Designing hulls for efficient slow motoring

[JonathanCole]

Originally Posted by mackid068

What about those companies that will rent you a boat to travel along canals in europe?

1000 Euros a week in off season. comfy for 4. Usually 50 feet or more long, 8 foot beam, steel/iron hull, diesel powered, converted barge houseboats. I am going in the September to cruise the canals of France. The cool part is that in most places you can tie up or anchor for free.

I found such a converted barge in Germany for about $50k. they can range all the way up to $1 million. Lots of dealers for such boats in Yipster's home, Holland.

[mackid068]

I've heard about such boats. What about following those lines? 50', 8-9' beam, steel hull, diesel? That sounds good. Oh, I just had a thought. How about revamping, (if you don't mind a little bit of "camping-esque" boating, a totally enclosed lifeboat? Plenty of room and they are nice and slow.

[JonathanCole]

Originally Posted by mackid068

I've heard about such boats. What about following those lines? 50', 8-9' beam, steel hull, diesel? That sounds good. Oh, I just had a thought. How about revamping, (if you don't mind a little bit of "camping-esque" boating, a totally enclosed lifeboat? Plenty of room and they are nice and slow.

In the age of petroleum as an unlimited resource with unseen side effects, a diesel boat must have seemed great. But now in Europe, diesel costs $5.50 a gallon and it takes a gallon or two a mile to push the tub along. In many places in Europe the cities are literally choking on the fumes of diesel. I've spent a lot of time there and know what of I speak. If you get diesel on your hands, it takes days to get rid of the smell. If you get it on your clothes they can be washed a few times. If you get it on your shoes, you can just throw them away. I'd rather have gasoline or LP gas but those are even more expensive than diesel. The jury is still out on bio-diesel, but my guess is that it is more expensive than gasoline.

So in any case we need a more efficient boat than those old barges, most built between 1900 and 1930. Although at slow speeds and with a relatively large footprint for solar panels an electric conversion would not be unthinkable. Even if you have to charge batteries sometimes with a generator the total energy conversion efficiency (generator x battery x electric drive) can give you two or three times the efficiency of an internal combustion engine drive(about 20% tops). Although you can use much of the waste heat to heat water. How about a steam powered supercharger for boat engines?

[Raggi_Thor]

Nice little electric engine in a Granada 23 (small sailboat):
http://www.granada23.dk/b%C3%A5dregi...stallation.htm

[FAST FRED]

For a really inexpensive to operate canal cruiser simply get free fuel.

This would be acomplished by converting an engine ( 5 to 10 hp for slow canals) to run on METHANE.

Then instead of a fuel tank simply install a couple of toilets on the deck with the waste being collected in a tank , for conversion to methane.

Some kind farmers might contribute animal waste in areas where there aren't enough humans.

In tourist areas folks would line up to "contribute" to your joureney.

Bon Voyage!!

FAST FRED

[mackid068]

Sounds smelly But a good idea, theoretically. I'd go for a small i/o diesel, 2 hp as a SLOW backup with a set of solar panels on the whole of the outside of the boat except on a walkaround "path" and in the cockpit. Coat the boat in solar panels, that'll work. And have a battery bank, certainly.

[Raggi_Thor]

Nils Lucander...
When he passed away in 1999 Jim Leishman wrote:
"He viewed 'formula hull speed' as a barrier only to be overcome with knowledge and
development of hull shape and was very outspoken on the subject."

This indicates as I have said many times now, you are all trying to get "high" speed, not "slow" speed. If you can settle for a displacement (what do you want to carry) and a speed, then you can discuss monohull or multihull, swat and other things. As I understand "slow", I think a round bottom monohull with a low cp gives the best overall performance. Then you may want a cat for more deck space etc, but that's another issue.

[rxcomposite]

Thanks SAQuestor for the article. I missed that one.

Nils Lucander has a very good insight in the principles of hydrodynamics. His approach was based on sound principles of naval architecture. He just thinks “outside of the box”. His approach was to decrease the wavemaking resistance by;

1. Delaying/canceling the initial wave. (fine entrance).
2. Shifting the LCB aft (optimum LCB theory).
3. Having a fine entrance (a result of shifting LCB aft).
4. Cancellation of the stern wave by addition of a bulb (large keel by Lucander). Prof. Inui of Japan on his “waveless” form principles. (I am not an expert on this, just citing the similarity by which both gentleman has achieved what they were aiming for)

While skin friction is the dominant factor in resistance (Froude,1972-1874), wave making is the “limiting” factor at hull speed (speed to length ratio). As the boat nears its hull speed the resistance becomes quite stiff as the wavemaking resistance becomes substantial. Wavemaking is a function of hull form while Cp is a function of S/L ratio. Page 70, Table 17 of the Principles of Naval Architecture, Volume II, Second Edition gives a guide of form coefficients and element of hull shape.

The S/L ratio of the 1.34 rule is a guide and generally used for estimating ship’s speed of displacement hull. It is the point by which the Cp values narrows down as the S/L ratio is increased.

