Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[irishcarguy]

Could someone explain how to arrive at the correct waterline for a model, we talk a lot about the waterline but not how it is determined, any help would be good, Mick B.

[Colin Bishop]

The plans you are building from should indicate where the waterline lies.
Colin

[Neil]

hi Mick........................if working to plans, it is usually marked on them..........I have never known a set that hasn't been marked with LWL (load water line) or similar.
other than that all I can suggest is to google the type of ship you are looking at and take a rough guide from there.
neil.

[irishcarguy]

Thanks to you both for the fast reply, but how is it determined if you have no guide to go by, like when scratch building, is there a formula for it ?. Mick B.

[Neil]

sorry matey............but that is a scientific art.............. of which I was subjected to, in a lecture at our local club house by a guest speaker  many many moons ago..........and sadly I missed the punchline..................I had fallen asleep and was snoring, it was............................sooooooo boring and long winded I wasn't able to stay awake 

[derekwarner]

Mick.....the calculations that determine the waterline are relative to the vessels displacement....[forget about Plimsol]. One of the freebie CAD programs with threads on Mayhem would possibly offer the calculation to determine this
But for a stand off scale model vessel you can work backwards.....after the hull is water tight....check some images of where the real vessel appeared to sit  in the water & mark these FWD & AFT with texta marks .....immerse the hull in the bath & gradually add ballast until the vessel is down to her marks
Remove all of the ballast & weight [the ballast + the hull] & the result is the vessels total displacement
The total weight of the ballast by itself is the additional weight that you can allow for your build....motors batteries superstructure etc
I realise this dosn't answer your question, but does provide simple methodology of building .......Derek
 

[NFMike]

... how is it determined if you have no guide to go by, like when scratch building, is there a formula for it ?. Mick B.

If you're scratchbuilding a scale model of a real ship you'll have to find some prototype info like a photo to work out the waterline. If you are building a design of your own you'll probably just have to eyeball it and/or do some trial and error.

In reality the 'safe' waterline for a full size ship is a variable which is dependant on complicated stability calculations. The end result is the Plimsoll lines which simplify the whole thing for day to day operation. I doubt those calculations are likely to be practical for a model.