Venturing into really deep waters - Is the SAS the best way to go?

[roedj]

To All,

With the advent of the SAS system, and its predecessor the SNORT, the normal installation of a pressurized gas tank, i.e. Propel, CO2, pressurized air, is no longer the norm. This system is very ingenious for its design and functions well, from what I've read - still working on my first SAS SD, but, as has been pointed out by its designer, one may/should consider the addition of a backup pressurized gas system if sailing in really deep or murky waters is intended.

While the retro-fitted addition of a pressurized gas system has been built into the design of the SAS SD, I am wondering about its practicality. My concern is this: Does the additional volume of the pressurized gas tank and possible "gas saver", tubing and servo linkages, if placed inside the ballast tank, take away so much ballast tank volume that the overall system can no longer raise the sub to its intended surface level and still have enough volume to submerge it to the degree desired? Or can any potential problems in this regard simply be solved by the use of more or less foam?

Dan - Commander Curious

[Subculture]

HAve you got room to stick the tank on the outside of the cylinder. Doesn't look as trick I know, but if it works, who cares?

[He Who Shall Not Be Named]

The boat specific SD's have a ballast tank that is about ten-percent greater in volume than the weight of the water displaced by the topside structures. That said, you have about that much volume of space to give up within the ballast tank for an emergency blow on-board gas bottle and associated hose and blow valve.

If the possibility exists that the boat will be out-of-control in water fifteen feet or deeper, opt for the emergency on-board bottle and associated plumbing. No gas-saver -- those where too much problem for people to set up and maintain ... I blame you idiots. The design was perfect!

The emergency blow-valve makes use of existing after ballast bulkhead foundation and linkage -- it's a plug-in retrofit. The blow-valve trips only on fail-safe over-throw of the ballast sub-system servo. Normal use of the ballast system does not throw the servo to the extreme that would open the blow-valve -- it operates normally in the SAS mode

Damn! ... I'm good!

M

[Slats]

To All,

With the advent of the SAS system, and its predecessor the SNORT, the normal installation of a pressurized gas tank, i.e. Propel, CO2, pressurized air, is no longer the norm. This system is very ingenious for its design and functions well, from what I've read - still working on my first SAS SD, but, as has been pointed out by its designer, one may/should consider the addition of a backup pressurized gas system if sailing in really deep or murky waters is intended.

While the retro-fitted addition of a pressurized gas system has been built into the design of the SAS SD, I am wondering about its practicality. My concern is this: Does the additional volume of the pressurized gas tank and possible "gas saver", tubing and servo linkages, if placed inside the ballast tank, take away so much ballast tank volume that the overall system can no longer raise the sub to its intended surface level and still have enough volume to submerge it to the degree desired? Or can any potential problems in this regard simply be solved by the use of more or less foam?

Dan - Commander Curious

Dan -
having ran the SNORT system in no less than half a dozen Subdrivers, I'm about to embark on going SAS without the Gas back up and retrofitting another GAS / Snort boat to SAS with no gas.

Why?
Because I find that the Caswell Subdrivers when properly assembled and maintained are leak free.

In addition when I embark upon "Blue Water Ops" - meaning deep lakes, practicality dictates that I run only at periscope depth and I have a small change in ballast prior to sailing via a weight that sits right on the COG / COR that I remove to run the boat a little more positively buoyant than what I do compared to running in an easy recovery environment of a pool.

Over the years I have found my gas consumption to be higher in the controlled pool environment when I tend to go deliberately deeper and push the throttle wide open. The gas is then really used to have fun and simulate an Emergency Blow rather than a really Emergency. Occasionally going very deep in a pool the Failsafe cooks off in signal loss and the Gas takes her up.

In a deep lake you'd be nuts to go deeper than your eyes can see, and your throttle use accompanying a dive should match your skills to keep in visual control at all times.

I find that lake sailing my gas use has been zero. - That is I drive much more conservatively, much more in a scale manner and 90% of the time in Snorting range at PD. There is no signal loss as I simply don't let the boat get that far away from me.

To answer your question re the gas tank storage in the ballast tank taking away too much of the ballast volume, the answer in my experience is no. But to check you can do a simple Volume equation of TT x radius squared x Length to work out the ballast tank volume and subtract the gas tank volume. (Where TT=pi = 22/7, radius = for the ballast tank the inside diameter / 2, radius of the gas tank = outside diameter / 2). The ballast tank volume needs to support the weight of the material above the surfaced water line. You can estimate this via weighing the upper hull and sail and other topside equipment and then estimating the percentage that this is above the surfaced WL. The volume of the tank should EXCEED this to give you a bit of a fudge factor.

The reason why the best place for the gas storage tank is the centre of the ballast tank is that the centre of the ballast tank should sit exactly above the COG / COR point. As / or should you consume gas the horizontal trim of the boat is unaffected as the boat becomes lighter. This is also a good visual aid, as the boat which should have been ballasted with a full gas tank, will appear in its dived state to be more positive (lighter) with the gas supply being used.

