Reply
 
Thread Tools Search this Thread
 
Old 13 August 2010, 04:39   #1
Member
 
Country: UK - England
Town: Southampton
Make: Ribeye
Length: 6m +
Engine: 115
Join Date: Aug 2010
Posts: 2
115 HP and still can't get him up... on mono!

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
__________________

__________________
roland.fisher is offline   Reply With Quote
Old 13 August 2010, 05:15   #2
Member
 
Country: UK - N Ireland
Make: Ribtec
Length: 6m +
Engine: Yam 150hpdi/Merc 6hp
Join Date: Jun 2008
Posts: 23
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.
__________________

__________________
Grouse is offline   Reply With Quote
Old 13 August 2010, 05:18   #3
Member
 
Kernow Buoy's Avatar
 
Country: UK - England
Town: Cornwall
Length: no boat
Join Date: Oct 2004
Posts: 1,518
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
__________________
Kernow Buoy is offline   Reply With Quote
Old 13 August 2010, 05:51   #4
Member
 
Country: UK - England
Town: Southampton
Make: Ribeye
Length: 6m +
Engine: 115
Join Date: Aug 2010
Posts: 2
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
__________________
roland.fisher is offline   Reply With Quote
Old 13 August 2010, 06:01   #5
Member
 
Country: UK - Wales
Town: West Wales
Make: Vipermax 5.8, SR4.7
Length: 5m +
Engine: 150 Opti, F50EFi
Join Date: Sep 2005
Posts: 6,298
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.
__________________
Downhilldai is offline   Reply With Quote
Old 13 August 2010, 06:37   #6
Member
 
Country: Other
Town: Stanley, Falkland Is
Boat name: Seawolf
Make: Osprey Vipermax 5.8
Length: 5m +
Engine: Etec 150
Join Date: Mar 2006
Posts: 3,688
Quote:
Originally Posted by roland.fisher View Post
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
__________________
A Boat is a hole in the water, surrounded by fibreglass, into which you throw money...

Sent from my Computer, using a keyboard and mouse
BogMonster is offline   Reply With Quote
Old 13 August 2010, 07:14   #7
Member
 
Country: UK - England
Town: Sussex
Boat name: Bombard, Y-162
Make: Aerotec 380, Y-Class
Length: 3m +
Engine: Mercury Mariner 15hp
Join Date: Jul 2010
Posts: 2,691
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...
__________________
Max... is offline   Reply With Quote
Old 13 August 2010, 09:17   #8
Member
 
Country: UK - England
Town: Mighty Penryn
Boat name: Little Joe.
Make: Avon Searider
Length: 4m +
Engine: Honda BF50
Join Date: Aug 2005
Posts: 8,841
Quote:
Originally Posted by roland.fisher View Post
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!
__________________
Mollers is offline   Reply With Quote
Old 13 August 2010, 09:28   #9
Member
 
ribraff's Avatar
 
Country: UK - England
Town: Dartmouth
Length: 6m +
Join Date: Feb 2003
Posts: 1,209
Have you checked for water in the hull?
__________________
Hypalon Tubes built in-house,retubing, repairs, Accessories
www.ribtube.co.uk
ribraff is offline   Reply With Quote
Old 13 August 2010, 12:03   #10
Member
 
Country: UK - England
Town: Bursledon
Boat name: Mustard
Make: Ribeye 785
Length: 7m +
Engine: Yamaha 200/Merc 6
MMSI: 235068693
Join Date: Oct 2006
Posts: 618
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?
__________________

__________________
Tony
JABS is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 03:38.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.