[PSUBS-MAILIST] K-350 trim issues

Wed Oct 23 16:39:59 EDT 2013

Makes sense 
Thanks 

Rick

From: Smyth, Alec 
Sent: Wednesday, October 23, 2013 10:33 AM
To: Personal Submersibles General Discussion 
Subject: Re: [PSUBS-MAILIST] K-350 trim issues

This is simple, it’s just two steps:

1)      Add weights, most easily by just passing them down through the hatch, until you find the sub is neutral when MBTs are flooded. You’ll do a number of dives or attempted dives, adding or taking out weight.

2)      Shift the weights forward or aft until the sub is level.

Once you’ve determined how much weight and how far aft they go, you have the option of installing something externally.

Best,

Alec

From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of Land N Sea
Sent: Wednesday, October 23, 2013 3:31 PM
To: Personal Submersibles General Discussion
Subject: Re: [PSUBS-MAILIST] K-350 trim issues

Hi Joe,

My only concern with adding lead ingots to the stern to achieve a good trim is that I would be sacrificing freeboard once trimmed out I believe and that is a concern after hearing about the K-250 having that problem at the convention though my conn is a bit higher. Of course now that I think about it, I may have solved the trim problem without having to add extra weight but now will still be too buoyant to dive with all ballast tanks flooded?

Rick

From: Joe Perkel 

Sent: Wednesday, October 23, 2013 9:02 AM

To: personal_submersibles at psubs.org 

Subject: Re: [PSUBS-MAILIST] First Launch

      Rick,

      I have an accurate CAD model of a stock 350 hull and pods with assigned material densities. The software can make short work of determining changes in the longitudinal CG and what effects shifting the pods have. We would have to agree on a vertical datum, say the surface Edge of a hemihead for example. 

      As it lays now, the CG is right under the pilots butt, but it looks like George did not account accurately for the changes in buoyancy once launched. The trick would be trying to guess how far back to shift the CG. I can do this for you on my next group of days off if you'd like.

      However, I like James idea of external movable weights as a better solution because you still have this 400 lb light condition to contend with anyway.

      Joe

      Sent from Yahoo! Mail for iPad

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From: Land N Sea <landnsea1 at hawaiiantel.net>; 
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>; 
Subject: Re: [PSUBS-MAILIST] First Launch 
Sent: Wed, Oct 23, 2013 6:13:05 PM 

      I haven’t attached my pods yet to the pressure hull and after hearing about the aft positive buoyancy issue from a number of K-350 owner/builders I am now contemplating moving my pods aft one frame. I have all ready installed my drop weight threw hulls so I would have to extend the cross bar forward that goes between the pods for that plus not having any engineering experience, it would purely be a guess on what it would do to the trim. I doubt it would have the reverse effect and transfer the buoyancy problem to the front but not sure. 

      One thought I had was to bolt them on per plans but be able to adjust them aft as needed to attain the proper trim and then when I find the magic spot, weld in the bell reducers I have and connect the power cables. Any thoughts out their pro or con?

      Rick

      From: James Frankland 

      Sent: Wednesday, October 23, 2013 2:17 AM

      To: Personal Submersibles General Discussion 

      Subject: Re: [PSUBS-MAILIST] First Launch

      What im going to do is fix 100Kg under the aft tank, and then make the rest in blocks that can be moved around.  Then divers can place them with straps to the underside somewhere until its balanced.  Will make the blocks at the weekend. 

      On 22 October 2013 20:41, <MerlinSub at t-online.de> wrote:

      Hi James congratulations, 
      - seems more and more that to light is a normal standard on launching Psubs.

      May do not install fix weight in the stern next time. Install 
      it lose in the center and than trim it longitudinal on dive station
      with move it forward or aftward or more in or out. 
      Its the fastest way to figure out the right weight and trim. 

      By the way Alan our overalls are red, and it help the skipper 
      to figure out which guy is in his crew and which not..
      Also the guys with the brighter (many times washed out) overalls are the workers in the crew.. 
      http://www.hansesail.com/uploads/tx_gorillary/2013_38_euronauttauchtauf_01.jpg

      :-) vbr Carsten 

      "Alan" <alanlindsayjames at yahoo.com> schrieb: 

        Congratulations James,

        Look forward to the coming videos. 

        What a pain having to cut things short after all that effort.

        Maybe you cold buy everyone a set of orange overalls like Carsten

        does, to make things look professional.

        Alan

        Sent from my iPad

        On 22/10/2013, at 10:06 PM, James Frankland <jamesf at guernseysubmarine.com> wrote:

          Hi All,

          I got my boat in the water at the weekend for the first time.  Put the pictures up here.

          http://www.guernseysubmarine.com/operations.htm

          I didnt get any leaks at all, so i was super happy.  I wasnt really expecting to try and dive and would have been happy with just no leaks and a float test, but everything worked fine, so i gave it a go.  Unfortunately i didnt have enough lead.  I added 90KG (198lb) of lead, but it still wouldnt go down.  What i didnt mention on the website was that i was forced to stop testing because the harbour master came along to say that they had had an anonymous phone call from some bloody do-gooder who pointed out that we were using the comercial area of the harbour and didnt have a proper comercial dive team, which is officially a legal requirement.  So even though i had full permission from the harbour, i was forced to stop on a technicality.  They think it was some missery that has the hump on with harbour and just wanted to be awkward.  Shame because I was about to load a pile of anchor chain into the boat to get me more weight.

          The boat did seem to be very light at the back and i kept squirting air into the forward tank to level it out.  Thinking about it, i suspect that the forward tank was settling into the correct position and it was the aft tank that was riding high.  Just need to get some weight at the back.  I had a slight list to port as well which i've no idea where that came from.  Again i will trim that up.

          Anyway, i was really pleased with how it went on my first day.  Im meeting my divers tonight who took a load of underwater pics apparently, so i will see how they look later.  Might put some on the web if they are any good.

          Kind Regards
          James

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      -- 

      Carsten Standfuß
      Dipl.Ing.Schiffbau @ Meerestechnik
      Heinrich Reck Str.12A
      18211 Admannshagen

      0172 8464 420
      WWW.Euronaut.org
      Carsten at euronaut.org

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