Just been looking through this topic, interesting to see something so different from the original kit, built on imagination instead of following the same old.
One thing, did you change out that speed controller yet? A esc will remove so much resistance from the circuit and also save you tonnes of power, if you buy from China and can wait for up to 3 weeks you can get them for peanuts, I never buy anything in the UK anymore, things are so much more expensive when bought from UK sellers!
You can get a decent electronic speed controller for less than a tenner ( depending on your amperage requirements) and free postage you can get a flysky fs-i6 6ch 2.4ghz transmitter that can easily have it's software upgraded to 10 ch and it even comes supplied with a 6 ch receiver for £35! With 6 or even 10 channels to play with you could control all manner of bat gadgets on the boat!
The place to get all your rc electrics and just about any other gadget is a site called banggood.com yes, I know, it sounds like a adult site but it's an alladins cave of things for sale and they are trustworthy and reliable, in 170 orders from them so far, I've not had a single item fail to arrive and if sonething is wrong with an item there customer service is good.
Some things are so cheap I don't know how they manage to make a profit, for example, I can buy a main gear for my rc helicopter for just 80p and it's delivered from China for free, I bought 10 smd led's the other day from them for 75p and free postage!