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05 September 2011, 13:26
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#1
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Member
Country: Australia
Town: Sydney
Boat name: Lunasea
Make: Ribtec 890SX
Length: 8m +
Engine: Yamaha ME 421STI x 2
Join Date: Aug 2009
Posts: 475
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Does anyone recognise this SIB?
Took out our SIB for the second time and was a little disappointed at the performance with an older 15hp. It didn't seem that fast and was wondering if I should get the short shaft motor higher as there was lots of spray.
This boat planed with a 3.5 on it's first outing a year ago.
It has an inflatable keel and floor which I had at about 8psi. The tubes were at 3.5psi as per the compliance plate. I seem to recall that the floor and tubes should be 11psi but have lost the manual.
Amy suggestions?
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05 September 2011, 15:52
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#2
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Member
Country: UK - England
Town: Calne, Wiltshire
Boat name: Shot Away
Make: BWM DeepSea 21
Length: 6m +
Engine: Mercury BlackMax 200
Join Date: May 2011
Posts: 40
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If there was a lot of spray, shouldn't you lower the motor? Maybe I missed something, sorry!
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Don't worry, this is perfectly normal. Could someone pass me the flares please?
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05 September 2011, 17:39
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#3
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Member
Country: UK - England
Town: gravesend
Boat name: curach/Earl
Make: seago/Lifeguard 4M
Length: under 3m
Engine: 3.3 marinar/10 hp
Join Date: Jul 2008
Posts: 802
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Most sibs are short shaft designed,sounds like you may have had the leg at an angle?if it planed with a 3.5 ,very small hp?,would of thought you would of got on the plane with a 15hp,my 10hp get's my heavy 4m on the plane no prob
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05 September 2011, 22:07
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#4
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Member
Country: Australia
Town: Sydney
Boat name: Lunasea
Make: Ribtec 890SX
Length: 8m +
Engine: Yamaha ME 421STI x 2
Join Date: Aug 2009
Posts: 475
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No problem getting on the plane, just wasn't a Lot faster. Maybe I am expecting too much.
I tried different trim settings and can't go down with the engine so thought I might try up till it cavitates. Probably makes more sense to go down buy that is not an option.
I think the problem is more likely to be not enough air pressure but don't know how high to go on the floor and keel.
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05 September 2011, 23:40
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#5
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Member
Country: UK - England
Town: gravesend
Boat name: curach/Earl
Make: seago/Lifeguard 4M
Length: under 3m
Engine: 3.3 marinar/10 hp
Join Date: Jul 2008
Posts: 802
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Quote:
Originally Posted by kubcat
No problem getting on the plane, just wasn't a Lot faster. Maybe I am expecting too much.
I tried different trim settings and can't go down with the engine so thought I might try up till it cavitates. Probably makes more sense to go down buy that is not an option.
I think the problem is more likely to be not enough air pressure but don't know how high to go on the floor and keel.
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I might try up till it cavitates. Not to good for the engine,shakes the hell out of the gear box
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06 September 2011, 08:45
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#6
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Member
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,951
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The sib colour schemes and square bow make it look like a Suzuki often sold under their Suzumar label.
Pete
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Ribnet is best viewed on a computer of some sort
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06 September 2011, 08:49
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#7
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Member
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,951
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Next thought is you may have too much weight at the stern? Shift the seat to the middle position. You might need one of those aftermarket tiller extentions to reach but an old broom and some gaffer tape would do to confirm the problem first.
Pete
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Ribnet is best viewed on a computer of some sort
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06 September 2011, 17:06
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#8
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Administrator
Country: UK - England
Town: Brighton
Length: 3m +
Join Date: May 2000
Posts: 7,108
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Quote:
Originally Posted by kubcat
I think the problem is more likely to be not air pressure but don't know how high to go on the floor and keel.
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If you're not sure then the floor is almost certainly not inflated enough. Get that sorted first before you muck about with the engine.
Floor should be something like 10psi which is a lot more than you think it is. Keel doesn't need so much, but does need more than the tubes. Perhaps someone with a similar boat like a Quicksilver airdeck could see what their book says.
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06 September 2011, 17:56
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#9
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RIBnet admin team
Country: UK - England
Town: Cambridgeshire
Boat name: Nimrod II
Make: Aerotec 380
Length: 3m +
Engine: Yam 15 Tohatsu 9.8
Join Date: Nov 2007
Posts: 8,881
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I'd go for 10psi in the floor as in this Quicksilver manual...
http://www.mercurymarine.com/media/m...-899194001.pdf
It is unthinkable that performance would be similar between a 3.5hp and 15hp... something very wrong here.
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06 September 2011, 18:40
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#10
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Administrator
Country: UK - England
Town: Brighton
Length: 3m +
Join Date: May 2000
Posts: 7,108
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Quote:
Originally Posted by Fenlander
It is unthinkable that performance would be similar between a 3.5hp and 15hp... something very wrong here.
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Agreed, but let's make sure the boat is set up right first. A floppy floor will lead to prop ventilation and lousy performance whatever the motor.
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