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Lordwrench 07-10-2014 12:02 PM

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Bushwacker 07-10-2014 02:17 PM

Very educational post! That's what would happen to afishin82's Seafari-to-CC "conversion" without a core on the inside of the hull! The Seafari inner liner covers up very little of the inside of the hull because the tall coaming in the cap, which is highest right in the center of the hull where it's most needed, adds so much bending stiffness to the hull. The MA model can also have a more open inner liner because of it's taller and stiffer cap. I'm sure Moesly put a lot of thought into those solid inner liners in the CC's! They add a lot of bending strength to the hull, so if you cut them away to add rod stowage against the hull without restoring the lost stiffness, this is a good example of what to expect! Too bad the PO spent so much on beautiful cosmetics without getting the basic structure right!

Besides the addition of a core on the hull sides, I would assume most of the deck will have to come out so those cracks can be repaired from the inside. A friend that's been doing fiberglass repairs on big yachts for about 25 years says that when you see cracks like that on the outside, the delamination on the inside is usually much worse.

Bushwacker 07-10-2014 04:26 PM

Quote:

Originally Posted by Lordwrench (Post 229060)
. . I also decided to put this up for others as a lesson on modification planning for structural strength retention and rigidity. . .

Thanks for posting Bryce! It's valuable information indeed! Denny

flyingfrizzle 07-10-2014 04:52 PM

Sorry to hear that Bryce, that was a beautiful boat. I had a mitchcraft that had a bad split in the hull as well. It was a rolled one piece hull with no liner, coring or stiffeners. Like Denny said, once I cut into it, It was much worse on the inside.. Hope yours is not as bad.

Caymanboy 07-12-2014 05:55 AM

Da-aum, pretty boat to have her hog like that.:(

Happy pooch though. :)

Blue_Heron 07-12-2014 09:37 AM

Bryce,
Thanks for posting. Yours is certainly a cautionary tale for those considering modifications that may alter the structure of the boat, or for those considering purchase of a boat that has been so modified.

I remember this boat from the for sale section a couple or three years ago. I actually saved a couple pictures because I liked the color scheme and was considering it for my 25. But I don't remember if there was a thread in repairs and modifications. Was there one? I don't want to shame the former owner, but I'd like to see if the original stringers were kept, or if they were replaced. Do you know if it had the four stringer system, or the two box stringers? If I remember correctly, they made the transition in '71 or '72.

I agree with Denny that removing the inner liner from the hull sides reduces the stiffness. But the hull bottom, deck, and stringers should act together to create a diaphram type beam that's pretty stiff by itself, so I wonder if there isn't something else going on as well. For the diaphram to bend enough to crack at the keel, I would think the gunwales would have to bow out a LOT. Is that what's happening? Is there any separation at the joint between the deck and the hull sides?

Dave

dave s 07-12-2014 11:05 AM

That's a beautiful boat; shame you have to open her up again.
Sounds like more wrong than just the liner; I'd examine the substructure carefully, esp. the stringer to hull bond and stringer to sole.
Like Dave says, tying it all together forms an integrated I beam effect.

In my build I plan to add extra layup and bulkheads and core the sides, since I also removed the inner liner and seen how some of the original glass is looking dry.

Bushwacker 07-12-2014 11:36 AM

Quote:

Originally Posted by Blue_Heron (Post 229095)
. . . Do you know if it had the four stringer system, or the two box stringers? If I remember correctly, they made the transition in '71 or '72.

I agree with Denny that removing the inner liner from the hull sides reduces the stiffness. But the hull bottom, deck, and stringers should act together to create a diaphram type beam that's pretty stiff by itself, so I wonder if there isn't something else going on as well. For the diaphram to bend enough to crack at the keel, I would think the gunwales would have to bow out a LOT. Is that what's happening? Is there any separation at the joint between the deck and the hull sides?

Dave

Dave, my '72 is a 4-stringer hull, so I'd guess this boat also had 4-stringers. I think Potter made the switch in '73 or '74. The first 2 stringer hull I have seen was a '73, but there may be some fuzz on the year the boats were actually produced, since the year on the title is when they were sold.

You're right about the deck bonded to the top of the stringers creating one hell of a large stiff I-beam or diaphragm. If the new deck wasn't well bonded to the top of the stringers, that would significantly reduce the stiffness of the "assembly", especially in torsion, so that's something that should be looked at during the "autopsy" of this failure. I also agree that there is probably a lot of distress at the hull/deck joint. Yacht surveyor Dave Pasco mention deck joint distress as being very common on boats with structural hull failures. Rub rails are often attached to that joint with tapping screws, which don't hold well if there is relative motion between mating parts, because the sharp threads act like knives that cut into the glass.

Ryan 07-12-2014 08:06 PM

You might want to contact Mike at wildfire marine and see what he thinks. Pretty sure he did the restoration for Zach.

