Capsizing Blueback

[secrtwpn1]

So, I own two 1/96 Bluebacks. One is an original SWM and the other is the new one from Nautilus models. The second one is still under construction. With the SWM, I could not ever get the included WTC to work properly. So, I thought I could put in a new 2.5 cylinder I bought from Nautilus. I got everything hooked up and testing properly. I put in the bathtub for a trim test. It immediatley capsized to starboard. I am not using the WTC foundations. Soooooo, How can I fix it??????????? More weight in the bottom???????

Thx
Farlan

[sam reichart]

How is the WTC staying put in the hull without any foundations?

[secrtwpn1]

Velcro over the top of the cylinder.....

[JWLaRue]

Without seeing it, either weight on the side opposite the roll or floatation foam on the low side.

Also, I would make sure that the top of the dive module is at (or very slightly below) the intended surfaced waterline. That will help with roll stability.

-Jeff

[secrtwpn1]

Where does one get flotation foam?

[JWLaRue]

Farlan,

I use the pink or blue foam sheets from Home Depot that are used for home insulation. Full sheets are typically 4 feet by 8 feet, but you can usually find broken sheets that HD will sell for a lot less and/or in smaller pieces.

-Jeff

[Ralph --- SSBN 598]

Farlan, I have looked for foam to use in my current boat being built.
I found that Home Depot has 2'x2'x1" foam insulation panels.
I have not looked at them yet.
The description say it should be the closed cell water tight foam needed.

This page is from the HD on Bear Valley just east of 15 Fwy.

https://www.homedepot.com/p/Project-Panels-FOAMULAR-1-in-x-2-ft-x-2-ft-R-5-Small-Projects-Rigid-Pink-Foam-Board-Insulation-Sheathing-PP1/203553730

[secrtwpn1]

I will try that! Thx!

[sam reichart]

How is the WTC staying put in the hull without any foundations?

You may want to secure it in such a way that it doesn’t rotate inside the hull as well.
Sitting on the bottom of the hull and not in some sort of saddle also prevents you from having any space to add weight in the keel.

[salmon]

My Gato flopped on its side the first time I put it in water. Needed more weight.
To keep your cylinder from rotating, drill a 1/16 inch hole placed between the bigger holes in the ballast tank portion of the Sub-Driver. Then mount a corresponding 1/16 inch rod into the bottom of the sub. The cylinder will slide onto the rod when it is placed into the hull. Then the velcro will hold it. This will keep the WTC from moving forward or backwards

Let me backtrack, as I think about it, the WTC should be raised such that the top of the Sub-Driver should be where the water line is on the sub. Weight needs to be put as low as possible - you want to build that metacentric height for stability.

Once you add enough weight that it sinks with a flooded tank, look to see if it is bow heavy or stern heavy, can the weight be shifted to make it set level? The goal is to have about 1/2 inch or so above the surface. Foam (closed cell type like mentioned already) will be used to trim the sub, ballast tank is still flooded. You will use rubber bands to hold the foam blocks on. If everything was level with weight only, place all foam just above waterline to level sub. When you blow the tank, if the sub is not sitting level, move the foam for that area just below the waterline. It sounds simple, but you may trim a half a dozen times or more.
Did I make this confusing or help?

[Ralph --- SSBN 598]

Got up this morning as thought I would post some help.
But I see Tom has said what I was going to say.

It sounds like you cylinder is sitting on the bottom of your hull.
Two things come to mind.
1. No room to add ballast weight.
1/8" to 1/4" would be good to place lead under the cylinder.
2. The cylinder being so low in the hull leaves a lot of upper deck and sail above the cylinder that has to be lifted and gives weight that will roll the boat when the cylinder
is at it's surfaces position which is not necessarily the boats surfaced position.

Trimming can be easy or time consuming.

Tom explained how to approach trimming.

There is no need to open the hull.
Using rubber bands, place the lead weigh under the hull.
This is the same as being in the hull for the purposes of trimming.
Once your have enough to sink the boat, move the the weight in to the hull.
The foam can be place on the outside of the hull as long as your use equal amount on each side just below the waterline.
Easier to add or subtract foam at this time.
When you get the boat to rise up to 1/2" above the water surface, you can move the foam inside the hull.

Now you can check trim and move either weight or foam back and forth to get level trim submerged and surfaced.
Now from my own experience.
I was in a hurry so I could get to the pond.
I ended up moving the weight towards the ends.
This ended up exaggerating the trim issues.
Once I realized this and remembered how to do this, I got home and started over by moving the weights towards the center of the hull.
What every end of the boat is low, move the weight on that end towards the center of the boat.

When you get to this point it will make sence rather quickly.

A good point of moving weigh towards the center of the boat besides balance is turning moment.
The more weigh to the center of the boat, the easier the ends will swing around when turning.
The weight acts alike a pivot point.
The farther from center the weight is, the more effort needed to swing the weight around the center of weight.

[secrtwpn1]

Thx for all the advice. I will try that stuff out, when I get a chance.......

[subdude]

Ralph, and all

Not sure about the "new" dive module in a Blueback, but the SWM one sits directly in the bottom of the hull on a pair of very thin saddles which are molded in, and is retained with a pair of velcro strips which are glued into the hull. The top of the hull is right over the dive module top. In other words, there is no room to move the cylinder in any direction in the hull, it fills the hull completely except fore and aft.

There is room beneath the cylinder in places for some VERY THIN lead sheet, but not much. There is virtually zero room for foam.

Having been running mine for MANY years (I have SWM hull #6) I can attest that it works quite well.

srctwpn, if your boat is listing to starboard, add lead wherever you can as far to port as possible. This may need to be inside your cylinder. Also, look for things in your cylinder being offset to the side. Ideally you want EVERYTHING on centerline, and as low in the cylinder as possible.

Jim

[secrtwpn1]

Jim, the ballast system has been giving me fits. I can't get it to stop leaking when the valve is closed.

[roedj]

I, too, have the original SWM Blueback. As designed with the original WTC it was prone to tip on its side. I fixed all this by putting weights inside the WTC as low as I could fit them. I use the weights generally sold for PineCar race cars. I kept on adding weights and offset the added weight with foam outside the WTC until the whole assembly weighed more than originally designed - but - the sub sits in the water now without bobbing around like a cork.

Dan