RE: [PSUBS-MAILIST] Re: Compass instruments

["Alec Smyth" <Asmyth@changepoint.com>]

I just re-read your message. My first response was in a bit of a rush, as my wife was calling from downstairs that the house was flooding due to the melting snow. But priorities are priorities, and I had to finish my PSUBS message!

:)

Anyway, between you and Cliff I'm really indebted for the research. Imagine if I went out and spent a couple of thousand dollars on an electric gyro only to find out what you just said about the 15 minute duration! But my question is this... if you put a fluxgate in the sail, it should work whether you're surfaced or submerged. What's the need for having a gyro as well?

And less my earlier remark offend Cliff, I do want to mention my objection to an outside can is only a problem on Solo, because I don't have a sail in which to carry it cleanly. In his boat, the idea is perfectly sound. In fact he has been generous enough to share design documentation with me, and I should mention he puts me to shame in every way!

cheers,

Alec
PS: wife is calling to lunch now, gotta go. 

-----Original Message-----
From:	Alec Smyth on behalf of Alec Smyth
Sent:	Sat 2/22/2003 12:20 PM
To:	personal_submersibles@psubs.org
Cc:	
Subject:	RE: [PSUBS-MAILIST] Re: Compass instruments

Funny, I wrote that last night and since then changed my opinion about how to attack this one. I am back behind Cliff's proposed approach, except I now envision a small acrylic dome open to the inside of the sub, as opposed to a separate "pod". I'm shooting to put the ez-compass-3 in it together with GPS sensor and a panning micro video camera.

thanks,

Alec

-----Original Message-----
From:	Carsten Standfuss [mailto:MerlinSub@t-online.de]
Sent:	Sat 2/22/2003 1:49 AM
To:	personal_submersibles@psubs.org
Cc:	
Subject:	[PSUBS-MAILIST] Re: Compass instruments

Hi Alec, nice to hear from you - I still think that "Solo" is the best
choise for a name of a selfbuild onemansub ;-) The question is so good
that I transmit the answer to Psubs... 

I found out that an aircraft gyro need to be compensate all 10-15
minutes by a .. magnetic compass.. Its not a joke - on smaller crafts
the pilots do it by hand - fly straight course, same speed and level
than turn the compensate switch with his eyes looking on the magnetic
compass. 

On bigger or modern aircrafts this compensation is done automaticly by
an interlink between the gyro and the magnetic compass.. The reason for
that is that a ships gyro - which is north stabilzied needs some time
(hours) before he works properly - and is much bigger and heavier. 

I go this way : An aircaft gyro compensate by hand with the information
form a pretty small magnetic fluxgate sensor about 1.5 (5 feet) on top
of the sail at on one of the radio antennas. 

The only question concerned me : Is there a problem with the radio VHF
antenna and the fluxgate magnetic sensor ? 

See you Carsten

Alec Smyth schrieb:
> 
> Carsten,
> 
> I've finished my power distribution panel and am now getting into the instrumentation for depth, life support, navigation, etc. One of the basic decisions is what to do about a compass.
> 
> I see two possibilities; Cliff Redus's approach using an integrated circuit outside the hull, or an electric directional gyro inside the hull. I don't like the outside the hull approach because it would imply a hydrodynamic drag and might not even work given the amount of steel around.
> 
> I remember a month or two ago you were asking about gyros. Did you find anything reasonably priced? D'you know if they can be interfaced to a PLC?
> 
> thanks,
> 
> Alec

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