many questions about repairing/replacing stringers

[carboncow]

Originally Posted by Liam

I used 3/4 exterior grade fir doubled up,marine ply is better but cost is way higher,IMO properly sealed fir will last nearly as long. I am not sure what the original stringer material is on your year,mine was spruce but it is a 1973,others may chime in here

Thanks and great info.

To be clear...my question about putting the sole on top of the old sole is based on my photos. As you aw I have only 2-3 inches around that permitter and we were considering putting that on top overly lapping about 1-1.5 inches. This would have a water channel all around the permitter.

Were you talking that I would pick of voids this way...or were thinking I was laying the new sole over an old/wet one?

[carboncow]

Originally Posted by dan4836

I am doing the same project now.

I cut out my deck, removed the fuel tank and foam. Cut the tops of the stringers and bulkheads and was planning on using Seacast or Arjay to fill the void.

What I decided to do is pick up three sheets of 3/4" A/C plywood. Cost all the wood with polyester resin. Install the 3/4" stringers back into the stringer cavity.

What I found - the stringers were made with a piece of lumber (not plywood) the bulkheads are made with plywood and are much more difficult to get the wood out.

So it was not continuous wood but smaller pieces? Are they secured (sistered) in a way to connect one another? I should comment my floor was made of chunks of plywood and not one continues piece!

I will be glassing over using 1708 and chop strand with at least four layers.

I was able to consult with a boat builder and he said the plywood material I am putting in is just to fill the void. The 1708 and chopped strand will be the new structural stringer.

So you are using plywood in the stringer? Sometimes when I read this posts (no offense) it makes me question one we even pull the wood out! I'm guessing the factory glass is not amazing with a wet stringer but if you go mega-layered with glass then it really doesn't matter what is inside!?!?

After this is complete, I will drop my 3/4" plywood floor. I thought about using a composite but by the time I have to re-do the floor it should be many years....

I've read many a post on other sites talking composites...and I think it's fine for those with $$$ and who like the wow factor, but as you stated a good wood floor should last a long time too at a lower cost.

My floor will be laminated with two coats of chopped strand.

What type/weave will you use? We are trying to understand all the designations people are listing.

I will post photos soon...

See my questions up in the body of the text...

[carboncow]

Dan,

Any to be clear...you are doing your stringers in 3/4" plywood? Marine grade or standard? We've been getting mixed info on this but we seem to believe if the plywood is heavily resin'd then it doesn't need to be marine.

Will your stringer needs be greater then the length of plywood (assuming 8ft) and if so doesn't it matter how they "butt" to the next piece?

thanks.

[carboncow]

Guys...I need input on "how much" 1708 to buy.

We may need todo two stringers up to 10+ feet long and the sole as you see. We can do the math I'm sure but how many yards are we talking?

Seems it's in 50" width and I'm seeing 48 yards for about $290.

Thoughts?

[Liam]

Hey sorry i misinterpreted what you where saying with the deck,you will be fine using the perimiter to attatch,i am doing the same.
I have saddle tanks so am raising the tanks 3/4 inch to allow for the overlap.
I am only using one layer of 1708 on the stringers,50 inch will do both my stringers,tabbed in with 6 inch 1708 tape and CSM in the tight corners.
I suspect your stringers are taller than mine though so you may need to use one length of 38 inch per stringer.
For the deck i plan to use one layer of 1.5 oz CSM on the underside then one layer of 1708 with a layer of 3/4 oz CSM on the topside.Thats with 1/2 inch ply.
My stringers are longer than 8 feet, as the stringer is made from 2 pieces of 3/4 ply i just cut one piece 12 inches shorter and do the reverse on the next section of stringer,glue with resin and stainless screws,then one sheet of 1708 over the whole stringer.

[carboncow]

Liam,

Glad to think average minds think alike...

comments in body of the text.

Originally Posted by Liam

Hey sorry i misinterpreted what you where saying with the deck,you will be fine using the perimiter to attatch,i am doing the same.
I have saddle tanks so am raising the tanks 3/4 inch to allow for the overlap.
I am only using one layer of 1708 on the stringers,50 inch will do both my stringers,tabbed in with 6 inch 1708 tape and CSM in the tight corners.

How come only one layer on the stringer (I see many guys online doing multiple. Is it because you have strength in the old ones at the base and pouring in the fill will give additional stability?

I've seen the glass tape online...why are you using it? Is it easier then cutting something long and thin for tabbing needs?

I suspect your stringers are taller than mine though so you may need to use one length of 38 inch per stringer.

Yes now that I see the newer boats have only two tall stringers and from your post you have 4 shorter ones (I believe) which presents some challenge of the wood height and getting it in there. I like your idea of leaving a few inches of the stringer for a guide.

