115 HP and still can't get him up... on mono!

[roland.fisher]

Have a 6m Ribeye, standard configuration (bench, 2x2 jockey) with a nearly new Yam 115hp engine and I am pretty disappointed that with only one person on the boat I cannot lift a mono-skier. Is it the prop? is the boat just too heavy/underpowered? would a ski pole help? (also can I attach the ropes to the A frame or only to towing rings? - one up on two skis the rope catches in the wake if on the towing rings)

V.grateful for any advice.

R

[Grouse]

Hi i was in the company of a guy with the same boat /engine as yourself last week, he was doing deep water mono starts no problem. I dont know what prop he was using.He also had the ski rope attached to the A frame instead of the tow eyes. I have a 6.5m ribtec with 150 hp and also use the Aframe for attaching the ski rope.

[Kernow Buoy]

Wouldn't like to comment on whether the A frame is up to towing, perhaps some Ribeye owners can. Prop is a good place to start, what rpm do you get when at WOT and what speed do you get to, do you know the pitch of the prop your using now and also what its condition is i.e. any damage, wear etc

[roland.fisher]

Thanks Kernow.... not sure of prop pitch (will check when I go to boat), also not sure what WOT means, but we get about 50 on rpm meter (5,000 rpm I think) and top speed at about 38mph on the speedo, even with four or five adults on board. The prop is not 100% unblemished but it is pretty much undamaged.

Encouraged you did so well with same kit though.

R

[Downhilldai]

Change the prop for a finer pitch and make sure the motor is trimmed fully in (down) when pulling out the skier.

Take care not to over-rev the motor with the finer pitch prop. It may be ok for skiing, but too fine for general use.

You should have an observer on board when towing a waterskier.

[BogMonster]

Originally Posted by roland.fisher

also not sure what WOT means, but we get about 50 on rpm meter (5,000 rpm I think)

WOT = Wide Open Throttle - basically you choose the correct prop by making sure the WOT engine revs are in the right range, and while I don't know Yamahas, 5000rpm at WOT sounds a bit low to me - what does the book say for this engine?

As DHD says you may need a finer pitch prop which will give you more revs at any given engine RPM, possibly a higher top speed and definitely more oomph off the mark which is what you want if hauling somebody out of the water especially if they're a bit of a pie shifter.

Is your 38mph actually "mph" or is it knots (nautical mph) - I would have thought 38mph (33kt) is a bit on the slow side as my 5.8 Humber with 115hp would just touch 40kt (46mph) lightly loaded, which might also suggest your engine is overpropped.


Edited to add I've just looked and WOT range for the F115 engine is 5000 to 6000rpm so you could easily drop a couple of inches in pitch, as long as the engine doesn't exceed 6000rpm at WOT you will be fine

[Max...]

What sort of ski was he using? A traditional mono ski compared to a more modern (fun/wide bodied) mono makes a hell of a difference in terms of surface area and hence drag. The difference for me was about 3 or 4 seconds pull and sometimes it was just too much of a struggle...

In short it's not just the engine/prop to consider if power seems borderline but the ski and skier's technique too...

[Mollers]

Originally Posted by roland.fisher

Have a 6m Ribeye, standard configuration (bench, 2x2 jockey) with a nearly new Yam 115hp engine and I am pretty disappointed that with only one person on the boat I cannot lift a mono-skier.

You should cut down on your porklife mate, get some exercise!

[ribraff]

Have you checked for water in the hull?

[JABS]

We have had ongoing problems with water leaking into a Ribeye hull.

Do you store it ashore?

Is is drained?

On drystack, ours didn't drain.

There were three issues:

1) Leaking 'Golf Ball' valves

2) Badly fitting tramsom bung.

3) Leaking seam behind transom. This means that any water pumped out merely goes back into the lower void.

Does she sit down at the stern as you accelerate? Does it feel as if there is water in the hull?

Any sign of water below the rear seat?

[Starovich]

not sure id look at a boat problem to start with tbh, i used to teach from a 5.4 SR with a 50 (hull bunged up). Technique may be the issue.

[Jizm]

Originally Posted by roland.fisher

50 on rpm meter (5,000 rpm I think) and top speed at about 38mph on the speedo, even with four or five adults on board.
R

It's a 4 stroke, yes?

[Mollers]

Has someone stuck a one infront of the fifteen on that Yam?

[jyasaki]

If it's an F115, you should be pulling 6000 rpm WOT with a "normal" load. So you're probably 3 or 4 inches long on pitch to start with. The range is (as I recall) 5000-6000, but optimally you want to be in the higher end with a lightish load (say, one or two people, and say half a tank of fuel.) Going a touch over isn't going to do much, but being low on rpm means you'll never get rated power out of the motor.

If you'll be doing a significant amount of skiing, you might want to have a second, even shorter prop for a better hole shot, but you don't want to use that for long distance running without skiers for risk of overrevving.

jky

[jonmitch]

Dare I say it... may be the skiers technique. Used to monoski at 15stone off a Fletcher bravo with 60two stroke.

J