Searching for fuel efficient powerboat

On the Perkins documentation they wrotte for 13227 pounds and 40 feet lwl needed 25 hp for 8 knots,it means your quest of 1,33 usg/h @ 8 knots it could be realist (in theory).
But after that you must built one sea boat of 6 tonnes fully loaded for cruise long terms and not days-cruise

 

13000 to 14000 lbs displacement fully loaded for the long term coastal cruising that I due is certainly doable. My Gulfstar 37's design displacement is around 18500 lbs with 8000 lbs of lead and at least 500 lbs, maybe as much as 1000 lbs for the mast, rigging and all the sails that I carry. My boat pretty much sits on its lines with just a little bit of trim to the stern. So I don't believe that my current boat weights anymore than 20000 lbs with all the cruising gear that I want to carry. You take away the keel and rig but add in for more fuel and a slightly heavier engine and 13000 to 14000 lbs is a realistic displacement. The problem is finding an existing powerboat around 40' LOA with that kind of displacement. I haven't found one yet. Still looking.

 

Dry weight of this one 10600 lbs
some one already give infos concerning this one.
http://www.rangeboat.com/img/content/image_paint_ok_800.png
The PL39 is heavier but she carry 600 us gallons ( the range boat 180 )
Personaly I like the Tad drawing, but for us the problem is always the weight we don't know built light ! Even on our "long-cours 62" if we make a second one we could save lot of weight but we can't cut our weignt by 20 % to 60000 lbs we must make compromises or built her in too expensive (for us !) materials.

 

Heres one



http://www.schionningdesigns.com.au/www/page.cfm?pageID=183

The one in the link (capt. Morgan) had 2 x 56hp Yanmars and consistently seemed to get 1L/nm @ 10 knots
Pretty sure she had extra tank-age as well giving range enough to go about 1000nm

 

I have no experience, but A catamaran might be THE most effective ocean capable motor vessel. It would be well worth studying a cat.

 

I would have to concur with Tad here, all my recent experience would suggest that the cost of a one-off build is in the region of $50 / pound. A simple boat might be a little less, a complex one a little more.
By way of example, an 8m superyacht tender that I'm close to completing will come in at $45/pound built in Australia. (as an aside, $35/pound built in China (+ any associated freight etc costs)). Graphite http://imaginocean.net/contents/en-us/d8.html cost around $50/pound. She's a relatively simple boat, but built to a high standard. I'd expect to be able to build a 2nd one for a little less, depending on fit out....

I would also agree that a very light boat is perhaps not the best approach to offshore travel. In spite of the argument rather (in)famously put forward by one forum contributor, everything in yacht design is a compromise - and fuel economy is no different. Sacrificing comfort for the pursuit of ultimate efficiency would simply result in having us all paddling about inside overgrown coffin-like rowboats... not coincidentally exactly what the afforementioned poster was a proponent of!

 

There are ways of getting around the high cost per pound of a professionally built boat that has worked well for some buyers. A lot of the cost comes from the markup on materials that the builder adds on and the hourly rate they have to charge. The way around this is to hire a freelance boatbuilder rather than a boatbuilding company and then jointly manage the project. A lot of buyers are small business owners and have the place to build the boat and the management skills, just not the boatbuilding knowlege and expertise. I did quite a few projects for customers this way when i first went out on my own many years ago and had some fun projects. On one project the customer moved his machine shop into a larger building just to accomodate the 45ft motorsailer we would build,he was an engineer and did all the electrical,plumbing and engine installation himself and left the boatbuilding to me, i was hired by his business and paid as a machinist and he made up the cash difference on the side, it was a happy project and certainly a lot less expensive for him than going the usual route and he had a lot more control, this works best of course when there are not strong egos involved.
Steve.

 

I think the days of high materials mark ups are well and truly over. The builder's I deal with will generally add 10% to the trade cost of the goods they buy for smaller jobs. On larger one's some add little if anything.
You know this of course, but by far the single biggest cost contributor is labour. So if there's a saving to be made it's there....

 

Yeah, i dont mark materials up at all, but i bill my time at shop rates for the time spent scourcing and ordering, otherwise i waste a bunch of time looking for something only to be told by the customer that he can find it cheaper online.
Steve.

 

Chuck, Glen L s 31ftJack Tar motor cruiser can achieve 7knt 17 shp 7.8 knt 25 shp 8.4 knt30shp 9knt 45shp I dont doubt these figures, of course you would have to build the boat but it is a nice looking boat length 31 beam 10ft 11ins draft 3ft fuel 310 us gallon for 1000+miles, also the boat can be streched 10% which could stretch the miles per gallon.
Glen L use alarge diameter propellor for maxium efficiency.Check it out The Jack Tar31.
They have other designs ,one of them can do 7knts on 10shp that is .5gph or 14miles to the gallon. Cheers Ecurb

 

Ecurb
I have looked at the jack tar in the past but not recently. 45 shp is probably 50 to 55 hp at the flywheel. That's pushing 3 gph to go 9 knots or 3 miles per gallon. Not very fuel efficient in my book especially for a 31 foot boat. I don't really want to build a boat either. Even working full time at it would take at least 2 1/2 to 3 years. I want to find an existing boat if at all possible. I will keep looking. I realize that eventually I will probably have to make some compromises. There are a few existing boats that come close to what I want but nothing that I am willing to accept at this time. One of the primary drawbacks of the existing boats that I find is excessive displacement that then requires huge engines to push that displacement. Or huge engines to try to go an extra couple of knots which raises the fuel burn to astronomical levels. Thanks for your post
Chuck

 

I have always had a soft spot for this type of vessel with a 6lx gardner or its equivalent

http://cruisingunderpower.fastmail.net/index.html

In Australia, such a vessel will still cost several hundreds of thousands
But they are much cheaper in the US

 

Chuck..sounds to me you need a troller.
Go to yachtworld advanced search and just start clicking in likely looking boats.
At least you'll get an idea.

 

If only it was in Australia
http://www.yachtworld.com/boats/1982/Broadfire--2085353/Counce(Pickwick-Lake)/TN/United-States

May not be ideal, but its surely in the ball park

OMG they're everywhere over there
http://www.yachtworld.com/core/list...&fromLength=45&slim=quick&N=3969 944&is=false

 

Many of them.

Local one on craigs, a nice old Monk 1gph at 8 knots but not the best for open ocean down to Mexico.

http://vancouver.en.craigslist.ca/rds/boa/2659732619.html