For the deck i plan to use one layer of 1.5 oz CSM on the underside then one layer of 1708 with a layer of 3/4 oz CSM on the topside.Thats with 1/2 inch ply.
My stringers are longer than 8 feet, as the stringer is made from 2 pieces of 3/4 ply i just cut one piece 12 inches shorter and do the reverse on the next section of stringer,glue with resin and stainless screws,then one sheet of 1708 over the whole stringer.


Are you stating your will glue and screw those two stringer pieces together or are you screwing your deck to your bulkhead/stringers too?

What is CSM..."chopped" or "cut" matting? Obviously you have done some glass work before with the different weight usages. If we are buying a large roll of 1708 are we fine to use that for all deck needs and just change directions? How many layers would you recommend for the decking? (I see many opinions out there!

Again, this is great stuff. Thanks for letting me parse your comments as I learn this. I got a buddy who is off the charts handy with this stuff but green with glass but I like to understand everyone process to feed him the intel so we do our boat right and safe the first time.

[Liam]

CSM stands for "chopped strand mat"
As far as one layer,1708 is actually 2 layers it is one layer of 45 degree woven fabric with a layer of CSM stiched to the back of it. Providing you don't use polyester resin 1708 is extremely strong and waterproof.
The deck will be screwed to the stringers and bulkheads,there will also be a layer of thickened resin on top of the stringers/bulkheads to allow for any undulations. The stringers will be screwed at the overlap permanently,when i glued the two layers of stringer together i put resin between the two and screwed and clamped them until the resin had set then removed the screws.

Glass tape saves cutting as you mentioned and is used for tabbing in.

Your stringers are taller because you have a later boat that has a self bailing deck ,the deck was raised to be above the water line and they increased the cap height to allow for the loss in freeboard.

[bradford]

Excellent posts!

[carboncow]

Originally Posted by Liam

CSM stands for "chopped strand mat"
As far as one layer,1708 is actually 2 layers it is one layer of 45 degree woven fabric with a layer of CSM stiched to the back of it. Providing you don't use polyester resin 1708 is extremely strong and waterproof.
The deck will be screwed to the stringers and bulkheads,there will also be a layer of thickened resin on top of the stringers/bulkheads to allow for any undulations. The stringers will be screwed at the overlap permanently,when i glued the two layers of stringer together i put resin between the two and screwed and clamped them until the resin had set then removed the screws.

Glass tape saves cutting as you mentioned and is used for tabbing in.

Your stringers are taller because you have a later boat that has a self bailing deck ,the deck was raised to be above the water line and they increased the cap height to allow for the loss in freeboard.

Going to keep bugging you!

1. Why not poly...which one sticks better to the old glass too?
2. I'm trying to get a grasp on how many yards of 50" 1708. How much did you buy/use...or did I miss that somewhere?

We found one vendor selling a roll of 48" yard very reasonably but that seems like a lot if only doing one layer on the stringers and two on the deck. We'll take some measurements this weekend on the boat to come up with our theory of quantity.

3. How much resin would you also recommend based on my photo and if we had todo two tall stringers front to back. My buddy thinks 3 would due but I'm always the pessimist and think 5 is the safe thing.

[Liam]

Originally Posted by carboncow

Going to keep bugging you!

1. Why not poly...which one sticks better to the old glass too?
epoxy would be the best choice and will stick to old work the best,then vinylester,the fumes are pretty rough with vinylester though,then polyester which won't stick to epoxy nor is very waterproof over the long term. I am not saying it would be wrong to use poly, a lot of boat builders do,i believe the original construction on your boat is poly,but if you plan on keeping the boat for a while I would use vinylester,just get a good respirator,if money is not an issue and you are keeping the boat for ever use epoxy,lol

2. I'm trying to get a grasp on how many yards of 50" 1708. How much did you buy/use...or did I miss that somewhere?
I buy mine in smaller orders online from uscomposites,i buy enough for each part of the project,as I recall I bought 5 yards for the stringers

We found one vendor selling a roll of 48" yard very reasonably but that seems like a lot if only doing one layer on the stringers and two on the deck. We'll take some measurements this weekend on the boat to come up with our theory of quantity.

3. How much resin would you also recommend based on my photo and if we had todo two tall stringers front to back. My buddy thinks 3 would due but I'm always the pessimist and think 5 is the safe thing.

Your going to need a lot of resin,i used 3 gallons for the transom,1708 sucks up a lot of resin. You can keep the amount of resin down by building with the "wet on wet" method which makes for a stronger bond and uses less resin. I would guess 3 gallons would be about right for the stringers,make sure you order plenty of cabosil also,one quart of cabosil to one quart of vinylester will get you pretty close to a peanut butter consistency