[PSUBS-MAILIST] depth sonar

Tue Jul 24 19:58:26 EDT 2018

 Brian , the original Nekton subs dragged a garden hose full of lead pellets to stay at their desired depth.  A weight would work for shock absorption, but I want to know how far from bottom I am to avoid hitting something bad, plus a weight could get stuck in something.  E 3000 is going to be extremely tangle proof including a jettisoning occupant sphere.Hank
    On Tuesday, July 24, 2018, 5:50:29 PM MDT, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Might be nice to have a weight hanging below to act as a shock absorber when landing.
Brian

--- personal_submersibles at psubs.org wrote:

From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
To: via Personal_Submersibles <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] depth sonar
Date: Thu, 19 Jul 2018 11:54:13 +0000 (UTC)

 Cliff,No I have a 1000 foot sounder, but I am not worried about the depth below the sub when I am on the surface.  I need to know when I am going to reach the bottom.  With low visibility I can't see the bottom and rely heavily on the sounder.  I have also observed a 5% inaccuracy in sounders when measuring against a rope.  Hank
    On Thursday, July 19, 2018, 5:30:24 AM MDT, via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Do you have a sounder transponder speced that will reach 3000 ft?   
Cliff
On Jul 19, 2018, at 5:40 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Alan,Thanks' for the input, I like the sphere idea.  That could be made pretty easily.Jon, I was wondering the same thing, so I read a bunch of comments about transducer mounting.  There seems to be a lot of disagreement about what can work in terms of material.  I will have to test it out with acrylic for myself.  According to the acrylic calculator I can get away with 1\2 inch acrylic if it is 2 in dia.  I could make a housing with a acrylic bottom and even fill the housing with epoxy. 
Hank    On Wednesday, July 18, 2018, 8:54:28 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Jon, Hank,here's a bit of info pasted below.I am not sure about acrylic. You would have to attach the transducer tothe acrylic unless you put the transducer in a bag full of water & had thisforced against the acrylic. Again someone could try hanging the transducer in water while pushing it against a piece of acrylic.Alan
In-Hull Transducers

In-hull (a.k.a. shoot-through) transducers are epoxied directly to the inside of the hull. These are only used in fiberglass hulls. In-hulls will not work with wooden, aluminum, or steel hulls, or in foam sandwich/hulls that have air pockets. Any wood, metal, or foam reinforcement must be removed from the inside of the hull.

With an in-hull transducer, the signal is transmitted and received through the hull of the boat. As a result, there is considerable loss of sonar performance.

In other words, you won't be able to read as deep or detect fish as well with an in-hull transducer as with one that's transom mounted or thru-hull mounted.

Fiberglass hulls are often reinforced in places for added strength. These cored areas contain balsa wood or structural foam, which are poor sound conductors. The transducer will need to be located where the fiberglass is solid and there are no air bubbles trapped in the fiberglass resin. You'll also want to make sure that there is no coring, flotation material, or dead air space sandwiched between the inside skin and the outer skin of the hull.

Advantages

   - No holes drilled in hull
   - Excellent high speed performance
   - No obstructions in the water
   - Low maintenance

Disadvantages

   - Reduced maximuum depth reading
   - Reduced fish detection
   - Can only be used with fibreglass hulls

Sent from my iPad
On 19/07/2018, at 1:52 PM, Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Can it shoot through acrylic?

      From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Wednesday, July 18, 2018 6:55 PM
 Subject: [PSUBS-MAILIST] depth sonar

Hi all,I am looking for ideas on how to make a depth transducer survive to 3,000 feet.   I am thinking about a 1 atm housing with a fibreglass bottom that the transducer can shoot through. Alan, were you working on this idea?Hank_______________________________________________
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