Hail Yeah back under the knife - Page 2

BA17 · #11 02-08-2014, 08:17 PM

Here is the latest update. Got the floor out and cut the bottom out of the fish box. The entire front bulk has broken loose. Not sure how the best way to put that back in? You can move it side to side with your hands. Could this be the reason for the cracking and hole in the bow? There is a pic of the hole from the inside. It is the pic that looks like coconut hair. Stringers look rough where the tank beat them up, but forward they look good. Hard to tell how wet the foam is in the stringers, I found a couple of spots where it is wet. Would the best approach be to take all the foam out of the stringers just in case?

BA17 · #12 02-09-2014, 11:48 PM

Ok, another dumb question. Why would you have a power block like this in the bilge?

flyingfrizzle · #13 02-10-2014, 07:26 AM

Quote:

Originally Posted by BA17

Here is the latest update. Got the floor out and cut the bottom out of the fish box. The entire front bulk has broken loose. Not sure how the best way to put that back in? You can move it side to side with your hands. Could this be the reason for the cracking and hole in the bow? There is a pic of the hole from the inside. It is the pic that looks like coconut hair. Stringers look rough where the tank beat them up, but forward they look good. Hard to tell how wet the foam is in the stringers, I found a couple of spots where it is wet. Would the best approach be to take all the foam out of the stringers just in case?

That's got something to do with it. I had a 1978 20' Contental that did the same thing. She got ran hard in some close chop in the Pamlico sound near hobucken (you may know this area since your from nc too) and the repetitive beating knocked the forward bulkhead loose plus tore threw similar to yours. Mainly my fault for running it so hard and beating the he'll out of it but the way I look at it she will hold up or not. This time she didnt. I would think a seacraft would do better but there could of been other issues in the lay up maybe?

FishStretcher · #14 02-10-2014, 11:19 PM

Maybe this is the reason for a recommended trapezoidal foam spacer between the bulkhead and hull, to spread the load and remove hard spots?

BA17 · #15 02-10-2014, 11:26 PM

FishStretcher,
Huh? I need more info on that one.

FishStretcher · #16 02-11-2014, 12:01 AM

http://www.classicseacraft.com/commu...5&postcount=31

Dave Gerr's book mentions that trapezoidal spacer requirement. The PDF linked in that post shows a floated bulkhead and elastomer in the gap and to create the fillet.

I assume it (the USCG mandated spacer for certain boats- T-boats?) looks like pic # 2 here:

http://www.bateau2.com/howto/foam_phantom.php

I understand the concept but haven't actually implemented it yet in glass and foam or wood. I did something a bit similar on a 30 ton aluminum boat- but that's more like a skin doubler.

BA17 · #17 02-11-2014, 12:29 AM

FS,
I don't even know what to say. That is so far over my head, that I don't even know how to communicate what I don't understand? You didn't graduate from GA Southern I'm betting. I think I understand this, the original design may not be good? I cut out a larger section of the step up today so I could get the existing bulkhead out and see what was going on under the fish box. Each corner of the fish box is sitting in two big piles of potter's putty that is only a couple of inches from the bulkhead. I thought that this bond between the hull and the fish box may be contributing to the problem. I will try to get some pics of it tomorrow.

Normagain · #18 02-11-2014, 07:45 AM

It looks to me like someone may have replaced the tank and removed the foam in there adding that front bulkhead and maybe removing some key foam. The tank looks like it broke loose, maybe whatever they put underneath it was not tied in well and stable and the tank was not bolted well. Here is a picture of my 74 SF. There was a block of foam in both the front and rear of the coffin and those were both on the top of that bottom tank board, no wood bulkheads at all. The front foam block starts further forward of where your bulkhead is, you can barely see it in this picture.

Normagain · #19 02-11-2014, 07:51 AM

One other thing that struck me as odd in on your boat is the scupper in the one photo doesn't look factory at all.

flyingfrizzle · #20 02-11-2014, 08:46 AM

I agree with fishstrecher on the "Hard Spots" (a very common cause for tears in a hull like you got). I might can dumb it down, I would think of a hard spot as where the bulk head meets the hull or and other item such as the bond between the fish box and hull with the potter putty as being an area where the load is not spread out correctly over a wide area. The bonding point is a sharp or small area that applies all the force to a given spot. Filets and the trapezoid spaces mention help spread the force out to more of the hull and not the one spot. If all the force is not spread and applied to one area it can be more prone to failure.

It usually takes me reading multiable examples, pictures, and then I still have trouble understanding this type stuff. Im still learning each day myself and feel like Im just now starting to make since of some of it. hopefully this will help some if im on the right track.