sparky24

What is the proper way to bed in a transom so that this doesnt happen:

Ive seen some use mat others use thickened resin not sure what they thickened it with though.

Any help appreciated



This famous guy with the searay on youtube uses cabosil chopped glass and resin: video of him speading it out at about 9 minutes in to the video. Is this the best way???

http://www.youtube.com/watch?v=w5DaQvwTY3I

glassdave

iTrader: (1)

cabosil can be used but its far (far) down on my list for many reasons. first off is has poor properties that dont lend itself that well to high strength bonding and its really best used as a gap filler. I've always thought it was a pain to mix and trowel as well (when compared to pre mix). For bonding a transom into a nice flat prepped surface vinylester and ounce and a half mat still works well with cabosil as an edge fill. I really like CoreBond though, great properties and works well over uneven surfaces plus much longer work time. CoreBond is used much like setting tile where you use a notch trowel. Vers easy and very forgiving as well as a tenacious bond. I have some pics I will post tomorrow of the last one I did.

sparky24

Ok thanks. Really looking for specifics because i just had a transom installed and it came out really bad the transom wasnt bonded in about 50% so i have to rip it out again. What a mess.

What will be stronger the MAT or the corebond? The transom should be relatively flat, it was the first time i ripped it out, now who knows. I will build it up if i have to.

When you say use cabosil as an edge fill what does that mean exactly?

scippy

iTrader: (3)

As a fillet

glassdave

iTrader: (1)

chances are second time around if it had bond issues then it will most likely not be very flat, it needs to be pooltable flat for bonding with mat (well maybe not pooltable flat put close lol) When you pull out the remains of a properly installed transom it leaves a fairly flat surface that can be bonded
with mat no prob. The remnants of a second transom probably wont be that true, CoreBond works great over uneven surfaces. I dont have the specifics but I tend to think CoreBond gives a stronger end result. I would just get all the old transom wood out and grinder finish it in 36 and go with CB.

yep. . . . edge fill = fillet

ka0tyk

when i did my transom i used all west systems products. they're not the cheapest but I am not a fiberglass technician doing repairs every single day. Its a product Ive used in the past and its a product that I feel comfortable with, pumps make it bulletproof, etc.

I used 105 epoxy resin, along with 205 hardener and 404 filler on the bare fiberglass transom. the 404 filler is a high adhesive filler that thickens up the epoxy. if you've used epoxy before it likes to run, especially on a vertical surface. also the transom itself isnt perfectly flat so the 404 filler fills the gaps and voids, giving you a fully bonded transom to wood. The 205 hardener is a FAST hardener so if you're working in a high temp area, you might want to go with their slow hardener. I wanted to maximize adhesion and minimize epoxy pooling in the bilge though.



before:





Once I mixed up my filler and resin I added the required amount of hardener and gave it a good mix. I rolled a nice amount of it onto the bare fiberglass transom and then moved onto the wood that I was going to apply. I covered that in resin without the filler and wetted out one layer of mat. Then I applied the wood to the transom and used bolts thru the various parts of the transom to pull the whole thing together and let it kick. once that layer was done I applied a 2nd panel, doing the same resin coating, a layer of mat between and through bolting it together. then a final center section to give me the 2 1/4" per spec for a mercury transom assembly.



then finally i routered the top edge round, and applied some CSM around the edges and to the floor, which was bonded to the tops of the stringers using west systems Six10, etc.



I could have covered the whole deal with a final layer of glass and fillet the edges but I chose to leave it as-is and cover with bilgekote.

my drive plug, you can see the 4 layers of glass and resin, nice and solid.



I am by no means any professional, but I think it came out good and so far the drive is still hanging off the back of the boat.

phragle

iTrader: (3)

The trick to west systems pot life is the container you mix it in. The shallower the container the longer the life,

sparky24

Alright i will plan on using arjay corebond 4001. I think that once i pop the transom out and grind the reminants of the mat off it should be ok. Right now the bond is so bad i think that when i cut the tabbing out it will litterally fall out hah

JRider

iTrader: (1)

Wow that is a lot of work to rip it out again. You may be able to drill holes and inject resin and milled fibre. I have done this before with success. The boat that I will be working on in the spring has the same issue as yours. My plan is to drill holes from the outside where the rub rail will cover it up. The way I inject resin is with 20oz plastic pop bottles with squirt caps from gear oil bottles. May be worth a try before you get the grinder out.

sparky24

yea i thought about that. Took me about 8 hours to rip it out before. its just not going to be as strong unless i re-do completely

do it once do it right