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20 May 2014, 19:21
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#1
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Member
Country: UK - Wales
Town: abergele
Boat name: all mine
Make: ribtec 3m
Length: 3m +
Engine: tohatsu 9.8 hp 2st
Join Date: Sep 2012
Posts: 292
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9.8 hp tohatsu
Hi all I have the above engine (2 stroke) on a 3.2m sunsport v air hull,when there are two people in the boat with light fishing tackel I can get on the pane easey and at 5500rpm, if I add a small child I can only just get on the plane and can't get the engine to rev above 4100rpm I have a standered prop, what prop should I order to use when I have a heavier load that would take me to 5500-6000 rpm.
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20 May 2014, 19:30
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#2
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Member
Country: UK - England
Town: St Helens
Boat name: Wine Down
Make: Maxum
Length: 8m +
Engine: Inboard
Join Date: Apr 2012
Posts: 934
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You need to reduce the pitch. Stick with the Tohatsu prop, just an inch or so less pitch.
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20 May 2014, 20:30
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#3
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Member
Country: UK - Wales
Town: abergele
Boat name: all mine
Make: ribtec 3m
Length: 3m +
Engine: tohatsu 9.8 hp 2st
Join Date: Sep 2012
Posts: 292
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Ok thank's I have just been out to look at the size of the prop I have it just say's F8.5 so do i just buy a 7.5 ??
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20 May 2014, 20:45
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#4
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Member
Country: UK - England
Town: South Yorkshire
Boat name: Sold it !
Length: 3m +
Engine: Totallyhotsue 9.8 2S
Join Date: Sep 2011
Posts: 258
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I can plane at 3/4 throttle on my 3.3m with 2 adults, 2 x 25kg kids and some kit.
When fully loaded WOT then a passenger shifts back then forward whilst it hops on the plane easily. I use the standard 8.5 prop.
We shift weight to get it up on the plane. You can feel it and the acceleration. I have to back off as 20 knots in a small loaded boat is scary.
Make sure that your boat is up to pressure to.
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20 May 2014, 20:52
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#5
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Member
Country: UK - Wales
Town: abergele
Boat name: all mine
Make: ribtec 3m
Length: 3m +
Engine: tohatsu 9.8 hp 2st
Join Date: Sep 2012
Posts: 292
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yes the boat is up to pressure, the boat fly's with me and a freind around 30 stone (pair of us) and light tackel, but if I add a small child it won't rev over 4100rpm I'm looking to get the revs up, I will change props according to my passengers'
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20 May 2014, 20:55
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#6
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Member
Country: UK - England
Town: St Helens
Boat name: Wine Down
Make: Maxum
Length: 8m +
Engine: Inboard
Join Date: Apr 2012
Posts: 934
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OE prop range for the 9.8 was 6.5" to 9.5".
I think the 6.5 may be a little too far, the 7.5 sounds good if you only need a little bit of extra help to plane.
Just to add, a 6.5 on say a Yamaha would be classed as a "High Thrust" prop for moving heavy displacement boats about, it may turn into an egg whisk on an inflatable.
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21 May 2014, 00:14
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#7
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RIBnet supporter
Country: UK - England
Town: Warwickshire
Boat name: Impulse
Make: Ribcraft
Length: 5m +
Engine: Suzuki 140
Join Date: Sep 2011
Posts: 1,020
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7.5 will work I have both depending if I am using the engine on sib or as aux on the RC check out eBay reasonably priced new props on there
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21 May 2014, 17:51
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#8
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Member
Country: UK - Wales
Town: abergele
Boat name: all mine
Make: ribtec 3m
Length: 3m +
Engine: tohatsu 9.8 hp 2st
Join Date: Sep 2012
Posts: 292
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Thanks all for the replys I will get a 7.5 over the weekend and let you know the results
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21 May 2014, 18:18
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#9
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RIBnet admin team
Country: Ireland
Length: 4m +
Join Date: Feb 2008
Posts: 14,910
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I'd be interested to hear how that goes - I'm thinking about the same move...
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21 May 2014, 18:20
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#10
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RIBnet supporter
Country: UK - England
Town: Warwickshire
Boat name: Impulse
Make: Ribcraft
Length: 5m +
Engine: Suzuki 140
Join Date: Sep 2011
Posts: 1,020
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Quote:
Originally Posted by willk
I'd be interested to hear how that goes - I'm thinking about the same move...
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Haven't you been thinking about that for over a year now?!!!!!
Take a punt!
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21 May 2014, 18:23
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#11
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RIBnet admin team
Country: Ireland
Length: 4m +
Join Date: Feb 2008
Posts: 14,910
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Quote:
Originally Posted by AJ.
Haven't you been thinking about that for over a year now?!!!!!
Take a punt!
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Ach, it was winter. I got her out today and she started third pull, half choke - been winterised since late October. Water time on Saturday!
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21 May 2014, 18:26
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#12
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RIBnet supporter
Country: UK - England
Town: Warwickshire
Boat name: Impulse
Make: Ribcraft
Length: 5m +
Engine: Suzuki 140
Join Date: Sep 2011
Posts: 1,020
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Quote:
Originally Posted by willk
Ach, it was winter. I got her out today and she started third pull, half choke - been winterised since late October. Water time on Saturday!
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Wahooo. Yeah think I might bring mine out of hibernation
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21 May 2014, 18:33
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#13
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RIBnet admin team
Country: Ireland
Length: 4m +
Join Date: Feb 2008
Posts: 14,910
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And she was looking good - bit smokey but that will be the fogging oil burning off...
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11 June 2014, 19:58
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#14
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Member
Country: UK - Wales
Town: abergele
Boat name: all mine
Make: ribtec 3m
Length: 3m +
Engine: tohatsu 9.8 hp 2st
Join Date: Sep 2012
Posts: 292
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bit the bullet and ordered a 8.5x7.5 prop today should be here friday, I will let you know how it goes I'm hopeing to get out saturday
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13 June 2014, 15:26
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#15
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Member
Country: UK - Wales
Town: abergele
Boat name: all mine
Make: ribtec 3m
Length: 3m +
Engine: tohatsu 9.8 hp 2st
Join Date: Sep 2012
Posts: 292
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So I took the day of work, it's hot calm and life is to short, I got the boat out, engine in the test tank for a warm up and the door bell ring's, it's the courier with my new prop (8.5X7.5), I fitted it with in ten minutes, then invited my uncle to come fishing for a few hours lol he bit, well I can say it topped out at 5900rpm and 14mph on the gps, 11mph was nice and I don't like running at WOT all the time, and it jump's straight on the plane, got five mackrel and two whiting so I am a happy person today,
Thank you for the replys
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