There is a risk to putting to sea without a gas backup. Its up to the individual to ascertain this risk.
For me I base my risk, on known parameters. Over the past 4 years-
-leaks in the Subdriver (none)
-events requiring a gas back up (only my deliberate acts)
-gas consumption (close to zero - save for my deliberate acts)
-habits driving at lakes (Periscope depth and hugging the shore line).
Also to be honest I'm sick of wasting gas by venting the tank to put away the Sub - rather have that gas saved for running torpedoes.


I believe that the SAS system is state of the art. Its what I have come to expect from David and Mike, who have always been evolving their products and technology.

I hope that helps Dan.

best

John

[Slats]

The boat specific SD's have a ballast tank that is about ten-percent greater in volume than the weight of the water displaced by the topside structures. That said, you have about that much volume of space to give up within the ballast tank for an emergency blow on-board gas bottle and associated hose and blow valve.

If the possibility exists that the boat will be out-of-control in water fifteen feet or deeper, opt for the emergency on-board bottle and associated plumbing. No gas-saver -- those where too much problem for people to set up and maintain ... I blame you idiots. The design was perfect!

The emergency blow-valve makes use of existing after ballast bulkhead foundation and linkage -- it's a plug-in retrofit. The blow-valve trips only on fail-safe over-throw of the ballast sub-system servo. Normal use of the ballast system does not throw the servo to the extreme that would open the blow-valve -- it operates normally in the SAS mode

Damn! ... I'm good!

M

Dan - also take note
ALL of my Subdrivers to date that have run GAS / Snort have utilised the GAS saver and please bare that in mind when I mention my gas usage as being minimal. I have no data on what gas consumption would be without this device. I'd imagine it would have to be higher. Gas blows are limited with the gas saver by the state of the ballast tank. If the tank is empty of water, you can't blow gas.

In my view it was **** easy to set up. Once the tank was fully blown, the gas saver arm would drop down faster than a two dollar hooker.

J

[vital.spark]

I have 3 Subs up and running, all with the gas/snort installed. I have followed David's SAS System posts with great interest but I have followed the KISS philosophy all my life and personally see no need for the SAS system if one has Gas. Maybe I'm old fashioned and like steam boats and the old WWII jeeps. I can go into details why but I think most of you understand any way.

[greenman407]

Vital.spark, I hear you. However, as a lifer as far as playing with toys goes, I have many hobbies, some though I have given up and have moved on from them. Why do we go from entertaining ourselves with control line planes and move on to RC planes? Why do we move on from Heavy dry cell batterys to LIPO? Because as advances are made, we can see the benefit to ourselves and we upgrade, if not sooner, then later. The SAS is another toy to play with, if you have the interest. I still like my Gas systems but trying out one or two of these things wont hurt me I dont think. My goal is to entertain myself and reduce the stress of everyday life. Thats just my two cents worth. But whichever way you choose, enjoy it, otherwise, life is no fun.

[roedj]

Thanks to all for a very nice discussion and informative answers.

All in all, it's nice to know I can utilize the SAS and still pass gas if I choose to.

Dan

[Slats]

Thanks to all for a very nice discussion and informative answers.

All in all, it's nice to know I can utilize the SAS and still pass gas if I choose to.

Dan

Off topic -
I have to share this re "passing gas".

My 4 yr old son let one rip the other day - his mother turned and said "what do you say?" - expecting the polite "excuse me / pardon me".
Not from my young charge. -He fired back. "just clearing the ballast tank mum". Suffice to say Pauline's questioning his time with me in the shop and I'm lucky I didn't spend the night on the couch.

J

[He Who Shall Not Be Named]

Kid threw you under the bus, John. You nasty bad influence, you!

M

[trout]

Off topic -
I have to share this re "passing gas".

My 4 yr old son let one rip the other day - his mother turned and said "what do you say?" - expecting the polite "excuse me / pardon me".
Not from my young charge. -He fired back. "just clearing the ballast tank mum". Suffice to say Pauline's questioning his time with me in the shop and I'm lucky I didn't spend the night on the couch.

J

Oh my I am laughing over the response.... I know what I can teach Sam next! :-)
t

[Slats]

Oh my I am laughing over the response.... I know what I can teach Sam next! :-)
t

Well one thing I didn't teach him was the leg lift, and the well timed launch in front of the wife's church friends....that part seems hard wired into DNA.
I blame Merriman. Kid's born on Merriman day - took a heck of a lot of planning believe me!

J

[He Who Shall Not Be Named]

I am so, so sorry!

M

[Slats]

I am so, so sorry!

M

Don't be.

Just hurry up and get better and fill that dam order of mine.
I might go out in sympathy and buy a Skipjack....I hate you.

[He Who Shall Not Be Named]

No!...

... I hate you!

M