The HF6V and the HF6VX are great antennas but can be a pain in the butt to set up and get tuned without an antenna analyzer.  I would also recommend trying to find a good used one as I think the antenna has become way over priced.  I bought one new in the middle 1980's for about $125 if memory serves me correctly.  

Al, n7ioh

Here are a few links below that may help with what you are looking for.  Some of the links are specific to marine communications and others are general marine information pages.  Not too sure what you were looking for.

Al, n7ioh

http://www.boatus.org/onlinecourse/ReviewPages/BoatUSF/Project/section0x.htm

http://www.boatus.org/onlinecourse/ReviewPages/BoatUSF/Project/section2.htm

http://www.boatingbasicsonline.com/course/safety/index.php

http://www.boatingbasicsonline.com/course/safety/4_3.php?PHPSESSID=4589e5236070fea92a915e53d71a5d9f

http://www.boatsafe.com/nauticalknowhow/safetips.htm           See Communications section

Hi Joao, I would agree with the others about a better antenna as it sounds like you are going to have a better receiver soon.  I don't know what you have for room as far as antennas are concerned, but here are some thoughts.  The receiving loop would be a good starting place.  These are very easy to build and can be built in a few hours.  A vertical antenna will tend to pick up more man made noise than a horizontal antenna.  If you could build a horizontal antenna for the frequencies you most listen to that should help.  Then of course get it outside and as high as possible if that won't be a problem.  If you are really into short wave listening I would have 2 or 3 antennas and buy the MFJ-1026 to use along with them.  The MFJ-1026 can do wonders when properly set up with 2 antennas.  What it does is works one antenna against the other to phase out the noise.  Another item that can help is an inexpensive antenna tuner.  These can help put your antenna at or near resonance and work kind of like a preselector.  Here are some links to information about the MFJ-1026.

http://www.hard-core-dx.com/nordicdx/antenna/special/mfj1026.html

http://www.astrosurf.com/luxorion/qsl-mfj1026.htm

http://www.k0to.us/HAM/Noise/NoiseExample/MFJ-1026_example.htm

http://www.k0to.us/HAM/Noise/adjusting_MFJ-1026.htm

http://www.angelfire.com/mb/amandx/mfj1026.html

Al, n7ioh

Ground mounting the antenna will most likely be the easiest to do.  Not knowing what is in your back yard or what uses your back yard will normally get makes it tough to say if it would be best for you.  When you put down your radials they don't have to be straight assuming you are going to use insulated wire laying on top of the ground.  If you are going to use bare wire buried just under the surface than just run as many radials in all directions as you can and as long as you can.  Remember when bare wire is underground it detunes so what becomes important is getting as much metal under and around the antenna as possible.  If you could get a 20x25 foot piece of copper mesh to mount under your antenna and bond this to the antenna ground that would be about the best you could do with the small lot size.  

When you buy your coax be sure to allow for the two RF Chokes, 10 turns each by 6" in diameter.  It will be helpful if you can find someone with an antenna analyzer to help check the tuning of the antenna.  The job will go much faster and smoother with some help.  

Al, n7ioh

If you mean by both, the Larsen and the Austin, no I haven't used both.  But if I understand your intended use ether antenna would be fine.  The Larsen is taller so would require more space to store but should give you a slight edge because of its hight if you are in a valley.  The Austin is shorter making storage easier.  If you are planning on storing the antenna in car trunk until needed I think I would go with the Austin because of its size.  I don't think gain or angle of radiation is going to be as important as removing the antenna from the trunk unharmed when needed.  It's difficult to cover all the bases when we talk about what if or what is best.  Each situation is going to be different.  I would look at what is the most likely need and uses of the antenna.  For the most part it is going to be stored so I would give storage a little more importance.  If getting out in the worst possible conditions was important we wouldn't be using a hand held radio or a mag mounted antenna.  

