Any super economical motorboats out there?

It still looks like the Albin is really the only choice as it pretty much does everything im looking for, i was just hoping there would be other choices but it seems there are not. The Albin does get 12-15mpg depending on powereplant,has a very practical layout,is trailable and most of them come with a trailer,this is a great feature as it makes it practical to shop for one nationwide,they are plentiful and very reasonably priced and not bad to look at. I definatly have no desire to build a boat for this trip,i want to buy a boat in reasonable shape,do the minimal upgrades it will need, do the trip over a couple of years and then sell, i would not expect to lose much if anything because it will be proffessionally upgraded,well proven after completion of the trip and they are old enough to already stabilised their value. I dont see 5.5 - 6 knots cruise as any kind of negative at all as thats better than most cruising sailboats under 40 ft realistically do and sailboats is where i come from,this is primarily an inland trip with lots to see so slow is just fine.
Steve.

 

Steve,
what kind of accomodations are you looking for on your boat?

A few years back my wife and I did 1200 miles on the Mississippi, Ohio, Tenn Tom. We started in Minneapolis and went south for 28 days. The boat we used was an old 18' Kennedy pontoon boat. We camped out on beaches most days and stopped in bigger towns every few days to get a hotel room.

Old pontoon boats are readily available (and cheap) up in your part of the country and with a small outboard they get decent milage. Like someone else pointed out, if your boat is very expensive it does not matter how good the fuel economy is.

C.O.

 

"if your boat is very expensive it does not matter how good the fuel economy is."

The biggest factor is the "Round Trip" , boat cost vs selling price at the end.

 

That sounds like a fun trip cor, i think i need a bit more of a seaworthy design though as i will probably start in Duluth and circumnavigate the big lake as part of the trip, and also perhaps a trip across the gulf stream, im not looking for a dirt cheap boat, just cheap, i expect to pay between $10 and 20000, i could get an albin cheaper but it would need more prep. The importance of fuel economy is because of the distance involved, its simple math, using the Albins as an example just because i have researched them, an Albin 27 FC which is the boat i would really love to own with a single 78 hp Nissan diesel seems to get about 4mpg, so, 7000mls at 4mpg = 1750gals @ $4.5 = $7875 wheras the Albin 25 looks more like 7000mls at 15mpg = 467gals @ $4.5 = $2100, a huge difference of $5775 which can pay for a lot of dockage or whatever, its close to half of what i could realisticaly buy the boat for. I really dont think i would lose money on the boat when i sell it, im a boatbuilder by trade and could easily build a boat for the purpose but i couldnt do it for anything like what i can buy a boat for and since this is just a horse for a specific course, better to buy. The Albin 25 is actually damn near perfect for the job (for me) and since nobody has been able to introduce me to something that checks as many boxes im thinking there are none, at least in the US.
As a sidenote, im a guy who values efficiency highly,for 5 years i drove a B4 Passat TDI (until i totaled it) i loved that car as much in the end as when i bought it because of its absolute reliability and efficiency in the extreme, the only vehicle ive ever owned where i enjoyed my trips to the gas pump, so i bought it back for salvage and am looking for a B4 wagon to put the mechanicals into, while i could buy a newer version they are just not as efficient, they are heavier so dont get as good a mileage, so i prefer the older ones. I am currently driving my F250 powerstroke and feeling like an enviromental terrorist, consuming less fuel matters to me.
Steve.

 

Let's look at the input into your calculations:

Albin 27 FC, single 78 HP Nissan Diesel 4 mpg
Albin 25 15 mpg

This means the Albin 27 FC consumes 3.75 times more fuel than the Albin 25. What are the sources of this information? How much confidence do you have in these numbers? Are these numbers for similar speeds?

Albin 27 FC specs:
Length 27'
Beam 9' 8"
Displacement 6500 lbs, 6800 lbs

Albin 25 specs:
Length 25'
Beam 8' 6"
Displacement (dry) 1600 kg = 3500 lbs

 

Vashon pocket Trawler 23' One can be found on Seattle/Tacoma Craigslist right now for 15k. Looks to be a double ender style with 20ish hp diesel.

 

Your 4 mpg for Albin 27 FC sounds very much, if you are trying to save fuel and thus not trying to push close to or even above hull speed. 4 mpg equals to 1.1 l/NM. According to measurements made by a Finnish boat magazine Linssen 33.9 AC (9.87 m, 8300 kg, VP D2 75 hp) has a consumption of 0.55 l/NM at 4.8 knots, 0.67 at 5.4, 0.83 at 6.0, 1.06 at 6.4, 1.39 at 6.9 and 1.79 at 7.3. It has hull speed around 7.3 knot.

Then for a smaller one, Linssen GS 25.9 SCF (7.6 m, 6000 kg, Vetus 33 hp): 0.40 l/NM at 4.9 knots, 0.55 at 5.2, 0.70 at 5.6, 0.9 at 6.0 and 1.14 at 6.5.

These Linssen boats are made of steel and the hull is not optimized for low consumption.

Note, that the values are almost identical above 5.4 knots and there is a huge difference from 5.4 to above 6 knots. I think the same applies to Albin 25 vs. Albin 27, but both of them are likely to be clearly more economical than Linssen due to much lighter displacement and narrower hull.

