Minimum sized motor boat to round around non stop ?

On our actual boat

Is economic at 7 nds and the consumption is less than 6 lt per hour
Around 1 hp per ton
We have also 2,8 t of lead ballast but may it give a too big stability to us .

 

This is imo an example of a design goal where a sailboat will excel over a powerboat. On a small boat like that the engine and propeller efficiency and reliability are an issue. The roll-stabilizing effect of a sail and a keel, zero fuel consumption during most of the passage, constant keeping the crew busy - all points in favor of a sailboat, imo.

A point in disfavor is, of course, the necessity to have a physically fit crew trained to operate a sailboat. That's where a well-designed motorsailer can become an option. It gives a possibility to go on engine, on sails or on engine-sail combination, depending on weather conditions and the possibilities of the crew.

There are two interesting articles in the Power & Motoryacht Magazine site, related to this topic:
http://www.powerandmotoryacht.com/cruising/state-art
http://www.powerandmotoryacht.com/node/143284

Cheers

 

The original poster does not WANT to simply do a world circumnavigation he is interested in motoring non stop to get in the history books.

A simple circumnavigation has been done many thousands of times with sail as small as 20 ft.

That is not the OPs goal.

 

Oh, I see. I have misunderstood the intent behind this request.

 

Catch lots of oily fish on the way, use the oil to power the diesel, don't worry about the smell !

 

"constant keeping the crew busy " oups sorry I forgot to writte : I am a very lazy guy !!

 

Or may be get some training with Japanese or Norvegian whales catcher and use the oil of whales ??


@Daïquiri thanks for the links
But why they wrotte "the return of motor sailor" i feel motor sailor never let the market of pleasure boat .
For exemple we owned a Cheol Lee 53 , very similar concept with the Nordhavn motor sailor exept the mast is smaller (on the Nordhavn )and may be also the draft :

http://long-cours.62.over-blog.com/photo-1906459-cheoy-lee-53-16.30X5.05-1987_jpg.html

 

The history book for me, i don't care

As you can see on our blog I just ask of the boat ,no photo of me , no details on me , I am thinking the interesting thing is the boat, not the people on the boat .
At less on this type of forum , may be on a "psychiatric forum , my case could be an interesting subject ( like the case of people who choose a different way than the majority) but in this case I will be afraid they decide the best place for me are not behind the Wheel but behind ...walls

 

Years ago, a Mercury OB team of 2 took off with the then new 50hp big foot in something like an 18' open aluminum deep V that had canvas covers. Saying non-stop, I'm not sure what that is really. Does that mean never stopping? No sister ship or support of any kind? I assume you could stop in open waters and make a repair or take on fuel. The Merc team had support for fuel and food. I know they took off, from the pictures it looked pretty rough jumping waves like a jet ski. I believe they got to South American waters and planned to hang a left, then I lost track of the expedition, never heard about it again. If they had made it I'm sure we would have heard bout it in the ads for the big foot.

Some things are best left alone to history. Now, when we have 200hp hydrogen power from sea water, get to it....

 

My dream !!! and save 6.5 t of diesel plus the weight of tanks

 

All you need is a small nuclear reactor which will produce heat for transforming the sea water into a steam for a steam turbine.

If all of the sudden you start to glow in the night, you will know that something has gone wrong...

 

I think

it was already done with a nuclear reactor powered ....submarine , it is better nobody could see if they "glow in the night"

 

Sails provide comfort. Roll motion and most importantly ...shade.

Yesterday I motored all day. Mainsail sheeted tight and prevented staysail sheeted tight.

Very light wind...cloudless sky relentless sun and roasting heat. The sails managed to shade 60 percent of the deck , keep the interior of the boat civilized and block that relentless sun from burning my eyes and skin.

Without sails the interior of the boat would be uninhabitable till well after midnight.

 

Very few on this forum think electric is an option.
But battery and electric drive mfg might provide you with some funding.

As to hull type, submarines go faster submerged than on the surface, because they eliminate the greatest of the 3 resistances. Wavemaking.
They don't cut the surface so don't make waves. You aren't limited to a "hull speed".
Submerged can be calmer as well.
If you built a long skinny submersible, solar powered when on the surface. battery powered when submerged on rough days. Used a hand pump reverse osmosis water maker (to keep you busy) And plotted courses to take advantages of major ocean currents, you would still need to stow enough provisions. Maybe freeze dried food suppliers would help out funding or provisioning.

A submersible IS a motor boat.

Just be careful you don't adopt the submariners attitude quoted below.

"There are only two types of vessels. Submarines, and targets!"

 

I am not sure what would be the attitude of Coast Guards and Navies around the world when faced with the echo of an unknown submersible moving below them...
Capt. Nemo was lucky to have lived (fictitiously) in times where sonar and depth charges were yet to be invented...