Page 69, fig 62 shows a range of Cp values for a given hull speed. Note that the 1.34 rule is not used but a “design lane” of Cp for every S/L ratio.

Other hull form where the 1.34 rule is not followed.
1. Semi displacement hull (variable waterplane geometry presented as the ship tries to squat when it exceeds the S/L ratio)
2. Planing hulls.
3. Very slim, deep draught vessels. (not much is written about this but Froude experiments on long, slim wooden planks provided the assumptions on modern hull designs about friction)

[rxcomposite]

Mackid068,

I'll vote for the hybrid too. Seems a good idea. Commercially, there is no pure electric cars also.

Rx

[Stephen Ditmore]

On the subject of hybrids, there is really interesting stuff being done by Glacier Bay using permanent magnet high voltage DC gernerators and motors. Nigel Calder wrote about it a few months back in Professional BoatBuilder magazine.
http://www.glacierbay.com/ossa_powerlite.asp
or
http://www.ossapowerlite.com/

I'd be interested to know if photovoltaics can be made compatible with Glacier Bay's high voltage system.

On the subject of Lucander, I respect his thinking, but on a 50 foot (15.24 meter) waterline it applies to relatively heavy vessels that want to exceed 9.5 knots. At 7 knots (~8 MPH) a clean hull form with a Cp just over .5 and sections as near as possible to semicircles would do better than something tricked out. Check out rowing shells for inspiration (and check out Michlet, a computer program used to design them: http://www.cyberiad.net/michlet.htm).

Trimarans have real merit where fuel efficiency is concerned as long as the floats are mostly out of the water most of the time.

NOTE: AT THIS SPEED THE TRANSOM (if there is one) SHOULD BE CLEAR OF THE WATER... NOT ALLOWED TO DRAG!

-S

[mackid068]

Glacier Bay makes some nice boats, but I found that the 22' center console is a bit too slow for my tastes.

[sharpii2]

Hi everybody:

I would suggest using sea kayaks as an example.

I would envision a craft about 48ft long, 8ft wide, and displacing about 5 tonnes.

Its top veiw would resemble a diamond with its middle angles rounded off. It would have two chines and a dead flat bottom.

It would have an awning deck that would be almost all solar panels that would make it, from the side veiw, resemble an aircraft carrier. There would be at least 240sft of solar panels giving a maximum of 2400kw or approximately 3.2hp, or roughly 1/2hp per tonne (2240lb). The cruising speed would be approximately 5kts.

It would also have a feathering prop linked to a 10 to 15hp internal combustion engine of some kind to enhance reliability especially for up river travel.

As an alterternative back up propulsion system, it could have two gaff or lug sails totaling around 300sft. Each could be set or struck without having to go onto the awning deck. There would be an offset centerboard raised and lowered from the center cockpit.

To enhance stability, it would have two outrigger floats that would be set 16 to 20ft apart. They would each displace less than 2 tonnes when fully submerged and they would be almost as long as the boat. They would be rigged at least 1ft above the water, so that in no wind situations, niether one would touch the water. (These would make the boat a double outrigger as opposed to a true trimaran.)

Such a vessel would be quite in keeping with mid-nineteenth century steam ships where the lbs/hp for just the engines themselves was measured in tons.

Bob

[FAST FRED]

No need for a seperate prop and shaft , a quiet 5 hp Honda turning a good cont. duty alternator would make more electric than the solar panels .

The engine speed could easily be regulated to power required weather for propulsion of battery recharging.

Of course when you get all done, JUST the Honda & a prop would weigh less than a ton of batts , cost less than a small acre of solar , and leave far more room for boating.

Only thing you would loose is the WOW factor of a mile or two under "Solar Power".

Remember the dead dinasours came from eating plants and others that ate plants ,
so are as "solar " as power coming from a ton of lead.

Now a really interesting concept might be a 2 or 3hp diesel in a well insulated box that could get say 50 mpg at 5K?

FAST FRED

[Skippy]

Originally Posted by FAST FRED

Remember the dead dinasours came from eating plants and others that ate plants, so are as "solar " as power coming from a ton of lead.

Except the regeneration process is somewhat less time-efficient.

[JonathanCole]

Fast Fred,

Solar boats have already demonstrated the ability to go thousands of miles.
http://www.cmsb.com.my/tpis/sunboat/

Oil is not made from decayed dinosaurs, that is a myth. But whatever it is made of is rapidly causing this water planet to change in a way that may be soon very unfriendly to the human race. So I think I'll continue to work solar power with a bio-diesel (which really is solar) backup. As far as lead acid batteries, go, properly managed they last 15 years and at the end of their usefull life are recyclable. They are easily handled by displacement boats and can by stowed in compartments that require relatively little space. With $5 a gallon fuels just around the corner (already that much in Europe) Solar energy is already useful for many purposes I have been using it for nearly a quarter of a century and it is the most robust, reliable technology I have ever encountered.