[PSUBS-MAILIST] k-250 building questions

[James Frankland via Personal_Submersibles]

Hi Phillippe,

As others have said, AGM's and Emile for the dome.

I would try and make it so you can open the hatch from outside.

If the hatch hinge bracket is the same as the K350, make it stronger.  I
feel like if I lean too hard on the open hatch, it could bend the bracket.

With regards to the tanks.   If your only diving lakes and flat calm water,
the standard tanks are good.  Tried and tested.

Rough weather and open sea is a different story.

The tanks allow the boat to ride well and I find it takes the open sea
well, but the tanks spill air.  I made semi enclosed and they still lose
air in rough water.   I can tell you it is unnerving to be in open sea and
you boat is trying to dive without you wanting it to.

Enclosing the tanks fully would solve this problem.

If it were me, I would make the standard tanks, but then almost fully
enclose them all round with just a water inlet hole.  Could be made to fit
around the forward viewport so you can still see.  Then make smaller saddle
tanks as well like Alec.

You get all the benefits.  Good longitudinal stability for rough weather.
No air loss.  Auxiliary tanks for added cross stability and freeboard.

I might even do a picture....slow day at work... :)

Kind Regards
James


​







On 6 September 2017 at 10:23, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Hi Philippe,
> It is nice to hear of another project getting under way.  I think if you
> are building from scratch, the side mount MBT's are the only way to go.
> You can use four tanks with a space between the tanks for the side thruster
> wash.  I think however that steel tanks might be to heavy for a K250 ,
> making the sub behave poorly when you transition from floating to sinking.
> You will have to do some calculations first, I would recommend aluminum
> tanks over fibreglass.  My sub also had lead acid batteries in a sealed
> compartment with an air flow system for charging.  I went with AGM
> batteries for the simplicity and added safety.
> Hank
>
> On Tuesday, September 5, 2017, 6:56:48 PM MDT, Philippe Robert via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hi All,
>
> I undertook the construction of a k-250 submarine. I have most of the
> metal components to make the pressure hull. I have some questions about
> batteries, MBT and acrylics dome.
>
> -Is it a good idea to use deep cycle lead-acid battery inside the pressure
> hull ? I read on old psubs mailing list to open the hatch when the
> batteries is charging. (h2)?
>
> -Do you think that the MBT can be replace by steel saddle tanks ? I have
> no idea how to make the original one and if I can upgrade the original MBT
> it will be great.
>
> -I try to find someone to make my acrylic dome with some experience in
> submarine dome forming.
>
> -I live in Quebec, Canada. So, if you know k-250 owner near New Hamphire,
> Vermont or Main it will be great if I can take a look on the sub. An hour
> or two, I do not want to disturb the owner.
>
> tanks
>
> Philippe
>
> phelop at gmail.com
>
>
>
>
>
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