View Poll Results: Turning in or out
|
I know turning out gives more bow lift
|
|
1 |
9.09% |
I know turning in gives more bow lift
|
|
0 |
0% |
I think turning out gives more bow lift and I just wanted to be involved in this thread
|
|
0 |
0% |
I think turning in gives more bow lift and I just wanted to be involved in this thread
|
|
1 |
9.09% |
This option is for stupid people
|
|
9 |
81.82% |
|
09-11-2011, 09:08 PM
|
#1
|
Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
|
Turn In or Turn Out
on a un stepped 21' monohull with 7' beam and the engines mounted at 19" centres turning which way is best?
__________________
|
|
|
09-11-2011, 09:29 PM
|
#2
|
Registered User
Country: Ireland
Location: Dublin
Occupation: Boatbuilder
Boat make: Hydrostream V-king, 650SS OCR ,Ring 21, Ring 18, Phantom 18.
Engines: 300Hp Mercury 2.4, 130 Yamaha, Bridgeport EFI, XR6, Merc 200.
Cruising area: Malahide, Dublin
Join Date: May 2004
Location: Dublin
Posts: 1,803
|
In on a cat lifts the back, so everything usually being opposite for a mono, I'd say in will give you bow lift!
Cleaner water onto the blades on their upward stroke, pulls the back down = bow lift.
__________________
|
|
|
09-11-2011, 10:24 PM
|
#3
|
Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
|
ta but you havent voted dude
|
|
|
10-11-2011, 12:07 AM
|
#4
|
Registered User
Country: Ireland
Location: Dublin
Occupation: Boatbuilder
Boat make: Hydrostream V-king, 650SS OCR ,Ring 21, Ring 18, Phantom 18.
Engines: 300Hp Mercury 2.4, 130 Yamaha, Bridgeport EFI, XR6, Merc 200.
Cruising area: Malahide, Dublin
Join Date: May 2004
Location: Dublin
Posts: 1,803
|
Id love to say I know turning in gives bow lift but I wouldnt bet my life on it!
|
|
|
10-11-2011, 06:57 AM
|
#5
|
Registered User
Country: Guernsey
Occupation: Engineering
Boat make: None, boo!
Engines: Turbines mainly!
Cruising area: The inside of my workshop!
Join Date: Mar 2008
Posts: 2,646
|
I know it's not what you asked, but turning out gives much better stability doesn't it? Theory being that the outer prop is always trying to turn you back level when you heel over rather than trying to make it worse if turning in.
As for bow lift, I have my theories (and I'd guess turning in gives more), but they're not based on fact or personal experience so I'll keep em to myself!
James
|
|
|
10-11-2011, 07:47 AM
|
#6
|
BananaShark Member
Country: UK
Location: Salcombe South Devon
Occupation: Racer and builder
Interests: Winning races
Boat name: BananaShark
Boat make: BananaShark 34' Race
Engines: Twin Yanmar BY 260's
Join Date: Mar 2004
Location: Salcombe South Devon
Posts: 4,638
|
FWIW I was always told that turning in pushes the water down giving stern lift and faster but less stable, turning out is more stable but slower - if I'm right you take your pick!
__________________
Cookee
British Champions! RIB Formula 1 2005
National Speed Record Holder at 90.15 (still)
www.bananasharkracing.com
|
|
|
10-11-2011, 07:49 AM
|
#7
|
numbskull
Country: United Kingdom
Location: South
Occupation: none
Interests: none
Boat name: Leviathan
Boat make: Phantom 28
Cruising area: South Coast
Join Date: Mar 2004
Location: South
Posts: 15,959
|
My experience is (with old fashioned regular mono's) turn out, slower, but more stable in roll, turn in, faster, but less stable in roll. Swipes bears this out to the tune of a mph or so gain in speed turning in, though with Swipes, there doesn't seem to be a downside. Maybe we're not going quick enough to get tricky?
I think you have to just suck it and see.
JF
__________________
.
"I Agree with everything you say really!" - John Cooke to Jon Fuller - 26-01-2013
|
|
|
10-11-2011, 10:38 AM
|
#8
|
Senior Member
Country: UK
Location: Christchurch, Dorset
Occupation: Marine Engineer-ish
Interests: Boats, Cars.
Boat name: Splash 4
Boat make: Hunton
Engines: Mercruiser 640
Cruising area: Poole, Solent
Join Date: Feb 2005
Location: Christchurch, Dorset
Posts: 599
|
Quote:
Originally Posted by Jon Fuller
My experience is (with old fashioned regular mono's) turn out, slower, but more stable in roll, turn in, faster, but less stable in roll. Swipes bears this out to the tune of a mph or so gain in speed turning in, though with Swipes, there doesn't seem to be a downside. Maybe we're not going quick enough to get tricky?
I think you have to just suck it and see.
JF
|
Tend to agree with Jon, Turn in usually quicker but less stable, as pointed out by Larby turning out gives some righting force. Start turning out as its safer and when you want to go quicker swap.
Amount of bow lift is really a function of prop rake not rotation.
|
|
|
10-11-2011, 01:38 PM
|
#9
|
Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
|
I am turning out at the moment but in its little use i have had trouble getting the nose out, I have been offered to try some different props (thanks JF) but was just wondering if turning in may help? I'd heard that it was more unstable but wondered if that would be so much of an issue on a wider boat??
|
|
|
10-11-2011, 03:20 PM
|
#10
|
Registered User
Country: Ireland
Location: Dublin
Occupation: Boatbuilder
Boat make: Hydrostream V-king, 650SS OCR ,Ring 21, Ring 18, Phantom 18.
Engines: 300Hp Mercury 2.4, 130 Yamaha, Bridgeport EFI, XR6, Merc 200.
Cruising area: Malahide, Dublin
Join Date: May 2004
Location: Dublin
Posts: 1,803
|
Easy enough to swop the boxes over
Hydromotive QIV's have some wicked bow lift, so much that I stopped running one on my cat, scared the hell out of me a few times, had a good bit of stern lift too, picked the starboard sponson up and walked it a few times.
Would be a real nice prop on a twin rig, I'd say. its a big dia blade.
__________________
|
|
|
|
Thread Tools |
|
Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
» Recent Threads |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|