Re: [PSUBS-MAILIST] Marian S201 Propulsion Data

Brent

Along with the great submerged endurance which I find believable based on a very hydrodynamically clean boat shape, an efficient drive train and the lithium ion batteries, there are a lot of nice features to the Marlin 201 worth considering for anyone designing a 1-atm boat. Including:

very good hydrodynamics, (best I have every seen for non military sub)
external stiffeners on pressure hull maximizes space inside pressure hull
low sail profile to minimize pitching moment due to sail drag
removable heads on the pressure hull to promote equipment installation and service
removable FRP shell sections for maintenance and access
external air and O2 storage
nice flexible design for thru-hull penetrations
sound isolation that occurs by placing canned drive motor/propulsion shaft outside the pressure hull
Completely enclosed FRP MBT's rather than FRP parts sealed against the pressure hull. Eliminates leaks and corrosion issues.
flexibility to have a future large main viewport by simply switching out bow head
flexibility of either a forward MBT or straddle style forward MBT
direct coupled AC motor to prop drive shaft with advanced/efficient VSD
high power to weight next generation lithium ion battery bank (expensive)
Sail mounted forward control surface to minimize sonar inference and facilitate flexible main viewport options
Meets ABS minimum free board constraint by offsetting cylindrical pressure hull in cylindrical hydrodynamic shell and the use of FRP sail cowling around hatch
Initial phase low cost viewport arrangement
Hatch design that solves welding warpage issue
acrylic low drag cowling over forward viewport
very fast 17 month design through commissioning schedule for a new ABS A1 classed vessel.

It's obvious that a lot of lessons learned from previous builds were incorporated into the S201. One thing that strikes me as odd about the S201 is the fact it does not have a diesel engine. You would think that with a 10 ton displacement and 30 ft in length, they would gone for the diesel-electric hybrid arrangement. This must have been a client constraint.

Cliff

----- Original Message ----
From: Brent Hartwig <brenthartwig@hotmail.com>
To: personal_submersibles@psubs.org
Sent: Monday, January 21, 2008 4:19:08 PM
Subject: RE: [PSUBS-MAILIST] Marian S201 Propulsion Data

I was reading a PDF file I have on the Marian S201 and was amazed at the claimed underwater endurance using a large amount of Li-ion batteries. I would like to find out what brand and model of batteries they used.

"Marion S201 sets a new standard in manned research submarine design and operations. This versatile lithium-ion powered submarine can dive to a depth of 305 meters (1000 feet) and accommodate a two man research team for an unprecedented 48 hours duration with a range of 225 nautical miles submerged."

I found some links with more details about this Paul Moorhouse designed submarine.

http://www.promare.org/

Power:		Lithium ion batteries
Submerged Duration:		Forty eight (48) hours @ 5 knots

http://www.submergence-group.com/s201_marion_specs.php

At first I thought and endurance of 225 nautical miles submerged was not realistic, but after seeing the drawings of the sub and it's batteries in the above link, I'm starting to believe it. I've never seen batteries stacked that high in a submarine. If they were conventional lead acid batteries I would think the sub would be to heavy in the rear and not have a good metacentric height. But since Li-ions are a fair bit lighter and it's working, they must of got it right.

There are some interesting pictures in the below link, even though they are a bit small. Near the end there is a picture of the underside of the sub showing it's galvanized bottom skin and it's free floated formed acrylic fairing in front of the cameras, lights and the only viewport.

http://www.submergence-group.com/gallery/gallery.html

Regards,
Brent Hartwig

From: brenthartwig@hotmail.com
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] S201 Propulsion Data
Date: Thu, 17 Jan 2008 14:29:57 -0800

I found the below information from Marline Submarines interesting.

"A combination of new generation Phosphate-based Lithium-Ion batteries and rare-earth magnet technology main propulsion motor provide performance and endurance remarkable for a vessel of this size and type."

Also of interest to me is that both hemisphere ends are unboltable to make the sub easy to work on. Another interesting design detail is how he designed the side SBT's to attach to the external ribbing. I'm interested to know how he attached and sealed those tanks, since I've been thinking about different configurations to do just that. He might be using some sort of nasty sealant that would make the tanks hard to remove for maintenance. I was thinking of using some sort of gasket, lipped seal, or o-ring. But those can be harder to get a good seal in that sort of configuration.

Frank, you should note that they are using a molded acrylic fairing in front of there forward viewport and cameras, much like you wanted to do.

"Surrounding the forward part of the hull is the bow moulding, the upper half of which forms the bow main ballast tank by means of a GRP inner skin hugging the pressure hull forward hemisphere. This bow buoyancy counteracts the tendency to dive when running at speed on the surface. The lower bow fairing section features a bonded-in acrylic transparent section to allow observation from the viewport whilst maintaining the streamlined hull form.
Neutral buoyancy whilst dived is maintained by two internal 1 atmosphere variable ballast tanks with a total capacity of 140 litres, located in the forward pressure hull section. The variable ballast allows some compensation for varying crew and equipment loads. Water ballast is pumped out using a positive displacement pump driven by an electric motor and taken in using external pressure, with impeller pump assistance for surface or shallow depth use."

Regards,
Brent Hartwig