CORE REPLACEMENT - RESIN PRODUCT RECOMMENDATIONS

T

TheJollyRogers

New member
Hello!

We are currently working through replacing a good chunk of the balsa core in the floor and lower transom area due to rot.

We are looking at using either EPOXY or POLY for the repairs and wondering if any of the CBrats have recommendations on specific products to use. Even better if they are available in CANADA.

We have already spent months watching/listening "Andy at Boat Works Today" and have a good idea of our plan but we are looking for the best products available in Canada. We are looking at using West System Epoxy but open to other ideas.

Any thoughts are appreciated!

Cheers!
 
I replaced some of the core in my cabin floor (see my album entitled Hull Repair). Prior to doing this I also spent hours poring over the Boatworks Today videos and eventually hired Andy to advise me as my project involves structural and cosmetic repairs, as well as modifications including adding a hatch to the anchor locker, building a new helm station, converting the lazarettes to propane lockers, and making the cabin roof into a hightop.

Andy has been invaluable. We did two Facetime sessions where we walked around the boat and I showed him what needed attention. The bottom line is that he advised me to use epoxy resin for all structural repairs, as well as modifications, where new fiberglass would be adhering to the original polyester fiberglass. The reason is that epoxy resin makes a stronger mechanical bond to polyester resin than does polyester to polyester. The only area where I've used PE resin is where I've ground out some of the fiberglass underneath gelcoat spidercracking (see my album entitled Exterior Cosmetic Repair) and gone over the area with new fiberglass, and in those instances I've gone over the PE fiberglass repair with epoxy fairing compund.

In summary, epoxy wins everywhere except for cost. It's significantly more expensive than polyester resin, but...
1) It makes a stronger bond.
2) A respirator is not required for use.
3) It can be stored indefinitely, while PE resin has a shelf life of about six months.

I'm using West Sysytem 105 epoxy resin with 205 fast hardener or 206 slow hardener, depending upon the circumstance. Where needed I've added 403 microfibers or 406 colloidal silica as a thickener. In most instances I'm using TotalBoat TotalFair for an epoxy fairing compound.
 
For repairs I almost always use epoxy. The fiberglass guy redoing my Caracal also uses exclusively epoxy. (I have gotten too old to do these repairs at age 87). I use West Systems, because I have used it for many years and know exactly how it works. The main reason is the far better secondary bonding strength. It is also more water resistant than polyester (permeability).

For a new construction or if laying up a hatch cover or similar project I would use Polyester Resin.
 
I am going through a similar repair and have been using the West System epoxy. Mostly the fast hardener given the sub 50 degree temperatures I have been working in. I have no other experience in this time of work, but so far I have found it pretty easy to use and it certainly seems to be doing the trick.
 
The major commercial epoxies, West system, silver tip, etc, are all very similar in terms of performance.

Instead of performance, I'd recommend evaluating them based on on the parts of the system and the how easily available it is in your area.

West System is quite spendy, but they have great metering pumps that make mixing extremely easy, as well as a line of fillers, from sanding filler (easy to fair) to bonding filler (enhances the adhesive qualities for bonding hardware) to graphite filler (for casting bearing sleeves and rub surfaces). They also have several speeds of hardener as well a clear hardener, and are pretty widely available.

That said, a lot of pros like Silver Tip (from System Three) because it's I think a fair bit cheaper and wets out better. It's quality is fine, and you can of course just use West system fillers with it.

If you're epoxying, also remember: the number one best tool you can buy to make the job better/faster..... Is a good sander. (Like a Festool Rotex, ideally paired with a good vacuum)
 
I asked the tech (widely acknowledged as the best in the Pensacola/Orange Beach area where there are a lot of repair techs) who is doing our repair on the Caracal why he uses only West Systems epoxy. His reason was the same as mine. In overall specs West System Epoxy wins--compression, tensile strength etc. It is very consistent, and high quality.

The professionals buy in bulk and their price is considerably lower than what most of us pay. When we had OEM status because we had purchased a boat building company, we would get direct 60% off retail list, with another 10% off if paid up front.

For example my repair is estimated at $6,000 in labor and $500 in parts and supplies, and that includes using Coosa, which is more expensive than most other core materials.

The cost of the materials in repairs is not a lot when you consider that good techs (independent) are $70 an hour or more. When you get shop labor it runs from 150 to 200 an hour. One of my friends who is the sole technician in the largest outboard motor dealer and repairer in our area only employed himself. His shop rate is $200 an hour. The only other employee is his wife who runs the store.
 
I would like to present a slightly different opinion. Many repairs are done on parts of the boat that have not fully dried out. For those areas I would suggest using epoxy resins that can be applied to wet areas. Most of these resins are 1:1 or 1:2 mixes not the 1:5 of the West systems. I have not had good luck using the West system in damp areas. but I have had better luck with the Total Boat epoxies.
 
Tom Hruby":vr57a2rw said:
Many repairs are done on parts of the boat that have not fully dried out. For those areas I would suggest using epoxy resins that can be applied to wet areas. Most of these resins are 1:1 or 1:2 mixes not the 1:5 of the West systems. I have not had good luck using the West system in damp areas. but I have had better luck with the Total Boat epoxies.
Click to expand...

Why are your glueing or sealing moisture laden material? I have used Petit Splash Zone Compound under water, but it was formulated exactly for that use. There a number of epoxies which are specifically made for underwater or wet wood use. But not any of the most common epoxies. (Epoxy chemistry is beyond the scope of a post here. One of my close friends spent his career in the chemistry of epoxy coatings.)

There are a number of West System epoxies which are 1:1 ratio. Mostly the 105 resin is the 1:5 ratio. (although there is an exception with 207 and 209 hardeners which is 3:1 with the 105 resin.
 
If you want to learn some about the use and features of the West Systems 105 epoxy,Here is a link to the manual, which also includes links to all of the Epoxy-works, Magazine. Unless you are a seasoned pro, I suggest at least looking thru the offerings, and uses For example I put a sacrificial layer of cloth and 105, normal catalyst, and the aluminum powder tinted with a black pigment on the area of the 12 1/2 foot RIB we carried on our Cal 46 on our four trips to AK. We put the dinghy several times each day on a rocky beach, which would have worn thru the layers of glass in the hull. The aluminum powder gave an increase to the already tough epoxy to prevent any wear on the hull itself--only on the strips we put on there.
 
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