Physics of Docking - The Prop
HTML-код
- Опубликовано: 21 июл 2024
- For additional details pertinent to this video please read the description below.
The Prop is the second video in our Physics of Docking series.
Jeff Merrill and Douglas Cochrane have created this series to share some insights into the various aspects and techniques that trawler owners need to know and can learn to improve docking.
Filming for this video was done in San Diego, CA aboard a single engine Nordhavn 57 and we used the tender outboard motor for some close-up propeller feature discussions. We all know that the propeller drives us forward. In this video, we also show the details of how a propeller rotating underwater (slowly in forward or reverse) will affect the movement of your stern - essential to know when docking.
The SCREW effect of your propeller turning pushes you forward.
PROP WASH is the force of water turbulence created by the propeller that, when going slow in forward before gaining way, can be deflected by your rudder to move your stern in one direction making it easier to turn.
PROP WALK is the “paddle wheeling” effect that moves your boat to one side in reverse. The direction your trawler walks depends on whether you have a left-hand or right-hand propeller.
Propellers are designed to PUSH your trawler efficiently forward.
They behave differently by PULLING your trawler through the water when you shift into reverse.
On a long keel hull underbody shape like our Nordhavn 57, the rudder has much less effect on steering when you are travelling backwards since the propeller wash is directed towards the keel, not deflecting off the rudder.
There is much more to discuss about propellers, like pitch, the number of blades, etc.
With a better understanding of propeller effects, you can go out on your own trawler and experiment to see how your boat handles with some of these techniques. It’s fun to practice some new moves that will improve your close quarter handling and as you gain more confidence you will also have better control.
Docking success requires finesse, patience, and a sound understanding of all the “tools” your trawler has available. Anything you can do to improve your docking skills is time well spent. We recommend you practice different maneuvers away from crowded marinas, in open water, to simulate different situations.
Please keep watching as we have more to share in the PHYSICS OF DOCKING.
Like us on Facebook: jeffmerrilly...
Follow us on Twitter: / merrillyachts
Follow us on Instagram: / jmystrawlers
Contact:
Jeff Merrill Yacht Sales, Inc.
Jeff Merrill
Jeff@JMYS.com
+1 949.355.4950
Music: Corporate Upbeat Inspiring - Fishermann - Audiojungle.net Авто/Мото
Gentlemen, GREAT Information! Thanks for sharing your expertise!
Big Duke - THANK YOU for your nice comment. Very sorry for the delayed reply -didn't see this until now. Appreciate you taking the time to write!
Excellent video! Keep up the good work! And thanks for sharing!
Thank you Captain Rick, glad you liked it and we have more to share coming up!
Excellent information. Thanks for taking the time to share.
Thank you Larry!
Great series to watch.
Thank you for watching and commenting ApolloDL4!
Very good. Learn something new everyday.
Thank you for watching and glad it was helpful!
Excellent information, thanks for sharing.
C Q: Thank you for watching.
Super stuff!!! Instant subscriber 👍🍀
Thank you Random, really love comments like that! More videos in the works!
thankyou for making it so clear. Now i will know exactly why i have just clipped the other guys boat.
Not Guilty, I get it, take it slow. Thanks for watching!
Great content
Teaching: Thank you for watching and commenting!
Question:
On a single shaft that has counter rotating props, can you still get prop walk?
Good question! I guess they will mostly counteract each other for minimal effect unless one is rotating more forcefully. Do you have a specific example?
@@jeffmerrill1135 2003 34 ft Rinker.
It has dual shafts but two counter rotating props on each. Oh, it's also a stern drive.
It's up for winter storage right now so I can't try it right now.
@@dgeorge852 U tell me buddy!, your a Captain in the marines!, nah seriously a twin sterndrive 34 flybridge cruiser like your Rinker shall have some transverse thrust as the props are a similar diameter/pitch to a twin shafts 34 Rinker hull .(M-24, m.e.d.-3 certification of comp.).
@@kenlee-97 I seems you didn't account for the fact that there are two counter rotating propellers on the same shaft. If you have twin shafts, single prop per shaft and have both in forward or both in reverse, you won't experience any noticeable prop walk since the transverse thrust from one propeller is cancelled by the other. I've never driven a duoprop so it would be interesting to know but my guess is that they give very little, close to no prop walk.
Jeff Merrill • 4 years ago
Good question! I guess they will mostly counteract each other for minimal effect unless one is rotating more forcefully. Do you have a specific example?
I gave up boating because every time I tried to go some where I crashed into at lest 3 different boats. I was not the most favorite boat owner in the marina.
Jeff Merrill • 3 years ago
Jamie - that doesn't sound like much fun. Docking is the hardest part and something that takes practice to master. Thrusters can help out, but you can't rely on them.
One question to this Prop Walk is what happens when you have twin Engines
Peter: Twin engines usually counter rotate - one side rotates clockwise, the other counter. So if you have one in neutral you can get some walking movement from the other. Twins are much more maneuverable
Prop walk is commonly known as transverse thrust
Hello MrMikewr - that is a good term, haven't heard that description before, thank you!
Also people, not trying to complicate things even further, but in regards to the the trailing edge of the propeller being cupped, THAT IS ONLY APPLICABLE ON MOST OUTBOARD ENGINE PROPELLERS, this cupping doesn't really exist of propellers on anything other than props made for a planing/semi-planing hulled vessel.