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Old 10 April 2012, 09:38   #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, 11:33   #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, 11:42   #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, 11:44   #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, 12:37   #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, 13:04   #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, 13:36   #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, 13:59   #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, 15:21   #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, 16:13   #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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Old 10 April 2012, 17:59   #11
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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.
No they aren't easy to fix yourself, but almost nothing is nowadays. At least over here the opti's aren't considered unreliable although maybe a bit finicky. I don't know if the guts are identical to what you have though.

How many hours do they have and how many is a typical yearly total?
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Old 11 April 2012, 02:04   #12
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How old are they? I've read that the ones produced in the first couple of years were electronic nightmares. Then they sorted them out. Sorry to hear of yours being awful, it ruins your fun.
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Old 11 April 2012, 03:11   #13
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What about instead of a single 175 replacing with a pair of 90s?

Yeah, there's all the "more to go wrong / twice the servicing" etc, arguments but (and I generalise quite profusely here) smaller engines tend to be more self sustaining (i.e don't care if the battery is there or not). Also there are still quite a few used 2-bang 90s out there, and if one dies at least you have 90 Gee Gess to push you home .....

:openscanofwormssmiley:



On a more serious note, am I right in thinking from previous people's posts that the Optis are quite battery reliant? What state is your main isolator? Those things must be the least waterproof electrical item on a boat! I had to pull start a Suz 25 when the contacts in my battery switch had corroded too much. If your Opti is sensitive to battery condition, try shorting the switch with a jumper & see what happens.

An engine flagged injector fault is likely caused by the resulting emissions twist in the exhaust as a result of too much / too little fuel being detected. management thinks "everything testing OK for presense, so injector must be faulty" If your engine is only seeing, say 10.5V, the injectors will likely not be opening and responding to the ECU i nthe manner they were designed to. The ECU just sees dodgy emissions and hey presto, diagnoses an injector issue. Having said that I think most automotive injectors are reasonably accurate down to about 8.5-ish V. Worth putting a meter across the engine feed connectors to see what it's actually seeing?
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Old 11 April 2012, 04:46   #14
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smaller engines tend to be more self sustaining (i.e don't care if the battery is there or not).
No need to go smaller, even the 300hp Evinrude E-tec can be rope started, with no need for a battery to be hooked up at any stage of running. You couldn't contemplate starting a fourstroke because the electronics would go crazy, and you definitely couldn't rope start an opti due to the extra revolution required.
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Old 11 April 2012, 06:09   #15
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Tom, reading your story, I wonder if your engines are the real problem..
Perhaps a kind of direct statement from the other side of the North Sea, but your story sounds a bit like you rather need to visit another dealer instead of changing your engines. Sold these engines for years and the only thing I remeber about these is that their about the most reliable types there have ever been in the market..

When most of your problems are battery related, buy yourself a good set of gel-batteries (Optima) and perhaps even build a good battery-charger in your console with a connector to the power net to keep them in good shape..

Anyway, good luck solving the problem!
Regards, Wouter
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Old 11 April 2012, 07:58   #16
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Having read your posts totterfield, I'd agree that it sounds more like a battery or boat wiring problem than an engine problem. I'd suggest carrying some jump leads and a spare battery and seeing if they then start and run fine.
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Old 11 April 2012, 08:04   #17
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No need to go smaller, even the 300hp Evinrude E-tec can be rope started, with no need for a battery to be hooked up at any stage of running.
Cool. I thought that Optis needed a healthy battery, or was that an early version? Thanls for the correction.

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You couldn't contemplate starting a fourstroke because the electronics would go crazy, and you definitely couldn't rope start an opti due to the extra revolution required.
I would maybe disagree with that. How many pull start 4 stroke EFI 30/40/50s are out there?
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Old 11 April 2012, 12:05   #18
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Thanks for replies, in defence for my local dealer i do have faith in them, they have fixed our boats so many times, and at last minute, it always leaves there working.

The batteries are fine, both have a good full charge, we charge tjem in the boat shed quite often to keep them full.

The engine are around 5 or 6 years old and around the 400 - 500 hours, i can`t remember exactly.

With them being club boats it`s out of my hands, the masses have spoken, they have lost faith in the engines so we are going to replace them. They are now both in the shop getting looked at, just waiting to find out what has gone wrong this time.

It is difficult which motor to replace with, i think the fact they are not used on a commercial scale does them no favours, they are quite often stood around for a few weeks, especially over the winter.

Has anyone used the Yamaha V Max 2 stroke, any good? I think we will end up going down the 2 stroke electronic route as that is the only viable option really, just hope the next ones are sweet.

As for the twin engine debate, can only have max of two 70 hp engines, doesn`t seem like enough to me.

So it`s another 2 stroke yamaha, Evenrude or Honda in my eyes
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Old 11 April 2012, 12:27   #19
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Has anyone used the Yamaha V Max 2 stroke, any good? I think we will end up going down the 2 stroke electronic route as that is the only viable option really, just hope the next ones are sweet.
At least over here those are only available in 20" shaft length. I would guess your boats take 25" no? They are typically rigged quite high with cupped SS props on shallow deadrise bass boats for 70ish mph speeds. I have never seen one in a high load application like pushing scuba tanks and divers. Doesn't mean it won't work of course.
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