Why are submarines poor sailers?

[waikikin]

Nothing.

That's what the automated motion control system does.

So if they were designed and optimised for sail propulsion on the basis of the use of a motion control system they could be "good" sailers rather than poor. Not sure what the attraction would be to pursue such investment unless there was some tactical military prerogative in a changed future..... but we've all seen the work of fiction become truth just look at Dick Tracy and his wrist communications..

Jeff.

 

[upchurchmr]

Go ahead and show us.
All this talking makes me tired.

 

[High spirit]

Bear with me upchurchmr,
it is more difficult to be original than to be critical.
We are getting good suggestions here.

 

[High spirit]

Question- So beyond the adjustment of ballast a sub uses variable control surfaces to function and maneuver whilst submerged... what's to stop these being further developed to apply a righting moment to counter the heeling forces induced by a sail... sub under water- sail above water or even a kite above the surface(deployed by subsurface missile??) and controlled/flown by wire & suspended camera. Seems that some form of DSS or similar with some awesome reactive logic applied to the stabilising system could well be in the realm of possibility given budget and the desire however it may defy the usual logic applied. Remember there's no bad ideas in the think tank(just don't let escape to reality..).
Jeff.

Hi Jeff,
Thanks for your observation.
You hit the nail on the head.
One reason why I am exploring the idea of a submerged hull is exactly that.

One can off course design a fully foiling ship such as the Ketterman / Hobie TriFoiler or the America Cup AC45.
However, 100% foiling in ocean conditions is not very wise in rough sea's.
Now the effect of submerged buoyancy looks a bit like foiling (in that it takes the wave resistance out for the majority of the weight of the ship).
Hence combination of submerged hull + foiling could have the best of both worlds - the seaworthiness of a submarine and the speed of foils.
Especially in off-design conditions (low speed) where foils will not provide appreciable lift, the buoyancy will ensure seaworthiness.

In effect such a sail boat would operate like a SHARK / MARLIN / DOLPHIN- remember that the fins of all fast swimming fish / marine mammals are designed to provide enough hydrodynamic lift to keep them upright and have a neutrally buoyant hull.

 

[upchurchmr]

No you are getting cartoon suggestions.
Nothing here addresses the complete set of issues.
This is just like playing a video game - no reality at all.
Just because you want to imagine something doesn't mean it will ever work.

You certainly are right - originality is much more difficult. But you have to know something to preceed to something original.

Never mind, I won't be following any more.

Marc

 

[waikikin]

Hi Jeff,
Thanks for your observation.
You hit the nail on the head.
One reason why I am exploring the idea of a submerged hull is exactly that.

One can off course design a fully foiling ship such as the Ketterman / Hobie TriFoiler or the America Cup AC45.
However, 100% foiling in ocean conditions is not very wise in rough sea's.
Now the effect of submerged buoyancy looks a bit like foiling (in that it takes the wave resistance out for the majority of the weight of the ship).
Hence combination of submerged hull + foiling could have the best of both worlds - the seaworthiness of a submarine and the speed of foils.
Especially in off-design conditions (low speed) where foils will not provide appreciable lift, the buoyancy will ensure seaworthiness.

In effect such a sail boat would operate like a SHARK / MARLIN / DOLPHIN- remember that the fins of all fast swimming fish / marine mammals are designed to provide enough hydrodynamic lift to keep them upright and have a neutrally buoyant hull.

So is the attraction a speed record?
Other than just for the sake of it/speed record/unknown military requirement it would be an incredibly complex machine to generally operate and navigate... is the plan to operate at snort/low depth with periscope /radar mounted to rigging or deeper via kite with sonar & ?
J.

 

[BlueBell]

High Spirit,
Good for you to think outside the box.
I've seen a craft as you describe/dream.
Some university kids built an 80 cm model and it sailed!
I have a poor picture of it somewhere.
Can't post photos here so Personal Message me your email and I'll send you a copy... if I can find it.
Cheers

 

[jehardiman]

So if they were designed and optimised for sail propulsion on the basis of the use of a motion control system they could be "good" sailers rather than poor.

No, they would be poorer sailers because the drag of the control surfaces when displaced to provide righting moment offsets any advantage a SWATH would have over a common narrow hulled displacement cat. What you really need to make a "good" sailing vessel is minimum wetted surface for the displacement and stability required for the power of the rig. If you really want to use dynamics for righting moment you either move a large percent of the vessels weight (canting keels, pry boards, traps, etc) or you use lifting foils to reduce wetted surface while providing the necessary stability moment (i.e. the AC foiling cats).

 

[jehardiman]

In effect such a sail boat would operate like a SHARK / MARLIN / DOLPHIN- remember that the fins of all fast swimming fish / marine mammals are designed to provide enough hydrodynamic lift to keep them upright and have a neutrally buoyant hull.

Just so you know, sharks, marlin, and porpoise shapes are fairly inefficient as unpowered (i.e. sailing) hull forms. The body shapes (and they are all 3 very different) they are designed to create specific types of active propulsion drag, not reduced drag when being driven by a sail. Not only that, but the shapes are dependent on the physiological requirements of the specific animal (i.e. the shark is a lifting body because it lack positive buoyancy, the marlin is too thin because it needs heat dissipation, the porpoise is too fat because of heat retention).

Really, if you want the "sailing" speed record, the hull form that I think is poised to break 100 knots sailing speed was proposed back in the 1970's but is now possible due to modern materials and controls. This is a fully suspended mono-depressor hull pod utilizing a kite sail for lift and power. Only money and the will to see it through is stopping that today.