Core decisions on 43 DCMY

[Boatsb]

Epoxy adheres to polyester. Not the other way around. Finish with epoxy. Also some Matt has a styrene soluble binder that will not wet out well with epoxy. Make sure you have the correct matt. I also use choped strand in most bonding and strength related areas. Cabosil or aerosil is fine for small areas but I like the strand or a layer of finish cloth or two for adhesion.

 

[whoover]

I'm going to revive this thread as I have bad core in the fore deck. Also I am working under the top skin. So far the inner skin is cut back to solid balsa and the wet core is out. I want to get the edges and shape of the repair a bit cleaner and a better looking shape to work with. I've got the time to do this job but I want it done correctly so please educate me. I would like to know how the original poster made out too. All I will be doing now is prep sanding and making patterns so I will be ready to start the layup when the weather warms up in the spring so I have time to read/listen to those that know more.

Thanks
Walt Hoover

 

[Jammin']

I will be going down this road with my hard top, but probably not until late winter or so.

 

[Triskele]

I'm going to revive this thread as I have bad core in the fore deck. Also I am working under the top skin. So far the inner skin is cut back to solid balsa and the wet core is out. I want to get the edges and shape of the repair a bit cleaner and a better looking shape to work with. I've got the time to do this job but I want it done correctly so please educate me. I would like to know how the original poster made out too. All I will be doing now is prep sanding and making patterns so I will be ready to start the layup when the weather warms up in the spring so I have time to read/listen to those that know more.

Thanks
Walt Hoover

You seem to be on the right track. It looks like you have decided to attack it from the inside (bottom layer) rather than the outside (top layer). I did the same. In hindsight I'm not sure I would go that route again. I chose to do it that way because there was a lot of rot under the bow pulpit and I did not want to remove the bow pulpit to get to it. It was a miserable two month job. I also removed the windlass and cleaned it up. Changed gear oil, made a new Delron spacer and painted. In order to work inside the chain locker I had to make a platform to lay on and as well use for bracing the new plywood core. Besides working from inside the chain locker for two months, the worst part of the job was laying up the glass and plywood core. If you don't have help (which inside the chain locker you won't because only one person can fit in there), be prepared to use both hands and your feet. LOL. You will, for the most part, be working on your back. I would wet out the glass with epoxy in two or three foot sections and roll it on a 1 1/2 diameter pvc pipe that was about 18" wide (which was about as wide as you could use inside the chain locker). Then unroll it on the ceiling and at the same time bracing it; the whole while fighting gravity. Think of someone standing above you pouring a bucket of Kayro syrup over your head. Every time you touch the wetted glass, the epoxy starts running down your arms; not only from the glass, but after the glass is in place you need to get the air bubbles out as well as add more epoxy after it is laid up. Just be sure to have plenty of denatured alcohol in a spray bottle to wipe off any excess epoxy that has run all over your hands and arms. Otherwise you will become a sticky mess and will not be able to remove it once you climb out of the locker. Yes, take the spray bottle with denatured alcohol into the locker with you. You need to have all your glass, resin and tools layed out as well for wetting out the glass before going into the locker. You have to work fast before it starts to set up. It will help if you can get an assistant who will do the wetting while the other person stays inside the chain locker and lays up the core and glass. You also need your braces measured out and cut along with shims.

I was hoping to attach some pictures from my work, but I am unable to upload any more pictures and can not delete the ones I have in the system. Feel free to PM me if you wish to speak directly or ask other questions. BTW...I am very pleased how the repair came out. Scott (BoatSB) recommended laminating 3 layers of 1/4" marine plywood for replacing the balsa core. I chose to do it that way and it worked out great. You can drive a tank over that section of the deck. I put glass between each layer of plywood along with thickened epoxy. All thru holes (hawse pipe and windlass shaft) and bolt holes I oversized and filled with epoxy and then came back and redrilled the epoxy filled hole to size to ensure no water could wick into the core again. Good luck.

