[PSUBS-MAILIST] Inflatable sub support

Mon Aug 8 19:07:01 EDT 2016

Doug,
I did a study on just that idea a few years back. My suggestion is to think of rigging your boat poles at a 30 degree angle off center pointing aft and outboard from each corner of your boat transom. For transfer, you attach the sub on a short bow line to the central tow point on the boat, and use a V-bridle from each pole tip to both lift points on the sub from BOTH sides, which would (in theory at least) help to cancel out the sub's urgent desire to dart left and right, and keep it from wallowing quite so bad in the wash. If it get's sloppy, add a small drogue on a fairly long line from the sub's tail, which will make your tow motor work harder, but should stabilize fore and aft in a seaway as well and will also let you tow FASTER. And believe it or not, the faster you go, the steadier everything gets (we launched 8-12 ton subs at a minimum of 4 knots, just as a historical note). The idea here is to at least do our smaller scale stuff while gently underway, with lines and poles and all that pulling away from the sub no matter which way the little bastard rolls. I'd love to see that tried out. NOTE: Don't even consider doing this with poly rope, which will tie itself into knots, or nylon, which will stretch and heat up and defeat the whole purpose. Braided Dacron line is called for here, even though it sinks and is a pain to deal with near props. Floats on the shackle ends of your tow and drogue lines are essential kit for this set up. Give me a yell if you want to rig it up. I'll drive down and give you a hand. My main concern is that the poles will be too stiff under light load and too flexible when the going gets tough. It would be an interesting thing to try, just to see how much abuse the poles will put up with if nothing else.
Vance

-----Original Message-----
From: Douglas Suhr via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Sent: Mon, Aug 8, 2016 4:26 pm
Subject: Re: [PSUBS-MAILIST] Inflatable sub support

That is my biggest concern with the cat/floating gantry idea - the sub and tender will behave so differently in any given wave action.  

Here's an idea I've been pondering since last spring... it won't help with transport time, but it could potentially make entry/egress safer (ie preventing a cabin flood/sinking situation): The last couple of years down in Florida, I've seen these fiberglass mooring poles being used on boats in the canals. They're like fishing poles, but much stronger... semi-rigid but still quite flexable. The poles are mounted at an angle off your dock. They moor your boat, hold it away from the dock and flex up and down with the tides and waves.

Now supposing we had a couple of those babies mounted aft-ways off the Whaler. When we wanted to do a crew swap, a support diver would hook the pole lines to the lifting lugs on the sub. This would hold the sub away from the boat, flex to make the difference between boat and sub and provide extra support/tipping safety while changing crew. ~ Doug S.     

On Mon, Aug 8, 2016 at 3:08 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Doug,
Graham Hawkes had a modified catamaran for transporting one of
his subs. I couldn't find an image of it but it was posted on Psubs a few
years back. I am not sure whether this was successful or not. I am
guessing it wasn't as I haven't seen it again.
A problem with it could be that you would have to manoeuvre over 
the submersible, & then attach cables. In slightly rough seas you would
need lateral control of the catamaran to keep it from riding on to the sub.
   The experience out from Islamorada where 3 of us were trying to hold
your boat at arms length from Snoopy to transfer passengers, was a bit
of a lesson. I have said it before, but the sub seemed to remain stationary
in the water column while the boat bounced up & down around it, & was
in danger of landing on it. 
Alan

Sent from my iPad

On 9/08/2016, at 5:39 am, Douglas Suhr via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Alan / James / Dave, all great suggestions, thanks for the ideas! As much as we could all sit here and spec out our dream tender/support boat, I think you guys are wise to suggest the KISS method in one way or another. 

