Project 21 Ft Century

[Glang65]

Hey Everyone!!!! Great forum and lots of great projects and advice. I am getting underway on a project that I will be glad to share, thing is, I am gonna need some help along the way. I bought a 1995 21ft Century ( A boat package, Boat, motor, custom trailer) for my boys and I but I overlooked some bad stuff. I am recently divorced and they stay with me so I really wanted us to get back on the water so that we could start enjoying life again. So I bought in haste without proper due diligence. The bottom of the hull has a crack in it that I did not see. You have to lay on your back to see It and I assumed anyone selling a boat would let a potential buyer know its condition. The man I bought it from gave me 2500 dollars back on a 6500 dollar purchase price. He said he did not know it was there and so I basically bought the motor and trailer and the boat was free. All that being said, I decided to repair it and so goes the project. I do love the boat!!!!!I was told it had fiberglass stringers and I would need to retab them as that is what caused the crack. I cut the floor out and found just that, the stringers and tabbing were seperated. This is where i am kinda lost. the crack in the hull runs just along the stringer and that makes it hard to repair from the inside without removing a section of stringer. I understand the flooring and tabbing, just not sure if i need to remove part or all of the stringers. The boat also had termites so I have removed all wood within the boat, however, I am not sure how the foam filled fiberglass stringer are constructed, Could they hold termites and is there any wood within them. Well thats where I am at. I am gonna get a few pictures and get them loaded on the next post. Looking forward to hearing yalls comments and thanks for looking and to everone here that shares their experience and expertise.

 

[Glang65]

Crack in the bottom crack from the inside along stringer edge

 

[sphelps]

Welcome aboard G65 !
Kind of a little different stringer system than we normally see ... Is the foam water logged ? Is there wood stringers inside of the foamed area ? IDK If it were me I guess I would come up a few inches above the hull and cut the side of the foamed stringer out to gain access to the damaged chine ... Your gunna have to grind the area on both sides of the crack and lay new glass over the area .. Multiple layers of 1708 ... Then reglass the sides of the foamed system and tabbed really well to the hull .. Then patch the outside grinding the gell coat back tapering the edge to allow for several layers of glass ...
Hopefully some more knowledgeable members that have seen this type hull repair will chime in ...

 

[Woodonglass]

Is the crack on the bottom, on the Center Keel?

 

[Glang65]

Hey sphelps, thanks! This is the kind of advice I was hoping for. All the foam I took out was dry, I am not sure about the inside of the stringer though. Dont know about the wood inside either. I was hoping someone has seen something similar. I kinda thought the sam thing, I would have to cut into the stringer to gain access. How would I stub that back in, replace what I take out? Sounds like from what you saw in the pictures this is repairable? Well thanks again for your thoughts. Should be nice here this weekend so I plan on getting after some of it.

 

[Glang65]

No WOODONGLASS, the picture does look like it though. It is on the chine as sphelps mentioned. The center of the hull looks fine , its mostly fractured along the chines where the stringers sit.

 

[Glang65]

Diving into that stringer system today to expose more of the chine crack, Ill post some pictures later.

 

[Glang65]

OK yall, got a little done today! Sorted out some electrical, did some grinding and cut into the stringer system to expose the crack and I think it isn't to bad. I am not impressed with this construction, The stringer is a foam filled upside down U shaped channel that is tabbed to the floor. In my case untabbed! The repair to the crack seems straight forward but i am wondering how to stub the stringer back in. I hope yall have some ideas. Also what is the rib that runs down the center of the hull, whats its purpose and how is it constructed?

 

[Woodonglass]

The "Rib" is the Keel. Probably has a wood core. Provides structutural strength to the hull. Keep it. Big Ole Foam stringers provide flotation and strength to the hull IF, BIG IF, they are attached properly and don't fail. In your case they weren't and they did. If the foam isn't water logged, I see no reason to remove it. If the crack on the outside does not go all the way thru to the inner hull then I'd just repair on the outside and then cut away the glass on the inside where it's delaminated from the hull. Do some grinding and cleaning of the glass to ensure proper adherance of the new glass and glass those stringers in to ensure they WERE attached well to the hull this time. I'd prolly use epoxy!!! It won't melt the foam and it's lots stronger. Have you core sampled the transom to ensure it's ok??

