hull in that section? The deck? The cap?

 

[DennisG01]

I was checking out an old Offshore the other day. When I banged on the side of the hull midships, between the gunwale rod holders, it flexed and wobbled more than I expected. As I went forward or back it diminished. What is the structure that gives rigidity to the hull in that section? The deck? The cap?

Can you describe the place you're talking about better? The gunwale is the horizontal surface that you step on if you step from the dock onto the boat... in other words, it's what rod holders are mounted into.

If you're talking about the hull sides, themselves (generally speaking, where the striping is), then yes - that area flexes since it's a big, flat area. There's both an inner liner and the actual hull side there, glued together. The hull sides "strength" is in more of a vertical orientation, not from side impacts. Numerous components are utilized to give the hull it's overall strength and no one piece, by itself, is responsible for everything. Each piece has it's part to play and while it may be weak in some aspects, it is strong in others.

 

[BigI]

Yes, I'm talking about the vertical sides of the hull, under the striping. In the general area between the rod holders. Not the gunwale itself.
My boat flexes much less in that area but it's 4 ft. shorter.

 

[DennisG01]

Mine does the same thing. If you take a look at how that area is constructed, it makes sense. It's just a big, flat piece of fiberglass (and, as you pointed out, a larger area than your boat). There are no reinforcements on the back sides such as partial bulkheads or beams. On the outside, with the exception of right above the striping, there are no molded-in ridges or anything to add structure/rigidity. However, that's not to say that having flex is bad. Look at the immense amount of Offshore's produced and still in the water today. In fact, having some flex is a actually a good thing as it prevents cracking.

 

[lime4x4]

My 86 does the samething. Normal esp since there really isn't any support in that area

 

[BigI]

Thanks Guys!
Someday I hope to upgrade to an Offshore or Explorer.