I probably favor the idea of starting with a two hulled (cat/party barge) design the most, but it will depend on what is available for cheap at the time we go to buy :) ~ Doug 

On Mon, Aug 8, 2016 at 11:28 AM, David Colombo via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Hi Doug, I remember the tow out if the snoopy in the keys. It seems to me that bases upon the number of used boats in the area, I'd buy and fiberglass boat for just the bow. Get out the Sawzall cut off what I need, weld up a cradle that could link to hull of snoopy, use Alans ideal of a inner tube, but use it as an expandable cushion between fg hull and snoopy. Your then ready to tow.
David Colombo

On Aug 8, 2016 12:43 AM, "Douglas Suhr via Personal_Submersibles" <personal_submersibles at psubs.org> wrote:

Yeah, I like the simple logistics/mechanics of a rig like you described here Alan. Let's face it, anything would be better than a full-on tow! I'm often big smoke/no fire when it comes to projects like these, but at the same time, we are going to be hurting in the Keys without something to make entry/egress safer and transit to/from dive locations more efficient. ~ Doug S. 

On Sat, Aug 6, 2016 at 1:31 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Doug,
Cliff was thinking about this issue a while back.
Perhaps a purpose built hard fibreglass hull that conforms to Snoopy's lower hull,
with an inflatable pontoon attached, but with no back section. ( an inflatable boat
with the back missing.) Use an air pump to deflate & inflate it. It would probably
require a winch up front to help the sub get fully on board. If it was strong enough
you could trailer the sub on this inflatable base.
It would increase the towing speed & make it easy to board in rough conditions.
Alan

Sent from my iPad

On 6/08/2016, at 3:13 pm, Douglas Suhr via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Alan, I like that idea (a "pump barge"). Whatever we determine will work, it's gonna have to deal with relatively rough seas. ~ Doug S.  

On Tue, Aug 2, 2016 at 9:56 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Doug,
I have seen a number of inflatable pontoon systems for lifting boats
above the water. They all used pumps to pump out the water.
I wonder if there is merit in designing an inflatable pontoon that you could
lower, & drive Snoopy on to, then fill with air & tow.  It would
solve the problem of boarding in rough seas, as you could climb in while
it was up on the pontoons. The pontoons would also make it easier to
board without bashing your boat against the sub.
You would need a large barge if you are looking at hoisting in to the water.
It wasn't the easiest in perfect conditions in to your canal.
I think they use a ballasted platform in Hawaii ( similar idea) Scott might confirm 
that as he has just been there.
Alan

Sent from my iPad

On 3/08/2016, at 12:50 pm, Douglas Suhr via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Good point Alan, wave height is an issue on more than one hand with Snoopy (as I'm sure you're aware). 

BTW, we're starting to look seriously into building or buying a barge for the Keys. We've got to get Snoopy out to the oceanside more quickly than by towing her. ~ Doug S. 

On Tue, Aug 2, 2016 at 6:42 PM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Doug,
sounds like a cunning plan!
Be aware that it might work when the water surface is flat,
but fail if there is too much of a wave.av

I'm with Jon on having a descent surface communication system.
Alan

 From: Douglas Suhr via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Wednesday, August 3, 2016 8:29 AM
 Subject: Re: [PSUBS-MAILIST] OTS transducer location

'Sound' thoughts Jon... :) ~ Doug S.  

On Tue, Aug 2, 2016 at 4:25 PM, Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Nothing wrong with Radio comms on surface, in fact you should have a VHF for ocean water anyway.  Depending upon the location of the transducer on the vessel, at the surface you may find you don't have enough water column to communicate effectively.  Test first.

Jon

On 8/2/2016 3:09 PM, Douglas Suhr via Personal_Submersibles wrote:

Dad and I are planning to try a little experiment in regards to the mounting location of Snoopy's transducer array. The idea is to mount the array on a hinged whip behind the hatch. While she's on the surface the transducer will be under the waterline for surfaced communication with surface support (if the boat and sub are out of earshot of one another). When Snoopy submerges, the array's float lifts the mast erect over the sub, becoming the tallest part of the vessel while submerged.

Just an idea, but we're keen to try it when we get the chance. One possible drawback is entanglement danger... we've been thinking a lot about that lately. ~ Doug S.

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

_______________________________________________
Personal_Submersibles mailing list
Personal_Submersibles at psubs.org
http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.whoweb.com/pipermail/personal_submersibles/attachments/20160808/77151a6f/attachment-0001.html>