GPH efficiency?

[Art]

Originally Posted by BandB

Circling back for a moment to the OP. Three points made I believe. One, he likely can reduce consumption of fuel through reducing his speed. Two, fuel for some is a very significant cost and for others isn't. Three, if a $500 expense is enough to run his partner out of boat ownership, there needs to be a serious discussion before considering buying any boat as during the life of boat ownership there will be expenses equal to and in excess of that amount and unlike the fuel, they will be unexpected. Boating can be done at a modest cost but significant costs can and will arise at various points along the way.

Well put!

[Art]

Originally Posted by koliver

Keep the boat.
Get a different partner.
Enjoy

Ouch... Nasty!

[Mrwesson]

Originally Posted by BandB

Wifey B: 37 knots, 0.66 nmpg, 56 gph.

Not saying it's not worth it to some people but is it a major yearly cost of owning that boat?

[dhays]

The last time we got fuel we went from about 1/4 full to full. Cost was about $750 iirc. To me, $750 is a lot of money. However, if I compare that to my monthly cost of moorage and insurance, it really isn’t that significant.

[BandB]

Originally Posted by Mrwesson

Not saying it's not worth it to some people but is it a major yearly cost of owning that boat?

Wifey B: Everyone has to define "major" in their own terms. That's back to the point with the OP. Was $500 major? To his partner it was. Others argued whether fuel is or not. Well, it's what it is to the person talking.

Isn't it about expectations? If it's within expectations, within budget, then I don't think of it as major. If it's a sizable amount you didn't plan for, then it is.

To a non-boater, often the first time they see you fill up with fuel and it's $500 or $2000 it's a bit of a shock. They're use to 15 gallons in their car. To me, golf is shocking. We don't play much and only occasionally with friends who are avid golfers. We're use to tennis and probably my tennis outfits are the most expensive part of the sport. Court fees aren't bad. But golf. Greens fees, cart rental. Not cheap even on a public course, but some of the exclusive clubs, omg sticker shock to a non-golfer. And the really good golfers and all their clubs, they pay $500 and more for a single golf club and it takes 14+. We have two girl friends who are scratch golfers and they don't buy their clubs at Walmart.

[toocoys]

Originally Posted by BandB

Circling back for a moment to the OP. Three points made I believe. One, he likely can reduce consumption of fuel through reducing his speed. Two, fuel for some is a very significant cost and for others isn't. Three, if a $500 expense is enough to run his partner out of boat ownership, there needs to be a serious discussion before considering buying any boat as during the life of boat ownership there will be expenses equal to and in excess of that amount and unlike the fuel, they will be unexpected. Boating can be done at a modest cost but significant costs can and will arise at various points along the way.

While I appreciate the life advice, it's not what I'm hear for.

However, for the record, we are having that discussion now. We will probably be boatless for the rest of the season this year, and we've agreed to not buy another boat unless the both of us completely agree on it.

At this point we do both agree that we need better fuel efficiency, more range and room, and hopefully a single engine if we can find one.

[Simi 60]

$500 a month is nothing if you live aboard at anchor.
Its a lot less than rent and mortgage repayments on dirt dwellings.
Lifestyle is dramatically improved.

[toocoys]

Originally Posted by Simi 60

$500 a month is nothing if you live aboard at anchor.
Its a lot less than rent and mortgage repayments on dirt dwellings.
Lifestyle is dramatically improved.

We're working towards that. We sold the sticks and bricks back in 2016 and have lived full time in our RV since. Our RV is about 1/2 a mile from the marina. One day we hope to live aboard.

[alfamike]

Kadey-Krogen 42.

Full Displacement Single Engine Diesel Trawler.

Weight 39,500 Lbs. dry & empty

7.8 Knots = 2.0 GPH

6.0 Knots = 1.1 GPH



Alfa Mike

[smitty477]

Originally Posted by toocoys

While I appreciate the life advice, it's not what I'm hear for.

However, for the record, we are having that discussion now. We will probably be boatless for the rest of the season this year, and we've agreed to not buy another boat unless the both of us completely agree on it.

At this point we do both agree that we need better fuel efficiency, more range and room, and hopefully a single engine if we can find one.

"At this point we do both agree that we need better fuel efficiency, more range and room, and hopefully a single engine if we can find one.[/QUOTE]"


Just a thought - running slow will increase your fuel use by 400% or more, which will increase your range by 4X and you can cruise with one engine if your trans is of a type that will allow it.

[OldDan1943]

One or two diesel engines may be immaterial. One must learn to control the throttle (s). If one buys a "true" trawler, the hull speed will be 7-8 knots. Trying to push it to a higher speed will only increase the fuel consumption without a significant increase in speed.
The size of the engine (hp) is generally dictated by the size and weight of the trawler.
Even a fast trawler has a "sweet spot". Exceeding that RPM will increase the speed but, at the sacrifice of fuel economy. To me, buying a "fast trawler" affords me the opportunity to try to outrun the weather and or picking the tidal stage and time for entering a harbor or going through a "cut".
Dont know your "sweet spot", start at the middle range of your maximum RPM. That should be close. I will add, some naturally aspirated engines are designed to run close to 3/4 of the maximum RPM. An example would be the marine version of the John Deere, naturally aspirated engine.
IF you have a Flow Scan or some other method of determining the fuel consumption, you will be able to nail the "sweet spot".
If you cant live in the slow lane, don't buy a trawler and don't complain about fuel consumption.
A side note; consider your boat as a really BIG heavy car. You don't expect the greatest fuel economy running at 100 mph.

