1987 Champion Transom Seacast fix?

I am researching taking on the task of Champion transom rebuild.
Big beautiful boat, 1987 20' black Champion with 1996 200 EFI Mariner.
You wont believe the current repair job. Allthread through rotted transom into
empty glass in the spash well. The boat has a top plate on transom and an aluminum plate on transom back. So I am considering remove motor,
take plates off use a cut-off wheel to remove top of transom cap then fill with seacast. I really do not want to cut whole transom out, or split the shell.
a local shop quoted me 12,000 without looking at the boat to split shell and fix.
Any tips, comments, do's don'ts appreciated.

The cap/hull joint in Champions is a chemically fused bond and has to be cut. Way more involved in taking the cap off that boat than others that are screwed or riveted together. Reattaching would be another issue. I would suggest cutting the transom cap off, taking out the old wood and using the seacast if that's what you're set on.

i just finished rebuilding the transom on my 1988 stratos 181 pro. i also was considering using seacast or nidacore pourable transom but once i got into it i didn't think i could get the skins clean enough and prepped good enough to get a good bond without cutting out either the inner or outer skin. also being that it is made from polyester resin which has shrinkage as it cures i figured it may delaminate in time.

what i did was cut out a section of the splash well(enough to give you good working room) and cut out the middle knee/brace,cross brace and inside skin. then dug out the rotted wood. the top part was a breeze as it was very rotten but the lower half was just really soaked but not fully rotten so it was a process to chisel it out a little at a time. a hammer chisel and small wide pry bar work well. also if you can get a saw or grinder with a cutoff wheel you can cut it into sections and pry the sectioned pieces off making sure not to cut into the outer skin with the saw.

once all the wood was out i took the grinder with a 80 grit flap disc and ground clean all surfaces that were going to be bonded and fiber glassed(about 12 inches or more up the sides and bottom) to making sure all the old wood was gone and an fiberglass that may look like it was not bonded good from the original construction. then i got out the shop vac with the brush adapter and vacuumed up all the dust. then with a few rags i wiped all the surfaces clean with acetone putting in some elbow grease while wiping. now it was ready for bonding and fiber glassing the new wood in.

after i cut out my transom shape out of two 3/4 sheets of ply i glued them together with a mixture of resin and chopper fiberglass fibers and a small amount cabosil for sag control. i use an over abundance of the glass fibers as it will make the strongest glue for bonding. i wet both sides with resin allowed it to set till it was tacky but not fully cured then mix my glue mixture with the chopped fiberglass and cabosil and spread it on with a notched trow/adhesive spreader. screwed it together with some wood screws to hold it while it cured.

once the glue was cured i took out all the screws and placed it in the boat and clamped it in place and marked the center of the motor mounting holes. then i took it back out and with a hole saw cut out oversize holes. sanded the edges of the holes and cleaned with acetone along with the outer edges of the transom. the edges were sealed with resin. then i taped one side of the holes and filled from the other side with a mixture of fiberglass fibers and resin and then added one layer of fiberglass cloth to the transom side which was then glued and and screwed and bolted to the outer skin making sure some glue mixture squeezed out of the edges so i knew i had a good bond between the two surfaces. once cured it was then glassed in with multiple layers of mat and woven with mat in it. then i glass in a new middle brace and cross brace that tied it all into the transom knees with mat and mat with woven. i posted a few pictures of the transom glass in on another thread http://www.bbcboards.net...ratos. once all this was done i fiber glassed the top edge of the transom and built a section to go over the splash well where i cut out for access and glued it down and fiber glassed it all in faired it in and primed it for a paint job to come later. for now i'm fishing with a primer colored splash well. if you end up going this route make sure you drill the oversize holes and fill with resin with milled fibers and then drill the smaller holes for the bolts to mount the motor. this will save you're wood core from rotting again. if you plan on putting a transducer in the wood core area or have anything else that goes through the core do the same for those areas. 5200 is great stuff but will not stop the water from getting to your wood core it has been time tested over and over again there is always a spot that will allow seepage. it only takes a pinhole. that being said i still use 5200 even though i did drill oversize and and fill with fiberglass and resin mixture. i also use oversize 1/4" thick aluminum washers on the inside that a machine shop cut out for me and an aluminum plate that is pretty much the width of the transom on the outside

I used seacast in my project. It's a great product. http://xs-s.com/zf/images/smile/emthup.gif

http://www.bbcboards.net/zerothread/237362

You did a great job on that boat. But what did you do? Your picture looked like maybe you cut the whole back off scraped and cleaned that way. Then did you make a form with wood to pour the seacast, then re attach the back of the boat glass.
Thanks,

cut the splash well out and fix it right imo i dont like seacast but i have never used it i would fell a lot better knowing that the transom is strong and done right plus u can do it a lot cheaper than seacast check out my
thread on transom help please there r some pics of my splash well cut out there

The only reason why I did it the route of cutting the back skin off is because it was already trashed and it just seemed easier. There is a lot of prep you do with the inside of the cavity with resin and so forth before you actually pour. It's just as strong if not stronger than wood AND you never have to worry about the rot coming back incase some seal ever leaks. Just make sure you get all of the fibers mixed in and mixed up well enough before you pour. I think the problem with seacast is a lot of guys think it's a "cop" out to wood and resin because it seems faster however it really is just an upgrade. Seacast is not easier than wood, just a different route, just because it is different doesn't mean it is not right. It took about as much prep work to do my transom and pour as to replace my floor. Yeah it's pricey but I ACTUALLY feel more confident in it than I would've if I'd have used wood. ANd like I said again, NO ROT! http://www.bassboatcentral.com/smileys/wink.gif

You pointed out the other plus, NO ROT! Plus people say it is 3 times sturdier than plywood.
The Champion's taper back to a small width of back transom where the motor mounts.
To fill in with seacast or to put new plywood in and reglass
it has the potential to be cheaper than some wide beam transomed boats.
Thanks for all the info., I"ll keep doing my research so I can do a quality
job whichever route I go.

the way arjone01 did his seacast i would feel safe with. taking the outside skin off will give you plenty of access to sand and clean the bonding surfaces well enough to make sure you get a good bond. unfortunately it wasn't an option for me as my inside skin was toast. the top bolts had a homemade aluminum brace on it to spread the clamping pressure. unfortunately they did not file down the sharp edges and it dug right through the inside skin.

by the way arjone01 when are you going to start your own show called pimp my boat? you did a heck of a job on that boat. http://xs-s.com/zf/images/smile/emthup.gif http://xs-s.com/zf/images/smile/emthup.gif