I am happy to hear you are sorted. Sometimes new advice is just not compatible with old technology. :-)

Hi Everyone
Hope everyone is in good fettle, an update ....
Having listened to everyone's thoughts and ideas and proved it wasn't the Tx or Rx, decided to swap out the brushless ESC .

I also swapped out the motor and battery for traditional Torpedo 850 and Mtroniks 25A marine ESC plus Lead Acid battery. Now all rigged up and ready to go and you've guessed it . Full Astern

Interestingly the brushless JP 600 ESC was only used once, so it must be a overtime deterioration.
Anyone else experienced this I wonder ?
The sun is shining and you know where I'm off to😎

Thanks again everyone
Best wishes to you all
Jon

Ideally you should have your throttle stick self centring, this ensures your boat stops when the throttle stick is released no messing about trying to find centre off.
Start by turning on your transmitter then place your throttle stick in the centre off position. Next turn on your esc and wait for it to arm (beeping noise from the motor) ensure you do not move the throttle stick at this time. Now see if this has worked giving you forward and reverse.
If there is still no reverse then you need to set throttle range. Manufacturers have slightly different ways for this but more often this will work:
1) transmitter on throttle stick on centre
2) arm esc, wait for beeps
3) move throttle stick to full forward motor should beep
3) move throttle stick to full reverse motor should beep
4) move throttle stick to centre motor should beep
Note on some esc’s you have to set centre before setting reverse
Hope this is clear enough for you to try.

Dam ads make life miserable. But there might be some value in what you’re saying. I use a Flysky i6X and the throttle must be fully down to turn it on. If the rx is turned on in that position I also lose reverse. Ideally one shouldn’t use the throttle stick on a boat. Rather the one with springs that centres automatically.

I have tried to decypher my way thru all the posts, but I may be WAY off base. DISCLAIMER: I have never dealt with a brushless ESC. Is there a chance that the position of the throttle stick, at power up of the receiver( the transmitter should have been turned on first) determines the neutral point of this ESC? I ask because the brushed ESC's I use, and LOVE, form Germany do exactly that and I sometimes forget to center my throttle. The ESC then programs the throttle according to where the stick is at power-up. I have managed to embarrass myself far too many times.

I sympathize with your struggles, have also been down that road.
Would not recommend any ESC that requires programming by listening to "beeps". Very difficult to differentiate between numbers of beeps, so have little idea what is actually programmed.
After much screwing around have now upgraded all my brushless fleet to:
"Double Sided Brushless ESC 20/30/40/50/60/80A Underwater Thruster RC Car Boat Parts" available from Banggood.
These are simple, economical and reliable. My last purchase was air cooled, so converted to water with a home made cooling coil.

Hi Everyone
Cheers to one & all
All very useful info going forward, based on what has been suggested think I will invest in a new ESC and keep those fingers well and truly crossed.
I will post the results and my findings

In the mean time , keep well and stay safe.😊

Best wishes
Jonb.

Hi jonb
Glad to have helped eliminate one possibility. Chances are the ESC can be reconfigured but it is not a job for the novice and even experienced modellers can struggle with getting them to work as required. Most brushless ESCs have default settings which is where I suspect yours it now set. You have not said what battery and voltage you are using but if the default is LiPo a NiMh may be too low a voltage to even set anything, as RudyM correctly mentions. If you receive a series of beeps when switching on then that would suggest some communication. You could try holding the throttle stick down or up with the Tx on when you connect the rx to see if this triggers any response. The real problem is your lack of any info on the ESC as they communicate with a series of beeps to indicate the control being adjusted and you move the control stick on the tx to select.
If you do decide to replace the ESC I believe a 60amp would suffice as that would be the same as the jp600. You do need to select a marine type ESC as those for airborne models will lack the reverse function, those for land based models may have a reverse but often require you to select revers to brake the motor then select reverse again to move in reverse. They do work but can be difficult to use on a model boat where reverse may be required almost immediately. There are several suppliers of suitable ESC's but none are particularly cheap so I suggest you search on-line to find the best deal.
Dave976

If you do decide to swop ecs I recommend the Hobbywing Seaking 120A water cooled ESC.
If you go air cooled on the esc just connect the motor to the water intake and outlet.
The HW ESC has built in thermal protection and may cut out if it gets too hot. It also cuts out if the voltage drops below 6V. Its a default setting and cannot be programmed. If you don’t have air movement inside the hull I’d rather not go that route.

Hi Dave
Thank you for your continuing efforts with this issue ..this morning I took your advice and swapped over the rudder servo lead to esc , and your right , full functionality on rudder ....so, now have proved Tx & Rx are OK
Going forward need to try and reconfigure ESC or swap out .
Point of interest ....this is a water cooled ESC to link with water cooled brushless motor . If it was changed for a non cooled one and I rigged up an air cooled system for the motor , would I be up looking at a disaster in the making ?

Thanks again to everyone, you are all educating my grey cells