ShipSpotting.com
Login: Lost Password? SIGN UP
Ship Photo Search
Advanced Search
Pages: [1]
  Print  
Author Topic: Efficiency of propeller blades.  (Read 4091 times)
0 Members and 1 Guest are viewing this topic.
MattB
Home away from home
****
Offline Offline

Posts: 153


It's me and you may find me annoying.


View Profile
« on: September 03, 2016, 11:01:17 pm »

Hello Forum,

I saw these prop blades on board a cruise ship. They are secured to the deck with the help of eyelets.

My question is:- Does having the eyelet fastened to the prop make the propeller as a whole, inefficient? Do they remain on the blade or are they removed and the remaining hole 'filled in'? See attached cropped photo.

Regards,
Report to moderator   Logged
MattB
Home away from home
****
Offline Offline

Posts: 153


It's me and you may find me annoying.


View Profile
« Reply #1 on: September 03, 2016, 11:05:09 pm »

Here's another enhanced one.
Report to moderator   Logged
lappino
Home away from home
****
Offline Offline

Posts: 344


View Profile
« Reply #2 on: September 04, 2016, 01:04:53 am »

They are screw-on eye bolts, easily removed.

Cheers

Vlad
Report to moderator   Logged
MattB
Home away from home
****
Offline Offline

Posts: 153


It's me and you may find me annoying.


View Profile
« Reply #3 on: September 04, 2016, 09:11:53 am »

Thank you lappino. Sorry the photo's are grainy. That makes a lot of sense. I assume there's no easy way of storing propeller blades.

Regards,
Report to moderator   Logged
Frank Buckley
Just popping in

Offline Offline

Posts: 5


View Profile
« Reply #4 on: September 04, 2016, 04:44:31 pm »

Hi Matt Boy,
The reason for the eyebolts or lifting eyes is foremost for ease and safety while handeling the blades as they are some times because of their shape and form and weight quite difficult to lift and move. In 2001 I was in Rolls Royce in Ulsteinvik Norway when the Fore-man in the blade  grinding Department almost severed his leg off below the knee because it slipped out the crane while he was moving it about in the work place. Normally there is a hole bored through the blade. This hole is also chamfered (or slightly tapered at both sides).Then a special split plug is made which is fitted from both sides and retained by a bolt. The plug is fitted to the Blade and the blade is machined in two set ups on a 6 axis CNC Machning Center. First the face of the blade where it is bolted to the blade carrier on the propellor hub (and the hole patteren drilled). Then it is stood up vertically and the form or profile of the blade is machined with the plug in place. Then the finished machined profile is rough ground (by hand) and finished ground  still with the plug in place. Later for ease and safety reasons  while assembling the complete propellor the plug is removed.It refitted to the blade when finished for hydronamic reasons. The counter bore for the bolt head is sometimes filled with plastic resin and carefully smoothed off to give the apperance of that there is no hole in the blade. I hope that you can understand this. I have a lot of photos but first I must find then and upload the them but time is my problem (I have very little of it) Matt. I am not like Lappino I have to work for a living.  Sorry Vlad my apologies  its only a joke!!!
Best regards,
Frank
Report to moderator   Logged
MattB
Home away from home
****
Offline Offline

Posts: 153


It's me and you may find me annoying.


View Profile
« Reply #5 on: September 07, 2016, 08:44:19 pm »

Hey Frank,

Nice to hear from you. Thanks for that detailed explanation. Yes, I can understand exactly what you mean. You've explained it to the letter and I am muchly obliged to you. It explains a lot, the process involved. Engineering is a fascinating subject - just a shame I never followed it up in school. Only now, almost half a century in age, do I find myself wondering how things are put together or how they work and the shipping industry has certainly opened up my eyes to how these methods/designs have evolved. Besides the sheer size of some of these vessels too e.g. ships that carry ships or equipment almost twice their own size - the mind boggles !!

Very best regards to you sir,

MattyBoy
Report to moderator   Logged
Frank Buckley
Just popping in

Offline Offline

Posts: 5


View Profile
« Reply #6 on: September 07, 2016, 09:40:42 pm »

My pleasure MattyBoy. I am happy that you understand what I was trying to say.

Best regards

Frank
Report to moderator   Logged
Pages: [1]
  Print  
 
Jump to:  


Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC
Page created in 0.023 seconds with 19 queries.
Copyright © 2010 All rights reserved