Project 9 The Transom
The transom was cut from a frame that was made from the full sized blue prints. I had made the frame by mistake thinking it would be used at the ends of the stringers, but because the  transom top is a separate entity, we never used it.
The transom of the boat has been a long debated subject between us, whether to have a swim platform, solid or stainless steel bars/steps, or inverted around the edges. We finally decided to go with a "scoop" type of inverted transom. Of course this means more plate to be added on aft.
This took some real eyeing up on my part, and patience with me on Genas (haha!) The flat part of the plate was a simple matter of lining up and tacking on, but the radius extension was compound and had to be just perfect to be fair to the rest of the hull.
Any mistakes on these would be VERY noticeable! Amazingly enough my estimations worked out exactly as anticipated and the day ended on a happy note.
All of the plate won't be used as the edges will curve forward as height increases. The transom plate itself will remain in almost the original intended position, only with a slight less angle towards vertical.
This can be continued once the boat is turned over.
After reading many books on steel building, we found the least covered subject was how to make the transom fit! At first we were thinking of doing the same thing for this as we did to put in the bulkhead aft of the pilot house. ( Using wood sticks glued to a 2x2 ) But after some looking at it, we realised this wouldn't work ! We had no way of knowing where the wood tips should butt into the sides and bottom.
To make things even more unknown, the transom is curved in at the sides !
Here's what we did:
-First, I used the aft curve (on the deck) we have just cut to make another piece of plate


-Next this piece was put into the oversized transom plate and the transom pulled up to it, thus resulting in a predictable curve. The transom layback was taken into consideration so the curve was not standing vertically at 90º ! This means the new frame sits at the same angle it would to be level once the transom is in place.


-We trimmed off all the stringers to allow the transom to go further forward, where the hull is wider
except the top sheer stringer that would act as a stop near the top edge, and the stem where we knew the transom would be at.


-We then hoisted the transom over the aft and dropped it down as far as it would slide in. The measurements were pretty close near the widest part so it did go in about halfway.


-After trimming down the radius and side edges 1/2" at a time, and a couple hours had passed, we finally got it to fit!

 
The bizarre curve that resulted ^ after we took out the transom!


Transom ^ waiting to go in
Excuse the messy primer job on the inside of the transom, above, somehow it became a place to clean off the rollers for a while! We're finally ready to put it in for good. For the last few months we have been cursing our leaking, melted and holed poor old tarp and the water we have to repeatedly vacuum out of the keel. After hauling up the engine, there's nothing to do but seal up the aft of the boat.
 

We had already cut and trimmed it so it didn't take much to get it in. It's truly amazing how solid a curved structure is, especially once securly in place. Shortly thereafter the camber cut was made to the transoms' top to match the deck camber. I think this is important so the plate that will go up at a 45º lay in will only need have a single curve. I have seen some that are straight but they don't seem, at least to us, very continuous looking.

 

The way we did this assured an equal distance all along the angled plate, even though there is a curve in the transom. I took an extra piece of frame that was cambered for the poop deck but never used. Placing it in the appropriate position inside the transom and keeping it vertical as are the ones in the poop deck, I used it as a guide to cut the camber.
If one was to look at the transom from a distance from straight aft, it would appear to have the exact camber of the poop deck.
A narrow piece of split pipe will be placed on the top and bottom to give it a smoother edge, and also to smooth the aft edge of the poop deck as there is no support there.
 

