Fuel consumption, optimum speeds etc.

[ds797]

I am considering a 35 foot sport-cruiser (for example Cranchi Zaffiro 34, Sealine S34, Fairliner Targa 34 etc). What I am wondering is can someone advise me from experience what kind of diesel consumption I can expect? Also is there an optimum speed for best range? I am guessing that it would be just on the plane but not flat out.....

Also I might consider a semi-displacement such as Trader 41. Does anyone know how much fuel a boat of this style/size would use?

Thanks for your help.

David.

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[Deleted User YDKXO]

Wow, thats a chalk and cheese comparison. The 34' sports cruisers will be fast, noisy, bumpy and do 1.5 - 2.5mpg depending on what speed you choose. The Trader will be slow and wobbly and do about 0.7mpg at about 16knots. Dont let anyone tell you these things exceed 20knots 'coz they dont
Most economical speed for any boat will be minimum in gear speed ie minimum displacement speed but nobody buys a motor boat to go at sail boat speeds so I guess what you're asking is what is most economical planing speed which, with a full planing hull is, as you say, just beyond hump speed. However, with most planing boats, the fuel consumption does not increase much until you get close to max engine rpm. Choosing a cruising speed on a 34 footer will be more about sea conditions than fuel consumption
On the other hand, with semi displacement craft, fuel consumption increases with speed and sometimes quite alarmingly so

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[mainshiptom]

My boat Mainship 40 does a good 5-7 liter an hour when not pushed at about 7.5 knots, when pushed to 10 or 11 knots still about 10-15 liters an hour.

I carry 1200 liters so range can be very good, Just been up to St kats about 6 hours each way left with tank just over half full and came back with tank just under half full !

Tom

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[zazu]

My S34 with Kad 43s properly trimmed and with clean hull would use 10 gallons/hour total at 24/25 knots. Poole-St Peterport 3.5 hrs. £95 fuel.

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[KevB]

Just in case....

Just a thought. These boats you have mentioned although named XXX 34 are all in the 37' region therefore wont fit on a 10mtr berth. The difference between the cost of a 10mtr berth and a 12mtr berth in the Solent area is at minimum £1000 per annum.

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[ds797]

Re: Just in case....

Any more input PLEASE I need help!

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[jhr]

Re: Just in case....

Probably worth having a look at the <A target="_blank" HREF=http://www.boattest.com/main.aspx>Boattest</A> site. Unfortunately, it's a US site, so it doesn't have much data for European boats, but if you look up similar sized US craft, you are likely to find something with a similar engine configuration which should give you an idea of performance and consumption.

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[PhilF]

Re: Just in case....

loads of fuel and its bloody expensive, what more do you need to know

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[Newbroom]

Re: Just in case....

Semi Displacemaent like the Trader 41 are much heavy on fuel than a planing boat when used at speed. expect to use 8 to 10 galls hour at 10 to 12 knots and 20 to 25 gall per hour at 15/16 knots

Dave


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[jfm]

I agree with Deleted User. 1.5-2.0 mpg ish for the sportscruiser.

We had a fairline phantom 42 (shafts, so more drag than the outdrives on the boats you mention) and got 1.0mpg at 22kt cruise - 2x370hp at 3/4 throttle. We now have a 58 also shafts, and we get 0.7mpg at 24kt cruise, 3/4 throttle

Newer electronic diesels will give you better mpg, perhaps 15% more, something of that order?

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