Fuel d6 x 370 hp

I did a 110 miles trip last week in a Rodman 38 with a deep V and a keel and averaged 0.8 mpg at 18 knots (I was feeling brave and recorded everything from full tanks to full again) - about a 1/3 of the way was lumpy, the rest pretty flat in the med.
So:

Switch got @ 1.12mpg (@ 110 miles on google earth) dartmouth to solent with IPS in Jeanneau 42?
ICTM got @ 1.25 mpg on outdrives in a Sealine S38?

anyone else prepared to fess up the diesel bill?
 
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We are on a long holiday so will report back on all the fuel stops and millage ,just to be strait i am not shocked of usage just wondered what is sort of normal ,we have been pushing the tide north ,maybe i wont use any fuel on the way back :
 
tbh I only know what I spent on diesel when I total up at the end of the year. Therefore I can confidently say that what ever the cost of fuel is it obviously isn't hurting me. I guess Roy is just feeling the pinch now he has this flash new monster to bully the raggies in the channel with. :D I think I calculated after my first year of ownership that my fuel economy for that season to be 2.7 lpm / 0.6gal(imp) pm per engine across the spectrum in a 34 foot 8 ton sports boat with rather under propped C3's on. Which is about the same as yours.
 
ICTM said:
Just by way of comparison.........Same trip last week ! Topped up at Cowes and then on arrival at Dartmouth - 403 litres. D4 300’s sterndrives on a 40’ Sealine cruising at 22-24 knots.
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Same trip as what? Do you mean 113 miles like to OP? If so, and in a similar boat then you are looking at 1.28nmpg. I would have though it would be slightly less mileage from Cowes to Dartmouth than 113, but depends on your route I guess.
 
seastoke said:
So 113 nm 21 knots how much fuel would u think
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Our Bavaria had D4 260s and with clean everything 2,300 rpm + c23 knots, late 50s LPH - we had a total fuel data. Now have D6 370’s (again on stern drives), and despite not having total fuel data, estimate c75lph, at similar revs and speed, which gives a reasonable correlation to 2 extra cylinders......
 
anyone else prepared to fess up the diesel bill?

I get circa 4.5 nautical miles per gallon at the most economical planing speed(25knots) this is in a 25 foot , single engined (VP d4. 260) , outdrive boat. Feels like a Prius in this thread compared to those gas guzzlers.
 
CLB said:
Same trip as what? Do you mean 113 miles like to OP? If so, and in a similar boat then you are looking at 1.28nmpg. I would have though it would be slightly less mileage from Cowes to Dartmouth than 113, but depends on your route I guess.
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Should have made it clearer - apologies to the OP I was responding to Switch - “did a similar distance down to Dartmouth from the Solent last month. I have D6 370's (IPS). My fuel burn was around 430-450lts. I was doing 25knots but the conditions were perfect (flat sea).”

Just to allow anyone who is interested to roughly compare fuel guzzling.....boat is a Sealine 365, 40’ LOA, D4 300’s with sterndrives, out for a scrub the week before so clean copper coated hull. Cowes to Dartmouth via quick stop at Studland and well offshore past Lulworth and Portland Bill, a little bit of searching for dolphin photo opportunities across Lyme Bay, 110 nautical miles, give or take a couple.
 
Just done a crude spreadsheet for @ 40' mobos, based on the fuel burn figures quoted on here, and service costs for the various drive systems as discussed on a recent similar thread. I have only considered fuel and service costs for the shaft/outdrive/ips systems. Engine servicing costs about the same regardless of drive type. By all means point out the errors in my assumptions if you think I am wide of the mark. I have assumed diesel is £1/Litre to keep the maths simple. I am not anti outdrive or IPS etc, looked after properly they work very well, but they do need to be properly looked after. However depending on your own actual boat usage (annual mileage - not hours) it might surprise you.

average drive system service costs for typical 40' boats:-
shaft drive system annual service - change oil every five? years plus cutlass bearings once in a blue moon @ £50 per year for two
outdrives - oil and anodes every year, every two years bellows, anodes etc - @ £500 per year for two
IPS - oil and filters (and anode?) every year, plus rubber donut thing changing every 5 years? - @ £1000 a year for two

fuel consumption at cruising speeds from recent posts on this thread and past experience on other similar boats:-
typical 40' flybridge or shaft drive cruiser 0.9mpg
popular 40' targa style boat on outdrives 1.25mpg
42' hard top targa style boat on IPS 1.12mpg

An outdrive boat is cheaper than a shaft drive boat once I do more than 400 miles a year - so Dartmouth to Solent return twice a year
An IPS drive boat is cheaper than a shaft boat if I do more than 900 miles a year - so Dartmouth to Solent return 4 + times a year

Once past the 400 mile mark, a shaft drive boat will cost an extra £150 per 100 extra miles than an outdrive boat.
Obviously every boat is different, sea state affects fuel consumption etc etc, but food for thought when choosing a boat.
Also If the boat is less than 5 years old depreciation will most likely be the biggest cost of all.
 
No doubt your maths is correct but again it is just one side of the picture. To get the big picture you also need to factor in berthing costs and purchase price and depreciation to get a full picture. I havent been on more than a handful of 40 foot shaft driven boats but those I have have comparable living space to my 34 foot outdrive boat. Now the price per meter LOA for an extra meter is not to big a hike for an extra meter or two in your example except the price from a 10m berth to 12 is another jump. 12m berths in my locale are in short supply, 10 isn't so it also limits choice of marina. a 40 footer is also in the next order of engine size up and so too the fuel economy takes a hit. So does price of purchase and maintenance. One cannot just compare the two on such a simple basis imho when everything is a compromise to maximise what your model boat has to offer.
 
kashurst said:
I did a 110 miles trip last week in a Rodman 38 with a deep V and a keel and averaged 0.8 mpg at 18 knots (I was feeling brave and recorded everything from full tanks to full again) - about a 1/3 of the way was lumpy, the rest pretty flat in the med.
So:

Switch got @ 1.12mpg (@ 110 miles on google earth) dartmouth to solent with IPS in Jeanneau 42?
ICTM got @ 1.25 mpg on outdrives in a Sealine S38?

anyone else prepared to fess up the diesel bill?
Click to expand...

you lot are making feel much happier about Seralia's fuel consumption.
I get about 0.5mpg on the plane but shes 50ft and using vintage (that's being kind) Detroit 2 strokes

Did SCM to Andratx on Sunday - 12 hours at 8knts ish and 1 hour at 19 knts. total distance of 106nm plus some marina work before hand and topped up with 477 litres.
 
Whitelighter said:
... Did SCM to Andratx on Sunday - 12 hours at 8knts ish and 1 hour at 19 knts..
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wow I admire you patience, I've just completed about 400nm over the last 3 weeks, I try at 8 knts but just get itchy feet and only last for 45 mins before back on the throttles
 
you are 10000% correct, get it spent, the kids will just waste it on something stupid like errrrr a boat!

PS it's the engineer in me, can't help myself
 
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