Seaweed Shenanigans : HMCS Yukon Model – Dive 8

Intro

The adventure continues!

Here is a snapshot of the project status after Dive #7 and before this dive.

Obviously, still missing a few areas on the starboard amidships to hull area.

After the results from dive #7 (Cave Line & Cookies), I had one more possible way to align photos for the stern section. I can’t remember who suggested it, but somebody at some point said “why not have a diver on the wreck to act as a reference” or something like that.

The idea would be to have diver(s) position themselves on the wreck “over” the kelp and stay as still as possible so that I could take pictures of a static object that would correctly align. It seemed like a possible approach so I decided to try it on a single-diver scale on Dive 8 before recruiting a team of divers.

Lauren Martin was up for the adventure so we booked a dive on the Marissa on December 16th.

The Dive

The plan was to test out the idea of using a diver to act as a reference, then to take more photos of the engine room and then fill in the cargo area near the stern of the ship (I was doing this as a hedge in case I can’t fill in the hull area — more on that in another post). We had a planned one hour run time.

The first part of the dive was definitely a chuckle inducing exercise (just like my cave line and cookies approach previously). Lauren was a good sport and got lined up on one of the cut outs:

I then made a sweep past Lauren from the deck of the ship towards the bottom of the hull and then back up the hull back to the deck. By the time I made it back up to Lauren she was completely covered in seaweed! Haha. Well, that didn’t work.

Note that three picture in the sequence above are within a second or two of each other. You can definitely see the amount of kelp and the amount of movement that happens.

We then made our way to the engine room where I spent 10 minutes or so taking more pictures to fill out the model. There are definitely some tight spaces when you start poking around in the corners. Lauren had never been in the engine room so after I vacated the area she went it to do some exploring. I think she was a bit surprised as she had to fight the surge that comes in/out of the holes cut in the hull.

We then made our way to the stern where I took some photos of Lauren in the large cutout with the idea of showing a diver for scale inside the ship for the photogrammetry model. I’m not quite sure how that will turn out quite yet.

Finally, we made our way around to the cargo hold and I spent about 10 minutes taking photos to get a better definition of the cutout. One idea I had for “covering” the starboard stern hull is actually by “uncovering it!” In essence, I would show the inside of the ship in the area that has a ton of seaweed. I’m not sure yet where that will go but I wanted to get a better definition of the cargo hold in any case.

Results

The Yukon Photogrammetry Project is starting to get a bit long in the tooth. I should have been done a long time ago but I just can’t let go of it. The back half of the starboard side hull is still a struggle but I’m getting closer. I’ve tried 3 or 4 different methods to fill it in despite the moving seaweed and none of them have worked.

The engine room part of the project was a success along with placing a diver inside the wreck.

After analyzing this dive and the past couple, I discovered what is causing one of the problems. It occurred to me that there are sections of the starboard hull that aren’t covered in seaweed to any large degree, but I was still getting “drift” in the profile of the hull.

Below is a example of the sparse cloud showing this “drift”:

I think the problem is that it gets slightly off skew and then continues. One way of potentially solving that is to take photos going from the deck to over the starboard hull and then back INSTEAD of just taking photos along the hull. The “problem” with this approach is that involves a lot of depth changes which is a PITA on a rebreather. However, it could solve the problem in a large section of the wreck that is basically amidships.

In terms of using a diver to align photos, it didn’t work and resulted in a “skew” as well. As you can see in the screenshot below, the photos started to extend beyond the correct end of the hull out into the void. This is probably because a small movement in the diver position “ripples” throughout the follow-on photos. Below is a screenshot of the sparse cloud with the photos after the diver and then what it looks like after those mis-aligned photos are deleted.

Note: The engine is right in the middle of the hull on the above screen captures.

Below are some screenshots of the engine room area and then also of Lauren inside the hull. These are just low resolution for now as they were proof-of-concept ideas.

Engine Room

Diver In Wreck

Here is a low-res version of Lauren in the big cutout in the stern:

Here are a couple screen captures of the model after this dive. Note that the software crashed when I was editing the model to take out some anomalies so I only got a couple screen captures before that. Back up early and backup often!

The full profile is shown first and then you can also see that I still have missing spaces and a closeup of how one area of the hull that is “filled in” isn’t quite lined up correctly.

Next Steps

We are having a very long streak of bad weather, winds, and big swells. My last dive day was December 19th and I’m not sure when we’ll have conditions conducive to getting back in the water. Therefore, for now, it is just a “wait and see” cycle. Maybe the big storms will clean off some of the kelp from the wreck and make it easier to finally finish this project.