Blue_Heron 07-14-2014 07:42 PM

Quote:

Originally Posted by Lordwrench (Post 229128)

"But I don't remember if there was a thread in repairs and modifications. Was there one?"

Yes

I went back and found the thread. Not much there. Only two pictures with the deck off. There are only two stringers showing in the pics, not as wide as the usual two box stringers, not as narrow as the usual four stringer variety. And the fuel tank deck is in place, so you can't tell if the keelson was removed or left in place. Hard to tell what it looked like when they closed it up.

With the level of hull failure you're seeing, I can't help but think you're going to find some stringer issues when you open her up. Either delamination, or the deck not bonded like Denny said, or some modification to the original stringer layout that reduced overall strength. There's some serious flex in the hull bottom for that keel to crack open like it did.

Only time will tell. Good luck.
Dave

shine 07-15-2014 01:21 PM

Sad to read this. You have to "know" its strong as or stronger than original before you go and spend all the time and money to make it pretty.

Its all just speculation until its torn apart :( post pictures and I will be happy to comment on what I can see

jorgeinmiami 07-15-2014 03:27 PM

Would it not be better/safer to look for another hull with less issues and take what you have to it? It sucks to have to do that but better that than put a lot of work into the current hull and have a mishap at the wrong place and at the wrong time?

It sounds like you have to do a lot of work to repair the current hull and then there is always going to be that thought in the back of your mind

gofastsandman 07-15-2014 08:09 PM

Quote:

Originally Posted by jorgeinmiami (Post 229258)
Would it not be better/safer to look for another hull with less issues and take what you have to it? It sucks to have to do that but better that than put a lot of work into the current hull and have a mishap at the wrong place and at the wrong time?

It sounds like you have to do a lot of work to repair the current hull and then there is always going to be that thought in the back of your mind

Why can`t I ever take the fifth?
Good question GFS. Why indeed...

There are so many failure points on that bottom. I would not be comfortable with her.


I don`t know much about thermal imaging. Would you be able to see under her skin and all possible damage without grinding every inch of her down?

Yes, everything can be fixed, but then you are fixing everything.

I`m with Miami.

jorgeinmiami 07-15-2014 08:15 PM

Quote:

Originally Posted by gofastsandman (Post 229269)
Why can`t I ever take the fifth?
Good question GFS. Why indeed...

There are so many failure points on that bottom. I would not be comfortable with her.


I don`t know much about thermal imaging. Would you be able to see under her skin and all possible damage without grinding every inch of her down?

Yes, everything can be fixed, but then you are fixing everything.

I`m with Miami.


Your in Miami? I'm turning off the lights and hiding under my bed...LOL

jorgeinmiami 07-15-2014 08:19 PM

Quote:

Originally Posted by Lordwrench (Post 229267)
I stand corrected,I hadn't looked at these pics since I bought it, two kinda mid-sized stringers.

There are a lot of options going forward, Jorge, but I don't really see a scenario that includes scrapping this hull outright.There's another thread going about comments while out in a Seacraft, I just can't see myself not owning a 20 Super.I am in aviation and have total faith in a properly designed and fabricated repair,provide the total discovery sum is deemed repairable when exposed.That being said, I have free indoor storage and for now no rush, and I am poking around for something else, I know the boat I want but it's not available just yet.

The boat is at another location and I haven't had a chance to get pics of the other information available to post.

Shine, I saw in another post you might take on a second project at your shop this fall, are you booked up?





Thanks to all.

B


There is one in Miami a Master Angler that is cheap enough and comes with aluminum trailer and yami power that you can buy sell off engine and trailer and refub the hull to your liking

hermco 07-15-2014 09:20 PM

Quote:

Originally Posted by jorgeinmiami (Post 229270)
Your in Miami? I'm turning off the lights and hiding under my bed...LOL

:D

shine 07-16-2014 10:21 AM

Quote:

Shine, I saw in another post you might take on a second project at your shop this fall, are you booked up?
nothing firm at this point.

Blue_Heron 07-18-2014 04:08 PM

Bryce,
Please let us know what you find when you have a chance to open her up. I'll be following with interest. I'm planning some similar modifications to a project 20 that's waiting patiently in my barnyard.
Dave

gofastsandman 07-18-2014 10:57 PM

Quote:

Originally Posted by jorgeinmiami (Post 229270)
Your in Miami? I'm turning off the lights and hiding under my bed...LOL

When I get south of Plant City, I just relax and enjoy. The old thought.

Cheers,
Us

Caymanboy 07-20-2014 05:09 AM

Now I know the boat.
I ran into Zach over in Marsh Harbour this past spring.
That is a pretty hull, moving forward I would change the materials and schedules used in the repairs.
OP


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