Hi – I'm fairly new to model boat building, having built control line planes in my teens. After successfully building a slightly pimped Aeronaut Diva for granddaughter No. 1, I'm now about to build an Artesania Latina Atlantis trawler for granddaughter No. 2, who's only four. The kit comes with the usual poor quality running gear, including (unusually) a 3mm shaft, running in a slim 5mm OD tube. Motor looks to be a cheap 380 unit (although the can is longer than a standard 380, at 46mm) and the prop is a weird, cheap plastic 2 blade 40mm item. I'm going to junk the running gear that came with the kit (the shaft's bent, anyway). I have an MFA 385 that I'm hoping to run off a 7.2V NiMH supply. My dilemma is what propeller and shaft to use. The kit has a false keel designed for the slim 5mm OD shaft tube supplied. I'm hoping I can ease it out to take a 6mm (ish) tube, with maybe a 3mm shaft from the Prop Shop, who seem to be the only suppliers of 3mm shafts. All of this swinging a 30mm three blade brass prop, instead of the large 40mm 2 plastc 2 blade supplied with the kit. I am rather groping around here, so any advice members might have would be welcome! Yeah, I know, don't build the Atlantis!!….

This is the Diva:

Thanks Richard. It's sedate all the way for me – and speed limited as far as possible for the granddaughter! I swapped the Diva kit shaft and prop for a Caldercraft shaft and Raboesch three blade prop, which worked a treat. However, the Diva only needed a 25mm prop and I could use a 2mm Fineline shaft. I think I need more than a 25mm prop on the Atlantis, so need to go for a bigger shaft, which brings clearance problems with the false keel construction. I shall take your advice and (apart from the prop) match like-for-like as far as I can. Thanks for the advice about the 385 and 7.2V supply – wasn't sure about this, as the motor's rated to 12V, unlike the 380 in the Diva. After the Atlantis, I'm going to scratch build a 1/24th Thorneycroft MTB presented as a post-war private motor cruiser conversion, so there may be more questions on the way. You have been warned!! And thanks for the warm welcome – I'm pleased to have joined the Forum.

Many thanks Colin – I’ve discovered it’s all about decisions in the model boat building world!

Not sure if there is any theory to back this up, but my instinct is that it’s not good practice to run a shaft that’s a lot bigger than the output shaft of the motor. I feel a bit iffy about running a 4mm shaft off a 2.3mm shafted 385 – hence my leaning toward a 3mm shaft. No doubt I’m wrong!

Many thanks for the advice Colin – I’ll check out the links!