 

[whoover]

Thanks, i was wondering how the plywood for coring worked for you. I already have my windlass removed (Good automatic) and the bow pulpit. The coring under the teak insets was bad so it is in my workshop ready to be fixed and painted. I have been testing adhesion with PVC material and have good results. Im going to put this in the pulpit for coring becuase its rot proof. I will be over sizing the holes in the foredeck and filling also to prefent warer intrusion. I didnt think this was going to be fun so thanks for the tip on rolling the glass onto pvc pipe. Is West epoxy and slow hardener the way to go as it sounds like time is also an enemy here.

Thanks
Walt Hoover

 

[whoover]

This question will be for Scott. After a horrible experience trying to use mat with epoxy because i didnt know any better or about the styrene binder i will only be using cloth. What weight should i be using and do you put a layer between each layer of ply wood. Ill take as many pics as i can along the way.

Thanks
Walt Hoover

 

[Jammin']

My inclination for the hard top is to cut out the top where it is wet, dig our the core and use West System epoxy with Corecell coring and vectorply glass. Is that as good as anything?

 

[Boatsb]

Polyester is not good with PVC.

Strongest buildup is pure glass. Look at biaxial as a standard 1708.

Most resilient in my opinion is layers of 1/4 mahogany plywood and proper matt or finish cloth with epoxy. Kind of similar to the way the cold molded boats are done.

Thin the epoxy a bit and use a slow cure. I've cut holes after and it seemed to soak through the wood and completely protect it.

 

[carolinacoast]

On my FB deck repair Coosa was the specified material.

 

[Triskele]

This question will be for Scott. After a horrible experience trying to use mat with epoxy because i didnt know any better or about the styrene binder i will only be using cloth. What weight should i be using and do you put a layer between each layer of ply wood. Ill take as many pics as i can along the way.


Thanks
Walt Hoover

Walt, styrene binder in mat should not be a problem with epoxy. It was a problem with polyester resins and only below the waterline (I presume you are referring to gassing which led to blisters). Since I consider the deck to be a structural element due to the loads from the windlass I used cloth and biaxial fiberglass coated in cabosil. Maybe overkill, but as I said can drive a tank over it. I think I used 10oz cloth and 17 oz biaxial layered between each layer of plywood. Under the top layer of deck glass, I made a batch of thickened epoxy with cabosil and smeared it on the bottom surface of the deck glass. I then rolled in my wetted glass. Once the glass became tacky and started setting up, I put in a wetted layer (glass side) of 1/4" marine plywood and braced it into place. Let it dry and set up for 3 or 4 days depending on my time. Once this is in you can come back in and start the next layers when you have time, but probably no sooner than three days to insure a good solid bond.

 

[Triskele]

Walt, styrene binder in mat should not be a problem with epoxy. It was a problem with polyester resins and only below the waterline (I presume you are referring to gassing which led to blisters). Since I consider the deck to be a structural element due to the loads from the windlass I used cloth and biaxial fiberglass coated in cabosil. Maybe overkill, but as I said can drive a tank over it. I think I used 10oz cloth and 17 oz biaxial layered between each layer of plywood. Under the top layer of deck glass, I made a batch of thickened epoxy with cabosil and smeared it on the bottom surface of the deck glass. I then rolled in my wetted glass. Once the glass became tacky and started setting up, I put in a wetted layer (glass side) of 1/4" marine plywood and braced it into place. Let it dry and set up for 3 or 4 days depending on my time. Once this is in you can come back in and start the next layers when you have time, but probably no sooner than three days to insure a good solid bond.

BTW...I have loads of pictures I can share, I just can't figure out how to add mire to this site. I think I have reached the limit. If you want to PM me with your email address I can send you a few.

