Walrus class 1/60 scale - Scaleshipyard

[salmon]

Back to trimming. Why? because adding the towed array housing at the extreme end of the sub is enough to throw the balance off. Prior to this point I was able to shift weigh around for trim, but in this case, I added foam.


The piston was moved to the point where the sail is just at water's edge to check how the trim is.


On surface the aft end looks good. Since the adjustment was for submerged trim, The foam is attached above the waterline.


The prop, I forgot to talk about the prop. I will make that the next posting.

[salmon]

The propeller was something I wanted to build myself.
As a joke for a friend who is not a fan of 3D printing, I made this one:

Although tempting, to make for use, I still wanted to build my own.

David Merriman was very helpful in getting me going in the right path. He explained prop theory and practical steps.


I ultimately got side tracked and just needed a propeller. So I contacted Keith Bender (propmeup1@verizon.net). Keith is a machinist by trade but makes props. I had him make me a prop for my Thunder Tiger Neptune SB-1 and it came out real nice.
So I sent him this drawing from the plans with my notes of dimensions I need.


It was very reasonable and arrived quickly!


So that is how the prop came about!

[salmon]

Ran the Walrus in this configuration for several months.


Will suggested I try changing my Z cut hull to a mid-line split hull. I was very hesitant, but putting the top hull on was always a dance and you had to hold your tongue a certain way. So I bit the bullet and cut the bow in half. You have no idea how hard that was. In hindsight, I am really glad I did because it gave me a reason to do more finishing touches on it.
So I marked a line across the bow where I was going to cut. Using a diamond cutting disk, followed the line in light passes. repeating following the line or now the groove until it went all the way through. I took the lower bow and attached it to the lower hull. To build up the kerf that was taken out, I put Bondo along the lip.

[salmon]

Sorry for that short post got called away for a bit.
The Bondo is sanded down and thin CA is used to wet the surface of the Bondo and let it soak between the hull and Bondo to make sure the Bondo does not break free.
The masking tape is used to give me the height I need to get to and give a basic boundary as I slop it on. The plastic piece was going to be a template for the Garolite sheet. However, I could not find the Garolite, so I went to plan 2, 3D print something.


I made a 3D connector to help keep the hull aligned. It has a channel on one piece and a ridge or bar that fits into the channel. Both pieces have a curve to match the hull. I made a mold and cast pieces if I had left over resin. To affix the alignment pieces, I used the rubber CA to connect one half. Then on the other side, I used powerful magnets to hold the piece until the glue set completely.


I took off the old clip that was used to receive the screw that would hold the upper hull to the lower hull (because of the Z cut). Created a 3D part to be the lip that allow the aft to slip under the lower hull.


My original design was too heavy and I shaped it to lighten up the master. Running low on rubber, I could not make a mold, so I tried vacuuming the air out while the piece is submerged in an epoxy (Marine epoxy). Once the vacuum was broken the epoxy was sucked back into the piece.


I used the screw that was originally used for holding the old upper hull to lower hull. It is now holding the new lip clip.


Now the front locking mechanism I WAY over built it. So, again I needed to reduce weight and mass. It was cut way down and got it fixed to the lower hull. In cutting the structure, I learned the epoxy penetrates only about 3/8" to 1/4". I dug out all the non-epoxied matrix and ended up with a nice (even lighter) C shaped beam.



The front locking mechanism has two parts. The base the allows the bolt to go through and threads into the "T" piece.

Vacuumed this part in epoxy.

Applied epoxy to the top of the T and put the top on to hold it together.


Not knowing if the resin impregnated gypsum will hold up under water for a time, I made my own Garolite. Between two layers of wax paper I laid down several strips of fiberglass and resin. I put a glass plate over it and placed weight on that.

I made this to go over each side of the T.

[salmon]

Here are a couple fo photos showing the T installed.
The top of the T was epoxied and once it dried, I fiberglassed it in.