[toocoys]

Originally Posted by smitty477

Just a thought - running slow will increase your fuel use by 400% or more, which will increase your range by 4X and you can cruise with one engine if your trans is of a type that will allow it.

Running one engine only on long straight courses has never even crossed my mind.... But at slower speeds I bet that could be very effective. I'll have to research any potential trans issues that it could cause.

[Art]

Originally Posted by toocoys

Running one engine only on long straight courses has never even crossed my mind.... But at slower speeds I bet that could be very effective. I'll have to research any potential trans issues that it could cause.

Borg Warner Velvet Drive:

Velvet Drive Transmissions

[FF]

Folks that want " high" efficiency need to have a custom boat built.

Things like a variable pitch prop or a 2 speed transmission are not found in production cookies.

Weather their cost could ever be recovered in normal recreation operation is doubtful.

At displacement speeds a 20% savings on a burn of 2-3 GPH takes a long time to save $20.K


Crossing an ocean 20% better range , could make a difference.

[OldDan1943]

Last week a 30 ft, planning fishing boat, left out of here headed to the islands then, on to Mexico. They had 2 or 3 fuel bladders onboard.

At some point, the weight of the extra fuel will drag down the GPH so all benefits are lost and effect the boat's stability and trim.
In reality, one can add fuel bladders, eliminating the need for refueling but, unless one is not going to stop for food, I question the benefits of bladders.

When they left, the bladders were empty and neatly folded in the cockpit.
It would have been interesting to see how the boat trimmed out after the bladders were filled and in the cockpit, plus all the extra food, filters and spare parts etc.

It is almost like they were into self abuse.

[Mrwesson]

I'd ditch the boat and go with a single diesel in the 28-34 range that is semi displacement.

Could run hull speed and get awesome MPG or run 15-20 knots with a crew to help with gas.

I also looked at a Trojan 28' with a single Crusader 360 that got around 2mpg @ speed and decent mpg @ hull speed(around 2.5) for comparasion my Mainship 34 which I use for fishing often gets around 5mpg @ hull speed. The Mainship is also much much larger.

$500 for fuel is alot and short of the guys who live aboard and have 40'+ boats in prime locations is a major cost factor.

I fill up my boat once or twice a year on 220 gallons and I use it alot. I spend $300 a month on storage with electric/water/etc and DIY most things.

I'd flinch hard @ spending $500 on fuel for a weekend and I make good money.

[bayview]

I had a 38,000#, 44' ACMY with twin 450 HP diesels.

I got 3+ NMPG at 6 KTs. Bow was fully down and wake was insignificant
2 NMPG at 8-9 KTs. Some bow lifting was starting and wake was forming
0.5NMPG at 20 KTs. Fully on plane lots of wake.

8-9 Kts was our most common cruise speed for day trips. 20 Kts was reserved for longer offshore passages. This cruising pattern was because we enjoyed it and in the ICW with traffic etc is was more relaxing.

I could pick my fuel use for any trip. Those figures are probably typicalfor boats of that size and weight independent of engine size.

[OldDan1943]

I'd go with a naturally aspirated diesel if at all possible. Buy a comfortable captain's chair, sit back and enjoy life in the slow lane.

[Art]

Originally Posted by Art

7.58 knots is calculated speed for hull WLL of our Tolly. We often cruise somewhat under that at 6.5 to 7 knots for fuel efficiency. At that speed we get just under 2 nmpg using both engines. If we shut one engine down, leave other prop freewheeling [BW Velvet Drive trany is OK with that] and cruise at 4.5 to 5 knots our Tolly approaches 3 nmpg. When we want to cover some distance on plane we push throttles up and cruise at 16 to 17 knots doing right around 1 nmpg. WOT is 21 to 22 knots and OMG fraction of nmpg. I only ever use WOT when absolutely necessary or required... such as at first sea trial, when testing an engine repair and very seldom for a minute or so if things get too hairy on the water due to some sort of confusion that needs to be put behind us or that we need to immediately veer away from.

The above is a [partial] quote from my post #76. Simply stated are a few different speeds and engine usages. Any boat's use and ways of use can be contoured by the boat's Captain to attain big fuel use #'s or reasonable fuel use #'s. Fast costs money... but, you get there sooner. Slow saves money... but, your get there slower.

The feelings attained during both fast and/or slow boat speeds have their own attractions regarding personal enjoyment[s] derived while cruising; irrespective of fuel $$$ spent or saved.

[Stillwater]

Originally Posted by Steve91T

My 31’ Mainship with twin 454’s gets roughly 1 MPG at 7 kts. If you were to run her at 20 kts you’d be looking at at fuel flow similar to a DC3.

Love this. While comment is hilarious, it's funny mainly because its true...