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Old 10 April 2012, 10:38   #1
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What engine for a 6.5m meter Humber rib?

Hi, i`m a member of a dive club with 2 beautiful ribs, but i`m the equipments officer and the engine are giving us endless troubles. We have a pair of Mercury optimax 150 2 stroke, great engines except for the electrics are massively over engineered and is giving us problem after problem and making the boats very unreliable, so we are gonna bin them and get new engines, but what to go for is the BIG question. I feel i would like to go down a simpler 2 stoke engine route that doesn`t have the advanced electronic injection system as that has been the main problem previously, one of the old type Yamahas maybe, Also i feel the rib is somewhat underpowered when loaded with 8 divers and kit and cox, so was thinking a slightly bigger engine up to 175 or 200 maybe.....

I think the four strokes are out of the question because they weigh loads more and are not quite as tourqueeee.

What are other people using on similar boats??? what can people recommend?

Thanks in advance

Tom
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Old 10 April 2012, 12:33   #2
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You want a 175hp 2-stroke without fuel injection?!? Like with carbs? Like the one I had who burned through many a dinosaur worth of fuel in 1991? Checked petrol prices lately? lol

8 divers with 2 tanks each in a 6.5m RIB is alot. It would be even more over here since we're so damn fat. But even then I would stick with 150hp. You might consider upsizing to Suzuki's 175 4-stroke which is the same block as their 150hp.
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Old 10 April 2012, 12:42   #3
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You want a 175hp 2-stroke without fuel injection?!? Like with carbs? Like the one I had who burned through many a dinosaur worth of fuel in 1991? Checked petrol prices lately? lol
+1
Sounds to me like you need an E-tec, lighter than your Optimax, and simpler and cheaper to service..............
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Old 10 April 2012, 12:44   #4
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I would agree with a Suzuki DF 175, light for a 4-stroke and very economical compared to a 2-stroke.
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Old 10 April 2012, 13:37   #5
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The 175 opti is the same as block as the 150 too.

Re electrics, all modern 2 or 4 strokes are full of electrics with sensors that twitch at anything and put the engine in to safe mode etc. IMHO you'll just go out the frying pan in to the fire.

It's just a sign of the times. It just replaces the dodgy sticking carb's of yesteryear.

The only only way to avoid it would be to get an inboard diesel perhaps. Not a simple option of reporting though.
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Old 10 April 2012, 14:04   #6
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E-tec 175 would be your best bet. Great engines !

Simpler than the Optimax and proven in commercial use by the likes of Qinquari. They only need dealer servicing every 300 hours (3 years).

If you look after them they are solid engines.

Speak to Steve at Race Marine in Taunton. He sells them and really knows his stuff.

Chris
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Old 10 April 2012, 14:36   #7
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E-tec 175 would be your best bet. Great engines !

Simpler than the Optimax and proven in commercial use by the likes of Qinquari. They only need dealer servicing every 300 hours (3 years).

If you look after them they are solid engines.

Speak to Steve at Race Marine in Taunton. He sells them and really knows his stuff.

Chris
Yes i`ve been looking at the e-tecs, evenrude seem to have re built their reputation, the e-tec looks like a sweet engine with not too much electrics, certainly not as much as the optimax.

As for the suzuki 175 4 stroke, i`m very reluctant to buy one, read many reviews with funny noises at low revs, around the 1000rpm, in fact read quite a few bad reviews of them. bottom line i need reliability.

Thanks for input, keep it coming
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Old 10 April 2012, 14:59   #8
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How many hours do you have on the mercuries? I am curious what issues you are having with them and the cause(s)?

As national originators of the miracle of electrics in the MG, I'd think dodgy wiring would feel like home
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Old 10 April 2012, 16:21   #9
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Yes i`ve been looking at the e-tecs, evenrude seem to have re built their reputation, the e-tec looks like a sweet engine with not too much electrics, certainly not as much as the optimax.

As for the suzuki 175 4 stroke, i`m very reluctant to buy one, read many reviews with funny noises at low revs, around the 1000rpm, in fact read quite a few bad reviews of them. bottom line i need reliability.

Thanks for input, keep it coming
If you are used to the performance of an opti then I would say that the E-tec represents you best bet.

Not sure I agree on the electronics however, e-tecs still have them ! However the thing that always put me of the Optimax was all the injectors and the air compressor etc. Also I always found them intrusively loud especially at idle.

THe E-tecs are still not much different in their fundamental design from the V6 Evinrudes from 20+ years ago the main difference now is the injection system and the oil managment however behind all that its still a simple 2-stroke V6 block...

THe only thing you may find though is they are not cheap ! you can probably source an Opti for about 2k less that an equivalent E-tec.
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Old 10 April 2012, 17:13   #10
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If you are used to the performance of an opti then I would say that the E-tec represents you best bet.

Not sure I agree on the electronics however, e-tecs still have them ! However the thing that always put me of the Optimax was all the injectors and the air compressor etc. Also I always found them intrusively loud especially at idle.

THe E-tecs are still not much different in their fundamental design from the V6 Evinrudes from 20+ years ago the main difference now is the injection system and the oil managment however behind all that its still a simple 2-stroke V6 block...

THe only thing you may find though is they are not cheap ! you can probably source an Opti for about 2k less that an equivalent E-tec.
Well this weekend for example both boats have been out of use, and right after their yearly service, one boat lost all engine based electronics, thought it was the battery, checked the battery, it was fine but nothing on engine would work including the tilt (all fuses check). all other instuments worked fine, so boat binned for weekend. second boat was ok for day and a half then the "smart guage" registered an injection fault and sounded and audible alarm that would drive you crazy and kept popping into limp mode, so second boat binned.

We have had numberous examples like this go, the compressor has gone before in the scillie isles. They are the very definition of unreliable!!!

We as a club are no experts when it comes to fixing these problems, as i understand they have to be plugged into a diagnostic programme, think we have two hypocondriac outboards.

Can you still buy the V6 175 autolube yamahas? would love one of them hahaha
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