Motor Sailers?

Warram Rig

From Greenseas2:

This method has been used by other designers also and i agree completely.

If possible i would like to go a more high-tec way, the boatbuilding industry is not very innovative so i would like to see more non-standard solutions on the water. I like the v/d Stadt Swing Rig, http://www.stadtdesign.com/products/SwingRigInfo.html and http://boatdesign.net/forums/showthread.php?t=6493&highlight=free standing mast.

There are more threads on free standing masts in this forum but not too many. Perhaps we should continue the discussion in one of the existing threads or start a new one.

 

Agree

The next closest as far as sail efficiency goes is the sail in-mast furling systems. I believe that if we look at history as well as innovation, there isn't much that hasn't been tried. The newest thing that I've seen on the water was taken from surf board kite sailing (the Square ones). Recently there has been a few boats trying this out, but it's good for downwind only and there isn't much control for wind direction shifts. A good place to start an investigation would be with older sail lofts. They have probably seen a plethora of innovative sail designs. I don't know how much activity a new thread would get on sail design. There are some radical designs out there, but most are associated with sailing hydrafoils which are still a small segment relagated to R&D.

 

In mast furling

In mast furling has the disadvantage of a high centre of gravity from the furling installation and the sail beeing fully up the mast when furled. When you are at the point of furling a sail you also want the COG to go down.

When something goes wrong the problem is going to be high up the mast , out of reach. Stress bending the mast is a likely course of the sail jamming at a moment conditions are rough.

 

Junk lug rig option for motorsailor?

What About the Junk Rig...?

Kasten Marine Design, Inc.

Suitability to Motor Sailors: A motor sailor can make excellent use of the junk rig. A motor sailor can be 100% sailing vessel, as well as being 100% capable under power. There are many other approaches as well, such as that taken by the Gulliver 46, the Greatheart 48 and the Greatheart 60 designs. These types have an emphasis on sail that is more on the order of around 60% to 70%. In other words, the sails are provided primarily for the purpose of auxiliary propulsion, rather than primary propulsion. The sails serve the function of being the "get-home" motive power in the case of engine failure. In addition, the sails provide extra boost while motoring when the wind favors. As a bonus, the sails and rig provide excellent roll dampening. For this purpose, the junk rig is ideal.


I was wondering if in europe junk sail are used to incoperate into existing motorsailor design? What hull design would actually benefit from this sail rig?


WDH

 

The dual systems that I find there are this:

That is not what we are talking about.

Can you point me in the right direction?


Take a look at "bulkhead steering" You will find a shaft in which a wheel is mounted on one side and a sprocket to operate a bronze or SS chain on the other end.

These are used to operate cables arround properly sized sheves to a rudder quadrant.
2 quadrants can easily be on a single rudder shaft , alowing dual steering .
Both wheels will move together.

With generous sized lubricated sheves the steering losses due to friction or flexing the steering wires is quite low.

FAST FRED

 

Your critics

Proposed formula to easily estimate HP (DIN) for monohull motorsailers when displacement is not accurately known:

General HP / Lwl formula for 20 < Lwl (feet) < 40 :

HP = K * Lwl * (Lwl - 10)

being K values:

Light motorsailers (D/Lwl ratio's 250 zone) K= 0.06
Medium (350 zone) K= 0.08
Heavy (450 zone) K= 0.1

As D is not known K is a guess, for sure, but we can have an intuitive idea about the motorsailer being light, medium or heavy.

I would appreciate very much your comments and critics.
Cheers.

 

To calculate the BHP for a Motor Sailer is easy. To know the weight of the boat is one of the most important parts of the calculation. By guessing, the result can bee very little accurate. In the most of modern marinas they have a Travel-lift with weight indicator.

 

What if I have a small motorsailer that has a WL of 10ft?

1.0*10*(10-10)=0

Under your proposed formula it would need zero HP.

Did you mean that the minimum WL be 20ft?

Don't think I'm making fun of you here. I have made many a spread sheet myself that had the same disasterous results

Wouldn't it be easier to have people guess the displacement of the boat. People who have been around boats long enough can be pretty good at that.
Other than that, they probably shouldn't be making those kind of calculations in the first place.

Perhaps a more intuitive way of judging a boat's heft is by looking at its cross section rather than its profile. For this, I invented the Heft Ratio.
Heft Ratios start at around 0.50 (for an 'Open 60' type) and go up to 3.0 and above (for a Victorian 'plank on edge' type). But, more typically, they hover around 0.75 to 2.0 for more typical boats. A harbor tug, for example, would be around 2.0.

The formula for the Heft Ratio is:

20 volumes (in cubic units)/ Length * (Beam^2)(in linear units)

I've had great fun on the water front using this formula. I once asked a commercial fisherman how many horsepower his boat had. After he told me, I told him how long and how wide it was. He was amazed at my accuracy. He invited me to go down to the docks and pick it out, since I already knew so much about it. I declined, knowing that all the others would have similer dimentions.

Maybe, in the 20 to 40ft WL range (if that's what you really meant), your formula would work quite well.
But, since I critisized it, I felt I ought to offer an alternative.

Bob

 

Hi Bob,
If you give me the LWL and the weight of the boat and tell me if you have a narrow or a wide stern I can easy calculate the BHP for you.

 

Kjell and Bob:
Thanks for your kind contributiions.
Yes, formula is supposed only to work (more or less) between 20 and 40 feet LWL.
It's not conceived for NA's, marine professionals or knowledgeable sailors, absolutely, but for the common aficionado looking for -or intested in- motorsailers. They usually do not know displacement for a particular boat, and I have had several enquiries asking me how they could estimate the power needed.
That's all.

 

Trevor Bolt Designs

Any clue to where I can find info about his motorsailer designs in steel? The various links I´ve found on the internet have all been either 'dead' or with 'access forbidden'

 

This is my 40’ Motorsailer at cruising speed with 2 x 40 HP Lister engines.

 

Kjell, Your boat looks a lot bigger than 40ft.

 

Here Banjer 37 DUCK SOUP dressed for the beginning of 2006 season parade in Port Moresby, Papua, New Guinea. She won the prize to the best dressed boat.

 

Guillermo:

I think anyone with an appropriate sized motorsailor would be absolutely insane not to get an AutoProp. What other propeller continually optimizes itself when using engine and sails simultaneously? http://www.autoprop.com/

Do you agree?

Here's a book about owning a small motorsailor that some people might enjoy: http://armchairsailorseattle.stores.yahoo.net/sailinspoono.html