1/12 scale tug build, few questions
 

Hi guys,

Im waiting for the hull to arrive for my 1/12 scale (1.8meter) TID, the rest will be scratch built but i have a few questions that some of you maybe able to help me with!

Ive decided to use a 24v motor single screw the motor im thinking of is this one: http://www.mobilemarinemodels.com/bf24-motor-599-p.asp running from 2x 12v Gel Cells, But im not sure what size prop to use, im thinking 4 blade with 15cm diamater?

Im thinking of the mtroniks viper marine ESC but theres a choice of a few that support 24volt the only difference between them is the Amps but i dont know what one i need?

I also want to run sound/smoke and lighting etc, do i need to run this lot off a seperate battery from.my drive batterys or?

For the deck im thinking 3.6mm ply and 12mm ply for the bulk heads, would this be ideal? Also what thickness ply would be nest to use for the superstructure?

Thanks in advance guys :-)

I cannot answer on the drive questions but I can help with the construction ones:
For the deck im thinking 3.6mm ply This would be fine since you're not going to be dealing with major or compound curves while at the same time, it's strong enough to handle the load of any superstructure or detail parts sitting on it
and 12mm ply for the bulk heads, would this be ideal? NO, WAY TO HEAVY!!!!!!!!!!!!!!!!! I'm assuming it's a fiberglass hull so frames as thick as what you're thinking about is serious overkill. I build 1/8 scale hydroplanes and don't exceed 6mm ply for any part of the build, that being used for the boat's transom and the right side transom. The only reason I use this heavy of material in those two locations is that the rudder and turn fin are mounted to these frames. The rest of the boat is built using 1.5mm with 3mm used where more rigidity is needed. Since my boats are roughly 1.1-1.2 meters long, .5 meter wide and run at up to 100KPH, they are subjected to considerably more stress and pounding while running than your tug will be. All that said, I would look at the weight of the drive batteries. You might need the 12mm to support the weight due to the ply needing to lay flat instead of on edge
Also what thickness ply would be nest to use for the superstructure? I would use 3mm for any part that will be load bearing or butt glued at the end. Another option would be use use 3mm stick stock as gussets and use 1.5mm for the bulkheads. Everything else I would use 1.5mm to save weight. The last thing you want is a top-heavy tug so anything you can do to reduce topweight will aid in keeping the center of gravity lower

Hi Thanks for your reply much appreciated & nice info :)

Yup the hull is fibreglass & its going to need ALOT of ballast, the batterys weight (about 3kg each so 6kg in total) will help. So you think i should use 1.5mm for the superstructure mostly (excpet for load bearing places etc?) For the battery shelf i will probably use 1cm thickness (i will test it before perm fixing it) & for the rest of the fixings in hull (such as servo/reciever/ESC/Sound module & Smoke module etc) i will use 3mm as you suggest :)

The other thing im not sure on is what to use to fix the ply to the fibreglass hull, ive been looking at this build: http://www.danwalker.co.uk/Harbour_T...gdelivery.html which is a slightly smaller tug than mine, but this chap used mostly P40 Fibreglass Filler for fixing wood to the hull, he also used the P40 filler for most of the fixings in the hull, such as the motor plate/prop shafts et,) is this a good enough method?

Thanks again :)

His use of P40 might work but, as you said, his boat is smaller than yours. I would contact some of the scale boat clubs in the area(contact info can usually be found in some of the scale boating magazines) and get some advice from those that actually build tugs. One thing to be aware of is the way the person building the other tug was installing things in the hull isn't the best of ways to do so. By installing the electronics under the forward deck and screwing it down, if he has an issue later, he won't be able to access the units without doing serious damage to his boat. Also, encasing the bow thruster with wood prevents detecting and making any repairs should it start leaking. Make sure that anything either electrical or mechanical is accessible in some way that doesn't require damaging the boat to make repairs or adjustments later on.

Thanks Hydro Junkie

A raised lip inside the structure. Water may get under the structure but it won't get past a raised edge. A 1.5mm ply sticking up 1cm would work well, though you could probably be lower than that and still be fine

brill thanks :)