The fiberglass sheets I made extend past the bottom and fit on either side of the base. It helps align to the base.

One of the reasons for making the tongue and groove was to make it close better and to align the edges. With that installed, I needed to address where the hull was not even or there was a gap. I made a screed for the curve of the hull and sanded the hull to give it a surface for Bondo to grip on to.



Before it set too much, I ran a Xacto blade along the separation points. I sanded it and re-applied Bondo and sanded again.This seemed to go on forever......but it started to look better each time. I applied thin CA over the Bondo to lock it all together.


Painted it with a gloss black, no it is not going to remain gloss. My initial goal for the gloss is for decals and to do washes with.

[salmon]

Using this photo, I took the skull and swords and Dutch pirate ship out of the picture.


The bottom of the pirate ship below the skull was cut off in the photo. So, I touched up my copy to resemble the complete image. I manually distorted the image to make it look as it would straight on.


Printed the decal so there was a black border and using a copy on paper, made a template. This opening is where I need to paint white for the skull.




I tried the red depth markers without white behind it and it did not stand out.


After allowing everything to dry for a couple of days, I went to put a gloss coat over it. I used Rustoleum and had issues.


The areas that wrinkled were just the clear coat......So I sanded and applied a satin finish with no issues. Adapt and move on.

Many of the Walrus paint schemes have a grey sides. Some (I am guessing depending on mission) are all black. The lazy side of me wanted to just leave it all black, but since I picked the anti-piracy mission, I needed to make it somewhat close.



I tried a EU Grey and in the bottle looked perfect, but when it dried it was way to light and green. So I mixed German Grey with some black to darken it a bit and that came out nice.

[salmon]

I took the full length image and darkened it to semi match the image of the close up. This made the hull sides look closer to the finish I am going for.


The grey looks lighter here, but once the clear coat went over it, it darkened down. (Yes, I was goofing around with blur filters)


The matte finish sealed the decal in nicely.

[salmon]

I made a similar mask for the depth markers for painting white strips. Once it dried, I sanded it to smooth out the edges where the tape was.


The new decals now had black surrounding them. Applied decal and applied solvaset to get the decal to hug the surface better. Side note, once you apply the solvaset do not futz with the decal. I did and needed to remove the decal and start again.


Once dry, I coated with matte clear. Let dry and coated again. Wet sanded with 600 grit lightly. then I took some black paint used on the hull and stippled it in (to see if it blended it more. The results were so-so.


Then coated with more matte.

I will probably sand and coat a couple more times. I want the edges of the decal to blend better into the hull.

On the deck are 3 hatches. In my mind I want to add a little detail and maybe allow air out too. I turned some plastic that I glued to a brass tube. From the photos I could not tell if the hatch door wheel was a solid disk or not and two of the three may be different than one of them. Hard to tell.


I tapered underneath so that air may be directed up and escape out. Given the close proximity to the opening hole, it may not work that way.

They were painted black and then gray applied to only the top of the wheel. Once all dried, it was painted matte.

The holes in the deck were thinned down to a more scale like thickness and these were glued centered underneath.


We are almost at the live point. Next will be initial trim from modifications.

[salmon]

Placed the Walrus in the test pool and cycled the ballast tank. Knowing where my submerged trim with the sail is just at the surface.
The bow remained pointed down.


Grabbing a foam piece that I guessed would work, wrapped a rubber band and placed it under the bow to see if that is all I needed.


Surprisingly that was the perfect amount for getting it level.


However, it was overall heavy.


So, I will need to remove some weight. I could add foam, but I like using minimal foam with this piston system. You will see three pieces of foam used on this sub. Two are to lift the aft up when submerged and one is just to counter the weight of the battery pack for the lights. It makes the battery pack close to neutral buoyancy. I could pack the hull with foam, but I want to see if I can just remove some weight and keep it foam free-ish.


So, I pried two weights off and let us see.....


Now we are live. You are living on the edge with me. We will find out together if this will work.

