Thanks for the replies, I think at 8ft this is not going to be the easy project I imagined,
As I understand it you believe that if the Titanic had steamed flat-out astern (about 10 knots probably) with rudder to starboard (ie. in an anti-clockwise circle) then one or more dynamic effects would effectively reduce the waterline above the hole(s) in the hull, and thus reduce the water level inside the hull so it did not overtop the watertight divisions.
A number of people on your other forum have provided evidence or opinions to say this wouldn't work, so you are now embarking on a test with a model to prove it one way or the other. That means you need to be scientifically rigorous - just doing your own little test and saying "There you are" will not convince other people. The tests need to provide proof that allows for experimental error and they also need to be replicable by other people.
The difficulty with a scale model test is the size of errors involved. I would think that the effects you are hoping for would result in a reduction (if any) of waterline above the damaged area of the Titanic of probably only a few inches, but let's say it's a foot/300mm. Let's also say that 1 foot is all that is needed to stop the water overtopping the bulkheads. On a 1:400 model that 300mm becomes 0.75mm. Building your model to that accuracy and then operating it and measuring the various water levels to the same accuracy is nigh on impossible. Also any ripples on the pond (cos this won't be a bath test) will tend to swamp the results and surface tension will also make things trickier. Even at 1:100 that 300mm is only 3mm, which is still going to need a lot of careful work to replicate accurately enough to convince other people that the test proves your theory.
And don't forget that you'll need to run the test several times and given it's 'on the edge' it's probable that at least sometimes it will sink. So some means to recover the model for reuse will be required too.
So no, it's certainly not going to be easy, and in fact I'd say it will be very hard, and time consuming, and expensive.