Reply
 
Thread Tools Search this Thread
 
Old 08 November 2011, 07:44   #11
Member
 
Johnscubanut's Avatar
 
Country: UK - England
Town: Beds/South coast
Make: Ribcraft 585
Length: 6m +
Engine: Yam 115
Join Date: Jul 2010
Posts: 294
Speed

Hi there, I'd say if you increase the pitch to 15' you will definately get more speed but it will take longer to get up there? With a heavier load onboard you will find it will struggle to rev out? We used to have to drop the pitch on our dive ribs to around 13inch on our 90hp engines to allow the engines to rev out? Very heavy loads involved with us? Always trim out to the max (just short of ventilation) to achieve comfortable revs & cruising speed? I'm guessing that max revs on your engine would be around 5k?
Hope this helps & be safe but have fun out there? John
__________________

__________________
Johnscubanut is offline   Reply With Quote
Old 08 November 2011, 08:35   #12
Member
 
Country: UK - Wales
Town: West Wales
Make: Vipermax 5.8, SR4.7
Length: 5m +
Engine: 150 Opti, F50EFi
Join Date: Sep 2005
Posts: 6,298
Quote:
Originally Posted by Johnscubanut View Post
Hi there, I'd say if you increase the pitch to 15' ....
Do you know the pitch of the current prop?
__________________

__________________
Downhilldai is offline   Reply With Quote
Old 08 November 2011, 09:08   #13
Member
 
TomKat's Avatar
 
Country: Ireland
Town: Bangor
Boat name: Lencraft 4.8m
Make: Lencraft
Length: 4m +
Engine: DT55HP Suzuki
Join Date: Jul 2011
Posts: 469
No idea on the current pitch, tried to take it off and nut was a bit stiff so left it, will try again on Saturday. Am hoping to drop into the Suzuki guy tomorrow afternoon to get his views on the unconnected sensors, he might know what the pitch is by looking at it.
__________________
TomKat is offline   Reply With Quote
Old 08 November 2011, 13:15   #14
Member
 
Johnscubanut's Avatar
 
Country: UK - England
Town: Beds/South coast
Make: Ribcraft 585
Length: 6m +
Engine: Yam 115
Join Date: Jul 2010
Posts: 294
They are usually quite tight especially if not been removed for a long time? We use a bar jammed between the blades & the gearbox & an extension socket & with a bit of careful leverage the nut should come free? We've even removed a damaged prop at sea! Someone needs to hold your legs tho? lol The stamp of the pitch size will be either on the sections between the blades or on the boss/ring where it meets with the gearbox? Removal of prop is needed to see this! i.e 12 & 1/4 x 15 (Diameter x pitch) Hope this helps?
__________________
Johnscubanut is offline   Reply With Quote
Old 08 November 2011, 17:06   #15
Member
 
TomKat's Avatar
 
Country: Ireland
Town: Bangor
Boat name: Lencraft 4.8m
Make: Lencraft
Length: 4m +
Engine: DT55HP Suzuki
Join Date: Jul 2011
Posts: 469
good tip John - thanks!
__________________
TomKat is offline   Reply With Quote
Old 09 November 2011, 11:38   #16
Member
 
Johnscubanut's Avatar
 
Country: UK - England
Town: Beds/South coast
Make: Ribcraft 585
Length: 6m +
Engine: Yam 115
Join Date: Jul 2010
Posts: 294
Your most welcome!
__________________
Johnscubanut is offline   Reply With Quote
Old 09 November 2011, 13:25   #17
Member
 
TomKat's Avatar
 
Country: Ireland
Town: Bangor
Boat name: Lencraft 4.8m
Make: Lencraft
Length: 4m +
Engine: DT55HP Suzuki
Join Date: Jul 2011
Posts: 469
Checked the prop, it is 11.75 x 12, am I right in thinking that this is on the small side pitch wise and the engine should be revving out above 5500rpm at WOT?

I will fit a tacho this week to verify rpms on the water (hopefully this weekend weather permitting!)
__________________
TomKat is offline   Reply With Quote
Old 09 November 2011, 13:59   #18
Member
 
Country: UK - England
Town: Plymouth
Length: 6m +
Join Date: Mar 2011
Posts: 2,693
I think your currently revving at around 3,400 looking at the video. Not sure what its limit is off hand but if your right you've plenty of room to play with the prop

Peter ~ Boatsandoutboards4sale ~ askboatsandoutboards4sale@sky.com ~ 07930 421007
__________________
Boats&Outboards is offline   Reply With Quote
Old 09 November 2011, 14:26   #19
Member
 
TomKat's Avatar
 
Country: Ireland
Town: Bangor
Boat name: Lencraft 4.8m
Make: Lencraft
Length: 4m +
Engine: DT55HP Suzuki
Join Date: Jul 2011
Posts: 469
Thanks Peter

This is all new to me so bear with me, would an 11.75" pitch (the one on the boat) be realtively easy to turn thus allowing the engine to rev out higher that recomended WOT? i.e. if I put a 15" pitch prop on as has been suggested would this increase or decrease the WOT revs? If my logic is correct this should decrease the revs?

Cheers again
__________________
TomKat is offline   Reply With Quote
Old 09 November 2011, 15:04   #20
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
TomKat,

The engine shouldn't be in guardian/limp-home mode because the gauges aren't connected.

I'd be surprised if you could get 20-22 knots in limp home mode.

Quote:
I think your currently revving at around 3,400 looking at the video.
not doing >20 knots with an 11.75" pitch prop.
__________________
Poly 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 20:08.


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