I've been on the forum for a while just loitering, reading and learning. I'm planning to scratch build an anchor handler but having never built a model boat before I thought I'd start with something simpler and cheaper for a practice run, so a modified springer tug seems a good place to start! I'm also hoping it'll be a relatively quick build too to get out on the water...
I've decided to alter the lines slightly, going for 600mm length and a section of flat bottom, 250mm beam, 150mm depth plus a 50mm raised focsle to be a little more offshore tug like. Draft will be about 100mm. displacement will be about 10kg.
She'll have a single screw for simplicity, and here's where I have a couple of questions...
Does a kort nozzle make any difference to bollard pull force at model scale? I was thinking of either a 60mm open prop, or 50mm kort nozzle. I'll have an off-the-shelf rudder behind. Speed is not important, slow is fine (and probably better if my 5yr old son starts driving...)
From the prop and hull dimensions, how do I decide which motor and speed controller to use? From what I've read, a 540 motor should do the job with 6volt SLA batteries (ballast), but is there a more appropriate option? And how do I then select a speed controller?
I'd like to buy the running gear before starting to build the hull just so I know where everything is going. I'm planning to make it plank (or sheet) on frame, just to practice the methodology rather than out of structural need. Frames / sides / bow / transom / deck will alll be 3.6mm ply doubled up to 7.2mm, then I was planning to use just 3.6mm ply for the bottom - but can I get a 100mm bend radius on that thickness of sheet or should I opt for a thinner / bendier bottom sheet?
Thanks in advance for the help.