 

Low speed planing boat

Hy everyone,
I have a standard planing boat (LOA 10m, Displacement 8 ton, maximum speed 31Knots, cruise speed 26 Knots, minimum planing speed 16 Knots, 2 Yanmar engines 235hp that I must change, V bottom hull, fuel consumption 2,5litre/knot) and I'm looking to modify its performance getting to a lower minimum planing speed (10 Knots), lower top speed (22Knots), lower cruise speed (18 Knots), engines with fewer power (??hp) and lower fuel consumption (1,7-1,8 Litres/Knot?). To get my objectives I'm thinking to work on right balance among engines (Power and Torque) and propellers. I'm looking for a more confortable, economical and quiet cruise.
Have you got any advice or technical consideration on it?
Thanks

 

I think you have some of the figures wrong. A Yanmar 235 hp has about 50 l/h consumption at maximum power. Thus at 31 knots the consumption should be about 100 l/h and 3.2 l/NM. I don't think the consumption will be that much lower at 26 kn.

A 10 m planing boat having displacement of 8 ton is exceptionally heavy. Around 5 ton would be normal. A 10 m planning boat usually has its lowest consumption at 20-30 knots. At 10-18 knots the consumption is much higher. E.g. for Bavaria Sport 34 HT (10.8 m, 6.3 ton, 2*VP D4 260 HP) the consumption is 3.2 l/NM at 9.5 knots, 4.07 at 11.3, 3.67 at 15, 2.47 at 22.3, 2.33 at 26.2, 2.28 at 29.8, 2.53 at 34 and 2.76 at 37. Note much higher top speed with only slightly more power.

I don't think it is feasible to make a planing 8 ton boat to consume less than about 2.5 l/NM. For a semi-displacement boat close to 2 l/NM may be possible in the 10-18 knots range, but still 2.5 l/NM would be better than average.

 

Dear Joakim,
my Yanmars consumption at maximum power is 42l/h that brings to 2,7l/NM (so the 2,5l/NM at cruising speed make more sense). You're right on the displacement, it's 6,5tons with average load.
I know that a semisplacment boat could better fit my objectives but I want to keep my boat changing its engines and propellers. Do you think that my transformation could get to a minor fuel consumption (L/NM)? Which could be the right combination/choice in terms of engine (power/torque features) and propeller type (3-4 blade, diameter, pitch)?
Thanks

Guido

 

How do you know the consumption at maximum power? 42 l/h for 235 hp sounds way too small. I haven't seen measurements for Yanmar 235 hp, but Yanmar 190 hp takes 40 l/h, Yanmar 260 55 l/h, VP 225 47 l/h and VW 225 48 l/h.

It is impossible to answer anything to your questions, since you don't give any data about your boat. But if it is a typical planing boat, it will not work well under 20 knots. It's not about propellers and engines, it's about hull form and weight distribution.

 

This is correct. The 10 knot goal is possible, but not fuel efficiency with a typical hull form designed for much higher speeds. It's a bit like asking that your Corvette get the mileage of a Prius. It's just not capable in it's current form.

This said there are some modifications you can make to the hull and propulsion setup, but none of these options are easy, nor inexpensive.

To get back to Steve's original request for a very efficient cruiser for the great loop, you'll likely have to a go custom build. Several designers offer considerable efficiency savings over the typical production, fat butted offerings. These tend to be trim and light. I have a 33' riverboat design that gets about half the MPG initially requested (7 MPG), which is very good considering the typical manufactured offerings. It all depends on what constraints and compromises you're willing to accept in the SOR. In short, if you want exceptional (anything) then you'll need a custom or semi custom design, because production models don't do anything exceptionally well, but do a lot moderately so.

 

PAR,fortunatly i dont need to build a custom boat to get the economy,the Albin 25 does in fact achieve around 15mpg according to a number of owners on the owners group website, one example with a 30hp perkins running at 6 knots over a 260nm trip consumed 18gals which equates to 14.4nmpg or 16.6 statute mpg. The boat in fact meets my sor very well. I was just trying to see if there were in fact other older (read,affordable) production boats that i was not aware of that were at least as suitable or better. Apparently there are not so i would be happy with the Albin for this trip. I have the same problem when looking for cars, there are simply no alternatives to VW if you want a practical diesel car or wagon in the US, dont get me wrong, i love the vw tdis but it would be nice to have choices.
Steve.

 

I know this is way outside the price range. I'm giving this example to show that if you leave the "everybody knows" realm and explore the possibilities, you can get a lot more efficiency.

A typical 48 footer running at 20 knots burns a lot of fuel. Something like 2 to 4 gallons per mile is not unusual.

Sarissa, a 48 foot twin diesel designed in about 1985 by "the" Michael Peters for "the" George Griffith (father of the Cal 40). Sarissa gets 4nmpg at 20 knots, displacing about 12000 lbs (The designer says 14K, the builders say 12K lbs), about 11 feet of beam. Its not really planing, its really just a high speed displacement boat. When the displacement length ratio gets this low, the distinction of planing gets blurred (the slope of total resistance is not so steep).

http://www.mpyd.net/portfolio/details.aspx?Project=29

 

Any drawings you can post? This sounds interesting.