Diesel burn rate

[Perfect Excuse]

Has anyone calculated the burn rate for a Yanmar 50 on a Hunter410 at about 2000 rpm? I understand that this will vary with conditions, so I am looking at rough figures. I am planning a trip from Victoria, B.C. to San Fran and I attempting to ascertain the amount of diesel I should have as a minimum.

 

[FastOlson]

Difficult to say...

Has anyone calculated the burn rate for a Yanmar 50 on a Hunter410 at about 2000 rpm? I understand that this will vary with conditions, so I am looking at rough figures. I am planning a trip from Victoria, B.C. to San Fran and I attempting to ascertain the amount of diesel I should have as a minimum.

That's an interesting question, and only repeated trips in the same boat could even start to build a set of stats to answer it...
You're not the first mariner to ponder it, either.

I have crewed one trip from Astoria to SF, on a 36 footer. We carried several jerry cans on deck and about 40 gallons in the tank (that's a guess, since it's been a decade). We sailed all but the last 8 hours, closing in on the Golden Gate. No fuel shortage at all!

Prevailing winds are strong to carry you down the coast, and there's almost always a corresponding surface current to assist you.

You can add fuel along the way if needed, of course. It rather depends on how far out you plan to be from the coast. For instance, one good stop with an "easy bar crossing" is @ Newport OR.

Only vital piece of boat equipment, other than the engine to charge batteries, is a really good wind vane. Our Monitor (just one good brand among several choices) worked tirelessly, even through a 36 hour gale while transiting Cape Mendocino.

It's a great trip!

 

[anchorclanker]

Google the engine model with fuel chart, dyno chart, fuel flow, graph, etc.. You may have to search a while but its likely someone posted a chart somewhere showing fuel burn at various rpm.

Alternatively you could rig a clear graduated/calibrated beaker of some sort to the feed and return lines and measure it directly, which would give you a much more accurate measure.

 

[pfaffk]

I would think the burn rate would depend on a number of different factors. RPM you run at. how heavily loaded the boat is. Current, etc. I have a Hunter 290 with a 2GM20F Engine, and only after a number of longer trips I was able to calculate that I burn about 1/2 gallon per hour.

 

[SV Escapade]

Escapade is a 41DS. We generally run the aux at 2750 rpm. Just refueled after 25 engine hours. Most of those hours were with 20kt headwinds. (5 hours @ 2000 rpm to ensure arrival in daylight) Fuel burn was right at the lifetime boat average of 1.19 GPH.

 

[Don Lucas]

Has anyone calculated the burn rate for a Yanmar 50 on a Hunter410 at about 2000 rpm? I understand that this will vary with conditions, so I am looking at rough figures. I am planning a trip from Victoria, B.C. to San Fran and I attempting to ascertain the amount of diesel I should have as a minimum.

My experience at that rpm is about 0.6-gph in flat seas and calm conditions at about 5 knots. But I always plan on 1-gph for passage making.


Near as I have been able to tell 2000 - 2200 rpm seems to be the most efficient combination of boat speed to fuel use on my 410 with my 3-blade FlexoFold prop.

 

[Benny17441]

The burn rate will not change with conditions, only the boat's speed and range will. The Yanmar 50 should have a burn rate of 1 GPH on the average. On the specs for the h410 it indicates a fuel capacity of 50 gallons. Since not all of it is usable I would base my calculations on 45 gallons. You should have enough fuel for 45 hours. Now the distance that you may be able to travel in those 45 hours will depend on the prevailing conditions at the time of travel. You may base preliminary calculations based on anticipated fair conditions that will allow you to travel at 5 knots. By these preliminary calculations your boat may travel 225 nm before neededing to refuel. This figure may be extended or shortened depeding on the actual conditions encountered on the water. I would take an extra jerry can with 5 gallons of fuel in case of emergency and plan on refueling stops every 35 hours. Your boat will have a unique burn rate and you can easily calculate it when refueling by seeing at the pump how many gallons were taken on to full and dividing it by the number of hours since last fill up. Just keep a log of the hour meter readings at fill ups. The average calculation will take into consideration the various ranges of engine RPM that you customarily travel at. Sailing and even motor sailing will increase the boat's range. If you have to pound against wind and currents then keep your eye on the hour meter.

 

[Perfect Excuse]

Thank you all for your input. I have been considering sailing roughly 100 - 125 miles out attempting to catch a decent current south, while avoiding fog, the shelve and traffic. Does that sound reasonable? Friends in a similar boat made the trip in 5 1/2 days. I would like to be comfortable maintaining a 5 knot minimum. For myself, time offshore is not important, but my wife has concerns about limited access to harbours along the Washington/Oregon coast and therefore would like to limit the time spent on that leg. I respect her concerns, so seek to minimize them. Any other advice?

 

[Claude L.-Auger]

Thank you all for your input. I have been considering sailing roughly 100 - 125 miles out attempting to catch a decent current south, while avoiding fog, the shelve and traffic. Does that sound reasonable? Friends in a similar boat made the trip in 5 1/2 days. I would like to be comfortable maintaining a 5 knot minimum. For myself, time offshore is not important, but my wife has concerns about limited access to harbours along the Washington/Oregon coast and therefore would like to limit the time spent on that leg. I respect her concerns, so seek to minimize them. Any other advice?

Your respect for your wife's concern are understandable so you need to evaluate fuel burn and time to get 100 - 125 miles out. Estimating 1 GPH & 5 knots, you're looking at between 20 to 25 hours, thus also 20 to 25 gallons, i.e about half your available tankage just to bring her back close to shore if needed. I understand that these are not straight lines out and back, but when you're that far offshore, the shortest distance to land (not necessarily an inlet !) is at least that far away and you would need that much time and fuel to reach it ! I suggest you do serious calculations before deciding if it's worthwhile based on estimated length of time for the trip. Overall, It may not be worth it to go this far out.