Boat Fuel Economy Pt. 2 – Gas vs. Diesel

Published On September 30, 2015 | By Mark Baese | Recreational Boating

In part 1 I looked at my boat’s fuel economy. I used 1 mile per gallon as my average. Although, that’s just my best guess looking other similar boats with similar engines. It’s possible that driving it in its most economical state I could hit 1.5 mpg, but that’s not a good real world scenario. To achieve that, I would need to use my boat’s absolute lowest speed – which is essentially idle. For my boat, that’s 650 rpm. A crawl really. It would sip gasoline though.

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The reason for exploring fuel economy at all is that I tried to calculate how much it would cost to do The Great Loop. I know the distance was around 5000 to 7000 miles, and if I knew the fuel economy, I could estimate cost. By using the fuel guide from this site, I can average it out to around $4 us a gallon. That’s conservative. I should be able to get it for cheaper.

Using 1 mpg as a our benchmark, and $4 per gallon as our price, let’s go crazy and do the long route of 7000 miles. That’s $28,000 USD in fuel. ($37,400 CAD).

That’s the reason for today’s article. Can I do better with a diesel boat?

Ranger Tug R-29s

This is the R-29S, the new model we toured at the boat show. Our example below uses the older model R-29.

For this example, we’re going to use the Ranger Tug 29 – a boat high on our list for doing the loop. It comes highly recommended by others. It’s also a boat we saw at the boat show and we will be posting our video review of that in the coming weeks! Subscribe to our youtube channel and sign up for the newsletter so you don’t miss it.

The new Ranger Tug R29s is powered by a Volvo 260 HP D4 common rail diesel engine. If we use the numbers from others who have used the older model ranger tug to do the loop, we can see they basically were getting almost 4 mpg on an older model. So we’ll use 4 mpg as our baseline – even though we can probably do better on the new engine. We’ll also use $4 per gallon as our base diesel price even though current prices suggest we could get it for 25% less. We’ll be conservative in our estimates.

That means for the same trip we’re looking at $7,000 USD in fuel. ($9,400 CAD). That’s a fairly significant savings. If the new engine is more fuel efficient, and we get diesel below $3 usd a gallon, well, that’s a massive savings.

Fuel shouldn’t be the only consideration – and for us it isn’t. Diesel engines generally cost more to maintain and repair that their gasoline counterparts.  Hence the debate – Gas vs. Diesel.

Vizsla Boating

Pretty sure this is how George and I would spend our travel days on the Great Loop.

Diesel engines can also be pricier up front. So, even though we’d save 20k on the trip, is it worth it for the extra maintenance costs? I’d think on a trip like the great loop it would be, just due to the distance covered so quickly. However, if you’re a seasonal boater, like we currently are, running only 50 to 100 hours a year would almost certainly not be worth the fuel savings. All the yearly maintenance costs would outweigh the benefits of fuel economy. When things break, they tend to be more to fix.

There’s a great article about this here, which basically states all the various expenses tied to running a diesel boat seasonally. The nuts and bolts of it are that in a small boat you run seasonally, gas is more cost efficient. In a large boat you run often and further, the diesel will save you cash.

The other thing to keep in mind, is that the most fuel efficient new and modern express cruisers can expect to get 2 to 3 mpg on gas engines in the same 30 foot size range. Most of these tests are done at optimal settings however. The numbers I’m using for the Ranger Tug are more real world.

We’ll be exploring a lot of boats for our Great Loop adventure, but the gas vs diesel debate is pretty clear in terms of fuel mileage. I think for the loop, we’ll want a diesel for the range and savings.

Why are we not taking our boat? There are a number of reasons our boat isn’t ideal for doing the great loop which will explore in a future article. Sign up for the newsletter so you don’t miss that story.

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