I got the core hot coated on the back side that will be bonded to the old hull skin. I used thinned VE resin with 1% hardner so that it would cure slowly and allow the wood to soak up as much as possible. I also cut out a section of CSM and laid it up on the core to help hold a little more resin and full seal the wood off from soaking up any moisture. I double coated the outer edges that wick up the water the worse to ensure a good seal. Once this dries I will scuff it up with some 120 grit to give it some tooth for the Epoxy resin to bond to when I install it into the boat on the rear hull skin. I feel like the VE resin thinned with styrene will soak in to the ply a lot better than the epoxy would of done if I waited and done in place with a raw wood ply in the boat. I can lay it flat on a table and thin the resin thin as possible with in the recommended amount. If I would of installed the raw wood into the boat the resin would of run right off/out of the cloth with it standing up vertical. To keep the epoxy resin from sagging or running it needs to be thickened and that would keep it from absorbing in to the wood as well so I think it helps to pre-coat it like this with the thin VE resin. Plus I know that the wood is sealed as well as possibly now, if done once installed into the boat there is no guarantee you will get it 100% sealed off (it may trap air pockets) plus you would get much less to penetration into the ply. I will hot coat the front side as well but not till I am ready to install it into the boat. I will do it laying flat on the table like the back with thinned resin but would like to get a few coats then once it tacks up a little install it. Then while it is still tacky in the green window time, lay up the laments on the front side to get better continuous bond. This will give you a good wet on wet primary bond that will be stronger and have better peel strength than if let fully cure and bonded latter as a secondary bond. Secondary bonds can be good (especially with epoxy) but the more wet on wet green primary bonds you can do the better off the bond is. Sometimes you cant help it just like bonding to the old rear poly hull skin from 1975, that's why I use epoxy there to help get a better secondary bond to the old glass that is original poly. The epoxy has more peel strength and should maintain a better bond to the old skin than a standard poly or VE. Both resin types have their advantages and VE will help water proof the Glass where pours poly will not as much. VE thinned will absorb better than the non styrene based epoxy and the cost less while the epoxy has superior water proofing effect with a stronger peel strength and elongation. You can use the Epoxy over the VE and poly just fine with out problem but to use VE or Poly on top of epoxy is a no no. They say it will not bond well and if I dose it is a waist due the weaker bond under it will fail first. There are may ways to install a transom, and I do it differently sometimes from situation to situation but with wood I like to do it this way to make sure I wont have water intrusion problems in the future. If using foam I would of done this differently.
I will be waiting on some better weather so I can get the transom in. Due to the boat is a few feet to long to go into the heated shop, I have to do it outside or under my shelter that is not heated. It is suppose to get into the single digits this weekend at night. Highs in the 30s during the days so I will play around with the bracket till the weather breaks and it warms up a bit so I can get the core bonded in and glassed down/tabbed to the hull.
Picture of the core with the rear sealed: The resin is almost cured and turned white in this pic. It starts out redish bay colored then turns white as it cures. It will be solid white once fully cured and you wont be able to see threw it. The VE was formulated to do this, the rep gave me a few reasons such as- easier coverage with paints and gels, it keeps the lay up from shrinking, and a few other things as well. It is amazing how white it gets after starting out so red.
