62-Racer Transom Help

[65Bowrider]

Ok, I’m a rookie here and about to tackle a big job!
No where on CSC do I see pictures of how someone handles a wetted piece of 1708 that’s 8’ x 4’, without wearing half of it!!! There must be a trick to this, and would appreciate your sharing.

Our 21 is sitting on a 1”x6” on the floor, blocked, leveled, straightened and ready to begin. The transom skin has been grounded & 3’ off transom on hull & bottom. We’re using Coosa board, ¾ oz mat, 1708 & epoxy for the transom.

Just a reminder, our 21 has no transom core, no stringers, no floor, only a minimal cap that has fortunately kept her from spreading.

Here are some pictures, and would like to hear tips on how to put it all together. Thanks.
Blocked, plumb line off bow & transom boarded up

The last picture shows air pockets in the transom skin.

[JohnB]

I have done these a couple of different ways, and until I see or hear something different, this is how I did mine. I used epoxy, it has a lot longer working time, especially the slow stuff than glass.

Test fit the core, and level out any "dips" in the skin with thickened epoxy paste.

I would coat the coring material with the epoxy, lay it flat, and let it cure one day. With the plywood, I had to do this a couple of times, because it soaked up all the epoxy.

Then I would take and lightly scuff it, and wipe it clean.

Then I made an epoxy paste thicken with milled wood flour the consistancy of thin peanut butter, and trowled it on the skin, with a notched 3/8ths inch trowl. put the core against it, and clamp it in, but not too tightly, just so it starts oozing evenly out the sides.

I used 2 layer coring, so I repeated the process for the second core, but went with a thinner layer of epoxy between them.

Then I put 4 layers of 1708 on the inside, all with epoxy. If I was going to all the expense of using coosa, I would use epoxy. Unless your vacuum bagging the coosa, it is hard to get a real good bite with poly into coosa. Epoxy has a much stronger adheasion. If cost was the determinate, I would use good marine plywood, and poly glass. I don't think I would use poly with composite in a transom rebuild in the back yard. I am not saying it can't be done, and hasn't been done successfully, I just saying there is less room for error.

I did mine myself, I would suggest getting a second set of hands sticky.

[GradySailfish]

As John B said, you can leave the core out of the boat and glass the 1708 over the entire core outside of the boat. Once that has cured you can them install the core into the boat. I would use the paste, but only around the perimeter of where the core will sit, i.e. around the sides and bottom, bot fill the voids the best. However, insteado of spreading the past all around the inside of the transom skin, I would instead use wetted out 1.5oz matt, as I think it will give a stronger bond. Either way though you should be fine.

Once the core is in, you can further secure it (glass it in) by using 12 inch wide pieces running from the top of the top cap to the bottom, along all of the edges of the core. I would first apply the smallest pieces of 4 inch, and gradually work up to 12 inches....4,6,8,12.

This hard to put in words lol, but I hope you get the idea.

[JohnB]

If your using poly, I agree with GradySailfish, if your using epoxy, it would probably work ok, I am just am repeating what I heard from guys that know epoxy, and my own experience.
As far a the big epoxy vs poly, when it comes to transom, generally, people are hanging heavier and more powerful engines, on brackets, off the back of these boats. IMHO, you need to beef up the design and/or materials to compensate for this.

[3rdday]

Are you restoring to a full transome or notched for outboard. This will obviously affect the process of your transom repair.BTW looks like someone has been super busy grinding glass, looks great! Nice Job on the blocking.

[65Bowrider]

Our transom will be raised 5" for 25" shaft twins.
Using epoxy (better strength & adhesion to old fiberglass)

Ok, so use some thickened epoxy to fill air holes, then apply wetted 1.5 oz (not 3/4oz) mat to transom skin.

Then it's been recommended to add 2 layers of 1708 to transom skin to beef her up, bringing each layer 3" past previous layer. Can this be added soon after the mat, or will there not be enough time before mat sets? I've read/heard the chemical bond is the best.
And again, how to handle these big sheets? Just put sticky hands on all corners? or do you try to roll up then unroll on the transom? Amazing how much & how little I know!
Please keep the helpful hints coming ... Thanks.

[JohnB]

Too bad your not closer... will laminate for food and bait money
As for "wetting" out, I cut the piece to size, and used binder clips at the top to hold it in place, and folded the 1708 over the top. Than wetted down about 16" of inner skin with some slightly thickened epoxy to keep it from being runny. Folded the glass down over it, and then wetted it in from the inside. I did this 3 times, then, had to filet all the edges.

Hot laminating, one on top of the other is the way to go with epoxy, as soon as I got the first layer in, I was laying the next one on top of it. Doing it this way, the layer underneath is more or less wet, and it goes alot easier, but by the time I got done with 4 layers, it about killed me.

Maybe you could do it at once, but like I said, I did mine alone, so that was the only option.
As for wetting it out, I have used epoxy foam rollers, and plastic "blades". I would put the roller on a 45 angle, and pour a stream of epoxy on the roller as I went.
I liked the plastic blades in the corners, etc.
It is really hard to describe.

Tip, don't use the mixing plungers to measure in these amounts, use measuring cups.
Tip, get a couple boxes of gloves from harbor freight.
Tip, less is more. If you see something that is a little ugly, don't try to fix it, you will make it worse.
Tip, cut ALL the 1708 first, and start with the smaller pieces, overlaping 2-3" outward on each layer.
Tip, make sure your inner skin is clean and LEVEL. Mine was a mess from the factory.
Tip, if you have shoulder length hair, wear a hair net or plan on ripping it out, or getting it cut afterward
Tip, don't do this like I did during lovebug season.

Actually if you have any questions, pm me, I am not an expert, but have been down that road.

Here is what it looks like when it's done

Pulled the

[Briguy]

Invest in some full disposable body suits, hair nets and latex gloves. I can't tell you how many pairs of shorts/shirts I ruined and how many times I had to cut epoxy out of my hair after touching it.

Slower curing epoxy can help with the time issue but don't combine slow cure epoxy with cold weather.

[JohnB]

At about 40-45 degrees, epoxy will NOT kick, no matter what type you use or how you mix it. In Florida this isn't usually a problem. The sun does seem to kick it a little, I usually try to work in the shade.
In the summer, I put my epoxy jugs in ice water, and this keeps the pot life a lot longer, in the winter, I sometimes bring them in the house.

[65Bowrider]

How about some nice thick steaks on the grill and ice cold beer in the cooler ... will that temp you to join in?
Really nice "clean" job you did on your transom.

We're working in an airport hanger with S. Fla temps in the 70's.
Briguy, Good idea on the disposable suits ... and pleny of gloves.
JohnB, lots of great tips here. I like the idea of hanging the glass on the transom & wetting as you work down. Hadn't thought about the ice bucket to keep the epoxy cool, another good idea.

The medium drying epoxy (3-1 ratio) is good up to 80 degree temp, takes about 2 hrs to become tacky & ready for the next layer (per US Composites, fortunately close by). If that be the case, then can I use the same roller for all 3 layers on the same day, (one mat, 2-1708) or should I have separate rollers for each layer?
So many helpful hints here, I really appreciate it. Thanks!