Soft Spot in Hull

[Hawaii Sailor]

When I press into my hull near the thruhulls it flexes a little. It does this nowhere else on the boat. I can also press on it from the inside and flex it. Whole area might be 2ftx2ft. Should I be alarmed? Should I lay some fiberglass and strengthen it? It doesn't seem to be loosing it's shape. Water could've been protruding in one of the old the hulls. I am replacing all the thru hulls on my boat. I'm also applying a primer epoxy barrier coat as well.

 

[Christian Williams]

I remember Ignacio, who went offshore in his E35-II, saying he used to watch the hull under his cockpit flex in a seaway. He found it disconcerting, but eventually got used to it, solo to Hawaii and back.

The hull is solid, not cored, so my uneducated guess is that it's not significant. I had an old Laser dinghy that "oil-canned" like that, and I never thought it affected strength, although it made the hull unsuitable for racing.

 

[Hawaii Sailor]

I remember Ignacio, who went offshore in his E35-II, saying he used to watch the hull under his cockpit flex in a seaway. He found it disconcerting, but eventually got used to it, solo to Hawaii and back.

The hull is solid, not cored, so my uneducated guess is that it's not significant. I had an old Laser dinghy that "oil-canned" like that, and I never thought it affected strength, although it made the hull unsuitable for racing.

Thanks. Luckily a surveyor did not find any delam. It's a combo of being old/factory defect. Going to install an extra stringer for support and will post a pic later

 

[ignacio]

Took a video while underway:

It's not quite the localized flexing Hawaii Sailor asked, but thought the video would be of interest. I had just replaced the seacocks with the bronze triangular bases and bronze Ts you see in this video ... big lever arm. I had been watching this area for leaks because they yard hadn't done this job properly and it resulted in a leak before I departed. They redid the job, but was then kept a close eye while underway.

 

[Pete the Cat]

Thanks. Luckily a surveyor did not find any delam. It's a combo of being old/factory defect. Going to install an extra stringer for support and will post a pic later

I think putting a stringer in would be a good idea given the location. I would not be so concerned about oil canning other places but if that is in line with the aft of the keel and well into the bottom--there is a lot of stress there.
I would be careful about adding a barrier coat unless you have removed every smidgen of bottom paint and are sure the substrate is dry. I have seen several boats get into trouble with barrier coats over wet gelcoat.