[wingtip]

Great work ... thank you for taking the time to share your build process....

[sam reichart]

Great work ... thank you for taking the time to share your build process....

agreed. these build threads are great ways to show folks the way!

[salmon]

Thank you! Hopefully it will warm up this morning and I can trim.

[salmon]

Last time I put the Walrus in the outdoor testing facilities (kiddie pool) the sub sat really low even when trimmed.

The red line shows where it is and the blue line shows where I want it.

With some weight removed, let us see where we are at. I trim submerged first (submerged in this instance is the top of the sail is just at surface or slightly below). Putting the sub in the known zone for being in that position left it looking surprisingly like the other time I was in the test tank. I did not put any foam in, so the bow down was not entirely unexpected.


Have you ever seen that Price is Right game where someone has to guess the price of something in a certain time frame? They are given clues like higher or lower. It is a little bit like that with trimming a boat (with some variables added in). I put the lighter of the two weights taken out to see what that would do. It was not nearly enough to make a difference. So I took the heavier one and placed it aft to see.

O.K. that made it a bit tail heavy.

When I built my Gato, I learned a lot about weight and placement (or foam and placement). When fine tuning the trim, you can put a small weight at the very end of a sub and get the same effect as a larger one more central. By sliding the same weight used above just forward, we get a level sub.



With that done, I will bring the sub to the surface. Here is the results (red line)


Still not where we wanted it.
Took the weight off and cut about 3/4 to an inch off total (a bit on each side) and let us see what that does.

[salmon]

Placed the weight at the end and tested the effects.

Shoot that looked pretty level to me.

Let us bring it to the surface and see


Still looks a little aft heavy. Do you see the issue with doing this?
Look closer

See it? I left the weight on top. Now as it surfaces it needs to hoist that weight in the air. It took me a second to recognize that (plus the water was close to freezing and my hands were getting numb).

Moving the weight underneath shows our water line here:


I am not unhappy, but I would like it to be a few mm higher. I have pictures with it running that low, but most are like these:


So, now I will ponder (and the wind has picked up - it was 40 -50 mph gusts last night) and think whether this is good enough or if I want that higher bow (the aft end seems to be good looking at photos). If I go with making more changes, it will mean removing the larger weights and that may be a pain (still not wanting to add foam).

[salmon]

Could not leave it sitting that low. Pouring over photos of the 1:1 scale it usually sits higher. Just the wondering if it can be better made me want to try. The litmus test will be, can I remove the weights to move them? The first weight I tackled was the smallest one. It slowly gave up the grip. The middle weight was not budging. The larger one took a bit and while prying it up, I used an Xacto to help break the bond. I like using RTV rubber for affixing the weights. I have used CA, but a good bump might dislodge them (at least it did for me). I have not tried the rubberized CA. However, on this sub I will stick to the known good way for me.
I shifted the two weights rearward (I did not install the weight from prior trim). Why? Before I took the sub out, I removed the weight to see if the bow raised any and it did not. Since the weight that I was going to add was for finer trimming, shifting the main weights might take care of the trim and without the extra trim weight it hopefully would lift the hull higher.


This morning, I tested the new arrangement. First impression was "Wow it looked close to where I wanted it!"



Cycled the piston a couple of times to make sure there was no air trapped in it and brought it to the trimming depth (sail at or just below the surface).

The aft end was a little light.

Not by much, it took a while to settle with the aft up, telling me we are real close and a small weight might be all I needed.

I found a small tire weight and began by dropping it at the end. The sub settled to a beautiful level hover.



Brought the sub to the surface and all looked good. Even with the breeze picking up it stayed stable.




Now I can say it is done - sort of. I want to confer with Will, he suggests from his experience on how much it takes (in dial movement) to raise and dive the sub. Since my sub is more buoyant, the dial goes to ~85% to get that neutral buoyancy or trim state. I want to make sure that works in his experience. Before, I had to go to ~70%.