I recently did a modest refurbishment of my long abandoned childhood favourite Mk1 spearfish with new electrics and an MFA Torpedo 850 motor (from the old MFA Marlin) and 3s lipo, which runs nicely. Then by chance, a neighbour of a friend inherited someones RC vehicle collection and among them was an unbuilt MFA spearfish Mk2, which I picked up from him as I fancied building it up as a faster brushless setup (can't face cutting up the Mk1 deck to get access to do major changes) and these boats have a nostalgic appeal to me compared to modern RTR options.
I am not an experienced boat builder nor familiar with modern methods so I had a few questions before I got my hands dirty:
1. I have sourced a surpass hobby 3674 1580kv motor which I intend to run on either 3s or 4s lipo. Could I use this on the stock brass tube and shaft, or it is worth putting something else in? Any pros/cons with taking shaft out and lubricating regularly vs some sort of oiler you can squirt a syringe into?
2. Should I stick with threaded props, or is it wise to install a shaft which can take a drive dog?
3. Will GRP props work, or is metal the way to go?
4. Best options for mounting the motor - my default approach would be to use an angled metal mount, but looking at options there are various watercooled mounts which also offer ability to change motor angle. They look like a good idea, but they have vertical sides and no base plate so I wondered what the best way to fix these into the hull would be?
Thanks in advance for any answers, any tips appreciated. Also, if anyone has a scanned copy of plans for a Mk2 spearfish (not much to it, but there are various bits of ply which I'm not even sure were for this kit to sort out) they would be helpful!