Choosing which submarine to build a model of is a very personal thing. You may have a strong desire to model one particular submarine, this could be anything from a famous submarine in history, from Film, TV or a book, a famous historical submarine to a modern nuclear submarine, a static model, a ship in a bottle to a fantasy model from Science Fiction. There are thousands of subjects to choose from and each has it's own merits and problems. This is not intended to sway you towards a particular subject to model or one method of construction but more a collection of observations relating to the practical side of constructing model submarines either static or fully operational ballasted radio controlled models.
If you need some practical experience of living with a large model you could try borrowing a canoe. Try moving it about in your shed or workshop! A model of this size will weigh a lot more than the canoe and may be considerably more fragile.
If you are not building your own hull remember that most of the available commercial hulls are usually around the five to seven foot long size.
Don't think that your model has to be large for all the radio equipment; we have seen fully functioning radio-controlled models under a foot long. A popular mini-sub is available off the shelf at about 50 mm long! At this small size construction is somewhat specialised and the equipment may cost slightly more, but it can be done and it allows more room for a larger fleet even if you live in a small flat. It is often said that the ideal size is a submarine that can fit across the back of a family car (50" - 55").
So, there you have it, the problems associated with the size or not depending on your circumstances. After all you may have a truck with a hoist so an eight foot model should not pose too much of a problem, you may want to climb in and go for a dive too, it 's no joke as others have already done just that.
Finally, for those out there who want a "Big One", remember to take care of your back when transporting it, it will weigh even more when lifting it out of the water.
This large model of a Type X1d U-boat was made almost entirely of wood, and measured 2.7m long and weighed well over 100kg. It proved to be the proverbial 'white elephant' however, due to it's sheer size and wooden construction it needed so much ballast to weigh it down to it's surfaced water line, it required at least three adults to lift it in and out of the water, so therefore she was retired from active patrol duty after only a short operational life.