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Adding a Transom Door to a Chris Craft 42 Commander

Updated: Oct 3, 2023

After years of climbing over transoms I knew before even finishing the purchase of my 42 Sport Cruiser that it was going to get a transom door, as well as a swim platform but the latter is for a later post. Being a Convertible/Sportfish style boat with a clean transom makes this boat a perfect candidate.

First step was to decide where and how big to make the door, then layout the idea.

To keep the door from being overly bulky I decided to make the door a 2 piece with an upper gate and door.

Next was to remove all the extra structure and interior that had been added over the years, as well as the combing

I decided to angle the opening straight on the left outboard side and perpendicular to the transom on the right, hinge side.

I beveled the opening side of the gate so it has something to naturally rest on when closed. Made both cuts with my Circular saw.


After the top was off I was able to accurately measure the door to make sure it ended up plumb with the deck. Marked it all out on tape, next on to cutting. I did run into difficulty with the sawzall chewing up the tape, which made following my lines more difficult. The jig saw was much more accurate, however the scroll blades I bough only made it a few inches before the glass ate all the teeth off. I’ll sand it back strait, it needs cut back for the glass going on plus the opening anyways.

I spent a day staring at this and, figuring out how I’m going to frame this out as well as reinforce the structure. I think I have a plan now to move forward with. One thing that appears to be a hang up is hinges. I thought this would be something readily available as I’ve seen them on other boats with similar style transom doors, however so far I haven’t been able to find a set. I might have to have them custom made. I did find one at Marine Sales (Earl the Pearl)

I took the cardboard templates back to my shop and recreated them with a jig saw on some scrap luan I had. I also mocked up some hinges I bought that I thought would work. Unfortunately they only open

about 200 degrees.

I took those initial patterns back to my shop where I traced them onto the sheet of 3/4' Marine Plywood I bought and cut them out with a jig saw. I then made the trip back out to the boat to confirm they actually fit as they were supposed to, and made some fine adjustments. Once back in the shop I laid 3 layers of 1708 fiberglass in polyester resin on each side. I decided to router out the deck that protruded past the last beam to give these more beef and add room to work. I set both sides in Polyester structural repair putty and tooled in some radius to allow better tabbing in later. For the threshold I cut a 2-3/4' piece of Mahogany I had to fit between the transom and deck. I wrapped it in a layer of 1708 and polyester resin before setting it in a whole bunch of structural repair putty, more than I needed but I wanted to make sure all the gaps were filled. I set it 1/2' deep to allow for fiberglass buildup later.

Unfortunately this is where the heavy work started and the picture taking slowed down drastically. I tabbed in both sided and the threshold with 3 layers of 1708 on the inside of the hull. I laid three layers of 1708 in the threshold and up the sides, then created the radius in the corners with repair putty. I then went over that with three more layers of 1708. I really don't want those corners to crack.

After that all cured I sanded the door opening square and flush. I used my GelPlane tool and my sander to take off 1/8' on glass off the outside of the hull around the door to build the new glass that would wrap around into. I also radiused the whole opening with a 1/4" router. I laid 3 more layers of 1708 around the hull and into the door then topped it off with a sacrifial layer of chop strand mat.

Next up, sanding, lots of glorious sanding. I sanded the fiberglass to be fairly strait and smooth before topping it off with Polyester Fairing Compound, then more sanding. I got it to where I thought it was pretty good and was about to lay gelcoat. as luck would have it Tim Sarns who runs the restoration shop stopped by to check it out my work and let me know it was still low and needed to be faired out farther as well as gave me some tips to work it out better. It would have been nice to have been able to finish this weekend but it wasn't to be. John reminded me this is especially a place to take my time. So next time I'm off I'll add more fairing and more sanding. Once I realized I wasn't going to finish the cosmetics I turned to the structural adding more tabbing along with a 12' wide band 6 layers thick 24" high between the upper and lower hull sections to stiffen up the transom. When I first cut out the door I could push the transom on the long side back and forth an inch or so pretty easily. Now between the sides, tabbing and extra fiberglass it doesn't move. I still need to finish tabbing the box stringers into the sided too. More to come, I'll try to take more pictures.

Next up, repeated fairing, sanding, fairing, sanding. i used my flexi sander as much as I could to make things flat and smooth. However there was still lots of hand sanding on the radiuses.

I finished tabbing in the sides in, to the hull and the hollow tube stringers. Should be very strong with a minimum of 3 layers of 1708 fiberglass tabbing it all together, some are twice that where tabbing over lapped in directions.

I mixed up some Gelcoat using a piece off my 31 as a base to match the color to. I ended up not liking it as my swim platform is lighter. So I lightened it up abit, not a perfect match to the platform, but pretty close for the initial coat. It'll only show around the opening anyways as the hull will be getting painted.

After one more light sanding I catalyzed 8 oz of gelcoat and ended up needing a couple more. I rolled it on as thick as I could. it didn't go on as smoothly as I would have liked, more stucco than stipple. It'll get sanded down and either another coat or buffed if i don't sand through. That will let me see if the hull still needs more fairing before paint. All things considered though I think it's looking pretty good.

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