Stringer and deck replacement....

[Sabin1269]

I just purchased a 1986 Starcraft Medalist 1901 with a Mercury 115 ob on it. Boat runs pretty well and I took it out a few times with the family and didn't really notice anything wrong with it besides a little water here and there (typical boat stuff). One of the PO replaced the deck and carpet which didn't throw up any red flags to me at first but I wanted to get at the fuel tank and fix the sending unit so the fuel gauge would work.

Well, I had to pull up the desk since there was no access holes or hatches to it and then saw the ugly truth, the kind that makes your stomach sink...... ALL the wood thats under there is rotted including the stuff inside the stringers. While the fiberglass still feels and looks solid there is just way to much rot under there to ignore.

So my first question it what is the best wood to use to replace the cores? Can I use exterior grade plywood which I was going to either coat or paint with something and then replace/reglass over it or is there a better option? I've seen a few other forums that say the wood is only there for a core to mold the fiberglass around so, would it be easier and as effective to use foam for a core to prevent further rot or should I stick with wood? I know I'll need it around my tank for support. I was looking at using Greenwood XL 1/2" and glueing it together but I didn't know if there is a better alternative. I'll glue it to the hull with some homemade peanut butter ( I usually put 1/4' foam spacers between the stringer and hull to prevent too much direct contact). I've never had to do such an in depth stringer replacement though so any advice would be great!

I'll post pictures when I get home!

 

[tpenfield]

:welcome: . . . your story is much like many who have come before you.

Sounds like you are needing the old 'cut & gut' of the boat's structure. Post some pictures when you can (reduce them to about 800 x 600 so they will upload and display properly.

Greenwood XL is what many of the boat manufacturers now use. You can certainly use exterior grade plywood . . . that is what many of the boat companies used prior to Greenwood XL. The glue is the same in exterior grade as is in marine grade. Marine grade just has better veneers of wood.

You really need to get all of the rotted/wet structure out of the boat first. Then build it all back as it was meant to be.

 

[Scott Danforth]

the last thing to rot is the floor. the stringers and transom go long before the floor.

time to get itchy

 

[Sabin1269]

Tpenfield I'm currently in process of gutting everything out right now. I'll get some good pictures tonight and post them up. Between the Greenwood XL and exterior grade is there really any difference other than veneer? It will be in the bilge so I'm not too concerned wit h the finish quality but i also don't mind spending the money to do it right so it will last for a long time.

 

[CrazyFinn]

Exterior grade is fine. The void free marine grade plywood is important if you’re building a wood boat. As a core for stringers and transom in a glass boat, marine grade will simply make things cost more than they should.

 

[JASinIL2006]

The wood does indeed provide structural support. Boats with foam-filled stringers and bulkheads have MUCH thicker layers of fiberglass than is necessary with wood structure. I think it would be considerably easier and less expensive to replace with wood (encased in fiberglass) if that was what the boat had originally.

 

[tpenfield]

I used 5/8" exterior plywood, when I did some re-build work on my boat. The veneers are quite adequate. I think my boat was originally made from exterior grade plywood.

 

[Sabin1269]

Got into it more last night and got more of the stbd side stringers out. going to go with 3/4' exterior grade doubled up from the console going aft like it was built and a single 3/4' from the console fwd to the bow. The tricky part is getting everything out from under the bow seating section. I don't want to cut the existing fiberglass flooring and gel coat since it's still in really good shape.

Anyone have any reccomendations on a good company to get a poly fuel tank from? While I'm there I might as well put a new tank in there too.

 

[Sabin1269]

Here are some pictures of the boat. https://photos.app.goo.gl/UYRFSWryNjmjhYUQA

 

[Woodonglass]

Mueller makes good poly tanks. I'd recommend really making sure the aft stringers are OK. Just because the deck seems solid does not mean the underlying stringers are.

 

[Sabin1269]

Woodonglass, I'm in process of ripping out all the stringers, the aft ones were in a little better shape but still rotted. I have the lifting eye for my outboard coming in the mail today so once I rig that off I'll continue cutting the old glass and stringers out. I'm not sure how much of the old glass and stringers is still supporting the transom but i didn't want to find out the hard way and dump my outboard.

 

[Woodonglass]

OK Kool. Keep up the good work and I'll tag along on your project!!!

 

[Sabin1269]

SWell I’ll be getting the transom out tomorrow and will probably go with 2, 3/4” pieces of exterior grade sandwiched together instead of 1 1/2” Coosa since there doesn’t really seem to be much more of a benefit to the Coosa. My question is what should I use to tab in the transom and stringers? Should I use 1708 to tab them in then cover it in CSM? I’m going to cover the transom and stringers in 6 oz CSM before I even install them to hopefully get them to last a little longer than usual. I’ve been reading and it looks like tabbing them in with 1708 and the covering them in CSM seems to be the way to go. I figured I was going to use the same 6oz and double layer it when I cover them.

 

[JASinIL2006]

I tabbed with 1708. CSM doesn't add much strength.

 

[Woodonglass]

Theres no such thing as 6oz CSM. If your using Poly resin then all you need is the 1708 It has an adequate amount of CSM stitched to it so no additional CSM is required unless you want to put a final layer on to better HIDE the grain bleed thru from the 17oz fabric. Stringers and transom can all be done with 1708 only. Decks to but IMHO that's a bit overkill. CSM On the bottom and CSM and 6oz biax fabric on top yields a very nice deck surface.

 

[Sabin1269]

Sorry it isn’t CSM it’s just 6 oz cloth. I was going to use that as a wrap to help waterproof everything.

 

[Sabin1269]

After tabbing in the stringers and transom with the 1708 will one layer of 1708 on top be sufficient or should I use 2? I ordered enough to easily do 2 but I also don’t want to lay it if it isn’t necessary.

 

[JASinIL2006]

I used two layers, just to be safe. Just make sure you don’t exceed max thickness for the transom(2 1/4” for Mercruisers).

 

[Sabin1269]

JA thanks for the advice. I have an outboard on it not I/O. I’m going to go with 2, 3/4” pieces of exterior to make a 1 1/2” thick transom. I couldn’t really get a solid measurement on the old ones thickness but the few spots I could try and get looked to be about 1 1/4” to 1 3/8” thick.

 

[Sabin1269]

Ok so now that the weather will be agreeable in Maine for at least a few months I’m getting back into my boat. I’m templating the transom area today on some 1/8” board to get a better fit. I’m looking at some 3/4” BCX ply to make the transom. I’ve done a lot of reading but always looking for seasoned advice on how to bond them. I’ve read using Titebond III and screwing the boards together to clamp and I’ve also read laying a layer of CSM in between and resin. I like the TB idea since I’ll be sealing the whole thing before it’s bonded to the hull.

I’ve also read that I should seal the ply with epoxy then wrap it in 1708 before install which was my initial plan anyways. If I use the epoxy do I just paint it right on the bare ply then after it dries, do I wrap it then or wrap it with the epoxy still wet? After that’s all set my next step is bonding it to the hull which I’ve also seen conflicting advice on between using PL and epoxy. In everyone’s opinion what’s the best option here? I’ve got plenty of room to access everything so I’m thinking epoxy straight to the hull. I know it’s a lot of questions wrapped up in one post and I appreciate all the help I’ve gotten so far!