Considering a Motor Yacht and Fuel ( for the Mrs. )

[Bash]

Originally Posted by SouthernHiker

Today, went to the Atlanta Boat Show where they told me by phone there would be LOTS of sailboats (there were 4 all small ten footers).

It's clear that you went to the wrong boat show, and as a result you're not currently thinking clearly. Nor is your better half.

Sit down. Breathe. Down a stiff shot of bourbon. Remind yourself that fuel prices should be going up at least 25% between now and summer.

Feeling better? Okay. Now, what have we learned?

LESSON: If a boat show features ANY powerboats, any at all, it's the wrong show to which to take your spouse..

[SouthernHiker]

Originally Posted by Bash

It's clear that you went to the wrong boat show, and as a result you're not currently thinking clearly. Nor is your better half.

Sit down. Breathe. Down a stiff shot of bourbon. Remind yourself that fuel prices should be going up at least 25% between now and summer.

Feeling better? Okay. Now, what have we learned?

LESSON: If a boat show features ANY powerboats, any at all, it's the wrong show to which to take your spouse..

Thanks for the reminder Bash.

Went I got back from driving in ATL traffic on the same night as the Falcons' playoff game next door, I had that shot of bourbon. You're right, I think I made a few errors that day, but only b/c I was misinformed about the existence of sailboats at a boat show. I did get to sit through an enjoyable "how to charter a sailboat" seminar while there though.

[markpierce]

I expect to get between 0.5 and 1.0 gallon per hour at six to seven-something knots for a 35x13 foot steel (heavy) trawler.

A true recreational trawler shouldn't (be able to) go faster than hull-speed. Any faster and you're a "speed boat" with a large fuel penalty.

[BessLB]

We have a 35' Sundeck trawler, single diesel Perkins 135. We run at 7-8 kts per hour and burn about 1 gallon per hour. Lots of room to relax in the cabin and on the sundeck. If your wife likes to be on the water, but not actually sailing, a trawler might be the ticket. We went with a trawler because we didn't want to sail, and we didn't want to pay fuel for an express cruiser. We love it!

[kenny chaos]

Are you guys embellishing your fuel rates?
I've been studing a bazillion boats on yahtworld and
the specs seem to show 26-28 footers will get 1gph
and by the time you're at 34-36 footers, most seem to jump up to 2 or 3 gph or more.
Yes, single diesels.
I'm not trying to put anyone on the spot, I want to know because fuel consumption
is going to help determine what size we ultimately end up with.
Thanks for some insight.
Kenny

[ActiveCaptain]

Originally Posted by kenny chaos

Are you guys embellishing your fuel rates/?

It very much matters what type of boat is being looked at and the speed at which it is moving. You can't just go by the number of feet LOA and get any type of fuel burn factor.

I can tell you that I've tracked every drop of fuel I've consumed in the last 8 years and 20,000 nm. I have a 53' trawler with twin John Deere engines. Pushing our boat at 7.6 kts, we burn a total of 3.5 GPH. That's total, not each engine.

Bumping things up to 8.9 kts, our burn rate jumps to 8.0 GPH. That gives a pretty good example of what speed does especially as you approach the hull speed (1.34 * sqrt(water_line_length)). Fuel burn is far from linear.

[BessLB]

It's true, running at 1900-2000 rpm and 7-7.5 kts, we burn approx 1-1.5 gallons per hour. If we run at 2100-2200 rpm it jumps to 2 per hour. It all depends on speed, sea conditions and rpm. You can burn alot more, but you won't be going much faster.

If you're in a hurry, you either don't buy a trawler, or you leave a day ahead of schedule!

[SouthernHiker]

Originally Posted by BessLB

It's true, running at 1900-2000 rpm and 7-7.5 kts, we burn approx 1-1.5 gallons per hour. If we run at 2100-2200 rpm it jumps to 2 per hour. It all depends on speed, sea conditions and rpm. You can burn alot more, but you won't be going much faster.

If you're in a hurry, you either don't buy a trawler, or you leave a day ahead of schedule!

