thaigh
New Member
I am having an issue with my feathering prop, so I have had to change it to my old 2 blade fixed prop. One question I have is, what creates less drag whilst sailing ,locked in gear or in neutral. Any thoughts?
Locked Prop or Not
- Thread starter thaigh
- Start date
EdWingfield
Well-Known Member
Do what the engine manual tells you, doing the wrong thing may not be good for it.
eg. My Volvo MD2030 is to be left in neutral - and the shaft will rotate when I reach 5kn ish.
I've heard skippers say they must leave their particular engine in gear.
eg. My Volvo MD2030 is to be left in neutral - and the shaft will rotate when I reach 5kn ish.
I've heard skippers say they must leave their particular engine in gear.
ccscott49
Well-Known Member
Locked prop, less drag, no wear on ouput/thrust bearings, how you do it is up to you and your gearbox.
MarkJohnson12345
Well-Known Member
Bukh recommend that you lock the prop.
Does your engine manual make a suggestion?
Does your engine manual make a suggestion?
Malcb
Well-Known Member
My Volvo 2010 manual states, leave the gear in neutral.
ccscott49
Well-Known Member
That is purely for the gearbox, it doesnt matter if the prop is stopped from turning. Wrap a rope around the shaft and tie off, tie the engine keys to the rope.
FlyingSpud
Well-Known Member
The recent test in YM showed locking the pop on a 3 blade (they did not do a 2 blade) doubles the drag. The issue is if it is worth the noise and the wear on the gearbox.
The exception to this with a 2 blade if you have a long keel is if you can lock the prop so it is aligned with the keel.
What was the issue with the feathering prop?
The exception to this with a 2 blade if you have a long keel is if you can lock the prop so it is aligned with the keel.
What was the issue with the feathering prop?
Lakesailor
Well-Known Member
If you register with this site you can get the empirical results of the tests. (It'll cost you though)
Propellor Tests
Or for free you can wade your way through these engineers discussing it on a forum http://cr4.globalspec.com/thread/15712/Calculating-propeller-drag
Propellor Tests
Or for free you can wade your way through these engineers discussing it on a forum http://cr4.globalspec.com/thread/15712/Calculating-propeller-drag
thaigh
New Member
Thanks for your comments. RE the other prop. As soon as I know it is an issue with the Kiwi prop, not the sail drive I will post it on the forum.
ccscott49
Well-Known Member
All the reports I have read say exactly the opposite.
Which includes tests at the test tank in Southampton.
Which includes tests at the test tank in Southampton.
PeteMcK
Well-Known Member
"If you register with this site you can get the empirical results of the tests. (It'll cost you though)"
With the publishers' agreement, you can get a pdf of the penultimate pre-publication draft free of charge at http://strathprints.strath.ac.uk/5670/
Freewheeling produces substantially less drag than locked. Only lock the shaft if your gearbox manufacturer insists - in which case, get a folder or feathering prop asap. In fact, I'd get one anyway. If you can hide a two-blader close behind a big chunk of deadwood such as a long keel, locking makes sense (and this, I think, is where the myth - as it applies to modern configurations - arises). For a typical fin-keeled sailing boat, the proportion of total hydrodynamic drag caused by having a fixed blade prop is quite horrifying.
With the publishers' agreement, you can get a pdf of the penultimate pre-publication draft free of charge at http://strathprints.strath.ac.uk/5670/
Freewheeling produces substantially less drag than locked. Only lock the shaft if your gearbox manufacturer insists - in which case, get a folder or feathering prop asap. In fact, I'd get one anyway. If you can hide a two-blader close behind a big chunk of deadwood such as a long keel, locking makes sense (and this, I think, is where the myth - as it applies to modern configurations - arises). For a typical fin-keeled sailing boat, the proportion of total hydrodynamic drag caused by having a fixed blade prop is quite horrifying.