Al, n7ioh

That is one of the finest 2 meter antennas you will find for the money or even a lot more money.  The ham that recommended that antenna to you is very highly respected and knows what he is talking about.  Don't waste your time trying to find a better antenna.  I have the same antenna only without the magnet mount.  

Al, n7ioh

Hi Jack, I had a very difficult time getting echomac to work on my computer also.  There is a help file in echomac that will help you with some of the settings on you computer, router, and modem .  What I found to be the biggest problem was my modem settings.  I don't have a router but my modem has settings like a router that took a lot of playing with to get right.  I was able to get echolink to work on my PC running XP but not on my Mac with OS 10.4.10.  I finally got the settings right and now I can use ether computer without any problems.  I had to call the modem manufacture and have them walk me through the steps several times.  I then figured out on my own how to get both computers to work.  I don't have a clue as to where you are with the entry of SCUBA.  If you want to email me directly I am good in QRZ maybe I can help you more.  
Al, n7ioh

Hi Steve, if you email me so I can get your email address I will email you back a list that you can print out.  I am good in QRZ.
Al, n7ioh

Hi Chris, 40 euros is about $54US.  I just did a check and did not find any information on building your own cable.  The manufactured cables here are about $40US-$55 = about 30-41 Euros plus shipping.  Some have the software included and some don't.  The best I could do was I found what looks like it might be a good deal is a complete programming kit with cables and software.  It is listed as used but looks new.  The kit is discontinued so it might be getting hard to find.  Here is a link to the item below.  They do ship overseas and you will need to contact them to make an offer.  If you don't have any luck you might try posting your request in the, computersAndSoftware forum.  Good luck, Al, n7ioh

http://biocomp.net/o34831.htm

Hi Osama, it is a little difficult to understand exactly what the problem is.  With the Cushcraft A3WS, Cushcraft says you do not need a balun but if you want one to use a 1:1 balun.  What they recommend is to build a RF Choke using RG8/U coax, 8 turns with a diameter of 15.3cm.  They show you how to build it on page 7 in the manual.    If you are having high SWR it could be the antenna is not adjusted correctly.  Here is a link to the manual.    
http://www.cushcraft.com/support/pdf/951370.pdf

As for the Cushcraft D40, I would check to see that everything is put together correctly.  I don't know if a balun would help but if nothing else works try a 1:1 balun.  Here is a link to the manual for the D40.  
http://www.cushcraft.com/comm/support/pdf/HF%20dipole.pdf

Al, n7ioh

Thanks guys, that is what I was thinking was the case but I just couldn't remember for sure.  With that in mind it kind of makes you wonder why anyone would use an antenna that was not resonant at the operating frequency.  A 100 watt radio with coax losses, losses do to antenna mismatch, tuner losses, and often cheap, poorly connected PL-259 connectors.  And to make matters worse, some hams then want to buy an amp!  I was reading about how dB loss equates to power losses.  A 1dB loss equals to about a 20% loss in power and a 3dB loss equates to about a 50% loss in power.  Now I see why the big contesters spend the extra money for hardline.  It's not just the loss in power out but the loss of the received signals.  Again thanks for clearing things up for me.
Al, n7ioh

Thanks Bob, so if I understand you correctly.  If there is say 6dB of loss due to the mismatch, there is still 6dB of loss after the the tuner has matched the system?  
Al, n7ioh

I know I should know this but I don't so I will ask here.  If I were to use an antenna tuner to match say a 11 meter antenna to the 10 meter band and the SWR was 10:1 before using the tuner and with the tuner it is 1:1.  Am I still getting a loss in the coax due to the mismatch or is the mismatch gone due to the tuner?  I know the radio sees a 50 Ohm match, just wondering if there is a loss in the coax too.

Al, n7ioh

Maybe a good set of headphones?

Al, n7ioh

Thanks Mark, that will do exactly what I want.  I would still like to find a chart I can print out like I stated but if I don't find one it's now no big deal.  With the charts you can see at a glance how much better one cable is then another.  

Thanks, Al, n7ioh