HI Emma
Technology has certainly advanced in recent years and modern brushless motors have incredible power. Also we now have low resistance MOSFETs which are small and generate little heat.
The props are far too big and my intention is to discard the fitted props and shafts as they are in the wrong position, mainly because the motor of the era required the internal depth. The props were suitable for the low revs of the reduced speed from the motor via the rubber band and mine always worked well.
I will need to repair the hull where the props were but have heard of a Maplin product in the form of an extruded plastic gun/pen which should work fine.
We clearly have similar ideas re propulsion and batteries, and yes a rudder is Important if you want to keep in a straight line.
If you really want to blue sky the project I believe the bottom hull could be cut out and all the fittings installed on the hull bottom, which could then be refitted using the plastic gun to repair the hull. The rudder post(s) would need to be well sealed as they most likely would be below the waterline.
I too have many projects in place or contemplated and progress is likely to be slow. Your grandson is probably the greatest driver in your case so hopefully you will modify your model and I can benefit from your efforts 😀
I see you have found the other post. it worked paper clips notwithstanding but weight was a major problem.
Kind regards
Dave

HI Dave

many moons ago we played with using an analogue servo as a propulsion unit , but the motors were not powerful enough and increasing the motor size blew up the output transistor bridge of the servos - That was (c) 1977
it was easier with discrete components to uprate the output transistors and we did get a reasonable result .

I was thinking single brushed motor driving a single prop and rudder , doing away with the full depth of the rear well and using a baby servo for the rudder and 2s lipo , with a small lipo you can" feel" the boats performance dropping of as the battery goes flat

will hunt for the other posts , I don't like the idea of running contra rotating motors and no rudder , I have seen that on other small boats

will think on it whist playing with the larger projects that are already on the go ... 😋

regards emma
( electric recumbent tadpole trikes )

HI Emma
Still on the back burner. There is another post from a member who has carried out some mods and provided some valuable insight into the innards by the rudders. They are a push fit into two plastic posts sealed at the top and butting onto the rear well deck.
As you may know this is the major difficulty as access need to be made by cutting into the back well. I'm sure it can be done but will need careful planning and cutting to achieve a satisfactory result. One solution is to carefully cut the well deck to gain access, open up the posts and fit the rudders with conventional linked arms, possibly with the servo placed near the motors. You then have the problem of sealing the well deck, and as you know this is prone to flooding. Additionally the rudder posts will be very near the waterline so will need to be well sealed.
I am thinking of leaving the well deck in place and bringing the rudder shaft into the well deck, this will then need to be linked and a linkage made to the servo through the front partition with a bellows used to seal. Yes it will be visible but if kept small and painted grey to match may not be that visible.
I am now considering using two servos dismantled to use as drives for the props. Brushless digital versions are available but I need to try one to see how well it supports forward reverse and the prop load. Lipo's will help keep the weight down as will a minature servo for the rudder. I expect I will need some form of battery monitor to protect the LiPo but I have one for an aircraft and it has nice flashing light so should appeal to the younger generation.
As a flyer you may be able to advise on digital servos.
In flying terms this needs to be minimal weight and as the hull and superstructure are already heavy for the boat size we need to use all of our knowledge to achieve success.
This is always going to be a fair weather sailor, my original model sank many moons ago in Gautby lake one fine windy Sunday.
Do please keep me posted with your progress 😀

HI Dave

has the project come off the ground or still in the planning stage
2 year old post !!!!!
my grandson wants a boat and I have one of these that looks like it could be the answer !!!!!!

regads emma