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18 September 2011, 19:39
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#1
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Member
Country: UK - Scotland
Make: Humber Ocean Pro
Length: 3m +
Engine: Yam 200HP
Join Date: Jul 2009
Posts: 986
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Maximum horsepower or maximum weight
Just wondering what is best to go by, either maximum horsepower or maximum engine weight,
IE, what are the problems with going over the maximum stated horsepower is you are well under the maximum weight, say 50 kgs.
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18 September 2011, 20:01
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#2
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Member
Country: UK - England
Town: Plymouth
Length: 6m +
Join Date: Mar 2011
Posts: 2,693
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Insurance...
Peter ~ Boatsandoutboards4sale ~ askboatsandoutboards4sale@sky.com ~ 07930 421007
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18 September 2011, 20:03
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#3
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Member
Country: Other
Town: Rosas
Boat name: Conqueror
Make: Valiant
Length: 7m +
Engine: Outboard 150hp Merc
Join Date: Dec 2010
Posts: 549
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You don't really want to be pushing your transom through your boat do you or flipping it over backwards?
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19 September 2011, 04:49
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#4
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Member
Country: USA
Town: Seattle
Boat name: Water Dog
Make: Polaris
Length: 4m +
Engine: Yamaha 60hp
Join Date: Apr 2007
Posts: 1,152
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Over weight, break the transom
Over power, flip you out of the boat
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19 September 2011, 14:42
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#5
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Member
Country: UK - England
Town: Bournemouth
Boat name: Seadrive
Make: Capelli Tempest 470
Length: 4m +
Engine: Suzuki DF70
MMSI: 235079113
Join Date: Jul 2008
Posts: 550
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Quote:
Originally Posted by captnjack
Over weight, break the transom
Over power, flip you out of the boat
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Weight - don't need to use the max HP (but then why have it ?)
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19 September 2011, 15:45
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#6
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Member
Country: Canada
Town: Vancouver, BC Canada
Boat name: Black Ops
Make: Zodiac Hurricane 733
Length: 7m +
Engine: OceanPro 150hp x 2
Join Date: Oct 2008
Posts: 247
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Both.
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19 September 2011, 16:19
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#7
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Member
Country: USA
Town: Seattle
Boat name: Water Dog
Make: Polaris
Length: 4m +
Engine: Yamaha 60hp
Join Date: Apr 2007
Posts: 1,152
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Quote:
Originally Posted by longjohn
don't need to use the max HP (but then why have it ?)
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Tell that to your insurer or the agency certifying the boat as safe and seaworthy.
I don't understand how a boat can accept a motor vastly above the rated power while staying within weight limits anyway. That suggests to me that the transom is widely overbuilt (heavier and bulkier than necessary compared to the remainder of the hull design).
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19 September 2011, 16:53
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#8
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RIBnet admin team
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,626
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Quote:
Originally Posted by captnjack
I don't understand how a boat can accept a motor vastly above the rated power while staying within weight limits anyway. That suggests to me that the transom is widely overbuilt (heavier and bulkier than necessary compared to the remainder of the hull design).
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Simple the boat/transom is designed to take say 90 HP, so to take a modern 4 stroke that means it needs to be rated for something like 180 kg. Now you can get a 130HP etec, 125 HP optimax within that limit. If you shop around for an old 2 stroke you can probably get that power way under the weight limit. The rest of the boat might not be lightly build just flighty / likely to chine walk etc with too much power.
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19 September 2011, 18:32
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#9
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Member
Country: USA
Town: Seattle
Boat name: Water Dog
Make: Polaris
Length: 4m +
Engine: Yamaha 60hp
Join Date: Apr 2007
Posts: 1,152
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You have more RIB manufacturers over there ,but at least with Avons and Zodiacs which make up probably 80% of the US market they have not revised their transoms to accept heavier outboards. You'll often see a transom rated for 70hp but only be able to find a 50-60hp to fit it since there are very few (new) 4 stroke 70hps within the weight rating developed for a 2 stroke. (the reverse problem) Worse is trying to find something like a 40hp short shaft which many Zodiacs in the ~15ft size range take. They just aren't available anymore.
Once you get into the 90hp+ department there are very few RIBs over here being built/imported in that size range. So upsizing a 90hp four stroke to a 125 optimax really isn't something our Ribbers have to worry about or deal with (even if they wanted to).
Most of the Avon's and Zodiac's mentioned above are 8-14ft tender sizes.
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20 September 2011, 08:49
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#10
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Member
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,671
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Simply 'coz the Avons are maily sold as commercial / military where the emmissions rules don't apply so they can carry on using 2- strokes!
Puit it in prespective, when mine was built the average sub 100 Hp engine had 2 cyls. I have a 110Kg / 60Hp limit.... there's some 3 cyl autolube 2- strokes out there too heavy for mine!
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20 September 2011, 10:31
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#11
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Member
Country: Other
Town: Rosas
Boat name: Conqueror
Make: Valiant
Length: 7m +
Engine: Outboard 150hp Merc
Join Date: Dec 2010
Posts: 549
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I'm wondering who we're all preaching to at the moment..... Where's the OP?
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20 September 2011, 14:20
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#12
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Member
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,671
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Chill. They may be out ribbing!
Even I occasionally go incommunicado for a week or so ......
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