 

[Triskele]

Walt, styrene binder in mat should not be a problem with epoxy. It was a problem with polyester resins and only below the waterline (I presume you are referring to gassing which led to blisters). Since I consider the deck to be a structural element due to the loads from the windlass I used cloth and biaxial fiberglass coated in cabosil. Maybe overkill, but as I said can drive a tank over it. I think I used 10oz cloth and 17 oz biaxial layered between each layer of plywood. Under the top layer of deck glass, I made a batch of thickened epoxy with cabosil and smeared it on the bottom surface of the deck glass. I then rolled in my wetted glass. Once the glass became tacky and started setting up, I put in a wetted layer (glass side) of 1/4" marine plywood and braced it into place. Let it dry and set up for 3 or 4 days depending on my time. Once this is in you can come back in and start the next layers when you have time, but probably no sooner than three days to insure a good solid bond.

BTW...I have loads of pictures I can share, I just can't figure out how to add them to this site. I think I have reached the limit. If you want to PM me with your email address I can send you a few.

 

[Triskele]

Thanks, i was wondering how the plywood for coring worked for you. I already have my windlass removed (Good automatic) and the bow pulpit. The coring under the teak insets was bad so it is in my workshop ready to be fixed and painted. I have been testing adhesion with PVC material and have good results. Im going to put this in the pulpit for coring becuase its rot proof. I will be over sizing the holes in the foredeck and filling also to prefent warer intrusion. I didnt think this was going to be fun so thanks for the tip on rolling the glass onto pvc pipe. Is West epoxy and slow hardener the way to go as it sounds like time is also an enemy here.

Thanks
Walt Hoover

I used resin from the Epoxy Store in California. I liked it for this application because it was slow to set especially if add 5 to 10% acetone. Also, most epoxies wet out easier and set time regards when mixed with acetone. Can't speak so much for West Systems. The advantages are that you only have to mix out small batches and use what you need, thus less waste, but found it was sometimes harder to work with cause set up faster. The key is to get the stuff out of the pot and onto the glass. Longer it sits in the pot quicker it will start to cook. Trust me you'll have a few hockey puck batches, but that's how you learn. Acetone goes a long way towards controlling this. The other drawback is West is expensive. I have had luck with U.S. Composite and Raka on other projects (repairing hull blisters).

 

[Boatsb]

First of all thats backwards.

Polyester has styrene and will dissolve the Mat binder.

Second be careful when thinning epoxy. It will reduce its strength significantly.

 

[oscarvan]

I have used this outfit for epoxy in the past.... personal service and decent prices....

http://www.raka.com/epoxy.html

 

[whoover]

Thanks for the offer Oscar but I think I have a handle on it for now. Since I'm here in the great white north my supplies will be found locally. I have a pretty good local fiberglass supply store nearby and a place called Canada Composites located near the Toronto airport that supplies the aircraft repair industry.

Walt Hoover

 

[oscarvan]

Ah, didn't realize you were on the other side of the line. Yeah, that can get complicated.

 

[34Hatt]

Walt, styrene binder in mat should not be a problem with epoxy. It was a problem with polyester resins and only below the waterline (I presume you are referring to gassing which led to blisters). .

The problem is with Mat and Styrene epoxy doesnt break it down which makes it a PITA to wet out and why use it if using Epoxy? Matt is used in polyester resin as the binder aka the stick between different materials suchs as matt first then roven these days everyone uses biaxial stronger and easier to wet out. So then with Biaxial it comes as 1208 or 1708 and the 08 is the amount of mat added in with out styrene so it works with both materials and applies very nice in comparison to the old days old using roven and mat.
Some 1208 and cloth with epoxy and you can fix 95% of everything

My personal like is to use 1208 instead of 1708 and just use a extra layer you may think its more work but its easier due to the fact of it wetting out and conforming easier. It also then is stronger

 

[whoover]

Thanks for the description of the material. I have been all over the web and could not find any kind of chart with materials and weights of them. After doing price checking I am going to use West epoxy as it is only 50.00 a gallon more than other epoxies. So the plan now is to use 1208 material under the top skin then a layer of marine plywood. Let it cure then repeat until I reach the core thickness which I think is 3/4". This weekend is clean up the cut out area, make a paper pattern of the area and measure up for a stool in the locker to work on.

thanks
Walt Hoover

 

[jim rosenthal]

Are you set on marine plywood? Coosa board might be better. It is great in this application.