Advice needed on a new RIB for tourism in Brazil

[Searider]

Fair comment about the jets - as with engines back up is important!

[Manos]

Robbie twin 150s will be OK better than single I recon.
With the right props you will be getting 150 bhp performance under any load

[tim griffin]

hi robbie
great looking set up, i'd favour twin optimax 150 hp great lowend torque
easy to maintain my 7metre coded for ten reaches 30 knots with a bit of tweaking, how much is fuel petrol/deisel can you work out how many miles you will be doing as a round trip and then how much you will be charging per head for said trip then need to work out price per litre of petrol and deisel to see the two different profit margins then factor in the tits up scenario of engine going wrong on a deisel how much to fix and same again for the petrol.
the outboards will be cheaper to buy fix replace and that is a lot of petrol you can buy if going down this road some great threads on outdrives and legs going on at the moment hope this helps ,
regards
tim
www.griffmarineservices.co.uk

[Robbie D]

Tim,
It helps a lot and it's good to hear from someone more or less in the same business. I'll get a better idea on the math you suggested and get back to you with the data. I might be able to contribute for once!

[simmons0]

http://www.rib.net/forum/showthread.php?t=4422

Have a look at this thread. You could drop him a line and see what he decided on in the end.

[Robbie D]

Just wondering if anyone here has ever considered using 4 stroke outboards. The new honda bf150's seem like they'd be a good option if it weren't for the price. I just can't seem to find any head-to-head comparisons on the hondas vs. the Opti 150's... feul comparisons, low-end torque, the basics. Anyone here run the numbers?

[Manos]

The numbers is not important at this stage for the 4-strokes (in my opinion). These engines have not been proven yet since there is not much data about them and they haven't been around long enough. I think in the next 5 years we will see whether they are good or not.

On another note, not to forget that people use these engines in fresh water, or those who are using them in salt water do not leave their boats in the sea for months on end so there is not that much date regarding durability in the salt environment.

I really want to see and know if there is any data available on how a car engine (4-strokes marine engines are car engines) manages if is left say for 6-7 months in the sea at a time without being washed with fresh water at all during that time. Would it work??

[simmons0]

I really want to see and know if there is any data available on how a car engine (4-strokes marine engines are car engines) manages if is left say for 6-7 months in the sea at a time without being washed with fresh water at all during that time. Would it work??

The suzuki 4 strokes arn't car engines.

[Manos]

Didn't know that. Thought all of those 4-strokes are car engines.
Do you know what's the difference with the Suzukis?

[simmons0]

I know that the suzuki's were built as a marine outboard engine as opposed to all the others which are marinised car engines.

[John Kennett]

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

[Rogue Wave]

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

[tim griffin]

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.
regards tim
www.griffmarineservices.co.uk

[Robbie D]

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

[simmons0]

Work on 10 litres per hour per merc diesel.

And the optis? 30 lph per engine?

[Robbie D]

Originally Posted by simmons0

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?

[simmons0]

Well my mercruiser is still in its box so i cant be of much help.

[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 !

[Robbie D]

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...

[tim griffin]

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
www.griffmarineservices.co.uk