I bought a Relentless V2 some time ago just before HK stopped selling them as I thought it was a superb looking craft - and I wanted to have a change from my usual deep V boats and try a fast catamaran - without spending too much on my first "fast cat" venture!
When the boat arrived I was really impressed with the decor and the finish, I think it looked really impressive, and I still do over a year later - but running it is another matter!
When I first put it into the water it just burbled away at fast revs kicking-up lots of spray, sounding good - but not really doing anything much speed wise for about half the length of our club lake - and then "BOOM" - without any warning it took off like a scalded cat!
Several repeat launches showed exactly the same situation - high revs - impressive sound - no real speed for some considerable time and then it just took off like it had been released from a high powered catapult!
Once the boat was eventually running at high speed it really was impressively fast, but most of each trip was spend waiting for the boat to decide to "get going".
I was advised that this situation (before take-off) is called cavitation when the propeller fails to "get a bite" and just buzzes away without pushing the boat forwards at any speed.
I tried applying the power fast, and then with a slow build-up (both as suggested by knowledgable onlookers) and then I made adjustments to the "stinger" (?) to try different angles of thrust - but absolutely nothing made any difference at all.
I ordered a couple of alternative M5 props from The Prop Shop and tested them.
This did improve (but not remove)the problem quite significantly, to the extent that much less time was spent waiting for the sudden thrust forwards and more time was spent appreciating the surprisingly high speed across our club lake!
Having achieved more time running fast, I then spent a lot more time with my Relentless V2 upside-down in the water!
Constant adjustments (and even adding trim tabs) has failed to either cure the cavitation 100% or indeed do anything to prevent the boat preferring to flip up into the air and always land the wrong way up!
The aerobatic displays are as impressive as the top speed (when it arrives) - but I would prefer to keep the boat in the water (the right way up) and run fast for longer...
Does anyone know how to stop the cavitation on a Relentless V2, or how to stop it flipping over so often?
Note:- this same boat is also available as the Joysway US 2 - yellow coloured and not quite as pretty ( in my opinion at least!).