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Old 01 July 2005, 10:27   #11
Country: UK - England
Town: nr Lymington
Boat name: JU-JU
Make: Halmatic PAC22
Length: 6m +
Engine: 140.5 Mermaid
Join Date: Sep 2003
Posts: 1,400
Look at this Might be interesting Des

Scary Des is offline   Reply With Quote
Old 01 July 2005, 11:02   #12
Country: UK - Scotland
Town: Largs
Boat name: Spitfire
Make: XS850
Length: 8m +
Engine: 2 x 200 Verado
MMSI: 235905304
Join Date: May 2004
Posts: 174
Hi Pettal,

The problem with diesels will always be the engine legs - Yanmars are great engines but the Mercruiser Bravo legs (their standard counterpart) can certainly be troublesome.

I went for the 250hp Yanmar coupled to the Bravo 3X leg, because at the time (late 2002) the 300hp Yanmars appeared to be blowing even the 3X legs. The leg has now done 330 trouble-free hours. The engine and transom installation have completed 620 hours. The leg was replaced at 290 hours because I discovered that Barrus hadn't given Barnet Marine the 3X leg - I had the "bog-standard" 3 installed. (By the way, Laurence Lock was most attentive in resolving this problem, as ever). The steering pin in the helmet now needs replacing (the helmet has completed 620 hours), but apparently that is fairly common in RIB/diesel installations.

There are huge advantages to diesel - availability, price, economy, safety etc. But there are some downsides - servicing is more expensive (leg every 100 hours, engine every 120 hours, about £500 inc VAT in total). And you don't get the same accelaration "off the mark", although once you are in the turbo range (about 18 knts+) throttle response is pretty rapid. You also need a reasonable waterline length to offset the weight of the diesel engine, but I'm sure Laurence will have already given you good advice about this. He was the one that talked me into the Tornado 8.5 and I have to say it performs even better than he suggested. The rough water handling isn't limited by the boat, only my fear!

I'm not sure about the reliability of the new Volvos yet (D3/D6 etc) - Jeff Walker would probably be able to give good advice on the D6.

Waterjet drives seem to be more reliable, but the handling in rough water can be compromised.

I know that there were problems with the early Yamaha Hydradrives (search previous threads on this forum), but Tom MacLaughlin (Redbay boats) says that he wouldn't fit anything else, so I guess that speaks loads.

Good luck with your decision - I can assure you that it's a minefield and one that I've walked every inch of!

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Old 01 July 2005, 13:43   #13
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791

Have a look at this - brilliant site with spec on most engines - saves going to all the different makers sites!!!
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Old 01 July 2005, 14:27   #14
Country: UK - England
Town: Bradford on Avon
Boat name: tbc
Make: Sunseeker (AshleyD)
Length: 8m +
Engine: 2 x coal burners
Join Date: May 2004
Posts: 461
As always, this is a very interesting debate. I wonder weather it really boils down to factors other than money at the end of the day?

For example a large rib encourages longer passages, which means the availability of fuel at ports becomes more important. You can always get diesel but petrol? Forget it even at some large ports such as Weymouth.

Also, I am informed, that a diesel rib runs “flatter” in the water than an outboard equivalent. Effectively it goes through most of the waves rather than flying over them, and therefore provides a more comfortable ride?

As a counterpoint however, I heard an interesting conversation at Ribex recently, between a customer and a manufacturer. The guy already has a 10m cruiser with twin Yanmars, but is considering outboard petrol units for his soon to be ordered new cruiser, because of the uncertainty over fuel duty and the increased cost of buying, installing and servicing the diesel units.

Finally, I have always wondered about surface drives. It seems to me that the problem with inboard legs is the number of joints in the legs and the amount of power being transmitted through them. So why aren’t surface drives more common? Is it cost, steering problems, or perhaps trimming issues in rough water?

Any thoughts on this?


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Old 02 July 2005, 04:26   #15
Country: UK - Scotland
Town: Inverkip
Make: Redbay 11m Cabin
Length: 10m +
Engine: 2 x Yamaha422Sti 275
Join Date: Feb 2003
Posts: 567
Originally Posted by pettal
For the on-lookers:
Surely it's not £5k's worth of more difficult sticking a diesel engine and stern drive into a rib than it is chucking an outboard on the back!?
If you were to cost out things like engine bearers, engine covers etc etc that would be about right.
Hard or Soft it's never BIG enough
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Old 05 July 2005, 08:21   #16
Country: UK - Channel Islands
Town: St Peter Port
Boat name: Black Pig
Make: XS-Ribs
Length: 9m +
Engine: 2 x 225hp Optimax
Join Date: Sep 2004
Posts: 375
Thanks for all your comments/help/suggestions!

I'm still not 100% on going either way as you've all said there are up's and downs to both.

I'll have to sit doen and work out exactly how much fuel etc I'm using as I seem to be filling up the 170ltr tank every other week and although Guernsey is roughly half the price of UK petrol it still stings a bit.

On another point I'm suprised at the amount of servicing the legs need. I had another boat that had a bravo leg on it which got used every week. The boat got serviced once a year with no problems!?!? Am I just lucky???

Which part of "throw me the mooring line" didn't you understand!?
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