Reply
 
Thread Tools Search this Thread
 
Old 12 May 2012, 18:52   #1
Member
 
Country: UK - England
Length: under 3m
Join Date: May 2012
Posts: 48
How can I get my rib to plane?

Hi there

I am new to boating, recently bought a rib which is 2.7m with a 6hp short shaft 2 stroke fitted with dolefins.

It goes quite well on the plane with just me in it but with two and even three passengers it just chugs along trying to plane.

The rib is rated to a 10hp but was wondering if a slightly bigger engine or a change of prop will do the trick?

Any advice appreciated.

Thanks
__________________

__________________
eyespy999 is offline   Reply With Quote
Old 12 May 2012, 19:33   #2
Member
 
lockieboi's Avatar
 
Country: UK - England
Town: kent
Boat name: SIBotage
Make: Prowave
Length: 3m +
Engine: 15hp Johnson 2 smoke
Join Date: Sep 2010
Posts: 435
Stick 10 horses on it!
It still may not plane with 3 though.
__________________

__________________
lockieboi is offline   Reply With Quote
Old 13 May 2012, 00:11   #3
Member
 
Country: New Zealand
Town: Auckland
Boat name: GUN-IT
Make: Redknight
Length: 4m +
Engine: 40hp outboard
Join Date: Mar 2012
Posts: 18
You probably need on average about 7hp per 100kg to plane, so with 3 large people you would probably need more like 20hp...
__________________
Redknight is offline   Reply With Quote
Old 13 May 2012, 05:28   #4
RIBnet admin team
 
willk's Avatar
 
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 12,924
RIBase
First question: Have you a RIB or a SIB? If it doesn't have a hard hull, it's a SIB. I'm guessing you have a SIB? If so, is it a Slatted deck or Airdeck? Answers on a postcard pls and we'll see what we can do for ya.
__________________
willk is offline   Reply With Quote
Old 13 May 2012, 06:03   #5
Member
 
m chappelow's Avatar
 
Country: UK - England
Town: yorkshire
Boat name: little vicky
Make: avon ex RNLI
Length: 3m +
Engine: tohatsu
Join Date: Mar 2008
Posts: 2,310
Removing the doelfins will gain you a couple of knots
They may give the stern lift but you also cause drag especially with a small engine.
__________________
m chappelow is offline   Reply With Quote
Old 13 May 2012, 09:41   #6
Member
 
Country: UK - England
Length: under 3m
Join Date: May 2012
Posts: 48
Thanks all for your replies.

Its a brig falcon 275 with a hard hull and rigid deck. I have a 1997 merc 2 stroke 6hp.

I have read mixed review about the dolesfins if anyone has good advice whether to keep the on or take off.

Thanks again
__________________
eyespy999 is offline   Reply With Quote
Old 13 May 2012, 12:38   #7
Member
 
m chappelow's Avatar
 
Country: UK - England
Town: yorkshire
Boat name: little vicky
Make: avon ex RNLI
Length: 3m +
Engine: tohatsu
Join Date: Mar 2008
Posts: 2,310
Even though they can help on some craft What you have to think is doelfins were designed for much larger engines and only seem to be one standard size,
the surface area drag on say a 40 hp engine is nothing compared to a much lesser powered engine ,
It's only a 2min job removing or putting them back on to see any difference ,
I have known a few small engined doel finners to cut them down in size a little .
__________________
m chappelow is offline   Reply With Quote
Old 13 May 2012, 12:43   #8
RIBnet supporter
 
yoyo's Avatar
 
Country: UK - England
Town: Warrington/Anglesey
Make: Menai 480SR.
Length: 4m +
Engine: Tohatsoooooooo 70hp
Join Date: Sep 2005
Posts: 665
Get a 9.8 twatsoo 2 stroker nailed on the back end and then it will bat along nicely.
__________________
Yoyo.
---------------------------------------------------
life's full of ups "n" downs.
yoyo is offline   Reply With Quote
Old 13 May 2012, 12:49   #9
RIBnet admin team
 
willk's Avatar
 
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 12,924
RIBase
OK. Yeah, lose the doelfins. You might try playing around with the engine trim position - start in the lowest position and experiment. Move all the weight forward - you'll benefit from a tiller extension - 20 well spent. That said - I don't see you planing with three adults, maybe an adult and two kids.

It would go well with 10hp but I still think you'd be doing well to plane with three adults...
__________________
willk is offline   Reply With Quote
Old 13 May 2012, 13:32   #10
Member
 
Country: UK - England
Town: East Anglia
Boat name: Nimrod II
Make: Aerotec 380
Length: 3m +
Engine: Suzuki DF20 EFI
Join Date: Nov 2007
Posts: 3,275
>>>with two and even three passengers it just chugs along trying to plane.

Is that you plus two/three?

Anyway as some have hinted... simple fact is a 6hp is too small to shift that many folks on the plane. My experience with a 3m SIB and 9.8hp is very lively with one adult, still planes with two adults or one adult and two children. Go above that and it struggles.

Ideally if you want to carry that many folks you need a 3.2m-3.5m with 15-20hp. If you have to keep the 275 then this is the ideal combination...

http://www.looking4aboat.co.uk/%5Cdo...0-15-56-27.jpg

For me doelfins are mostly used to try and correct an outboard/craft/weight issue. Get the outfit right and they are not needed just adding drag as said above.
__________________

__________________
Fenlander 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 00:41.


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