# Deck Recore - Lessons Learned



## maccauley123 (Sep 2, 2004)

I am just getting close to finishing a deck recore on my boat and wanted to share some of the lessons I have learned. Note I did this from the top down because I will be repainting my decks.

- First, while not an easy job it is definitely doable. I would do it again if I had to. Knowing how to do it is a HUGE part of that. This was my first time doing it and a lot of On the Job Training. Making that first cut into the deck was not easy.

- Everything says to sound out the deck with a hammer to find where the soft spots are. This sounds great but is not nearly as easy as it sounds. On the first section I did this it was easy, the entire section was rotten and the top came up easy. After that it just got harder. I would sound it out, mark the part to remove and make the cut. When I would try to remove the section though it did not come up nearly as easy as the first. The rot will not be uniform througout and I found there were sections of rot with a good sized piece in the middle still solid and stuck on real good. This then required some ripping out of the old with the awful sound of tearing fiberglass. I have no idea if there is an easier way to do this. I can't imagine one.

- I don't know how anyone could possibly sound out a section where the edge of the piece removed is right at the end of the rot. The best I could do was make the cut close to the end of the rot and then scrape out the rotted stuff from underneath the remaining deck. I think this should work out best anyway because when I epoxied new core in it had to go under the deck I kept and bridged the gap created. This required two steps, one to put new core in around the spot under the deck and then fill in the middle.

- The most tedious part of the job I found was cutting new core to fit the section to be repaired. The rot does not occur with convenient right angles. Balsa core cuts really easy with a nice sharp utility knife. At first I foolishly tried to cut it with a saber saw which did not work at all.

- For cutting through fiberglass, which is some really tough stuff, I found an angle grinder to be the best. I tried a roto-zip and the blade dulled very quickly. A grinder cuts great but creates a LOT of dust so wear a mask. The angle grider let me do tight in work nicely though.

- When gluing the old deck back on grind down the edges to create the bevel BEFORE you glue it down. The first two I tried to do it after and had to use a small drum sander on my portable drill which took a while. I finally figured out to make the bevel first which only took minutes. I could make a much better bevel too.

- The gap that needs to be filled after the top is glued down is fairly narrow requires some long thin pieces of glass. I found a rotary cutting tool used to cut cloth worked awesome. This allowed me to make really precise cuts on fiberglass. I just hope my wife does not miss it.

- If you ever have to install new hardware on your deck be absolutely certain there is no way water can come in contact with your core. Overdrill and fill with epoxy. The PO did not pay attention to this so just drilled holes, did not caulk real well and water got in. He even left some open holes in the deck which let water get in very easily. This is where the worst rot was. While I would do this again it is FAR FAR easier to prevent the core damage than it is to repair it.

I hope some of this is helpful and in some way saves someone else time in doing something like this.


----------



## pegasus1457 (Apr 14, 2002)

maccauley123 said:


> - The most tedious part of the job I found was cutting new core to fit the section to be repaired. The rot does not occur with convenient right angles. Balsa core cuts really easy with a nice sharp utility knife. At first I foolishly tried to cut it with a saber saw which did not work at all.
> ---<snip> snip <snip> ---
> - If you ever have to install new hardware on your deck be absolutely certain there is no way water can come in contact with your core. Overdrill and fill with epoxy. The PO did not pay attention to this so just drilled holes, did not caulk real well and water got in. He even left some open holes in the deck which let water get in very easily. This is where the worst rot was. While I would do this again it is FAR FAR easier to prevent the core damage than it is to repair it.


Reading these two paragraphs in your posting makes me wonder why you
didn't take the opportunity to replace the wet balsa with foam core -- you would not have to worry about wet core in the repaired areas again.

I just had a professional repair a wet section of my deck and he did exactly that.</snip></snip>


----------



## artbyjody (Jan 4, 2008)

Its not that easy.. You look at failures in the core and you think they are only that area. 

Easy and cheap way is to address the issues until its confirmed it is bigger than that. HG is all fiberglass for a deck, my Catalina not so - hence why I relish my new boat to me...

