Reply
 
Thread Tools Search this Thread
 
Old 15 May 2011, 17:40   #1
Member
 
Country: UK - England
Town: midlands
Boat name: robeena
Make: honwave
Length: 4m +
Engine: twatsu 40
Join Date: May 2011
Posts: 172
Propellor guard s

Hi guys,,, what are your thoughts on propellor guards,, i want to fit one to my twatsu 40 hp on my sib,, what are the pros and cons? thanks ,, nige
__________________

__________________
TIMO is offline   Reply With Quote
Old 16 May 2011, 00:50   #2
Member
 
Country: UK - England
Town: Farnborough
Boat name: Eleven
Make: Arrow
Length: 8m +
Engine: 557cu, 700hp
Join Date: Jul 2003
Posts: 1,255
Prop Guards mess up all the flow over the prop and gearcase, plus add a lot of drag - the faster you go the more pronounced the reduction in performance will be.

They are good at avoiding blunt object impacts on the prop, but if you're travelling at speed, the gearcase and guard impact will still be non trivial - depends on the object which ends up worse off.

They are poor at small object deflection, hands, feet, ropes, sticks, etc. Whereas normally these objects sucked into the prop might get cut and then ejected, a prop guard does have a tendency to trap the object in, rendering it more like a food blender.

In shallow water running they do improve the protection of the prop from rocks etc, but not fully since stones, sand, mud etc will still get through.

IMVHO, (with very few exceptions) if you are in a situation where you need a prop guard, you either need to plan your boating more carefully to not get into that situation, or you have the wrong boat. (e.g. Get a waterjet, or don't try running amongst rocks, or swimmers etc).
__________________

__________________
Matt is offline   Reply With Quote
Old 16 May 2011, 04:58   #3
Member
 
Country: UK - England
Town: Ipswich
Boat name: Jammy Dodger
Make: Avon Adventure 7.20
Length: 7m +
Engine: 200 Yamaha
Join Date: Dec 2008
Posts: 331
Send a message via MSN to willfinch36
Just out of intrest, what are the RYA guidelines on support boats and prop guards?

Will
__________________
willfinch36 is offline   Reply With Quote
Old 16 May 2011, 07:11   #4
RIBnet admin team
 
willk's Avatar
 
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 12,927
RIBase
Quote:
Originally Posted by Matt View Post
IMVHO, (with very few exceptions) if you are in a situation where you need a prop guard, you either need to plan your boating more carefully to not get into that situation, or you have the wrong boat. (e.g. Get a waterjet, or don't try running amongst rocks, or swimmers etc).
Seconded.
__________________
willk is offline   Reply With Quote
Old 16 May 2011, 08:14   #5
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,114
Quote:
Originally Posted by willfinch36 View Post
Just out of intrest, what are the RYA guidelines on support boats and prop guards?

Will
http://www.rya.org.uk/sitecollection...d%20policy.pdf
__________________
Poly is offline   Reply With Quote
Old 16 May 2011, 08:18   #6
Member
 
Cypman's Avatar
 
Country: UK - Isle of Man
Town: Douglas
Length: no boat
Join Date: Aug 2006
Posts: 337
We were "forced" to fit them at our RYA Training Establishment and the resulting loss of power was considerable (75hp and 90hp O/Bs).
We eventually discovered the RYA guidance letter on the subject, which basically said "not recommended" and quickly persuaded our H and S gurus to let us remove them.
Safe operations and training is the best solution.
__________________
Cypman is offline   Reply With Quote
Old 16 May 2011, 08:22   #7
Member
 
Country: UK - England
Town: Farnborough
Boat name: Eleven
Make: Arrow
Length: 8m +
Engine: 557cu, 700hp
Join Date: Jul 2003
Posts: 1,255
As is often the case with H&S, they clearly didn't know the first thing about the subject they were being asked to advise on.
__________________
Matt is offline   Reply With Quote
Old 25 May 2011, 14:39   #8
Member
 
Country: UK - England
Town: midlands
Boat name: robeena
Make: honwave
Length: 4m +
Engine: twatsu 40
Join Date: May 2011
Posts: 172
When you tug the pull cord , does the prop stop spinning immediatly ? Also does it stop spinning immediatly when you change to neutral ?.. thanks Nige
__________________
TIMO is offline   Reply With Quote
Old 25 May 2011, 14:57   #9
Member
 
ashbypower's Avatar
 
Country: UK - England
Town: Salisbury/Poole
Boat name: Blue C
Make: XS 600
Length: 6m +
Engine: 125hp Opti
MMSI: 235082826/235909566
Join Date: Jan 2004
Posts: 1,439
Quote:
Originally Posted by TIMO View Post
When you tug the pull cord , does the prop stop spinning immediatly ? Also does it stop spinning immediatly when you change to neutral ?.. thanks Nige
No and No, additionally water flow over a prop when in neuteral can cause the prop to spin
__________________
Brian C
Harbour Sea School & APS Marine Centre
ashbypower is offline   Reply With Quote
Old 25 May 2011, 15:00   #10
Member
 
Country: UK - England
Town: midlands
Boat name: robeena
Make: honwave
Length: 4m +
Engine: twatsu 40
Join Date: May 2011
Posts: 172
Quote:
Originally Posted by ashbypower View Post
No and No, additionally water flow over a prop when in neuteral can cause the prop to spin
OK but , does it slow dramatically in either scenario, as not to be powerful enough to hurt someone? Ie would the water create enough friction/resistance to slow the prop right down . My concerns are particularly in a man overboard situation TBH Brian
__________________

__________________
TIMO 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 02:29.


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