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Old 16 April 2004, 06:26   #31
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None of the four stroke outboards are "car engines".

Whilst some of them may be based on the design of existing car engines they have been heavily modifed. Honda four strokes have been around for at least as long as any of the new technology 2 strokes, so are hardly untested. The manufacturer's five year warranty also speaks volumes about their confidence in these engines' reliability.

There is no reason to suspect that they will be affected by sea water any differently than other outboards.

I am not aware of any general reliabilty problems with Honda outboards, nor any of the other four strokes for that matter.

I don't know how the performance figures compare, although anecdotal evidence seems clearly in favour of, say, a 150 Optimax over a 150 Honda. The power to weight ratio of the Hondas can be a problem on smaller RIBs, but may be less of an issue on a larger boat.

John
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Old 16 April 2004, 07:34   #32
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Originally Posted by Robbie D
Hmmmmmm.... tempting! Now for the dreaded question. Optimax or Honda four stroke? Would a single 225 do the job or a pair of 150's?

I wouldn't buy a Honda Engine for commercial use. I'd get Opti Saltwaters and I'd buy a pair of 200's. Then if one packs up at sea you have enough grunt to get you home easily. Check the weight difference between a pair of Opti's and a big diesel.

If theres a big weight difference that might be a deciding factor. I however think a diesel will be more cost effective and reliable in the long run.

another issue is the balance of the boat. having half a ton inboard or hanging off the stern makes a deal of difference to the boat handling and ride, so have a long chat with the makers before you decide
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Old 16 April 2004, 13:20   #33
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some good advice from rogue their rob, also consider main dealers/engineers in your area no good having an engine that no one local can, fix i'm still in favour of twins the boat will be balanced to some extent by the rear helm position and passenger seating,check with the manufacturer recommended hp for twins , i see in the pics you posted that boat has twins, will have greater manouverability with twins cost is a big factor when starting up compare the price of a deisel against the twins and see how much money you save and how much fuel that can buy.
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Old 16 April 2004, 20:24   #34
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Thanks for the great replies!
Quick update. Just saw the RIB firsthand at the Rio Boat Show. The word from Flexboat is that the best performance of all motor combinations so far is with twin diesel sterndrives... Mercury 1.7 TDI with Alpha 1 legs. They've put 5 in the water so far, 2 for tourism, and the owners are very happy with results. Planes very quickly with a full load, the boat feels more "balanced" because of the weight positioning, and the fuel economy is excellent.
My problem is that I can't get over the fact that we're talking about 2 120hp motors! Merc and Flexboat here both claim that because the motor is designed to operate at higher rpm's, the torque generated compensates for the lower hp rating, especially for lower and cruising speed operation. It kinda makes sense, but I thought I'd run it by you folks to get some unbiased feedback. I've picked up in these forums that throttle respose is a key factor for those who operate in open seas, so I'm trying to stay aware of this as I make my decision.
Also need to bear in mind that diesel here is roughly 65% of the cost of petrol... in USD terms it's about 45cents per litre as opposed to 70cents per litre for petrol. Twin Opti's would run me about 23,000 USD for the pair here, and the twin diesels would run 34,000 USD for the pair (list prices, probably knock 10% off in real terms). I still need better fuel consumption data before I can calculate a cost/benefit analysis.
Side note... the seating is not the least bit cramped. Plenty of leg room and sufficient room to walk around on the deck. All in all seems like a well constructed, well thought out boat design. Also learned that MercRibs are putting their name on it and selling in the U.S.!
One thing's for sure... I'd be lost without this forum.
Robbie
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Old 17 April 2004, 05:32   #35
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Work on 10 litres per hour per merc diesel.

And the optis? 30 lph per engine?
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Old 17 April 2004, 11:21   #36
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Work on 10 litres per hour per merc diesel.

And the optis? 30 lph per engine?
Just now noticed that you run the Merc 1.7. Not sure about the Opti's, but do you really think the Opti's consume 3x more than the 1.7's in terms of quantity alone? Sounds a bit high.
What's your experience with the Mercs? I know the fuel economy will be fantastic, but what's the performance like? Throttle response, maintenance problems, and is the Alpha One a good match?
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Old 17 April 2004, 11:44   #37
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Well my mercruiser is still in its box so i cant be of much help.
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Old 26 April 2004, 00:22   #38
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I've been driving a 200 Opti all wekend on a corporate charter and I do like to run as quickly as I can. On Saturday I ran for about 4 hours at an average of 5000 revs ( the redline is around 6) and I used 139 litres of fuel.

The Mercruisers are well thought of and the lump is made by Isuzu ( which is a plus point).

More importantly petrol 70 cents a litre and nubile women.....When's the next plane to Brazil !


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Old 26 April 2004, 13:06   #39
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Quote:
Originally Posted by Rogue Wave
I've been driving a 200 Opti all wekend on a corporate charter and I do like to run as quickly as I can. On Saturday I ran for about 4 hours at an average of 5000 revs ( the redline is around 6) and I used 139 litres of fuel.

The Mercruisers are well thought of and the lump is made by Isuzu ( which is a plus point).

More importantly petrol 70 cents a litre and nubile women.....When's the next plane to Brazil !


How do you make money with petrol being what it costs up there? I'm actually trying to make a profit, which is why I'm going with the extra investment in diesels.
BTW, daily non-stops flights from Paris to Rio, and cheap if you plan it right. I'll even put you up in exchange for some training! (No RIB specific training down here, unfortunately). Nubile women to be discussed at a later time...
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Old 26 April 2004, 14:49   #40
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Hi Robbie
we make the money because we can claim back the duty the dear chancelor charges us currently .47.10 p so does bring the running costs down
tim
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