Foam core is also harder to actually do...pressure sensitive and takes alot of skill to do right..


----------



## maccauley123 (Sep 2, 2004)

*Balsa Core*



pegasus1457 said:


> Reading these two paragraphs in your posting makes me wonder why you
> didn't take the opportunity to replace the wet balsa with foam core </SNIP></SNIP>


I definitely considered it and looked at some other materials but decided to replace the core with what was there before. Based on my research balsa core is a superior core material. As long as it stays dry. I understand that even some of the foam and high tech materials are subject to water damage eventually if any gets to it. No matter what core I use keeping water out sounds like it is key. Balsa is an excellent core, is easy to work with and is economical.


----------



## sailingdog (Mar 19, 2006)

End-grain balsa is actually a better core material in many ways... PROVIDED IT STAYS DRY. It has higher sheer resistance and greater compressive strength than all of the foam based core materials. It is easier to work with, as the resins adhere to it very easily, which is not the case with some of the core foam materials. Also, it means that the repair will have the similar flex, stiffness and strength characteristics as the rest of the deck.

Balsa also has much better heat deformation characteristics... it doesn't really deform under any temperatures a boat would normally see. That isn't true of the foam core materials.

The foams are great materials, but unlike balsa, don't prevent the water from migrating. If you have a leak in a foam-cored laminate, it can often cause problems a long distance from the actual leak, which isn't the case with balsa. The ductile foams can absorb impact forces and as such are better than balsa for coring a hull, since they may absorb enough of the impact to prevent a total rupture of the laminate. The rigid foams are the least useful of the foam-core materials IMHO.

BTW, marine plywood is probably the worst of all the materials that were used for coring laminates. It is heavy, and it has the worst characteristics of both foams and end-grain balsa. It allows water to easily migrate long distances like foam, and it rots like balsa. 



pegasus1457 said:


> Reading these two paragraphs in your posting makes me wonder why you
> didn't take the opportunity to replace the wet balsa with foam core -- you would not have to worry about wet core in the repaired areas again.
> 
> I just had a professional repair a wet section of my deck and he did exactly that.


----------



## mikehoyt (Nov 27, 2000)

One comment. Go bigger than the rotted areas to ensure all rot out, use right angles and then use wood chisel to get the old wood out


----------



## catamount (Sep 8, 2002)

FWIW, I have done two deck re-core projects, the first on a San Juan 21, working from the inside; and the second on a Peterson 34, working from the outside. In both cases, I used Balsa for the replacement core, and I laminated new skins in place rather than trying to re-use the old skins that I had cut off (laminating upside down overhead was kind of tricky, but we got it done!). It's definitely important to do a proper job of sealing any holes penetrating cored decks.


----------



## canadianseamonkey (Sep 4, 2006)

MacCauley - question for you. What thickness do the balsa sheets come in? Are most decks replaced with the same thickness or does it vary?

Thanks,


----------



## catamount (Sep 8, 2002)

Baltek Contourkore comes in 2' x 4' sheets, in several different thicknesses (1/4", 3/8", 1/2", 5/8", 3/4", 1"). In doing a re-coring, you would want to match the thickness of the original core material. My San Juan 21 used 3/8" coring (if I remember correctly), while my Peterson 34 used 1" coring.


----------



## maccauley123 (Sep 2, 2004)

SeaMonkey, it comes in varying thicknesses. My Ericson had 3/4" core throughout so that is what I replaced it with.

If you do a search for balsa core you should be able to find a number of dealers easily. I then just picked one that had the thickness I needed.

I think I used Merton's. My order came very quickly and I have no complaint with them.

Merton's Fiberglass & Marine Supply: Balsa Core


----------



## Capnblu (Mar 17, 2006)

If you are stuck finding balsa for a core repair, a good hobby store can get you a 4x4 or 6x6 of balsa 6' long. Then just cut it with a chop saw to your required thickness. Of course searching online will turn up alot of sources as well.


----------

