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Old 19-12-2013, 06:14   #31
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Re: Installing radar and AIS Question

Originally Posted by twistedtree View Post
I'm curious why? What parts of a Class A device are important for long range cruising? I ask because I'm building just such a boat, but have selected Class B. Trying to see what I missed.
Class A is 25 watts instead of 2 watts. Thats a hell of a difference.

Ships are expecting to see people a long way away and some Class B installations only show up under 10 nms. Fine for sailing boats.... But not for a ship doing 20 knots at 3 am when the junior officer shakes in his hoes at the thought of waking the captain.

The price isnt much different, $900 for the Raymarine 650 and $3000 for the raymarine class A equivalent.

The only reason why class b was brougt in at all was boats pleading not enough electricty to power it. However in modern, new build boats we have much better generation and battery banks. And remember the 25 watts is only for a fraction of a second... But i dont know what the hourly amps ungd would be... But cant be much.

Now, into Class A information itself.... The heading of a sail boat in a seaway can be all over the place, ony updated every 39 seconds you could be 30 degrees off course surfing a wave.... But on the ships screen it looks like you are heading safely away. Class A not only updates every ten seconds but shows the ruder angle too. Also, and quite importantly, it shows the destination.
When i am watching a ship and he is doing something "weird" as ships seem to do, the destination and ETA can help you work out what the hell is going on. If his destination is X but pointing towards Y then look for a shipping channel he has to turn into, etc.
Similarly if you have Class A you make it easier for them to work out your plan.
When. I solo sail at night where. I mingt oversleep my alarm I have in my boat name box Solosailor (actually its soloslr as the box aint big enough), i think it gives ships better warning of me too. With class A i could put up a limited manoverability flag etc, or NUC etc. All valuable stuff for your safety.

So why only. Long range cruising? Because allthat extra information is cost effective for a fie year circumnavigation or ten year retirement, but maybe not for a one year lets sit on the anchor in the caribbean.


Notes on a Circumnavigation.

Somalia Pirates and our Convoy
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Old 19-12-2013, 06:53   #32
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Re: Installing Radar and AIS Question

MarkJ....glad to see your reply...very beneficial from a true long range cruiser...

I'll bet Boatman has a similar opinion also.......Life is Good......

enjoy the winds for they are free

S/V Water Wings
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Old 19-12-2013, 07:29   #33
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Re: Installing radar and AIS Question

Originally Posted by DotDun View Post
Nope, 4kw is enough for my needs! But I would question a lesser unit (i.e. Broadband).
I have broadband radar and (as a coastal sailor) made that decision over a 4kw because: 1) lower power, 2) instant on, 3) better close-in resolution for hard targets such as small skiffs, private uncharted nav aids, etc.

I have cellular broadband Internet aboard and use smart phone and laptop for getting Doppler radar; showing storm intensity, size and speed/direction. Far superior in resolution and amount of info compared to the blob you might pick up on a 4kw boat radar. That said, if I were equipping for offshore I would definitely choose a 4kw pulse unit.

Getting back on topic, I'll also add that I chose to install a separate antenna on the stern rail for my AIS class B transceiver. When I considered the splitter as an alternative the benefits to having the separate unit are: 1) no insertion loss to VHF signal, 2) can serve as a backup VHF antenna if I ever lost the mast, 3) insignificant cost difference around $50, 4) any loss of AIS range is insignificant because it's low power anyway, and as a coastal sailor I'm not concerned with targets beyond 10 NM away. BTW I have had VHF confirmation that I show up with ships as far as 12 NM away.
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Old 19-12-2013, 07:30   #34
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Re: Installing radar and AIS Question

Originally Posted by MarkJ View Post
Class A is 25 watts instead of 2 watts. Thats a hell of a difference.
Class A is 12 watts
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Old 24-12-2013, 16:23   #35
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Re: Installing Radar and AIS Question

I installed Raymarine 650 class B box on my cruiser recently and it was easy ish. I opted for the Raymarine antenna splitter (AIS100?) which has worked well. Very happy with it all. Shame about having to install separate GPS antenna, but hey-ho.

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ais, radar

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