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Old 03 October 2010, 13:46   #1
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Country: UK - England
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Boat name: nitrox
Make: F-rib
Length: 3m +
Engine: 15hp
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twin or single

would you fit a single 300hp or twin 150hp engines on 8mtr rib. the boat is rock solid and weighs about 1600kg. what length leg do you require as transom is cut for 30". would 25" legs on twins fit neal
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Old 03 October 2010, 14:48   #2
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Boat name: Black Ops
Make: Zodiac Hurricane 733
Length: 7m +
Engine: OceanPro 150hp x 2
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This is an endless debate.

A big single is far more fuel efficient, perhaps even faster (less drag)

The twins offer planing speeds with an engine failure.

I currently have twins and enjoy the security twin engines provide. (I do a 20 mile crossing of relatively unprotected water) I do wish I had the fuel burn of that single though...

My boat runs twin 25" shafts, it takes a 30" single, yours would probably be the same.

http://rib.net/forum/showthread.php?t=37459
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Old 03 October 2010, 15:33   #3
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Make: Arctic 28/FC470
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Looking at where your boat is at in the build process I'd say you left it a bit late to ask this question!

How many fuel tanks have you got fitted? Many people inc. myself would suggest that there's no point in having twins if they're not rigged completely independant of each other.
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Old 03 October 2010, 15:36   #4
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Ouch! This one's going to sting a bit. Firstly, performance wise a 300hp single will bury twin 150s. To get anywhere close to the performance of a single 300 you would be looking at least twin 175s possibly 2x200s. Bearing in mind you might need to run & plane on one. Fuel wise, twins generally use more than an equivalent single. But! I have found the difference marginal, I've found that powering boats in the upper end of the max rating & not flogging the engine(s) uses less fuel than running them at minimum hp & revving the knackers off 'em.
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Old 03 October 2010, 16:01   #5
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Agree with all of the above, the twins do make handling heavy load easier, if your going to have big groups of divers you may be glad of two props pushing you along.
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Old 03 October 2010, 16:05   #6
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twins as per Martini's specs. the difference in performance at that level of power is just a bit of the top end the difference in Handling and control is massive
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Old 04 October 2010, 15:18   #7
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Country: UK - England
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twin or single

thanks for the info, single 300hp is the way. not sure which one, evinrude or suzuki cheers neal
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Old 04 October 2010, 18:07   #8
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Country: UK - England
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thanks for the info, single 300hp is the way. not sure which one, evinrude or suzuki cheers neal
Suzuki all the way!! Absolutely no competition. I skipper a dive rib rigged with twin 200hp evinrudes and they simply aren't as reliable as I'd like them to be given the kinds of conditions I'm operating under and how important engine reliability is.

J
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Old 04 October 2010, 18:25   #9
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E-tecs all the way, can't fault them and now on my second.

Pluss these guys seem to rate them and they should know...

http://www.quinquarimarine.co.uk/vessels/7/
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Old 04 October 2010, 19:01   #10
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Engine: Etec 150
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E-tecs all the way, can't fault them and now on my second.

Pluss these guys seem to rate them and they should know...

http://www.quinquarimarine.co.uk/vessels/7/
They apparently supply them to the British Antarctic Survey and I'm guessing if there is one place you probably don't want a breakdown it is there...
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