So essentially with a trawler at this rate...a motor to the Bahamas from FL would take you about 15 hours?

and cost between $60-100 in fuel?

Do you see any significant savings in boat maintenance (I'm thinking the cost of sails, sailing rigger, etc... mainly).... or does that come out in additional motor maintenance?

[Mav]

I have often wondered if those with twin engines on planing hulls only motor on one engine. I am about to do 300nm on a 36' planing hull Silverton Express cruiser with twin 454 engines coupled to V drives. The boat holds 286 US gallons split evenly between two tanks, one for each engine. So each engine has a fuel supply of 143 US gallons.

If running only one engine and not pushing the speed, maybe running at 7K, I am wondering how far I could get on one fuel load?

With 1k = to 1 nm/hour I reckon I should be able to complete the voyage in 5.5 days traveling 8 hours per day.

Using Foggysails numbers for his Silverton I should be able to do the 300nm on one full load of fuel running one engine @1500 RPM, I may be able to go a little faster seeing as my Silverton is a 1998 36' compared to Foggysails 40' 1999 model.

My boat is currently having new risers fitted to both engines and full servicing of both engines including new plugs and fuel filters. Today it had new anti-fouling done so she will be pretty clean for the trip.

I am not adverse to motoring on both engines to get there sooner plus I intend to utilise the EAC where it passes close to the coast to give me the extra few knots for free.

[Pete7]

Originally Posted by SouthernHiker

So essentially with a trawler at this rate...a motor to the Bahamas from FL would take you about 15 hours?

and cost between $60-100 in fuel?

Do you see any significant savings in boat maintenance (I'm thinking the cost of sails, sailing rigger, etc... mainly).... or does that come out in additional motor maintenance?

Interesting question, I suspect the extra money you spend on fuel and engine maintenance is probably the same amount you would spend on sails and rigging if you kept the boat for a couple of decades.

Pleased to hear you have moved away from the sport cruiser market. We had a 24 footer for a year with a small block volvo 5.7l and fitted with a fuel computer. It would read 80 litres per hour (21 US gallons) without too much trouble in flat water. Like I said we only kept it a year.

You should have more room and a better view looking out from a trawler type which SHMBO may prefer. The other option is a motor sailer but one of the newer types which we recently discussed:

http://www.cruisersforum.com/forums/...nce-52965.html

As a point of reference our 31 foot yacht uses 0.4 US gallons an hour at 5.5 knots, a tiny amount or put it another way, I only need a tankfull or two a year.

I do worry about future fuel costs though which is one of the reasons we bought a yacht 3 years ago when UK fuel prices started to become excessive. Time I can afford, we are in holiday mood on board. Queues at airports and expenvie fuel costs are not for us.

Pete

[ActiveCaptain]

Originally Posted by Mav

I have often wondered if those with twin engines on planing hulls only motor on one engine.

I seriously doubt planing on a single engine is a good idea - you'll either use more fuel or damage the second transmission (typically).

What you're possibly not considering is that the prop for the non-working engine is still in the water causing friction. If allowed to freely spin at any speed without being cooled by the engine cooling system, you'll likely cause major damage to the transmission. If you lock the shaft in some jerry-rigged way, then it's just fighting against the flow of water the entire time adding a major inefficiency to the working engine.

There are some transmissions that can spin freely - although it would be unexpected that they could do so at higher speed. Still, even if the prop is spinning, it's taking friction work to move the engine which is taking power away from the other engine too.

It's rare to see a feathering prop on a motor boat but that might make it a more interesting possibility..

[Mav]

Originally Posted by ActiveCaptain

I seriously doubt planing on a single engine is a good idea - you'll either use more fuel or damage the second transmission (typically).

What you're possibly not considering is that the prop for the non-working engine is still in the water causing friction. If allowed to freely spin at any speed without being cooled by the engine cooling system, you'll likely cause major damage to the transmission. If you lock the shaft in some jerry-rigged way, then it's just fighting against the flow of water the entire time adding a major inefficiency to the working engine.

