motor offset, whats it all about?

[martynwilley]

im setting up a new ring20 hull and am at the stage now to bolt the motor on, rig an test it

the holes that are already in the transon are central, what are the gains to offsetting the motor and if any how much should i offset?
also im not sure about offsetting the motor as this ring 20 hull has a step and a flat pad on the very back off the V, is this to give the prop more clean water when running high on the transom and if i offset would that flat pad step still work?

cheers

[larby]

Offset is normally about an inch, and is done to counter the prop torque.

As for the pad and step, not a clue, can't imagine it'd affect it, it's more down to if that particular boat suits having it a little offset?

[martynwilley]

so what does offseting to counter the prop actually do? stop torque bite or stop the boat skipping sideways at high speed? i had that problem in my ring 18 in calm conditions trimmed right up at high speed it would skip sideways and be very difficult to hold a straight line, would offset of cured this???

[Big Dutch]

Yep the offset was to stop the boat being thrown over to one side basically torque as in the old days we only used cable and pulleys.
The offset would depend on how large the motor was going up to 2 1/2" for 235hp.
The idea of the pad was to give better exhaleration out of the corners aswell as to get more water to the inlets.
Probably this hull was designed before the onset of low water pickups like we now have.
I had a pad and a step in the Chris Craft-quite interesting and lively
Bet that Ring is an old Ski Race one

[Burty]

leave it in the middle dude, just mount all your heavy stuff ( battery, trim pump etc) on the right ultimately you will always go faster with the motor in the middle plus it looks betterer

[steve h]

Originally Posted by Burty

leave it in the middle dude, just mount all your heavy stuff ( battery, trim pump etc) on the right ultimately you will always go faster with the motor in the middle plus it looks betterer

[martynwilley]

cool,
suits me as it means i dont have to start drilling any holes thru my fresh paintwork and new s/s transom plate

dont think its a ski boat simon, it was raced many years ago by andy priaux, quite a coincidence really as this is the second ring boat iv owned that andy priaux has owned, the first being a 16ft called 'finishing touch'

be interesting to see how well it goes when i start testing an settin up later next week, CANT WAIT!!!!

[Tony Davis]

Originally Posted by Burty

leave it in the middle dude, just mount all your heavy stuff ( battery, trim pump etc) on the right ultimately you will always go faster with the motor in the middle plus it looks betterer

[John.Richardson]

Awesome news Martyn - hopefully will get to see her on the 15th then!?!

[martynwilley]

i really hope so john, sign writer is coming on monday to apply the graphics and im gonna start rigging it tomorrow. just hope i dont come across anythin else i need to spend money on, livin off the bones of my ass to get this boat lookin nice.
should be ready late next week for some testing, gotta play round with props an motor hight all over again, be good to get out an put a few hours on it b4 the race thou

[martynwilley]

well, iv raced the new hull andd done fair bit of testing but really have got a handeling issue.

iv tried a few props now and played with the bow tank, the new 20 hull seems much lighter than the 18 and very very flighty.

when i filled the bow tank (moulded right up front) to try and give some ballast so i could keep the power on the whole boat twists to the port side, literally riding on the bump strip! trimming out does not cure this, so i told my nav to dump half the bow tank but the problem was still there, empty bow tank the boat sits quite level and goes quite well, just far to flighty to keep power on.

iv had several ideas on how to cure this just dont know which 1 or combinations to try first.

offsetting the motor? im running a late 200hp xr2with 20inch mid and standard box, with transom mounted l/w pick up. bullet level with the V, if offset is the answer how much and should i drop the motor a touch?

iv thought rather than adding weight by using bow tank/ballast weight i could try shifting the balance of weight i already have. iv got a 100litre s/s fuel tank mounted in the back, i was thinking of cutting out a section of my reardeck and extending the fuel tank pad to behind the front seats so i could adjust the position of my tank according to conditions.

next idea was a set of manually adjustable tabs (cant afford hydrolic) i saw a set on a boat localy that trigged my intrest (pic below) my mate is a s/s fabricator and says he can make me a set for next to nothing.

need to solve this handeling issue fast or ill be bolting the motor back on my old 18 to race!!

[Techteam]

So I have a few questions:

What sort of steering do you use?
What is the condition of your saddle and bushes?
How long have you been driving?
Who taught you?
Ever tried running the boat just by yourself (no passenger)
Where is the weight distributed in the boat (side to side as well as fore/aft)

[martynwilley]

right ok-

steering is a hynortic cow horn type system looks exactly like seastar only a little bigger ram and cow horns

my saddle bushes all seem to be in good condition, no play,fitted new tilt tube couple of months ago when i switched to the hynautic steering so thats all tight, there is a little play in my steering but thats just a bush i have to have made for the steering bolt.

iv been in speedboats for the last 6years, im 26. started in ring16 for a year with 120hp force, then moved to my ring 18 with 1st gen xr2, still have that hull and have been thru many motors/setups on her, now running ring20c stepped hull with late xr2, im mostly self taught and thru lots of testing/breaking things think i am gettin a good idea of how it all works

i dont reallly like takin the boat out on my own, but yes i have, i just seem a lot more confident with my nav as my second eyes onboard. the boat seems to still ride flat with just me in, its only with weight in the bow i seem to have this leaning issue.

all my weight is in the back on starboard side, battery, trim pump all cables/hoses etc

[larby]

I'm wondering if the bow tank is as central as you think it is, or maybe it's upsetting the balance of the boat with the step when full? If it runs flat when empty, it's gotta be to do with that tank!

How wide is the bow tank? As it wouldn't be absolutely 100% full, I'm thinking that it could be the water sloshing from side to side, wouldn't take much with that quantity of water.

Other than that I'm pretty stumped!

James

[martynwilley]

I don't really wanna run the tank in all fairness. I'D like to Iet it set up right so no balast i weight will be needed. the tank is moulded perfectly central and have had it full to the point breathes is overflowing and empty and everywhere between.

Want to use other options other than balast weight

[Big Dutch]

Martin
You drive a R 20 on the trim-they dont need a bow tank
What offset and height is the motor
What prop are you using ?
Trim tabs should not be needed either

[Burty]

sounds like your motor is very high, when you fill your tank i expect the prop is too high out of the water which is causing the boat to list over to one side. the ring spray rails wont help matters when you load the nose with water

[OCRDA]

If it falls on its left side without warning lift the engine a hole or 2 !! Change the Hynautic steering as its not good it will have far too much creep for a 2 litre Ring. That model i seem to remember had a bit of a tendancy to swap ends if not set up right. Be worth asking Mr Ring for some advice !!

Bob

[martynwilley]

im running level with the V and centre of the transom.

tried my worked QSS chopper23p that i used to run on the 18 but gave FAR too much bow lift.
then raced with 21p laser2 which was slightly more controllable than the chopper

iv got a worked yam-prop 23p that ran very well on the 18 but was very nose down compared with the chopper. gonna move motor down 1inch below leave it central and try the yam-drag prop, hopefully tomorrow

[Burty]

sounds good