 

[Glang65]

Hey Woodonglass, The crack is through the floor, I was gonna lay several layers of 1708 from the inside and have the exterior gel coat repaired. having gone this far, do you have any suggestions on how to repair the window i had to cut out of the stringers? The transom was repaired with seacast and it is solid. As far as the glassing materials, any suggestions on the best way to purchase and from where?

 

[Woodonglass]

I like uscomposites. Once the glassing is done to the hull on the inside, I'd use 1/2" plywood as forms along the sides of the existing foam stringer. Staple Black Plastic (garbage Bag) to the inside and then use the 4# pour in foam to fill the void back in. Make a lid and stand on it while the foam expands so it will be nice and flat. Hope all that makes sense.

 

[Glang65]

Hey Woodonglass, thanks. It all made sense, soon as I can get my materials i will start with the crack repair and go from. I will post some of that as it gets done. Thanks a bunch.

 

[Glang65]

One other thing, I plan on using the epoxy resin from US Composites, I am thinking I get the thin 3 to 1 resin. I live in south Louisiana and it will be really warm here soon enough. I am gonna use this for the crack repair and tabbing the stringers back in. Please let me know if my assumption is correct and do you have any Idea how I much I may need for this part of the project. I also am planning on using 1708 bi Mat chopped strand tape for the repair and tabbing 6 and 12 inch rolls. Am I thinking about this correctly? Thanks

 

[Woodonglass]

Any reason for the epoxy? Your boat is made from Poly and Poly is plenty good for the repairs. The 635 Poly resin from USC is what most of the members use. I'd start with 10 gallons and 10 yards of the 1708. Since it has CSM stitched on it you don't need much CSM. I'd say 5 yards of the 50" would be a good start. If you go ahead and use epoxy you DON'T use 1708 You only need 17oz biaxial fabric NO CSM.

 

[Glang65]

Maybe I misunderstood Woodonglass, I thought you said in a earlier post to use the epoxy resin for its strength and bonding ability. " Do some grinding and cleaning of the glass to ensure proper adherance of the new glass and glass those stringers in to ensure they WERE attached well to the hull this time. I'd prolly use epoxy!!!" This is why I was planning on epoxy for the repairs and tabbing the stringers back in.

 

[Woodonglass]

Well duh!!! I did and you should due to poly eating the foam. Now that we're on the same page....:facepalm:
The 635 IS the right stuff to use and as I said just get the 170z Fabric NO CSM needed with epoxy.

DB170 - 17oz Biaxial - NO MAT

[SIZE=-1]+/- 45 degree Contains double bias(17oz) stitched at 45degrees. Does not have a mat backing. Thickness: 0.030"[/SIZE]

[SIZE=-1]FG-DB170-50[/SIZE]

Remember 1 gallon of epoxy will wet out approx 4 sq. yds of 17oz biaxial fabric. Also remember that epoxy has an extended curing time so on vertical surfaces it WILL run off and down to the deck. You MUST "Baby Sit" if for the full cure time and constantly drag the resin back up the vertical surface to keep if from becoming resin starved It's a pita but absolutely necessary.

 

[Glang65]

Thanks, that helps with the clarification on the epoxy resin. I am still working on it a little here and there. I will try to get some materials ordered so I will have them by next weekend. Thanks again and I will post my progress.

 

[Glang65]

Hey all, I am making a little progress, i got some of my materials in and the center of the hull mostly ground. I have a few questions. As i was grinding the crack area, it enlarged due to glass delaminating. Should I fill this with Cabosil thickened resin before doing the layup repair.Would it require more than 3 layers. It is hard to see, but the window into the stringer was made bigger for grinding . I am gonna refoam the stringer but it seems like I should replace the material removed by tabbing in something to the original stringer. Any suggestions. Man the clock is slow, i mean this is moving too slow. Woodonglass, any thoughts on the cabosil fillets. I was gonna also redo the opposite side chine area as it seems thin and poorly laminated as well. Well any and all thoughts please.

 

[Woodonglass]

Yeah, I'd prolly fill it with some PB (Resin and Cabosil, what we call Peanut Butter) and then lay a strip of glass over it for good measure.

 

[Glang65]

Thats what i thought as well, Would I do the whole repair all in one layup, Cabosil resin and 2 or 3 layers of 17oz cloth?