Reply
 
Thread Tools Search this Thread
 
Old 15 August 2005, 07:15   #31
Member
 
randski's Avatar
 
Country: UK - England
Town: Cornwall
Make: Waveline
Length: under 3m
Engine: Yamaha 2.5
Join Date: May 2005
Posts: 421
Quote:
Originally Posted by Kernow
Yes agree with Roy, think you should be going a bit quicker than that, he's asked all the relevant questions, lets see how much of your money we can spend!
OH NO not more money!
__________________

__________________
randski is offline   Reply With Quote
Old 15 August 2005, 07:27   #32
Member
 
Country: UK - England
Town: Newquay, Cornwall.
Boat name: None :(
Make: None :(
Length: 5m +
Engine: None :(
MMSI: None :(
Join Date: Jun 2005
Posts: 1,280
Quote:
Originally Posted by randski
I am just going out now for a couple of hours will try with the leg trimmed right out & see what it will do.
you should find that buy the time you get the engine trimmed to about 3/4 up you have gained several knots in speed as the hull lifts out of the water and reduces friction.

the boat should continue to gain speed as you trim up until one of 3 things start to happen.

1. The prop starts to ventilate (this is most likely)
2. you raise the bow too much giving the boat too high an angle of attack (thus slowing you down a bit)
3. the boat starts to chine walk (this is less likely)
__________________

roycruse is offline   Reply With Quote
Old 15 August 2005, 12:05   #33
Member
 
randski's Avatar
 
Country: UK - England
Town: Cornwall
Make: Waveline
Length: under 3m
Engine: Yamaha 2.5
Join Date: May 2005
Posts: 421
Water wasn't totally calm but still only managed 34.9 knots.

I have got slight damage to my prop, (did I fail to mention this? ) so I assume a new prop is the answer?

Any advice on where to go or which would be best? (Ok Kernow, I've got my wallet out)

Did chine a bit but have adjusted the trim tab.
__________________
randski is offline   Reply With Quote
Old 15 August 2005, 12:24   #34
Member
 
Kernow Buoy's Avatar
 
Country: UK - England
Town: Cornwall
Length: no boat
Join Date: Oct 2004
Posts: 1,518
Any idea what rev's you were getting flat out?
__________________
Kernow Buoy is offline   Reply With Quote
Old 15 August 2005, 13:34   #35
Member
 
randski's Avatar
 
Country: UK - England
Town: Cornwall
Make: Waveline
Length: under 3m
Engine: Yamaha 2.5
Join Date: May 2005
Posts: 421
He's not here at the mo but I think it was about 6
__________________
randski is offline   Reply With Quote
Old 15 August 2005, 13:52   #36
Member
 
Kernow Buoy's Avatar
 
Country: UK - England
Town: Cornwall
Length: no boat
Join Date: Oct 2004
Posts: 1,518
Crikey, assuming thats 6000 rpm according to the net your at the top of your rev range ( which suggests the engine is fine )
Any idea what size prop your using? look for something saying 14x17 or similar stamped on it and let us know
__________________
Kernow Buoy is offline   Reply With Quote
Old 15 August 2005, 14:02   #37
Member
 
randski's Avatar
 
Country: UK - England
Town: Cornwall
Make: Waveline
Length: under 3m
Engine: Yamaha 2.5
Join Date: May 2005
Posts: 421
Ok, I exaggerated slightly. Apparently it was about 5800 revs.

It says 3x14x21 on the side of the prop
__________________
randski is offline   Reply With Quote
Old 15 August 2005, 14:28   #38
Member
 
Kernow Buoy's Avatar
 
Country: UK - England
Town: Cornwall
Length: no boat
Join Date: Oct 2004
Posts: 1,518
Hmmm. I would have thought a 21" pitch prop was about right, I've fed the details into a prop calculator ( had to guess your gear ratio) and it came up with 45 knots !!!
How bad is the damage to your prop?
__________________
Kernow Buoy is offline   Reply With Quote
Old 15 August 2005, 14:41   #39
Member
 
randski's Avatar
 
Country: UK - England
Town: Cornwall
Make: Waveline
Length: under 3m
Engine: Yamaha 2.5
Join Date: May 2005
Posts: 421
When the engine went in for a service the fella said the damage wasn't too bad but there are a couple of 1 centimetre chunks of metal missing from one blade and a few scrapes on others.

We got a chain wrapped round it
__________________
randski is offline   Reply With Quote
Old 15 August 2005, 16:01   #40
Member
 
Country: UK - England
Town: Newquay, Cornwall.
Boat name: None :(
Make: None :(
Length: 5m +
Engine: None :(
MMSI: None :(
Join Date: Jun 2005
Posts: 1,280
Quote:
Originally Posted by randski
there are a couple of 1 centimetre chunks of metal missing from one blade
crickey - not that i have much experience in these matters but a couple of 1 centimeter chunks sounds bad to me. I would certainly be looking to get that one repaired.

I( would be worried about balance and the vibration it causes damaging the bearings in the drive shaft of the engine, especially if the damage is near the edge of the prop and not near the centre.

Please correct me if im wrong someone - may be 1 centimeter chunks missing is perfectly normal. but i would guess its gonna cost you a knot or two...
__________________

roycruse 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 22:40.


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