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Old 17 August 2009, 10:50   #81
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Rupert, I do my own servicing and it costs little and is simple to do, so any servicing cost you figure into your buying choice will depend on the level of ripoff factor your marine engineer is used to applying. Presuming, of course, you aren't diy-ing it.

Your choice of power, diesel/outboards, should mainly be based on what you expect from your boating. These engine types produce a very different driving experience. You need to have good, lengthy test runs in both types, go home and swither about it then possibly do it again before laying out your cash.
Availability of fuel would be my high priority, as Polwart mentioned. If you fall in love with your boat, you may find yourself going places you didn't initially consider.
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Old 17 August 2009, 10:53   #82
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Jwalker

Some good point to ponder on. Thanks.
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Old 18 August 2009, 06:49   #83
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A twin engine rib with an inoperative engine, will have a better chance of maintaining hull speed,than using an aux. Mainly due to the fact that the larger twin engine will have a larger prop turning slower, creating more thrust than a small aux with a smaller diameter prop turning faster creating less thrust. For displacement speeds, a large prop turning slower is more efficent and creates more thrust.
If you can get he rib on the plane with one inoperative engine what a bonus. If not at least you will have a better chance of making headway.
One thought, If you were flying over a mountainous area in a light aircraft and the engine failed would you rather another engine on the other wing be the same size or a little aux instead.
regards
rpm
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Old 18 August 2009, 07:04   #84
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RMc

If you were flying over a mountainous area in a light aircraft and the engine failed would you rather another engine on the other wing be the same size or a little aux instead.

A little aux is quite sufficient so long as it is geared to fly the craft adequately, even in adverse conditions. I live in a mountainous area some part of the year, and a large part of accidents are caused by visibility problems, so essential is also radar, etc. as Malthouse pointed out in a previous post.
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Old 18 August 2009, 07:08   #85
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....One thought, If you were flying over a mountainous area in a light aircraft and the engine failed would you rather another engine on the other wing be the same size or a little aux instead.
regards
rpm
Neither... I'd rather have a parachute.... You're analogy is somewhat flawed... never seen a plane able to "heave-to" or drop anchor.....
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Old 18 August 2009, 07:15   #86
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jono

parachute not a great idea. Too many wind currents. A gut died last week. Delta plane got blown into electric cables.

When the the helicopter tried to save him (mountaineous area so no other way), the vortex sucked him up and he fell with the chute wrapped around him.
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Old 18 August 2009, 07:17   #87
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Quote:
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If you were flying over a mountainous area in a light aircraft and the engine failed would you rather another engine on the other wing be the same size or a little aux instead.

A little aux is quite sufficient so long as it is geared to fly the craft adequately, even in adverse conditions. I live in a mountainous area some part of the year, and a large part of accidents are caused by visibility problems, so essential is also radar, etc. as Malthouse pointed out in a previous post.
.

You would most probably find the little(hp) aux would have to have a very high rpm (work harder)to create enough torque at the slower prop speed for the same thrust.
As for the people crashing planes in poor visibilty, If they are meant to be flying visually
they should not be flying in those condition, or they should have an instrument rating and a suitably equiped plane.
regards
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Old 18 August 2009, 07:20   #88
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Rmc

Nice quite that simple.
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Old 18 August 2009, 07:48   #89
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One thought, If you were flying over a mountainous area in a light aircraft and the engine failed would you rather another engine on the other wing be the same size or a little aux instead.
I think your argument counts in favour of single engine vehicles...

There are many single engine planes around and they rely on their engine not only for thrust but also to stay up, if your RIB's engine also kept you afloat would you need two?

Planes with one engine are maintained like their pilot's life depends on it, why not apply that thoroughness to a boat?

If a twin engine plane suffers unrecoverable engine failure it becomes an emergency, this is not always the case with boats but I think it mostly should be (see my previous post on this topic).

All of that said there is a local twin outboard boat that can quite happily get around on one, so much so I have suggested to the owner that he gets rid of the redundant one! He will go about as fast as he currently cruises and half his running costs. The boat used to go out in all weathers and work close in to rocks with 6 knot tides running, so the twin installation was a good idea.
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Old 18 August 2009, 09:42   #90
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Plenty of single engines helicopters as well - including the most common of all - the Jetranger and my favourite - the Hughes/MD Defender as from Magnum.

The smallest twin engined helicopter is the MBB105 which suffers a bit from the extra weight.
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