In the thick of thought and planning, I figured that the plate between the transom and the poop deck would be more or less straight, give or take a bit for the camber. Pic to left says this isn't so he he.
Lucky I decided to check it out beforehand with a strip of plastic board. I was going to only cut it 11"+3" for camber, but it needed to be at least 18"
I realize now that I didn't think about the fact that the poop deck curve (horizontal ) was not going to be perpendicular to the 45º plate, it's 45º off also...of course! So my guess would be the curve difference would require 1.414 ( sqrt(2)) greater than the actual width of the plate. No wonder most boat designers are using computers to draw up blue prints !
(Photo below-left) Transom Top Plate into poop deck edge. The edge is joined by a narrow section of split 3/4" pipe, as is the top edge, for a rounded look.
The addition of the 3/4" slit pipe sections made it even more fun. Happily, everything went into place just fine. The 45º on the cockpit coaming matches the slope off to the transom.
The rest of the day was spent welding this new addition ( 42 feet - Gena must hate my split pipe sometimes ), and rejoicing in a sealed aft !
The Sugar Scoop - Swim Deck Modification
Cutting the shape for around the swim platform was difficult, at least the idea of it was.
How could one take a shape like that and sheer off a nice line? Originally I had planned to just run a piece of flat bar around to the bottom on each side, coming off at a slightly more vertical angle than the plate coming into the transom. But then it became evident that this would cut off a lot of the swim platform.
The solution was to force the flat bar into a twist as it left the center by pushing out on the bar as it passed the radius. It wasn't hard at all just tapping it out with a hammer while securely clamped at the top.

The edge near the top needed to curve into the 45º plate so instead of trying to force that in, I just left it and rounded it by eye afterwards. The reason I didn't want to run it in hard there is because the rest of the cut is a curve, so to retain continuity the top should be too.
Wow!! -at last those horrid sharp corners are gone !
The next thing to do is put the swim platform in.
Because of the 'V' in the aft area, the platform will have to sit about 8" above the center to get any reasonable width. Flat things seem to have no place on the hull of a boat but this was almost unavoidable!
First the transoms curve had to be derived. This was easy as we still have the piece that was used to curve the transom.

Next the sides point inward as they move aft. As the width of the platform was to be 6 feet, and the curve length is to be 100.5" , the length between the transom and the edge of the platform where it meets the hull on each side should be enough dimensions to draw it up. I took a perpendicular tangent measurement off the transom to the point where it meets the hull and the measurements came true!
These lines also have a curve which had to be just roughed in for now. In the photo to right the tips appear to be nipped off but that's just because we didn't have any plate longer than 8 feet.
When we put it in place it was quite drastically oversize, so trimming and grinding can bring it in closer. Something we hadn't considered was that the platform should have a slight tilt downward to prevent water being trapped in the corners. Oversize is a good thing!
Using some what was almost was scrap, 1/8" thick 12" wide strips of plate, we marked cut and bent into place the aft vertical edge of the swim deck. They went in with some resistance as they also had to twist outwards near the bottom. Getting the curve cut right took a couple of tries on the first one.
It was necessary that they be inset into the hull plate rather than sitting on top, so a soft edge could be ground away later. Better it be ground off the thick plate!
It took a while to decide how the sides should come in to the bottom, and obtaining the max width on the swim deck is priority. I origionally wanted the sides to come down equally with the hull shape, but even a 4" thickness there would have substantially chewed space off the deck width.
We have left some curve in the sides to minimize need for support framing. The bottom plate was cut to fit into the hull plate just as were the sides. It was pretty easy to do considering the whole piece actually twists as it approaches the center. All that worry for nothing!
In the photo above ^^, you can see the solution for smoothing off the join. As all the aft edges are going to be left fairly "sharp", using a piece of split pipe here probably would have looked out of place. Some "humanization" is required though as I imagine we'll be sitting on this for diving preparation, boarding the dingy etc.
3/8" steel rod will make a nice prompt rounded edge.

The plate can't be welded in yet as Gena painted the inside and it needs the dry! Once this is on we will no longer have access to the area inside. It is a huge open space, and although it's tempting to use for a storage area, we won't. Cutting a big hole from inside would weaken the structure ( we think ) and after having read about the constant problem of external lockers leaking and filling with water, we definitely won't be accessing it from the outside.
Gena has been welding the ( more or less ) triangle shaped side pieces I cut earlier. This pieces were traced off of the edge and took both of us to get it bent into position for marking. The corner is actually 90º still. We just moved it back until it fit flush against the transom ! As the edge is inset instead of on top, care was given to the accuracy of the cut - well it usually is, but even more here!

Below is the final result with all the ornaments ( handrails, steps, ladder, little port lights, etc.. ) in place.  Having this "lower deck" is very convenient and I couldn't imagine not  having it.

The weight aft is a bit high, and anyone doing this might want to consider using 1/8" plate instead.

beautiful!


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