There are some transmissions that can spin freely - although it would be unexpected that they could do so at higher speed. Still, even if the prop is spinning, it's taking friction work to move the engine which is taking power away from the other engine too.

It's rare to see a feathering prop on a motor boat but that might make it a more interesting possibility..

I did not actualy mean to travel on the plane on one engine but to poodle along.

Point taken on the free spinning prop. I have been thinking about the power steering as well which may pose a problem too.

I think at this stage I will stay with both engines on but reduce the RPMS to give me optimum mileage. It will cost around $2500.00 in fuel to do the trip as our gas prices here are quite a bit higher than what you folk pay in the USA. Our petrol price per US gallon is around AU$6.60.

[Dockhead]

Originally Posted by Pete7

Interesting question, I suspect the extra money you spend on fuel and engine maintenance is probably the same amount you would spend on sails and rigging if you kept the boat for a couple of decades.

Pleased to hear you have moved away from the sport cruiser market. We had a 24 footer for a year with a small block volvo 5.7l and fitted with a fuel computer. It would read 80 litres per hour (21 US gallons) without too much trouble in flat water. Like I said we only kept it a year.

You should have more room and a better view looking out from a trawler type which SHMBO may prefer. The other option is a motor sailer but one of the newer types which we recently discussed:

http://www.cruisersforum.com/forums/...nce-52965.html

As a point of reference our 31 foot yacht uses 0.4 US gallons an hour at 5.5 knots, a tiny amount or put it another way, I only need a tankfull or two a year.

I do worry about future fuel costs though which is one of the reasons we bought a yacht 3 years ago when UK fuel prices started to become excessive. Time I can afford, we are in holiday mood on board. Queues at airports and expenvie fuel costs are not for us.

Pete

I am a hard-core sailor and would not consider a power boat. But not because of fuel costs. Like Pete, I doubt that long term there is a really big difference in cost between power and sail, when you compare like for like in terms of interior volume.

If you add up the cost of maintaining, laundering, and replacing sails, the cost of keeping up and replacing all of the running and standing rigging, and add that to maintenance and fuel for a diesel engine which you have anyway, I doubt that you come out much better than a trawler in terms of cost per mile, and I would not be surprised if sailing can be more expensive than power. Just a set of sails for my boat cost probably $20,000. You can buy a great lot of fuel for that.

Like I said, I sail not to save fuel, but for the passion. So I would advise you to choose because of what you would like to be doing on the water, rather than cost.

If you are looking at sailboats which seem to you have running costs a small fraction of a power boat, then I suggest that you are either:

1. Not considering all of the running costs of the sailboat -- as mentioned above.

2. You are not comparing like for like -- a palatial power boat with a small sailboat, for example. Remember power boats and sailboats are not comparable length for length. A 40 foot power boat is a BIG boat; a 40 foot monohull sailboat might be half or one-third of the interior volume.

[swagman]

We enjoyed a few years cruising Swagman which had a 75 hp turbo diesel. We obviously sailed mos tplaces, but under engine ( which was used required more often than you'd imagine in the Med) she consumed .7 litres per mile making 7 knots in medium conditions. That's about 1.4 US gallons per hour.


We replaced her this past year with a power boat so we could explore inland waterways and chose a 45 year old river / coastal power boat.


She has twin 110 hp self aspirated but lower revving diesels and on our delivery trip bringing her from Holland to UK we averaged 7.5 knots and got 10.4 litres per hour. That's around 2.75 US gallons.

IMHO for us it was a no brain move as we want to explore inland - but even looking at it objectively it will not actually cost us much more driving a low revving big power craft than it cost us before on sails and fuel for the yacht...........

Cheers
JOHN

[Pete7]

You have a good range of fuel consumption figures above for different engine sizes and some numbers for sails from Dockhead. For a slightly smaller yacht at 31 feet our new rigging both standing and running has just cost us £1900 ($3000) and be good for 10 years. A set of ordinary but good quality sails will cost £2000 ($3200) and be good for 10 years.

You need to find a big second hand boat show to take the wife and have a fun weekend away looking and considering all the options, take a camera too

Pete