If you know what spot frequency you are on it will help you to avoid interference - you should not try to sail with anyone on the same frequency, and you should display the right colour flag to warn other people. Is there a marker anywhere on your boat or instructions that has a number something like '27.nnn'? For instance, 27.045 would be Red....

Thank you think I will stick to original.i used it in the sea in Angelsey and it worked well and looked good.i would end u spoiling it many thanks for your time to reply.David

This is a plastic boat which used to be sold in large numbers for the RNLI. It is now rather rare and is collectable. Here is one on Ebay for £127! Note - that does not mean that they will get a sale at that price - but they will still sell for quite a lot!

https://www.ebay.co.uk/itm/IMPACT-RNLI-SEVERN-RADIO-CONTROL-LIFEBOAT-RNLB-VOLUNTEER-SPIRIT-GREAT-CONDITION/264428640626?hash=item3d912cd972:g:8OYAAOSwrdRdUWr8

These were often converted to 'proper' 2.4GHz by modellers. I've never examined one, but I think they are 27Mhz, driving two motors which provide steering and power. If that is so, a conversion would mean buying a 2.4Ghz radio set, a single motor and propshaft and a servo and rudder, taking out the entire inside of the boat and re-installing the new equipment. You would need some modelling skill to do this.

It is unlikely that the other 2.4Ghz sets interfered with your signal. The 27Mhz set installed in your boat will have limited range compared with the 2.4Ghz systems, but it should work adequately close to you. Perhaps your batteries are weak, the aerial is badly positioned, or there was some 27Mhz interference close to you?

If someone else was using a 27Mhz radio close to you then it may interfere if they and you were on the same 'spot frequency'. The 27Mhz band is divided up into sections, and only one boat can use one of those sections at a time. These sections are given colours, and you fly a coloured flag on your aerial to tell everyone that you are using that section - called a 'spot'. Do you know what spot your boat is on, and was there anyone flying a coloured flag on their aerial near you?

I think you have a difficult decision. Either keep it as it is and make it work as well as it can, or get some help and spend some money converting it. I would try to get it working as well as I could first. Have you tried a range check? Get someone to hold the boat while you walk away with the controller and see how far it will work... and the next time you take it to the pond, ask one of the experienced modellers if they can help a bit...